Illustrated and descriptive catalogue of physical apparatus

- - ••-o .
  - ILLUSTRATED AND DESCRIPTIVE CATALOGUE OF
  - PHYSICAL
  - APPARATUS
  - INCLUDING ALL APPARATUS FOR TEACHING;
  - ELEMENTARY AND PRACTICAL PHYSICS, MECHANICS, MAGNETISM, ELECTRICITY,
  - WIRELESS TELEPHONY, ETC., ^ *
  - SOUND, - \
  - LIGHT,
  - HEAT, ETC*
  - F. E. BECKER & C?
  - W. & d. GEORGE (LONDON), LTD,, PROPRIETORS.
  - 17-29, HATTON WA|^i.ONDON, E.C.1.
  - COMPLETE LABORA*
  - IP
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- - ALAiN BRIEUX
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- - May*/
  - PRIZE MEDALS
  - SYDNEY, 1879.
  - CALCUTTA, 1883-1884.
  - LONDON, 1884.
  - ALLAHABAD, 1910
  - 23rd EDITION.
  - ILLUSTRATED and DESCRIPTIVE
  - CATALOGUE OF
  - PHYSICAL APPARATUS
  - INCLUDING :
  - APPARATUS FOR TEACHING:
  - ELEMENTARY AND PRACTICAL PHYSICS MECHANICS MAGNETISM ELECTRICITY
  - WIRELESS
  - TELEPHONY, Etc.
  - SOUND
  - LIGHT
  - HEAT, Etc.
  - F. E. BECKER & CO.
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - NIVOC HOUSE,
  - 17, 19, 21, 23, 25, 27 & 29 HATTON WALL,
  - LONDON, E.C.1.
  - Government Contractors and Makers of Scientific Apparatus
  - for the Laboratories of
  - HIS MAJESTY’S HON. BOARD OF INLAND REVENUE AND CUSTOMS
  - HIS MAJESTY’S FACTORIES
  - THE GOVERNMENT LABORATORIES
  - THE ROYAL MINT
  - THE ROYAL ARSENAL
  - THE WAR OFFICE
  - THE ADMIRALTY
  - THE NATIONAL PHYSICAL LABORATORY HIS MAJESTY’S BOARD OF TRADE HIS MAJESTY’S BOARD OF WORKS INDIA OFFICE
  - CROWN AGENTS FOR THE COLONIES DEPARTMENT OF PUBLIC EDUCATION, CAPE TOWN CANADIAN AND TASMANIAN GOVERNMENTS THE MINISTRY OF EDUCATION, EGYPT
  - THE AGENTS-GENERAL FOR NATAL, CAPE TOWN, NEW SOUTH WALES, VICTORIA, Etc., Etc.
  - ALL INDIAN GOVERNMENT DEPARTMENTS OF PUBLIC INSTRUCTION
  - NEW ZEALAND TECHNICAL EDUCATION BOARD THE UNIVERSITIES OF OXFORD, CAMBRIDGE, GLASGOW, LONDON, BIRMINGHAM, SYDNEY, MADRAS, Etc.
  - THE ROYAL INSTITUTION KING’S COLLEGE, LONDON
  - BOARD OF EDUCATION, SOUTH KENSINGTON IMPERIAL COLLEGE OF SCIENCE AND TECHNOLOGY DEPARTMENT OF AGRICULTURE AND TECHNICAL INSTRUCTION, IRELAND
  - ROYAL COLLEGE OF SCIENCE, DUBLIN
  - THE PRINCIPAL EDUCATION COMMITTEES OF THE UNITED KINGDOM
  - THE JAPANESE GOVERNMENT, Etc., Etc.
  - Established 1872. Telephone: 1436 CENTRAL. Telegrams : "BECKER, HATTON WALL, LONDON.’’ Marconi Code.
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- - REFER TO OUR
  - CHEMICAL APPARATUS CATALOGUE
  - 23rd EDITION
  - FOR ALL CHEMICAL APPARATUS INCLUDING:
  - BALANCES & WEIGHTS MICROSCOPES GLASS & SILICA APPARATUS
  - ELECTRIC FURNACES LABORATORY FITTINGS CHEMICALS REAGENTS, Etc.
  - REPAIRS
  - Having our own Manufactories, in which only experienced men are employed, we are enabled to quote very reasonable prices for all repairs to GENERAL SCIENTIFIC APPARATUS.
  - | We also repair and adjust
  - ( BALANCES and WEIGHTS
  - OF ALL MAKES.
  - I1IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIM
  - iiiiiiini
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- - Since this photograph was taken we have added considerably to our premises. Additional warehouses and glass-blowing shops are in an
  - extensive block of buildings directly adjoining the extreme right of the premises shown in above photograph.
  - How to get
  - to our
  - Warehouses,
  - Showrooms and
  - Scientific
  - Glass-blowing
  - Shops
  - IHbeckei
  - holborn
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- - TERMS
  - COUNTRY ORDERS must be accompanied by a Remittance, or by a reference to some person in London.
  - FOREIGN ORDERS must be accompanied either by a Remittance, or by instructions for payment in London on delivery of the Bills of Lading.
  - STOCK. A Large Stock of the Apparatus, Balances and Weights, Etc., in this List being kept ready for immediate delivery, Shipping Orders for large collections can be executed with promptitude.
  - BREAKAGES. We do not hold ourselves responsible for any breakages. Experienced Packers are employed, and every care is taken to ensure the safe delivery of all goods to their destination. In the event of breakages, the carriers should be notified immediately. Damage in transit is entirely the carriers’ responsibility, but they will repudiate liability unless notified in writing within three days of delivery. Always sign carriers’ sheet “ Goods unexamined.”
  - EMPTY PACKAGES. Full value allowed when returned in good condition (carriage paid) within fourteen days from date of invoice.
  - PLATINUM. The prices of all apparatus in the making of which Platinum is used are subject to the current market price of Platinum.
  - QUALITY. Unless otherwise stated we shall in all cases send apparatus of the best quality.
  - GLASS BLOWING. We have our own Glass Blowing Shops at Hatton Wall, London, in which we employ only the most experienced glass blowers, and we can make up any special piece of apparatus to customers’ own specifications and drawings.
  - ILLUSTRATIONS. Although in most cases the Illustrations in this list have been taken from actual photographs of the apparatus, the figures are not to be taken as binding in detail, owing to the necessity for making improvements as occasion arises.
  - The Prices in this Catalogue cancel all of an earlier date, and are subject to fluctuation without notice.
  - Quantities of less than half-dozen will be charged at “ each ” rate. Quantities of less than half-gross will be charged at “ dozen ” rate.
  - A COMPREHENSIVE INDEX WILL BE FOUND AT THE END OF THIS CATALOGUE.
  - 1924.
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- - IMPORTANT
  - With the exception of a few proprietary brands the majority of the apparatus in this catalogue is manufactured in our own Works. We pride ourselves in being the most self-contained Laboratory Apparatus Manufacturers in the country, and can make practically any type of apparatus, both Chemical and Physical, without recourse to outside sources.
  - The following Departments of our Works are now equipped with the most modern machinery and appliances :—
  - General Engineering
  - Sheet Metal Works
  - Stamping, Pressing and Spinning
  - Thermometer Making
  - Balance and Weights Department
  - Glass Instrument Making
  - Dry Battery Making
  - Dividing, Engraving and Etching
  - Sandblasting
  - Electro-Plating
  - Lacquering and Japanning
  - Electrical Testing
  - Woodwork and Cabinet Making
  - By purchasing from the actual manufacturers customers will be assured of obtaining spare parts and replacements from stock, and prompt execution of repairs.
  - Before placing your orders for anything appertaining to the Laboratory ask the actual Manufacturers to quote.
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- - CAUTION
  - We regret we cannot hold ourselves responsible for Apparatus ordered through other houses. Please send all orders direct to us.
  - Colonial clients ordering through Merchants should state on their Indents that the Apparatus, etc., must be obtained from
  - F. E. BECKER & CO., Hatton Wall, LONDON, E.C.
  - W. & J. GEORGE (London), Ltd.
  - The numbers in small type at the end of most of the specifications may be ignored by customers. These numbers have been included in the Catalogue for the convenience of our Warehouse Staff as they indicate to the Staff the stock positions of the goods.
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- - SECTION 1
  - APPARATUS AND MATERIALS FOR
  - EXPERIMENTS IN ELEMENTARY SCIENCE
  - INCLUDING
  - MEASUREMENT OF LENGTH. MEASUREMENT OF AREA. MEASUREMENT OF VOLUME AND CAPACITY. MEASUREMENT OF MASS, DENSITY, Etc., Etc.
  - 1.—Chart of the Metric System, beautifully printed in colours and illustrating in a striking and unique manner the Metric System of Weights and Measures. Absolute truth in delineation. All Weights and Measures their actual size. Connection of the various Units clearly shown. Large enough to show a square metre. Explanatory Handbook with Exhaustive Tables, gratis with the Chart. Size 50 by 42 in. On Cloth, Rollers, and Varnished3 .. .. 12/6
  - 2.—Hand Chart Of the Metric System. For Pupils. With coloured Diagrams TVth the actual size of Weights
  - and Measures, and Explanatory Letterpress on back. Size, 17I x 14 in. 6.. .. .. .. .. . . 2d.
  - 3.—Gill’s Chart Of the Metric System. Size, 60 X 40 in. Mounted and Varnished 6 .. .. 11/3
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 2 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 4.—Boxwood Rule, very accurately divided. English and Metric Scales. Front divided into inches, 8ths, i6ths and 32nds on one edge, and cm.’s and mm.’s on the other. Reverse side is quite flat, and divided so that both scales can be compared.10
  - Each ....................3/-
  - 5. —Boxwood Rule, best quality,
  - 12 in. long, divided into ioths of an inch on one edge, and mm.’s and cm.’s on the other, bevelled edges.11
  - Each .......................5d.
  - Per dozen .. .. .. .. 4/6
  - 6. —Boxwood Rule, best quality,
  - 12 in. long, divided into 8ths of an inch on one edge, and mm.’s and cm.’s on the other, bevelled edges.13
  - Each .................. .. 5d.
  - Per dozen .. ’..............4/6
  - ENCLISH
  - S , 6
  - O LONDON
  - 1
  - BECKER LONDON
  - 2
  - 5
  - I
  - 6
  - 7
  - 8
  - 9
  - 7. —Boxwood' Rule, i metre long, best
  - quality, graduated in mm.’s and cm.’s. 15
  - Each..............................2/3
  - Per dozen .. .. .. .. .. 23/-
  - 8. —Boxwood Rule, as No. 7, but metre
  - long. 17
  - Each..............................1/2
  - Per dozen .......................12/-
  - TTTT TTTT TTTT TTTT 1 i.n 11 m. 11 1 II 1 1 1 1 1
  - 1 2 1 3 1 4
  - LONDON BECKER LONDON.
  - 1 ME1 THE 2| 3 4 5 6 r 7 8 9 1
  - ITT II 1 TT "TnTTTTT TTT ‘TT till Ill II 1 uuty {III TT ill M
  - 9. —Boxwood Rule, 1 metre long, best quality, divided into ioths of an inch on one edge, and mm.’s and cm.’s on the other. 10
  - Each .. .. .. .. .. .. 2/4
  - Per dozen .. .. j .. .. .. 27/-
  - 10. — Boxwood Rule, as No. 9, but f
  - metre long. 21
  - Each .. .. .. .........1/4
  - Per dozen .. .. .........15/-
  - LONDON
  - BECKER
  - 11. —Boxwood Rule, 1 metre long, best quality, divided into i6ths and 8ths of an inch on one edge, and mm.’s and cm.’s on the other. 23
  - Each........... .. .. .. 2/4
  - Per. dozen .. .. .........27/-
  - 12. —Boxwood Rule, as No. II, but \
  - metre long. 25
  - Each........... .. .. ..1/4
  - Per dozen .. .. 15/-
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E. BECKER <ft CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BOXWOOD RULES
  - 13. —Boxwood Rule, best quality, i metre long, graduated into inches and ioths of an inch, on one side, and cm.’s and mm.'s on the other. 87
  - Each...............................2/4
  - Per dozen .. .. .. .. .. 27/-
  - 14. —Ditto, \ metre long. 28
  - Each .. .......................1/4
  - in 11i'll r TTTT TTTT'
  - 1 1 2' 1 " ~ k BECKER LONDON. 1 k
  - BECKER LONDON. <
  - ME I 1 TRE 1 # 1 3 4 1 5 <
  - lllllllll lllllllll llll 1111 llll llll mill ii 1,
  - Front.
  - Back.
  - 15. — Boxwood Rule,
  - |-metre long, best quality, divided in mm.’s up to 50 cm.’s on one edge, and in mm.’s from 50 cm.’s to 100 cm.’s on the other. This rule will be found very useful for Wheatstone Bridge work 29 .. each 1 /6
  - lllllllll iiiiiiiii mi mi lllllllll PUIjm lllllllll llll llll lllllllll
  - 1C XJ9 9 1 9 8 9 7 9 (4 1 5 3'5 2 5 i 5 0
  - BECKER LONDON 1
  - c m i® i3 i4 6,4(7,4 8,4 9,5 0
  - IMF IMF ijmTfry irrmiiiiilirTTTTTTr |l|lll||l IFn
  - (liiiiiiir lllllllll llll TUT TTTT TTTT niiiiiiit
  - (5 9 6 9 7 9 00 (O 9 I m
  - BECKEI R LONDOr ll.
  - 16.—Boxwood Rule, 1 metre long, best quality, divided in millimetres and centimetres from o to 100 on one edge and the same on the other, except that divisions read from right to left 30 .. each 2/9
  - 17.—Boxwood Rule, metre long, best quality for use in vertical positions, graduated into mm.’s, as figured. 31 Each .. .. .. .. .. ..2/9
  - 18.—Boxwood Rule, for use in vertical positions, both edges divided into mm.’s, and furnished with one set of figures down the middle of scale, as figured. 32 Each.....................2/9
  - 19.—Boxwood Rule, for use in vertical positions, two sets of figures on the outside edges, with mm. divisions down centre, as figured. 33
  - Each.......................3/3
  - r 2
  - r 3
  - 98
  - 96 ~I
  - I00
  - 98 “1
  - I~ 96
  - too
  - 100
  - 98 = 98
  - 96 = 96
  - F9G 4 “1
  - EE- 3 i
  - rss 2 1
  - f- 1 “1
  - -E
  - 2
  - I
  - 0
  - 4 =
  - 3
  - 2
  - = 3
  - = 2
  - 0
  - 17
  - 18
  - 19
  - I II iII | II11111111111
  - c
  - TTTTT
  - faWi
  - 1 60 u
  - 20.—Demonstration Rule, metre long, 2 cm. square, with one plain face, one face divided into decimetres alternately black and white, the third cm.’s, and the fourth graduated into mm.’s. A splendid rule for illustrating the Metric System. 34 Each ................
  - .. 10/6
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- - 4 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE ’ (LONDON). Ltd., PROPRIETORS.
  - STEEL RULES
  - 1 Hi hi up if
  - >,ETFiEll 2 3 4| - 5| 6 7 8| 9 2 6 2 7 218 219 3 0
  - LONDON ^ 3 j /A 0 N*378D
  - 22.—Steel Rule, similar to No. 21, but 15 cm. long, nickel-plated 60
  - 21.—Steel Rule, nickel plated, 30 cm.’s long, very accurately divided, made of best hardened and tempered steel, true and straight on the edges. Graduated into inches and cm.’s, as per illustration. 6S Each ...................... .. ..2/6
  - .. each 1 /6
  - 23.—IVI ach ine-Divided Steel Pocket Rules,
  - 12 in. long X \ in. wide X 25 W.G. thick, and folds into three. Marked on one side into inches, i6ths, 32nds and 64ths ; cm.’s into 2 .. each 2/6
  - 24.—Best Quality Steel Rule, 3 inches long graduated into inches, £ths, TVths, /^nds, and -g-Vths. Illustration full size. Fitted in leather case, complete 64 .. .. .. .. 1 /6
  - 25 —Ditto, graduated in cm.’s and mm.’s on one edge, and inches and rVths on the other65 each 1 /6
  - immmuHni—imunnwnmm
  - |7 2l8 2l9 3l0
  - jliil 1!, 11 i •'; lI
  - 26.—Students’ Steel Rule, cheap pattern, 12 in. long, divided into inches, cm.’s and mm.’s as per illustration. 66
  - Each.......................1/4
  - Per dozen .. .. .. .. 15/-
  - GLASS SCALES
  - 27. —Glass Scales, Vertical
  - pattern, figures and divisions engraved on mirror glass, for preventing optical parallax in reading. 73 Length 15 cm.’s Each.............4/-
  - 28. —Ditto, but 25 cm.’s long. 74
  - Each.............6/-
  - 29.—Glass Scales, as No. 27, but plain glass 75 .. .. .. .. .. .. •• •• each 2/-
  - 30. —Glass Scales, Horizontal pattern,
  - figures and divisions engraved on mirror glass to prevent optical parallax in reading. Length 12 cm.’s 76 .. .. each 3/-
  - 31. —Ditto, Length 20 cm.’s 77.. each 5/-
  - 32. —Glass Scales, as No. 30, but plain glass. Length 12 cm.’s 78 .. .. .. .. •• each 1/6
  - 33. —Ditto ditto ditto ,, 20 ,, 79 .. .. .. .. .. each 2/6
  - PAPER SCALES
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 5
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MEASURING TAPES AND CALLIPERS
  - LINEN Wind-up Measuring Tapes, marked both sides.
  - 40.—Leather case, flush handle, 25 ft. 33 ft. 50 ft. 66 ft. 100 ft.
  - linen tape, § in. wide97 .. 8/- 9/- 11/6 13/6 18/-
  - 41 .—Brass case, flat brass handle, linen tape, § in. wide.
  - A neat compact pocket 12 ft. 18 ft. 25 ft. 33 ft. measure99 ............... 5/- 6/6 7/6 8/6
  - STEEL Wind-up Measuring Tapes.
  - With Flush Handles. Tape £ in. wide.
  - 25 ft. 33 ft. 50 ft. 66 ft.
  - 42.—In leather case, marked English
  - only, nickel-plated fittings 89 .. 18/- 21/- 27/- 34/-
  - 43 •—In leather case, marked English
  - and metric90 ................... 21/- 25/- 34/- 44/-
  - 44. —Linen Spring Tapes, divided into inches and sixteenths on one side, and cm.’s and mm.’s on the other. 88
  - A. 3 feet long.................................................................each 3/3
  - B. 6 feet „................................................................... „ 4/3
  - 45. —Steel Spring Tapes, divided into inches and sixteenths on one side, and cm.’s and mm.’s on the other. Superior quality.87
  - A. 3 feet long................................................................ each 6/-
  - B. 6 feet „.................................................................. „ 9/-
  - 46
  - 46.—Callipers, bright
  - steel, for inside and outside measurements.104
  - Each .. . , .. 1/6
  - 47
  - 47. — Callipers, bright steel, best quality, for inside and outside measurements. 103
  - Each .. .. .. 1/3
  - 48
  - 48.—Cal I i pe rs,
  - bright steel, straight arms.
  - Each .. .. 1/3
  - 45
  - 49. —Callipers, self-
  - registering, for inside and outside measurements, English and metric scales, reading to 3! in., and 80 mm.106 .. Each 4/-
  - 50. —As above, but fitted with lock screw link and key bar for adjusting,,107
  - Each...............4/9
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 6 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GRADUATED SLIDING CALLIPERS
  - Front..
  - Front graduated both English and metric, reading up to io cm.’s in mm.'s, and 4 inches in ioths ; with verniers reading to ioth mm.’s and iooth inch.
  - Back.
  - Back graduated in cm.’s and mm.’s on one edge and inches and ioths on the other as figured.
  - 51.—Graduated Sliding Callipers, boxwood, with brass slider and ends. Two verniers reading to TV mm. and ik inch.
  - These callipers are strongly and accurately made, and will take balls up to i£ inches in diameter.109
  - Each ...............3/-
  - Per dozen...........33/-
  - 52.—Graduated Sliding Callipers, boxwood, 4 in. x i£ in., same shapes as No. 51, with strong brass slide marked in TVths of an inch and mm.s, with vernier. The reverse side gives a most useful table showing millimetre equivalents in decimals and fractions of an inch.
  - Each .. .. .. .. .. .. .. .. .. . • • • • • 3/3
  - Per dozen .. .. .. .. .. .. .. .• •• •• • • 37/-
  - 53. —Steel Calliper Gauge, with English and metric scales and two verniers. Measures up to 12 cm.’s on one side and 5 inches on the other.113
  - Each .. .. .. .. .. .. .. .. .. . • 5/6
  - 54. —Steel Cal I i pers, English and metric scales and two verniers; measures up to 8 in. and 20 cm. ; nickel-plated.117
  - Each.. ................................. ................................7/6
  - 55.—Steel Calliper Gauge,
  - nickel-plated, for inside and outside measurements (may also be used as a depth gauge), with English and metric scales and two verniers; measures up to 4 in. and 10 cm.115 In flap case .. .. each 7/-
  - 57.—Steel Calliper Gauge,
  - No. 55, but with micrometer adjustment.116
  - In flap case .. .. each 10/6
  - 56.—Standard Callipers, made entirely from specially hardened steel, with micrometer adjustment ; may be used for both inside and outside measurements; English and metric scales, two verniers; measures up to 9 in. and 23 cm.119
  - Price, complete in velvet-lined case ... £1 15 0
  - 58.—Steel Calliper Gauge, with double scales, as figured112 .. .. .. .. .. .. each 15/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 7
  - W. St J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MICROMETER SCREW GAUGES
  - steel, nickel-plated, without friction head.125
  - A.
  - B.
  - Reading from iooth of mm. to io Each.....................6/6
  - Reading from ioooth in. to .. |
  - Each...............7/-
  - 15 20 mm.
  - 7/6 8/6
  - \ | inch
  - 8/- 9/6
  - C. With Friction Head. Reading from iooths of mm. to 15 mm.........................................each 8/6
  - 60.—Micrometer Screw Gauge, Standard Pattern, of finest cast steel, and guaranteed accurate.
  - A. Reading from iooth of mm. to 25 mm. each 17/6
  - B. Reading from ioooth of inch to 1 inch each 19/6
  - 61.—Standard Pattern Micrometer Screw Gauges, with ratchet
  - stop, for work requiring the greatest accuracy. Fitted in nicely finished velvet-lined cases. Reading from iooth of mm. to 25 mm. 1310
  - Each.........................37/6
  - WIRE GAUGES
  - 62.—Wire Gauges, Circular pattern, guaranteed best make.140 ! '
  - A. S.W.G., 1 to 26 .. S/-
  - B. „ 18 to 40 .. 11/6
  - DEPTH GAUGES
  - 63.—Hole and Cylinder Gauge,
  - steel, scale reading in ioths of mm., nickel-plated.134
  - A. 1 to 15 mm............each 3/6
  - B. 15 to 30 „ .. .. „ 4/-
  - C. 30 to 45 „ .. .. „ 6/9
  - 64.—Depth Gauges,
  - best quality, English and metric scales, two verniers, reading in ioths of a mm. and 200ths of inch.135 Length of Scale.. 4 8
  - Length of Face .. 3$ 4
  - Price .. 3/3 4/3 6/-
  - 63
  - 64
  - SPEED INDICATORS
  - 65.—Speed Indicator, with bell. For large or small numbers of revolutions, to read right or left as shaft may run. This instrument is always ready for use, as it is not necessary to shift the hand back to zero. It is fitted with a bell which rings at each 100 revolutions, so that the number can be determined by the ear. 150
  - Price, nickel-plated .. .. .. .. .. each 11/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 8 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 66.—M 6 d e I of Vernier, for
  - demonstration before a large class.152
  - Each .. £2 5 0
  - 10
  - 67.—Paper Scale, metre long, divided in millimetres, with paper vernier for use with same.153
  - Price.........................................6d.
  - (Paper Scales, 5d. each ; , verniers, id. each.)
  - 68.—Boxwood Metre Rule, divided in centimetres, with boxwood vernier for use with same. 154
  - Price .. .. .. .. .. .. 3/-
  - (Boxwood Rule, 2/3 ; Boxwood Vernier, gd.)
  - 69. — Model Vernier,
  - 12 in. long, English and metric Scales.155
  - Each....................5/-
  - 70.—Model Barometer Vernier, length nearly 40 cm., reading to ^-J-xj-ths, for explaining barometric readings168 .. .. .. .. .... .. .. .. .. .. ... .. .. .. 7/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 9
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - furnished with a table 5 cm. wide, which’ is divided into 100 parts by a scale furnished with two sets of figures reading in opposite directions, and reads to ^-mm. The pitch of the screw is | mm. 170 Each ........................................22/6
  - 76.—Sp herometer, Standard patterns, reading to -ooi of a mm. Accuracy guaranteed, highest quality and best finish, complete with plane glass plate in polished mahogany case 172 £5 10 0
  - 72.—Spherometer, Students’
  - pattern, for measuring concave and convex surfaces, silvered scales showing rf part of a millimetre.
  - Each ................ 8/-
  - Per dozen............£4 7 6
  - 73.—Optical Lever, for
  - measuring by the optical method. Complete in velvet-lined case.168
  - Each.................9/6
  - OPISOMETERS
  - ©fi
  - 74. —Opisometers 163
  - Each .......................................2/-
  - Per dozen .................................22/6
  - 74A •—Ditto, simple pattern, with toothed wheel.
  - Each .. .. ... .. .. .. .. 1/2
  - Per dozen .................................13/-
  - 75. —Op iso meter, large size, superior quality, with nickel-plated wheel.165
  - Each .......................................5/-
  - 77.—Large Demonstration Spherometer,
  - with coarse screw. Radius about 1 inch. Diameter of dial about 4 inches, and reading to -ooi inch.
  - Each ............................£6 0 0
  - 79.—Model of Circular Vernier, better make, and provided with vernier and lockscrew, as figured.180
  - Each
  - 22/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.9 - vue 17/555
- - 10 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - VERNIER MICROSCOPES
  - 80.—Vernier Microscope, “B. S. ” pattern, with micrometer screw, reading to x jhrth of a millimetre. 173
  - The microscope, which is held in position by means of two springs, is pro vided with a “ Ramsden ” eye-piece with cross wires and gives a clear flat field. The steel rod bearing the microscope holder is actuated by the micrometer screw, the point of which forces it along.
  - Price
  - £2 12 6
  - 81.—Vernier Microscope, "T. S. ”
  - pattern. The slide is actuated by rack and pinion for a distance of about io cm., read by vernier to o-i or 0*05 mm. 174
  - The microscope is provided with one eyepiece, one objective, and cross wires, and can be used in the four positions shown.
  - A. Price, without case .. £5 10 0
  - B. Case .. - .. .. .. 0 10 0
  - C. Additional Objective each 0 11 6
  - D. Best quality Objective ... 1 2 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.10 - vue 18/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 11
  - ’ W. & J. GEORGE (LONDON), Ltd., PROPRIETORS. <
  - 82.—VERNIER MICROSCOPE
  - (IMPROVED PATTERN FOR SIX POSITIONS.)
  - Can be used in six different positions, as shown in^the illustrations.
  - Small objects can be measured to TyVth mm.
  - Length of scale, 16 cm.
  - "Absolutely rigid.
  - Guaranteed finest workmanship and finish.
  - Axis horizontal; Scale horizontal.
  - A Telescope Object-Glass can be used in place of the Microscope Objective, thus converting the instrument into a vertical or horizontal Cathetometer.
  - SPECIFICATION.
  - The above instrument is guaranteed accurate and is provided with best quality optical parts. The bed is of cast-iron, the upper surface of which is planed into a V and plane, along which a slide can be clamped in any position. This slide carries a second slide, dovetail in section, which is actuated by a fine screw. A vernier is fixed to the second slide, and its position is read on a scale to 0-02 millimetre. The microscope is carried by a knuckle-jointed projecting arm which is attached to the second slide. The microscope can be set not only vertically and horizontally, but also turned through an angle of 90° on an axis at right angles to the axis of the microscope ; thus it can be set in six different positions with respect to the position of the scale. A glass micrometer scale is placed at the common focus of the eye-piece and objective by means of which the size of small objects can be measured to the 35th part of a mm., and by estimation to at least one-fourth of this.176
  - A. Price of the above instru-
  - ment with either a i-inch, 2-inch or 3-inch objective
  - £7 10 0
  - (When ordering please say which objective is required.)
  - B. Extra objectives for ditto,
  - i-inch, 2-inch, or 3-inch. Each ... ..- :. 22/6
  - C. Telescope Object Glass,
  - extra.
  - Each ....................217-
  - Axis horizontal; Scale vertical. Case, extra .. .. 12/
  - Axis of Microscope vertical; Scale horizontal.
  - Axis horizontal; Scale vertical (second position).
  - Axis vertical; Scale vertical.
  - Our stock of puire Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.11 - vue 19/555
- - 12 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - “COLLEGE” VERNIER MICROSCOPE
  - 83.—The “ COLLEGE” Vernier Microscope. This
  - instrument is arranged to give readings on the horizontal or on the vertical scale. 176
  - It consists of a horizontal and a vertical slide along which the scales, about 16 cm. in length, are engraved. The horizontal carriage carries the vertical slide and the vernier, and is actuated by rack and pinion. The vertical carriage carries the microscope and the vernier, and is also actuated by rack and pinion. The microscope rotates in a vertical plane, and can be clamped in any position ; the horizontal and vertical positions of the microscope are marked. A glass micrometer scale is placed at the common focus of eye-piece and objective, and serves to measure very short distances and objects without moving either slide.
  - By substituting a telescope object glass for the microscope objective, the instrument can be used as a reading telescope, or as a short range catheto-meter.
  - A i, 2 or 3-inch objective and one eye-piece are supplied with the instrument.
  - A.
  - B.
  - C.
  - D.
  - E.
  - F.
  - G.
  - H.
  - J-
  - K.
  - In case, with scales reading to -i mm.
  - >> >> >> >> "05 >>
  - In case, with scales on silver, reading to -02 mm.
  - In case, with scales on silver, reading to *oi mm. .. .. .. ..
  - Small adjustable circular level fitted to the horizontal carriage, extra Small divided circle attached to the horizontal axis of the microscope reading to 2 degrees, extra Telescope object glass, extra Rack motion focussing arrangement, extra Fine adjustment for focussing with higher powers than 1 in., extra Micrometer eye-piece reading the size of the object to -ooi mm.
  - 0 18 9 12 6 0 15 0
  - 18 0
  - 6 15 0
  - 84.—Telescope, as used may be had separately. 178 Price
  - in apparatus No. 87,
  - 22/6
  - 85. —Cathetometer, cheap make and finish, millimetre scale, with sliding telescope, fine micrometer screw adjustment, eye-piece with cross wire, metal scale on heavy iron base with levelling screws.179
  - £11 10 0
  - 86. —Ditto, better quality, with vernier 180 £12 15 0
  - CATHETO METERS
  - 87.—Reading Telescope. This is a simple and cheap form of instrument which may also be used as a cathetometer.177
  - The slider carries a telescope which can be focussed from 3 metres to infinity. Telescope is furnished with cross wires and an erector, so that figures, etc., are seen in their proper position.
  - Mounted on heavy iron base; upright rod is nickel-plated.
  - Price
  - £3 5 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.12 - vue 20/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 13
  - W. & J. QEORGE (LONDON), Ltd., PROPRIETORS.
  - THE “COLLEGE” CATHETOMETER
  - Highest Quality and Finish. Laboratory Pattern.
  - 88.—The “ College ” Cathetometer is a splendid laboratory instrument, and we can recommend it with every confidence. The Telescope, which can be focussed from 3 ft. to infinity, is fitted with an object glass of 15 cm. focus, and 22 mm. aperture. The Telescope Carriage works along an accurately graduated rod over a distance of 50 cm.
  - The Telescope is provided with level and cross wires, and can be set horizontal by means of a fine adjusting screw.
  - Prices include rack and fine vertical adjustment and rack motion focussing arrangement to Telescope, as figured, and mounted on heavy tripod foot.
  - A. Range 50 cm., reading to -5Vth mm.
  - Price £10 17 6
  - B. Range 50 cm., reading to xforth mm.
  - Price £12 5 0
  - 89.—Cathetometer, Government pattern, highest quality and finish. Extra strongly made. Can be used either horizontally or vertically. A millimetre scale runs almost the entire length of the bar.
  - The position of the Telescope is read by means of a vernier attached to the telescope support. The Telescope, which is provided with a level and cross wires, has a focal length of about 7 in., and is adjusted horizontally.
  - Can be focussed from infinity to within 3 ft.
  - A. = range 50 cm. and reading to V^th mm.........£12 5
  - B. = range 50 cm. and reading to T<hrth mm.
  - C. = range 100 cm. and reading to sVth mm.
  - D. = range 100 cm. and reading to x-^th mm.
  - E. = Rack motion to Telescope
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.13 - vue 21/555
- - 14 E. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & j. GEOROE (LONDON), Ltd., PROPRIETORS
  - CUBES, SPHERES, PRISMS, Etc.
  - 90.—Set of 16 Models and Figures, in box, with diagram of Geometrical Drill.183
  - Per set
  - 4/6
  - 91.—Set of 8 Wooden Cubes,
  - cheap quality, i in. side, in box.184
  - Per set .. 1 /-
  - WOODEN CUBES
  - 92. — Wooden Cubes, cheap quality. 185
  - Side i 2 4 5 c.m. i in.
  - Perdoz. 1/9 2/- 3/6 5/- 2/9
  - 93 .—Ditto, more accurately finished.186
  - Side 1245 cm. 1 in.
  - Perdoz. 2/6 3/- 5/- 8/6 5/-
  - 94.—Ebony Cubes, accurately finished. 187
  - Side 2 4 cm. 1 in.
  - Each 8d. 1/6 8d.
  - 96. — Sets of 8 Wooden Cubes, comprising ebony, walnut, ash, beech, mahogany, oak, American poplar and boxwood, in box complete. 189
  - Side 2 4 cm. 1 in.
  - Per set 3/- 6/- 6/6
  - 95.—Set of 5 Wooden Cubes, accurately finished, comprising. mahogany, walnut, boxwood, and two of ebony, complete in box.188
  - Side 2 4 cm. 1 in.
  - Per set 2/6 5/- 5/6
  - . in
  - 97.—Wooden Cube, 10 cm. side divided on all sides into centimetres.190
  - Each..........................4/-
  - Oup stock of pure Chemicals and Acids is very considerable j hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.14 - vue 22/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.*. 15
  - W. & J. GEORGE; (LONDON), Ltd., PROPRIETORS.
  - WOODEN CUBES
  - 98.—Wooden Cube, io cm. side, one side divided into square cm., top squares when taken off show io cm. X I cm. X i cm. X I cm. cube.191
  - Each ............9/6
  - 101.—Set of 2 Wooden Cubes,
  - decimetre and centimetre, divided into centimetres.194
  - Per set ..............5/-
  - 102. — Hardwood Cube, 4-in.
  - side, cut into six slabs.198
  - Price .....................6/-
  - 99.—Wooden Cube,
  - 3 in. side, cut diagonally to form two right-angled triangular prisms.192
  - Price .. .. 1/6
  - 100.— Set of 2 Wooden Cubes, decimetre and centimetre. 193
  - Per set
  - 4/-
  - 103. —Binomial Cube, consisting of eight rectangular blocks ii box to show that
  - +J)2 = «2-f 2 a
  - (a b)z = az 3 a * b $ a b 2 b *
  - Price .. .. .. .. .. 8/6
  - 104. —Ditto, roughly finished196.................5/6
  - 105 — Hardwood Cube,
  - 4-in. side, cut into six pyramids.197
  - Price .. 15/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.15 - vue 23/555
- - 16 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CUBES (Various)—Metal, Cork, Glass, Marble, Etc.
  - 106. —Set of 6 Metal Cubes, very accurate, i cm. side, comprising: copper, brass, iron, lead, zinc, and aluminium, in mahogany box with sliding lid. 211
  - per set, 7/6
  - 107. —;Ditto, 2 cm. side 212 .. .. ,, 10/6
  - 108. —Ditto, i in. ,, 213 .. .. ,, 15/-
  - 112.—Brass
  - made 199—
  - A. i cm. side
  - B. 2 „ „
  - C. i in.
  - Cubes, accurately
  - .. each
  - V-
  - 1/8
  - 2/6
  - 113.—Iron Cubes, accurately made.200
  - A. i cm. side .. .. .. .. each 1 /-
  - B. 2 „ „ .. .. ,. .. „ 1/8
  - C. i in. „........................... „ 2/6
  - 114.—Copper Cubes, accurately made. 201
  - A. i cm. side .. .. .. .. each 1 /-
  - B. 2 „ ................... „ 1/8
  - C. i in. „.................. „ 2/6
  - 115.—Lead Cubes, accurately made. 202
  - A. i cm. side .. .. .. .. each 1 /-
  - B. 2 „ „.......................... „ 1/8
  - C. i in. „.......................... „ 2/6
  - 116.—Zinc Cubes, accurately made. 203
  - A. i cm. side .. .. .. .. each 1 /-
  - B. 2 „ „.......................... „ 1/8
  - C. i in. „.......................... „ 2/6
  - 109.—Set Of 8 Cubes, very accurate, i cm. side, comprising: copper, brass, iron, lead, zinc, tin, aluminium, and marble, in mahogany box with sliding lid. 214
  - per set 12/-
  - 110 .—Ditto, 2 cm. side 215 .. .. ,, 15/-
  - 111.—Ditto, i in. „ 216 .. .. „ 18/-
  - 119.—Cork Cubes, best quality. 206
  - A. i cm. side .. .. .. .. each 5d.
  - B. 2 „ „.................... „ 9d.
  - C. I in. „.................... „ 1/-
  - 120.—Marble Cubes.207
  - A. i cm. side .. .. '.. .. each 1/3
  - B. 2 „ „.................. ,, 2/-
  - C. i in. „.................. „ 2/6
  - 117.—Aluminium Cubes, accurately made.204
  - A. i cm. side................each 1/-
  - B. 2 „ „.................... „ 1/8
  - C. i in. „ .. „ 2/6
  - 122.—Gutta-Percha Cubes.209
  - each 1 /6 » 2/-
  - „ 2/6
  - A. i cm. side
  - B. 2 „
  - C. i in. „
  - 118.—Tin Cubes, accurately made.
  - 123.—Paraffin Wax Cubes.210
  - A. i cm. side
  - B. 2 „ „
  - C. I in. „
  - each 1/-
  - „ 1/8 „ 2/6
  - A. 2 cm. side
  - B. i in. ,,
  - C. i£ „ „
  - each 1 /6
  - ... . 1/9
  - 2/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.16 - vue 24/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 17
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CUBES (Various)
  - 124-—Set of 12 Cubes, each being exactly the size of a cubic centimetre. Each set consists of one cube each of the following: silver, magnesium, bronze of aluminium, nickel, aluminium, iron, copper, zinc, tin, brass, lead, and bronze. 217
  - Price, complete in velvet-lined box with Table of Specific Gravities £3 7 6
  - 125.—Set of 12 Cubes as above, but metals as follows : copper, brass, iron, lead, zinc, tin, aluminium, bronze, silver, nickel, bismuth, and antimony. In velvet-lined box, without Tables 218 .. .. .. per set £3 10 0
  - 126. —Hollow Tin Cubes,
  - to hold i litre .. each 1 /3
  - 127. —Ditto, to hold i c.c.
  - each 1/-
  - 128. —’Ditto, to hold i
  - cubic inch .. .. each 1 /-
  - 129.—Hollow Cubic Decimetre Cubes, for
  - illustrating the relation between length, volume, and weight in the Metric System. 222
  - each 2/6
  - 130. —Weight, . to counterpoise No. 129, when filled with water.
  - each 5/-
  - 131. —Hollow Brass Cube, to
  - hold 1 c.c. of water at 40 Centigrade 224 ............ 3/6
  - 132.—Hollow Cubic Decimetre Cube, one side of glass, with scale. Price, with Stopcock, as figured 225 .. 8/6
  - 133.—Brass Cube, 2 cm. side, in brass box, accurately made, for Archimedes’ experiment 226 .. per set 5/6
  - SOLID
  - 134.—B o x w o o d Spheres, 3 cm.,
  - accurately turned, each 9d., per doz 8/6
  - 135 .—Ditto, 11 in., each 1/3, per doz. 14/-
  - SPHERES
  - 138. — Hardwood Spheres.
  - 10 cm. .. per doz. 15/-5 cm. .. per doz. 8/-
  - 136.—Ebony Spheres,
  - 3 cm., accurately turned.
  - each 10d.
  - 137 .—Ditto, i£ in. „ 1/3
  - 142.—Set of 5 Spheres, each 3 cm. diameter, iron, glass, gutta-percha, wood and stone per set 5/6
  - 139.—Hard and Soft
  - Spheres, 3 cm.
  - diameter per pair 1/4
  - 143. — Wooden Sphere, 10 cm.
  - diameter, and glass vessel equal in height and diameter to the Sphere. 241
  - per pair 7/-
  - 144. — Boxwood
  - Sphere, 3 cm. diameter, and tin cylinder, open one end. 240
  - per pair 1 /3
  - 140. —Set of 2 Hardwood Spheres, 2
  - in. and 4 in. diameter respectively, per pair 2/6
  - 141. —Set of 3 Hardwood Spheres of
  - 3, 5 and 8 cm. diameter respectively, per set 3/6
  - 145. —Brass Spheres
  - 3 cm., accurately turned 235 each 3/-
  - 146. —Ditto, i| in. „ 5/-
  - 147. —AI u minium Spheres, 3 cm.
  - each 2/3
  - 148 ,—Ditto, 11 in.
  - each 3/9
  - Our stock of pure Chemicals and Acids is very considerable , hence all orders are executed with the
  - utmost despatch. For prices, etc., see Chemical Apparatus Catalogue.
- p.17 - vue 25/555
- - 18 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 149.—Solid Metal Spheres,
  - regards sphericity and uniformity.
  - SOLID SPHERES
  - guaranteed to be within the limits of one ten-thousandth part of an inch, both as
  - 242
  - DIAMETER IN INCHES.
  - MATERIAL. \ t t f 1 if if if if if if if 2 2l
  - A. Brass ea. 4d. 6d. 9d. V- 1/6 2/- 3/4 4/6 6/- V- 8/- »/- 10/6 13/6 17/6 i m
  - B. Phosphor Bronze „ 6d. 9d. 1/2 1/8 2/6 2/4 3/6 4/6 6/- 8/- »/- 10/6 12/6 16/6 22/6 m
  - C. Manganese Bronze „ 9d. V- 1/3 1/8 2/2 3/- 4/6 6/- 7/6 9/- 10/- 11/6 14/6 19/6 25/-
  - D. Steel .. „ 3d. 4d. 7d. lOd. 1/4 1/9 2/9 4/6 5/6 V- 8/- 8/6 10/6 12/6 16/6
  - Prices of Larger, Smaller, and Intermediate Sizes on Application. Prices of Metric Sizes on Application.
  - 150.—Apparatus for indicating that the surface of a Sphere has four times the area of the hemispherical section 243 .. .. .. .. .. 6/-
  - (See “ Exercises in Practical Physics,” by Gregory and Simmons.)
  - CONES
  - 151.—Boxwood Cones, accurate, diameter of base 3 cm., height 3 cm. 244
  - each 8d., per dozen 7/-152 —Ditto, diameter of base in. height ij in.
  - each 8d., per dozen 8/-
  - 153.—Boxwood Right Cones,
  - accurate, diameter of base 3 in., height i£ in. 246 .. each 1 /3
  - 154.—Boxwood Cones, truncated, 2 X if in. 247 .. .. each 10d.
  - 155.—Ebony Cones, accurate, diameter of base 3 cm., height 3 cm., as No. 151 .. .. per dozen 12/-
  - 156 meter of base if in.,
  - height if in. .. per dozen 15/-
  - 157.—Brass Cones, accurate, diameter of base 3 cm., height 3 cm. 260
  - each 2/-
  - 158 .—Ditto, if X if cm. 250*‘ „ 1/-
  - 159 .—Ditto, diameter of base if in.,
  - height if in.261 .. .. each 2/9
  - 160.—Brass Cones,
  - i| X 1 in.......
  - 161.—Brass Right Cones accurate, diameter of base 3 in., height if in., as 153 .. each 3/8
  - PYRAMIDS
  - 162.—Boxwood Pyramids, accurate, height 5 cm., base an equilateral triangle, sides, 2f cm... each 1/-, per doz. 11/-
  - 163.—Boxwood Pyramids,
  - accurate, height 2 in., rectangular base 2 X i| in. 255 .. each 1 /-
  - per doz. 11/-
  - 164.—Boxwood Pyramids, accurate, round base, each 8d., per doz. 7/-
  - 165.—Brass Pyramids, accurate, height 5 cm., base an equilateral triangle, sides 2f cm. 257 .. .. each 2/-
  - 165A.—Brass Pyramids, accurate, height 2 in., rectangular base 2 X i| in., as No. 163 .. each 2/9
  - 165B.—Brass Pyramids, accurate, round base, as No. 164 .. .. .. .. .. each 2/9
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.18 - vue 26/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 19
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PRISMS
  - 166.— Box-wood Prisms,
  - accurate, height 5 cm., base an equilateral triangle, sides 2i cm. 260 Each .. 1/-
  - Per dozen 10/-
  - 169. — Boxwood Pentagonal Prisms.
  - Price .. ..1/4
  - 174. — Brass Pentagonal Prisms.
  - Price .. .. 3/-
  - 166A.—Boxwood Right Prisms,
  - accurate, height 5 cm., base X 2% cm.
  - Each .. 1/4
  - 167. — Boxwood Oblique Prisms,
  - accurate, 2 in. high. Price .. .. 1/4
  - 168. — Boxwood Prisms, accurate, round base.
  - Per dozen
  - 12/-
  - Price
  - 1/4
  - 170.—Brass Prisms,
  - accurate, height 5 cm., base an equilateral triangle, sides 2\ cm.
  - Each .. 2/6
  - 171. —Brass Right Prisms, accurate, height 5 cm., base 3| X 2\ cm.
  - Each .................... .. ..2/6
  - 172. — Brass Oblique Prisms,
  - accurate, 2 in. high, as No. 167 .. each 3/-
  - 173.—Brass Prisms, accurate, round base .. .. .. .. .. each 3/-
  - 175. — Set of 3 hollow Brass Right Prisms,
  - accurate, having respectively a rectangular, triangular, and circular base for measurement of volumes. 270
  - Per set .. .. 8/6
  - SET OF HARDWOOD AND BOXWOOD BLOCKS
  - 176. —Set Of 6 Boxwood Blocks, all i| in. high, comprising: cone, cube, sphere, pyramid, cylinder, and prism, for comparison of volumes. Complete in wooden box: 271
  - Per set .. .. .. .. .. .. .. . • • • • • • • 7/6
  - 177. —Ditto, but made of brass 272 .. .. .. .. . .. •• •• •• 13/6
  - 178.—Set of 2 Hardwood Blocks for comparison of volumes, consisting of prism and pyramid with same base, 2\ X 2\ x 2\ cm., and of same height, 5 cm. 273
  - 180.—Set of 3 Hardwood Blocks for comparison of volumes, consisting of cone, sphere and cylinder of same height, 3 cm., and same diameter, 3 cm. 275 Per set .. 2/-
  - Per set
  - 179.—Ditto, but made of brass
  - 1/9
  - 181.—Ditto, but
  - 3/9
  - made of brass
  - 7 /-
  - A O IS
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the >
  - Leading Scientific Press.
- p.19 - vue 27/555
- - 20 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SET OF HARDWOOD AND
  - BOXWOOD BLOCKS
  - 182. —Set of 10 Wooden Blocks,
  - accurate, height 2 in., base 2 in., diameter ; triangular prism, rectangular prism, cylinder, cube, pentagonal prism, hexagonal prism, octagonal prism, tetrahedron, cone and sphere, in wooden box. 277 .. .. Per set 15/-
  - 183. —Ditto, but made of brass ,, 37/6
  - 184.—Ellipsoid of Revolution, made of hardwood, major axis about io cm., minor axis about 7f cm. 6/-
  - 185.—Regular Dodecahedron, hardwood, about 7 cm. diameter .. 10/-
  - 186.—Regular Icosa-
  - hedron, hardwood, about 7 cm. diameter .. 11/6
  - 187.—Right Cone,
  - pearwood, height io in., in 4 sections, showing circle, ellipse, parabola and hyperbola .. 23/-
  - 188 .—Ditto, hardwood,
  - height 6 in. .. 15/-
  - CYLINDERS, various
  - 189. —Hardwood Cylinders, ifxifin.
  - each 6d., per doz. 5/-
  - 190. —Boxwood Cylinders, 3 x3 cm.
  - each 8d., per doz. 7/-191 .—Ditto, if x f in. .. .. each 8d., per doz. 7/-
  - 192.—Ditto, if x if in. .. .. each 10d., per doz. 8/-
  - 193 .—Ditto, 10 x 4 cm. .. .. each 2/-, per doz. 22/-
  - 194.—Ebony Cylinders, accurate, 3 X 3 cm. each 10d.
  - 195 .—Ditto, if x f in. .. .. .. .. each 8d.
  - 196 .—Ditto, if x if in. ................ .. .. each 1 /4
  - 197 .—Ditto, 2f x if in. ......................... ,, 2/-
  - 198.—Hardwood Cylinders, 2§ x if in., for making screw thread by means of curve paper.. .. .. .. .. .. each 8d., per doz. 6/-
  - 199.—Set of 12 Boxwood Cylinders, various heights and diameters.
  - Per set 6/6
  - 200. — Brass Cylinders,
  - accurate, 3x3 cm. each 1 /8
  - Ditto, if x if cm. .. ,, 1/-
  - Ditto, if x | in. .. ,, 1/-
  - Ditto, if X if in. .. „ 2/-
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.20 - vue 28/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 21
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - METAL CYLINDERS
  - 201.—Iron Cylinders, accurate. 295 3 x 3 cm. .. .. .. .. each A X i| „ A X f in ii X i£ „ 1/8 10d. 10d. 2/3 204.—Lead Cylinders.304 3 X 3 cm. A x A >> A X f in. A x A » .. each
  - 202.—Copper Cylinders, accurate.296 3 x 3 cm. each 1/8 205.—Tin Cylinders.305 3 X 3 cm. .. each
  - A X A „ 10d. A x A » ,,
  - A X | in 10d. A X i in.
  - A X A » 2/3 A x A »
  - 203.—Aluminium Cylinders, accurate. 297 3x3 cm. .. .. .. .. each 1 /8 206.—Zinc Cylinders.306 3 X 3 cm. .. each
  - A x A » 10d. i£ X A » ,,
  - A X $ in 10d. A X f in. ,,
  - AxA» » 2/3 A x A » • • • • •• ”
  - 1/8
  - 10d.
  - 10d.
  - 2/3
  - 1/8
  - 10d.
  - 10d.
  - 2/3
  - 1/8
  - 10d.
  - 10d.
  - 2/3
  - WOODEN BLOCKS, Etc.
  - 207.—Rectangular Wooden Blocks.
  - A. 2x2x1 in. .. Per doz. 3/3
  - B. 2 X I X if ,, .. 3/-
  - C. 3 x 3 X i| „ .. 5/-
  - D. 4x3x2 „ .. .. 9/-
  - E. 4 x 4 x J „ .. 4/-
  - F. 5 x 5 x i „ .. .. 3/-
  - G. 5 x 5 x \ 3/6
  - H. 5x5x1 „ .. 5/6
  - K. 5 x 5 x A » •• .. 9/-
  - L. 8x4x3 • . . 19/6
  - 208.—Set of 3 Rectangular Wooden Blocks, each 4 X 2 X 2 in.
  - per set of 3 1/6
  - 209.- -Wooden Discs.
  - A. 2 in. diam. X 1 in. thick .. .. per doz. 3/6
  - B. 3 „ „ x i- „ „ 6/-
  - C. 4 .» XI,, 7/6
  - D. 6 „ „ X 1 „ „ 15/-
  - E. 8 „ „ X 1 „ 22/6
  - F. 9 » X 1 „ „ 30/-
  - 210. —Set of 6 Wooden Laths, planed deal, consisting of one each lath. 310
  - 36 X 2 X l in. 36 X 1 X | in.
  - 36 X I X j „ 24 X i X | „
  - 18 X I X l „ 4 X 1 X J „
  - per set 1 /6
  - 211. —Wooden Laths, planed deal, 24 X | X \ in.
  - per dozen 3/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.21 - vue 29/555
- - 22 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - C.1
  - CORK and LEAD CUBES
  - 212. — Cork and Lead,
  - equal in mass, unequal in volume. 312
  - Per pair 4/9
  - DISPLACEMENT
  - VESSELS
  - 213.—Glass Vessel,
  - with lip and spout, for finding the volume of a solid by displacement. This pattern is for use on Retort and Burette stands. It will take a sphere in. in diam. 317 Each.............1/9
  - 215.—Tin Vessel, for
  - finding the volume of a solid by displacement. 319 Each.............1/3
  - 214.—Glass Vessel,
  - for finding the volume of a solid by displacement. 318
  - Each
  - 2/3
  - J L
  - 216.—Set of Regular
  - and Irregular
  - Shaped Metal
  - Objects.316
  - Per set •• 2/-
  - ARCHIMEDES’
  - EXPERIMENT
  - 217.— Brass Cylinder and Bucket, students’ pattern, for showing Archimedes’ principle. 320 Each ........3/6
  - 218. — Brass Cylinder and Bucket, superior quality and finish for
  - 1 i J HE lecture table work. 321
  - II H Each ..7/6
  - jj HI 219.—Ditto, extra large
  - f® size321a 10/6
  - 217
  - 220. —West’s Graduated Tube,
  - for showing Archimedes’ principle, as described in School World, January, 1908. This tube is graduated in TVth c.c. up to 10 c.c.'s, and is provided with a glass hook at bottom and metal hook at top. Its use will be readily seen from the illustration. 322
  - Each.............2/2
  - Per dozen .. .. 23/-
  - 221.—Wooden Model of Screw and Nut,
  - large size 313...................9/6
  - 223.—Screws and Nuts. 315
  - Per dozen .. .. .. .. 2/-
  - Leading Scientific Press,
- p.22 - vue 30/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 23
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS._____
  - SPECIFIC GRAVITY BOTTLES, Etc.
  - 224. — Specific Gravity Bottle,
  - students’, unadjusted, drilled stopper, no stated capacity. 323
  - Capacity
  - Each
  - 25
  - 1/-
  - 50 grammes
  - 1/2
  - 225.—Specific Gravity Bottle,
  - with perforated stopper, carefully adjusted. 325
  - A. 10 grammes .. each
  - B. 25
  - C. 50
  - D. 100
  - E. 1000 ernment
  - grains, Special Gov-Laboratory pattern
  - each
  - 3/9
  - 4/6
  - 5/6
  - 6/6
  - 12/
  - 226.—Specific Gravity Bottle,
  - with open top with fine mark etched round the neck. 329
  - Each .. Per dozen
  - 9d.
  - 8/-
  - 227.—Specific Gravity Hydrometers, direct reading. 338
  - 0700 to o*8oo .. each 2/6
  - o-8oo „ 0-900 . . „ 2/6
  - 0-900 „ 1-ooo . • „ 2/6
  - 1-ooo „ 1-200 „ 2/6
  - 1-200 ,, 1-400 „ 2/6
  - 1-400 ,, i-6oo „ 2/6
  - i-6oo „ i-8oo . . „ 3/3
  - i-8oo „ , 2-000 .• „ 3/3
  - Chemical Apparatus Catalogue.)
  - 228.—Trial Jars, for hydrometers. 362 Each Doz.
  - 6 in. high, i£ in. dia. 9d. 7/6
  - 11d. 9/6 1/- 10/6 1/2 12/-1/4 14/-2/6 28/-2/9 31/-
  - (Other sizes to order.)
  - 8 „
  - 10 „
  - 12 „
  - 14 „
  - 16 „ 1*
  - 18 „ ii
  - 229.— Glass Bulbs, with two stopcocks and
  - glass hook, for taking the A specific gravity of
  - llj gases.332
  - \V, W A. 1,000 c.c. capacity
  - ' each 14/- B. 2,000 c.c. capacity each 16/-
  - 230. — Specific Gravity Bottle,
  - unadjusted, with slotted stopper, Harrow School pattern. 324
  - Each
  - Per dozen
  - 9d.
  - 8/-
  - 231.—Nicol’s Specific Gravity Tube327
  - Each...........1/6
  - ~lp
  - J 232. —
  - 232. — Sprengel’s Specific Gravity Tubes, with stoppered ends. 328 Each .. .. 4/-
  - 231
  - 232
  - 233.—Sinker for measuring the density of a liquid. 330
  - Each
  - Per dozen
  - 1/2
  - 12/6
  - 234.—Simple Form of Hydrometer, consisting of a rectangular rod of wood 15 cm. long and 1 sq. cm. in section, with divisions 1 cm. apart, weighted at one end. The number of cubic centimetres in the part of the rod under water is equal to the number of cubic centimetres of water displaced. 337
  - Each 11 d., per dozen 10/-
  - 'S HYDROMETERS’
  - 235. —Nichol-s o n’s H y-d r o m eter,
  - for taking the specific gravity of solid bodies, japanned tin. 353
  - Each .. 2/6
  - 236. — Glass Immersion Jar, for ditto. 354
  - Each .. 2/3
  - 237. —Nichol-s o n’s H y-d r o m eter,
  - larger size, and nicely nickel-plated. 355 Each .. 6/6
  - 238. — Glass I mmersion
  - Jar, for
  - ditto. 356
  - Each .. 2/3
  - 237
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.23 - vue 31/555
- - 24 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MODIFIED NICHOLSON’S HYDROMETERS
  - (For ordinary form, see previous page)
  - 239.—Bucknell’s Balance Hydrometer
  - {Patent applied for). Designed by E. T. Bucknell, F.C.S., St. Philip’s Grammar School, Birmingham. 352 —. This is a modified, form of Nicholson’s Hydrometer, in which a long graduated brass tube takes the place of the short thin wire in the Nicholson pattern.
  - The balance hydrometer is not of fixed immersion (although it may be used as such, and by means of it the densities of substances, both heavier and lighter than water, may be readily determined.
  - The brass tube is divided in centimetres and millimetres, and is sufficiently long to deal with substances up to about 7 grammes in weight.
  - Other new features of the hydrometer are the side pieces, which are attached to the top pan.
  - METHOD OF USING.—Lead shot, _ etc., is placed on the top pan until the zero of the scale coincides with the meniscus of the water in the glass jar. Observations on the reading must always be taken from this point. Place the substance, of which density is required, in the top pan. Note the reading when the hydrometer comes to rest. Now place the substance in the bottom pan, and again take the reading. The reading of the scale, when the substance is in the top pan, divided by the difference of the two readings, gives the required density.
  - Example to find the density of nickel silver :—
  - Reading of scale with alloy in top pan .. = 8-20 c.m.
  - ,, ,, „ „ bottom pan = 7-25 c.m.
  - Upthrust or loss in weight of alloy .. = -95 c.m. Density = 8-20 = 8-63.
  - 240.—Improved Hydrometer (Downes’Patent).
  - The replacement of the mark or line on the narrow stem by a needle point. This said needle point to stand away from the stem such a distance that it will not be affected by the rising of the water around the stem, due to adhesion. This is easily seen when the needle point and the shadow of same meet, thus very accurate results are attained.
  - The prevention of the adhesion to the hydrometer jar is by means of four metal points arranged round the cylinder of the hydrometer in such a manner that only the points and not the body can come into contact with the side of hydrometer jar.
  - The prevention of the sinking of the scale pan of the hydrometer below the surface of the liquid is by means of a loose metal ring with arms which rest upon the top of the hydrometer jar; the ring is smaller in diameter than the scale pan, thus same cannot sink below this point.
  - These improvements embody no new principle.
  - The same methods of work are used, giving the student the same valuable instruction in the use of and in the manipulation of fraction weights. 6723 Each 8/6
  - 242.—Hare’s Apparatus, Harrow School Pattern, for the Determination of Relative Densities of Liquids which mix. 6720
  - •95
  - The hydrometer should prove of value in the Physical Laboratory. It may have its “ Calibration curve ” constructed in a similar manner to the dynamometer. It will be seen that the hydrometer may be used as a direct reading instrument, thus saving time, and doing away with the use of weights. To ensure greater accuracy, the brass scale, after being immersed, should be lightly rubbed over to remove any adhering drops of water. Price 10/6
  - This apparatus is a great improvement on the ordinary forms of Hare’s apparatus in that the board on which the U-shaped tube is mounted can be raised or lowered, thus making it unnecessary to use blocks under the beakers.
  - Price, without beakers 10/6
  - 241.—Specific Gravity Tubes for
  - measuring the specific gravity of volatile liquids as described in Watson’s “ Text-Book of Practical Physics,” page 89, 1906 Edition. 331
  - Fig. A. Fig. B. Fig. C.
  - each
  - 3/3
  - 4/-
  - 2/3
  - CAUTION.—As no grease must be used on the stopper or tap, care must be taken not to force these in too tightly or they will stick, and great difficulty may be experienced in removing them.
  - 242
- p.24 - vue 32/555
- - F. E. BECKER & CO., N1VOC HOUSE, HATTON WALL, LONDON, E.C.1. 25
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RELATIVE DENSITY TUBES AND HARE’S APPARATUS
  - '“‘tJ ’ ' —»*/ niwaHK'ir
  - 243. —Glass U Tubes, 18 inch limbs, mounted on wooden stand, with paper scale each 8/6
  - 244. —Glass U Tubes only, as used in 243.
  - each 9d.
  - 245. —Double U Tube, mounted on wooden
  - stand.................. • • • • 37/6
  - 245A .—Ditto, cheap pattern .. each 17/6
  - 246 247 248
  - 246.—Glass Communicating Vessel, for two liquids, 18 in. limbs, unmounted 369 .. .. .. each 2/-
  - 247. —Glass Communicating Vessel, for two liquids,
  - 18 in., mounted on wooden stand 370 .. .. each 10/6
  - 248. —Communicating Vessel, large size, mounted
  - on polished stand, with bold scale371 .. .. each 32/6
  - 249.—Joly’s Specific Gravity Spring Balance,
  - best quality. 359 £3 15 0
  - 250.—G lass Three-limbed Tubes, as used for making up Hare’s Apparatus. 376
  - Each.........11d.
  - 250 Per dozen 10/-
  - 251.—Hare’s Apparatus, simple
  - form, with rubber tube and clip. 373 Price (not including the two
  - 251
  - beakers)
  - 252.
  - Joly’s
  - Specific
  - Gravity
  - Balance,
  - students’! pattern. Price com-p 1 e t e a s] figured. 361 25/-
  - 252
  - 253
  - 253. — H a r e’s Apparatus,
  - superior make, large size, with graduations and figures, and the whole mounted on nicely ^polished support. 375
  - Price (not including beakers) ..£220
  - 254
  - 255
  - 254. —Hare’s Apparatus for
  - determination of relative densities, of liquids which mix. 372
  - Price (not including the two beakers) -Each ....................10/-
  - 255. —Hare’s Apparatus,
  - improved pattern, with graduated limbs 374 (not including the two beakers).
  - Each
  - 17/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.25 - vue 33/555
- - 26 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BOYLE’S LAW TUBES AND APPARATUS
  - 261.—B o y I e’s Law Tube,
  - superior make and finish. Mounted on nicely polished mahogany support, with boxwood scales. 380
  - Complete as figured—
  - £17 6
  - 259.—Boyle’s Law Apparatus, with Jolly’s air-bulb attachment, which can be taken off when not required. Mounted on heavy iron foot. 381
  - £1 17 6
  - “ University ” pattern, large size. 382 Price £5 10 0
  - This apparatus, which is of substantial make and finish, is provided with a plain glass tube which can be raised to desired height and held there by means of a clamping screw, a graduated tube with stopcock A, a graduated tube with two stopcocks and funnel B, Jolly’s air-bulb C, all of which are fitted with side attachments and pointers. The side of the tall upright carrying A is so arranged that A, B, and C can be fixed at different heights. Pointers can be moved along the tubes to show height of mercury.
  - Oup stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.26 - vue 34/555
- - F. E. BECKER & CO., IMiVOC HOUSE, HATTON WALL, LONDON, E.C.1. 27
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MARRIOTTE’S APPARATUS AND BOYLE’S
  - LAW TUBES
  - 262—Plain Glass Tubes, closed at top, for Boyle’s Law apparatus.389
  - each 6d.
  - 263.—Plain Glass Tubes, open at both ends 390 .. .. each 6d.
  - A
  - 264.—Boyle’s Law Tubes, graduated 50 c.c. in ioths, with glass stop-cock. 391
  - each 6/6
  - D
  - 265. —Vapour Tension Tubes,
  - graduated 50 c.c. in ioths, with 2 stopcocks 392 ...........each 9/-
  - 266. —Ditto, fitted with steam jacket. 393
  - each 12/6
  - 270
  - 272
  - 273
  - 267.—Vapour Tension Tubes, as
  - No. 265, but provided with funnel top.394
  - each 10/6
  - 268 —Ditto, fitted with steam- jacket
  - each 13/6
  - 269.— Glass Reservoirs for Mercury, strongly made. 388
  - Capacity.. 125 250 500 c.c.
  - Each .. 1/8 1/11 2/6 Capacity.. 700 1000 c.c.
  - Each .. 3/6 4/6
  - 270. —Marriotte’s Apparatus for proving Boyle’s Law-
  - For half-atmosphere pressure. This apparatus consists of a straight thick-walled barometer tube, closed at one end and 36 in. long, and a tall glass cylinder. Fully described in Watson’s “ Elementary Practical Physics ” 383 .. .. .. .. 15/-
  - 271. —Marriotte’s Apparatus for proving Boyle’s Law. For half-atmosphere pressure. Consists of stout bent glass tube, nicely graduated, with 2 stop-cocks. Can be clamped to any stand by means of an ordinary retort stand, clamp, and boss.384 £110
  - 272. —Marriotte’s Apparatus for proving Boyle’s Law. For half-atmosphere pressure. Consists of stout bent glass graduated tube, with 2 stop-cocks, mounted on heavy foot, with upright
  - support 385 .. .. .. .. .. .. £2 5 0
  - 273.—Apparatus for half-atmosphere pressure. This consists of a graduated tube ending in a stop-cock at the top. A wider tube is fixed in the metal stand as figured 386 .. ..£2196
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.27 - vue 35/555
- - 28 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORQE (LONDON), Ltd., PROPRIETORS.
  - USEFUL LIST OF MISCELLANEOUS APPARATUS FOR GENERAL PHYSICAL LABORATORY WORK
  - 274.—Measuring Flasks, without
  - stopper, one mark on neck.
  - Capacity 25 50 100 150 200 c.c.
  - Each iod. nd. 1/- 1/3 i/4
  - Per dozen 9/- 9/6 10/9 13/- 14/-
  - Capacity .. 250 500 1000 2000 c.c.
  - Each .. .. 1/6 2/- 2/4 4/-
  - Per dozen .16/6 21/- 26/- 45/-
  - 275.—Measuring Flasks, with
  - stopper, one mark on neck.
  - Capacity .. 25 50 100 200 c.c.
  - Each • • i/3 i/4 1/6 r/10
  - Per dozen .. 14/- 15/- 17/- 21/-
  - Capacity .. 250 500 1000 2000 c.c.
  - Each .. 2/- 2/8 3/3 5/6
  - Per dozen . . 23/- 31/- 36/- 60/-
  - 275
  - C.C
  - -IJ-I50
  - t,
  - as
  - 276
  - 276.—IVI easuring Cylinders,
  - graduated, with lip.
  - Capacity .. 10 25 50 100 200 c.c.
  - Divided into TV i i i t c.c.
  - Each .. 1/2 1/3' 1/4 1/8 2/-
  - Per dozen .. 12/- 13/- 15/- 19/- 22/-
  - Capacity.. Divided into Each Per dozen
  - 250 500 1000 2000 c.c.
  - * i ¥ ¥
  - 2/6 3/3 5/~ 10/6
  - 27/6 37/6 57/6 1 28/-
  - 277.—Measures, japanned tin, for lecture purposes-| litre | litre 1 litre
  - 1/6 .1/9 2/3 each.
  - 278.—M easuring Cylinders,
  - graduated and stoppered.
  - Capacity .. .. 10 25 50 100 c.c.
  - Divided into .. } \ j c.c.
  - Each .. .. 1/8 1/10 2/- 2/5
  - Per dozen .. .. 18/- 20/- 22/- 26/-
  - Capacity .. 200 250 500 1000 2000 c.c.
  - Divided into r f f Jr°- t1
  - Each .. 3/- 3/3 4/6 7/6 13/-
  - Per dozen .. 33/- 40/- 50/- 80/- 150/-
  - 278
  - 279.—M easuring Cylinders,
  - graduated in cubic inches. Tall form with spout.
  - 1 2 5 10 cubic inches.
  - 1/6 2/- 3/- 4/9 each.
  - 279
  - 280.—Conical Form Measures for Laboratory and Photographic work.
  - Capacity 1 2 4 8 dr.
  - Each .. iod. nd. 1/1 1/3
  - Dozen .. 9/- 10/- 12/- 14/-
  - Capacity 1 2 4 6 8 oz.
  - Each nd. 1/2 1/4 1/6 1/9 Dozen 10/- 12/6 15/- 17/- 20/-
  - FIozHdr!
  - \3 — 2 41
  - \s— 16/
  - k~ —12
  - r -a — 61
  - \4 ^4/ - 01
  - S-l/
  - 280
  - 281.—Cup Form Measures.
  - Capacity 4 6 8 10 oz.
  - Each .. 1/4 1/6 1/9 1/11
  - Dozen .. 15/- 17/- 20/- 22/-
  - Capacity 16 20 32 40 oz.
  - Each . . 2/3 2/9 3/3 3/9
  - Dozen .. 25/- 27/- 35/- 42/-
  - H Itoz 8
  - /2 —7
  - —6
  - —5
  - 'h
  - h —3
  - —2 —1
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.28 - vue 36/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 29
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - MISCELLANEOUS APPARATUS FOR PHYSICAL
  - LABORATORY WORK
  - 286.—Beakers. Squat form with spout. School quality.
  - 282.—Burettes,
  - graduated.
  - Mohr’s, with glass tap, accurately
  - 10 c.c. in /oths
  - 25 ,, in i'0ths
  - 50 ,, in xVths
  - 100 ,, in xths
  - IOO ,, in TVths
  - each
  - 2/9
  - 3/6
  - 4/3
  - 5/9
  - 6/9
  - 283.—Burettes, Mohr’s, with pinchcock and jet, accurately graduated.
  - .. each
  - 10 c.c. in roths
  - 25 ,, in xVths
  - 5o ,, in roths
  - IOO ,, in -]-ths
  - IOO ,, in TTirths
  - 284.—Pipettes, marked on stem, to deliver one quantity, cubic centimetres, accurately graduated.
  - Each. Dozen.
  - 1
  - 2 3 5
  - io
  - i5
  - 20
  - 25
  - 5o
  - 100
  - 4d.
  - 4d.
  - 5d.
  - 6d.
  - 7d.
  - 8d.
  - 9d.
  - 10d.
  - 1/2
  - 1/6
  - 3/6
  - 3/6
  - 4/6
  - 5/-
  - 6/-
  - 7/-
  - 8/-
  - 8/6
  - 12/-
  - 16/-
  - 285.—Pipette, with curved end for fitting into barometer tubes .. .. .. .. each 8d.
  - REFER ALSO TO
  - CHEMICAL APPARATUS CATALOGUE.
  - Capacity . . ioo 175 250 c.c.
  - Each . . 6d. 8d. 9d.
  - Dozen . . 5/- 6/6 7/-
  - Capacity . .
  - Each
  - Dozen
  - 350 500 700 c.c.
  - iod. 1/1 1/4
  - 8/6 10/9 14/-
  - Capacity 1000 1350 1750 c.c.
  - Each . . 1/8 2/3 2/6
  - Dozen .. 17/6 22/- 27/6
  - 287.—Beakers. Tall form,
  - plain without spout. School
  - jet, quality. Capacity 100 200 300 c.c.
  - 1/4 Each . 6d. 8d. gd.
  - Dozen 5/- 6/9 7/-
  - 2/- 3/- Capacity 450 550 700 c.c.
  - Each nd. 1/1 i/3
  - 4/9 Dozen 9/6 11/- 13/6
  - 6/6 Capacity 1000 1250 1650 c.c.
  - Each .. r/8 1/10 2/3
  - Dozen .. 17/6 19/6 23/-
  - 288.—Flasks. Ordinary, fiat
  - bottom. School quality.
  - Capacity . . 50
  - Each .. 5d.
  - Dozen .. 4/-
  - 100 150 c.c.
  - 6d. 6d.
  - 4/6 5/-
  - Capacity .. 250 350 500 c.c.
  - Each .. 8d. qd. nd.
  - Dozen . . 7/- 7/6 10/-
  - Capacity 750 1000 1500 c.c. Each .. . 1/2 1/5 1 /io
  - Dozen .. 12/- 15/- 19/6
  - 286
  - 288
  - 289.—Flasks. Ordinary, round
  - bottom. School quality.
  - Capacity .. 50 100 250 c.c.
  - Each 5d. 6d. 8d. :
  - Dozen 4/- 4/6 7/- 111
  - Capacity .. 500 750 1000 c.c. 7
  - Each nd. H 'io' H Cn lummsmmm
  - Dozen 10/- 12/- 15/- (Mllllffllll 1H«
  - Capacity .. .. 1500 c.c.
  - Each .. 1/10
  - Dozen .. 19/6 289
  - Our stock of pure Chemicals and Acids is very considerable ,* hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.29 - vue 37/555
- - 30 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MISCELLANEOUS APPARATUS FOR PHYSICAL
  - LABORATORY WORK
  - 290.—Bell Jars, open at top, and well-ground flange at bottom for air pump work, etc.
  - Height 7 8 8 9 in.
  - Diameter .. 5 4 5 6 in. Each.. .. 5/- 5/- 6/- 7/-
  - 294
  - 294.—Porcelain Basins, finest quality, for photo-
  - 290
  - graphic and general laboratory use.
  - Inside
  - Measurement.
  - Semi-Deep.
  - Each.
  - Deep.
  - Each.
  - 291.—Bell Jars, stoppered with
  - well-ground work, etc. flange for air pump
  - Height .. 6 6 8 8 9 in.
  - Diameter 3 4 4 6 6 in.
  - Each .. 3/6 3/9 5/9 8/- 8/6
  - Height .. TO 10 10 12 12 in .
  - Diameter 5 7 8 6 8 in.
  - Each .. 8/- 12/6 14/- 12/6 19/6
  - 291
  - 292
  - 292.—Thick Glass Beakers,
  - with lip, tor cold solutions, filtrates, etc.
  - Capacity i * 1 2 litres.
  - Each . 1/3 1/10 2/6 3/9
  - Capacity • • 3 4 5 litres.
  - Each .. .. 4/6 5/6 9/-
  - 293
  - 293.—Zinc Beakers, 7! cm. X 7
  - cm. Sometimes used instead of glass beakers and will be found useful for specific gravity experiments, etc.
  - Each.......................1/-
  - Per dozen .. .. . . .. 10/6
  - 4i X 3% 5X4 5i X 3l 7X5 9x7 10 X 8 12 X 10 15 X 12 18 X 14
  - 1/9 2/-
  - 2/- 2/3
  - 2/- 2/3
  - 2/9 3/3
  - 4/3 5/-
  - 5/3 6/-
  - 7/9 9/-
  - 16/- 21/-
  - 32/6 40/-
  - 295.—IVI easuring Cylinders, graduated in both English and
  - Metric Systems, tall form with
  - lip.
  - Capacity (English). Capacity (Metric). Price. each.
  - 4 OZS. IOO C.C. 3/6
  - IO „ 250 ,, 4/6
  - 20 ,, 500 „ 6/9
  - 35 „ 1,000 ,, 12/6
  - 296. —E namelled Steel Beakers.
  - Capacity, approx. 8 12 18 oz.
  - Diameter 7 8 9 cm.
  - Each .. 1/2 1/4 1/6
  - REFER TO OUR CHEMICAL APPARATUS CATALOGUE for any items not included in the small Miscellaneous Section.
  - Every requisite for • Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.30 - vue 38/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 31
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MISCELLANEOUS APPARATUS FOR PHYSICAL
  - LABORATORY WORK
  - 297. —Burette Stands, white hard wood for i Burette each 3/3
  - 298. —Burette Stands, white hard wood for 2 Burette s each 4/3
  - 299.—Burette Stands, hard
  - teak, with boxwood screws, for 1 Burette .. .. each 4/9
  - 300.—Burette Stands, hard
  - teak, with boxwood screws, for 2 Burettes .. .. each 5/9
  - 301.—Burette Stands, polished mahogany, with boxwood screws, for 1 Burette .. each 5/6
  - 302.—Burette Stands, polished mahogany, with boxwood screws, for 2 Burettes .. .. each 6/9
  - 303.—Funnels, correct angle,
  - plain.
  - Dia. .. 2-| 5 61 7-| 9 10 cm.
  - Each . . 6d. 7d. 8d. gd. iod. lid.
  - Dozen .. 5/- 5/6 7/6 8/- 8/6 10/-
  - Dia. ii| 12^ 15 18 20 23 25 Each 1/1 1/3 1/5 2/- 2/4 3/3 4/6 Doz 12/-14/-16/- 22/- 27/- 38/- 50/-
  - 304.—Porcelain Mercury Troughs, wide
  - shape.
  - 304
  - Capacity Length Width .. Each ..
  - 8 16 lb.
  - 18 20 cm.
  - 6 7\ „
  - 6/6 12/6
  - 305.—Porcelain
  - 305
  - Mercury Troughs, 22£ x
  - 4|- cm., to contain 4 lb.
  - Each.................4/6
  - REFER TO OUR CHEMICAL APPARATUS CATALOGUE for any items, more or less common to both Physical and Chemical Laboratories and not included in this small Miscellaneous Section.
  - 306. — Mercury Vessel, made of iron, to hold 25 lb. of mercury.
  - Price, including lid and metal tap as figured 8/6
  - 306A.—Ditto, to hold 76
  - lb. of mercury .. 12/6
  - 307.—Glass Reservoirs for
  - Mercury, strongly made.
  - Capacity 125 250 500 700 1000 c.c. Each .. 1/8 1/11 2/6 3/6 4/6
  - 308. — Japanese Fibre Mercury Trays.
  - Each.
  - A. 12 in. square 3/-
  - B. 15 „ „ 4/6
  - 309. — Mercury Trays, made of
  - wood, dead-blacked.
  - 12 in. long, 8 in. wide, 1 in. deep .. .. each 2/-
  - 310. Canary Wood Mercury T ray, with
  - plug in corner, and two handles.
  - 310
  - Size about 23 in. X 16 in. x 2 in. . . .. each 15/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.31 - vue 39/555
- - 32 F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MISCELLANEOUS APPARATUS FOR PHYSICAL
  - LABORATORY WORK
  - 311a. —Extra Wire Cages Each ...............
  - 11.—“ N i v o c ” Foot Bellows, very strongly made, gives a steady air pressure. These bellows are fitted with the Nivoc Special Wire Cage as No. 311A, but the reservoir is reversed, and mounted on strong cast-iron feet, as shown in the illustration. No. 5 size each £3 5 0 “ Nivoc ” Foot Bellows. .........................5/6
  - 312/3
  - 312.—Rubber Circles for
  - Foot Bellows, best quality, 10 in. diam. .. .. each 2/6
  - 313 .—Ditto, ditto, 12 in. diam.
  - each 3/-
  - 314.—String Net, with wire for foot bellows .. each 2/- and 2/6
  - 315.—Cork Borers, best make, with rod.
  - A. Set of Three .. . . . . . . per set
  - B. ,, Six
  - C. ,, Nine . . . . . . . . ,,
  - D. ,, Twelve
  - 1/8
  - 3/-
  - 4/9
  - 7/-
  - 316.—Spirit Lamps, with
  - cap, wick-holder and wick.
  - Capacity 2 4
  - Each .. . . 1/9 2/-
  - Per dozen .. 18/9 22/-
  - ground
  - 8 oz.
  - 3/-
  - 34/-
  - 317
  - 317.—Pneumatic Troughs, round, thick strong
  - glass. Diameter .. 6 8 10 12 14 in.
  - Height .. .. 4 4 5 5 6 in.
  - Each .. 2/- 3/- 4/3 7/6 15/-
  - 318/9
  - 318. —Flexible Metallic Steel Tubing, of
  - great durability and strength, free from smell. Supplied in 2 ft., 3 ft., 4 ft., 5 ft., and 6 ft. lengths, with rubber ends complete—f in. for Bunsen burners.
  - A. In lengths of 2 ft., with rubber push-on at each end—
  - per 2 ft. length 1 /8
  - B. In lengths of 3 ft., with rubber push-on at each end—
  - per 3 ft. length 2/-
  - (Other lengths supplied at 6d. per foot extra.)
  - C. Rubber push-ons only .. . . per dozen 4/-
  - 319. —Flexible Metallic Copper Tubing
  - (rubber ends, 4/- dozen extra). Supplied in any length. Size f in. (for Bunsen burners) .. .. per foot 1 /4
  - 321. — G a s Burner with B a t s w ing
  - Jet for lighting or glass bending.
  - 8 in.
  - 12 ,,
  - 322. —Cork Borers, Special Quality for Lec-tureTable,
  - all steel tube, with separate handle to each borer.
  - 321
  - 320.—New Pat-
  - tern Blowpipe,
  - as used by the experts in the glass-blowing industry. Of very solid construction and specially designed for intensity of flame. Size of jet can be modified by the insertion of different sizes of glass tubing in the jet tube. Easily dismantled for cleaning.
  - Each .. ... 14/6
  - A. Set of Three per set 4/-
  - B. ,, Six ,, 8/-
  - C. „ Nine „ 12/-
  - D. ,, Twelve ,, 16/-
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.32 - vue 40/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 33
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MISCELLANEOUS APPARATUS FOR PHYSICAL
  - LABORATORY WORK
  - 323.—Nivoc Bunsen Burner, improved pattern, very strongly made, removable solid jet, gas and air regulation, diameter of tube ^-G in.
  - The improved pattern NIVOC BUNSEN BURNER is being generally adopted in Science Laboratories as it has many advantages over other patterns. The dome-shaped heavy base gives it greater stability, and as the base is quite free from interstices it cannot retain liquid which occasionally boils over from the vessel being heated.
  - Each, 1/6; per dozen, 15/6.
  - 324.—Ditto, size larger, diameter of tube, | in. .. each 2/8
  - per doz. 30/-
  - 325 .—Ditto, diameter of tube | in.
  - 'ii each 4/3
  - per doz. 48/-323
  - 326. —Test Tubes. Best thin hard white glass, packed in cardboard boxes.
  - Per gross
  - Length in Diameter Per single taking 10 gross
  - inches. in inches. gross. of one
  - 2 X i •• ..1/9 .. 1/6
  - 2 X 1 •• 2/9 .. 2/4
  - 3 X i •• • • 3/- •• 2/6
  - 3 X 3 8 •• 3/6 •• 3/-
  - 3 X i •• .. 4/- • • 3/6
  - 4 X i ... 5/- •• 4/-
  - 5 X i •• .. 6/6 .. 5/6
  - 5 X 1 •• .. 7/- .. 6/-
  - 5 X 1 •• .. 7/6 .. 6/3
  - 6 X 1 •• .. 8/- .. 6/6
  - 6 X 3 ¥ .. 10/- .. 9/-
  - 6 X I .. 15/- .. 13/6
  - 6 X ii •• .. 24/- .. 22/-
  - 7 X ii • • .. 26/- .. 24/-
  - 8 X ii •• .. 46/- .. 40/-
  - 327.—Triangular Files, in polished handles, for cutting glass tubing and rod .. each 9d.; doz. 8/-
  - 328 —Ditto, without handle .. each 7d.; doz. 6/6
  - 329.—Flat File,
  - for sharpening cork borers each 9d.
  - 330.—B ottles, narr ow mouthed, flat stoppered.
  - Best quality white glass, free from lead, for reagents, etc.
  - Capacity .. 2 4 6 8 oz.
  - Per dozen 5/- 6/6 7/- 8/-
  - Per gross.. 55/- 70/- 78/- 92/-
  - Capacity 10 12 16 20 oz.
  - Per dozen 10/- 10/6 13/- 14/-
  - Per gross 110/- 120/- 130/- 160/-
  - 330
  - 331.—B ottles, wide mouthed, flat stoppered.
  - Best quality white glass, free from lead, for dry salts, etc.
  - Capacity 2 4 6 8 oz.
  - Per dozen 5/6 7/- 8/- 9/-Per gross ..62/- 80/- 90/- 102/-
  - Capacity 10 12 16 20 32 oz.
  - Per dozen 11/- 12/6 14/6 17/- 21 /6 Per gross 128/-140/-155/-196/- 234/-
  - 33i
  - 332. —Gas Jars, with and well-ground flange. glass foot
  - Height 6 8 8 10 12 in.
  - Inside dia. i| i| 2 2 2 in.
  - Each 10d. 11d. 1/3 1/5 1/6
  - Per dozen .. 8/6 9/6 12/6 14/6 16/-
  - Height 12 16 20 24 in.
  - Inside dia. .. 3 3 3 4 in.
  - Each 1/9 2/9 5/- 7/6
  - 332
  - 333.—Rat-tail Files, for enlarging holes in corks . . . . . . each 10d. ; per doz. 9/-
  - 334 —Ditto, without handle each 8d.; per doz. 7/6
  - 335.—Flat File and Rasp, 8 in. .. each 1/6
  - f
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
  - D
- p.33 - vue 41/555
- - 34 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MISCELLANEOUS APPARATUS FOR PHYSICAL
  - LABORATORY WORK
  - 336.—Ordinary Corks, finest quality, picked for chemical purposes. Cheaper qualities are not recommended for Chemical Laboratory work.
  - Diam. narrow end .. | | f f f in.
  - Price................ 1/9 2/3 3/- 3/9 4/8 gross.
  - Diam. narrow end i i| rj if i| in. Price .. .. 6/9 8/6 10/- 11/6 14/-gross.
  - 337 .—The above sizes assorted .. per gross 4/-
  - 338. — S h i V e S (for wide-mouth bottles), about J in. to § in. thick.
  - Diameter, narrow
  - end f i i i& i£
  - Price .. 2d. 2d. 3d. 4d. 5d.
  - if ij in.
  - 6d. 7d. doz.
  - Diameter, narrow
  - end .. if if if 2 2| 3 3l 4 in-
  - Price .. 8d. 10d. 1/- 1/3 1/5 2/6 3/- 4/- doz.
  - VARIOUS STANDS AND SUPPORTS
  - Absolutely Rigid.
  - Fig. A Fig. B Fig. C Fig. D Fig. E
  - Geometric Tripod Stands. The geometric forms were designed in the first instance by Professor C. V. Boys. Their use will be readily understood from the illustrations, the three rounded feet of the upper tripod fitting rigidly in the V grooves in the tripod below, and so on until the desired height is attained.
  - Made in two heights, viz. :—“ Shallow ” pattern, Fig. A, height i in. “ Tall ” pattern, Fig. D, height 2-| in.
  - Fig. B shows two sections of the " Shallow ” pattern—making a total height of 2 in. ; Fig. C shows nine sections, making a total height (without table-top) of 9 in.
  - Fig. E shows a table fitted with three levelling screws for placing on top of either of the two patterns above mentioned.
  - PRICES.
  - 339. —“ Shallow ” Pattern, total height 1 in., made of iron (see Fig. A).............. per doz. 14/-
  - 340. —“ Tall ” Pattern, total height 2| in., made of iron (see Fig. D) .. .. .. ,, 15/-
  - 341. —Iron Table Tops, very accurately planed and fitted with three levelling screws (see Fig. E) each 16/-
  - 342. —Plain Ground Glass Table Tops, may be used instead of Fig. E ......................... „ - 3/6
  - 343. —Table Top, consisting of one iron geometric tripod (Fig. A) to which is permanently fixed a !
  - wooden table top ' each ; 4/6
  - 344 .—Ditto, but larger size tripod (Fig. D) .. .. .. .. .. .. .. .. .. ,, 6/-
  - 345
  - 345. —Blocks of Wood,
  - round, stained black, consisting of six pieces of different sizes. Per set' .. 4/6
  - 346. —Blocks of Wood,
  - square shape, stained black, consisting of six pieces of different sizes.
  - Per set .. 4/6
  - 347.—Bunsen’s Universal Clamp Support, polished mahogany, with loaded foot, best make and finish. .. each 12/-
  - 346
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.34 - vue 42/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 35
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - BURETTE STANDS AND BURETTE CUPS
  - 348.
  - The “W.J.”
  - Burette Stand.
  - Invented and patented by the Rev. A. Wentworth Jones, M.A.
  - This burette stand is made of selected Teak wood and will stand an enormous amount of wear and tear. It is the simplest ever devised and has the following advantages over all other patterns :—
  - There are no screws to turn or get out of order.
  - It is extra strongly made and will therefore withstand a great deal of wear and tear. One hand only is needed.
  - Burette is simply dropped on to a ledge —no force required.
  - Impossible for Burette to drop out.
  - Burette is always vertical.
  - Graduations are not hidden.
  - Will take Burettes of all sizes.
  - Fig. i.
  - Burette being dropped into position.
  - Fig. 2. Fig. 3.
  - Burette in Stand ready for use. Double Burette Stand.
  - PRICES.
  - A. To take one burette, see Figs. 1 and 2, including two india-rubber rings .. . • • • • • each 5/-
  - B. To take two burettes, see Fig. 3, including four india-rubber rings .. .. • • • • .... ,, 6/9
  - C. India-rubber Rings for above .............................. ............................. • • ,, 2d.
  - N.B.—These rings are made specially for use with the above stands, and are not ordinary umbrella rings which, although much cheaper, are not nearly so efficient.
  - BURETTE CLIPS
  - 349.—Mohr's Burette Clips, brass, nickel-plated.
  - Small. Medium. Large.
  - Each.. 4d. 4d. 5d.
  - 350.—Screw Clips
  - nickel-plated, improved pattern.
  - The lower bar is hinged, so that the clip may be removed from the rubber tubing without unscrewing.
  - A
  - Per doz. 2/9
  - 3/3
  - 4/6
  - Inside width, in. Price, each .. Price, per doz.
  - 2
  - 8d.
  - 6/6
  - 9d.
  - 7/6
  - 11d.
  - 9/-
  - Our stock of pure Chemicals and Acids is very considerable ,* hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.35 - vue 43/555
- - 36 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 36
  - i
  - RETORT STANDS
  - 2
  - j
  - !
  - i
  - i
  - 55K
- p.36 - vue 44/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 37
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - Iron Retort Stands, RETORT STANDS without Rings, with upright rods screwed into bases. For illustrations, see page 36.
  - Catalogue Reference 351 352 353 354 355 356
  - Height of Rod 15 22 24 30 36 in.
  - Diameter of Rod .. & h in
  - Length of Base 4l 4 8 9 12 12 »
  - Width of Base 3 4l 5 5l 6 7 »
  - Price, each 1/6 2/3 3/- 3/6 4/9 6/-
  - ,, per dozen .. 17/- 26/- 35/- 41/- 56/- 71/-
  - Metal Stands, with Heavy Tripod Feet, having smooth rods screwed into them, as illustrated on page 36.
  - Catalogue Reference .. 357 358 359 360 361
  - Total Height 16 20 26 33 40 in.
  - Diameter of Rod . . RT 1 & i i n
  - Spread of Foot . . 2f 3i 3t 5f 7\ „
  - Price, each .. 1/9 2/3 3/3 4/6 6/9
  - „ per dozen .. 20/- 26/- 38/- 53/- 80/-
  - RETORT RINGS
  - Malleable I Ivon Rings, with bosses and screws for clamping to retort stands as figured. Bosses will fit rods up to | inch in diameter.
  - Catalogue Reference .. 362 363 364 365 366 367 368
  - Diameter of Ring 2! 3i 3f 4i 5 6 in.
  - Price, each .. .... .. 11 d. - 1 /- 1/1 1/2 , 1/3 1/4 1/5
  - „ per dozen .. .. 10/- 11/- 12/- 13/- 14/- 15/- 16/-
  - 369.—Malleable
  - Diameter . Each
  - 1 i 1 .....
  - ron Rings, plain, to fit into open bosses.
  - 2 2| 3 4 4i 5
  - 7d. 8d. 9d. 10d. 11d. 1/-
  - 6 in.
  - 1/3
  - 370.—Table Support, iron plate with boss-head and clamping screw for fitting on to retort stands to support Bunsen burners, etc,"
  - Each................... ..1/9
  - 371.— Double Boss Heads,
  - iron with thumbscrews.
  - Each 1/2; per dozen 13/-
  - heavy
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the - Leading Scientific Press.
- p.37 - vue 45/555
- - 38 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RETORT STAND CLAMPS
  - 372/4-
  - The “Moveable Joint ” Clamp.—As will
  - be seen by the illustration the jaws of this clamp can be moved either to the right or to the left, thus enabling the operator to make slight adjustments to his apparatus without having to remove the boss-head from its original position.
  - The clamp is strongly made of gun-metal and is fitted with an iron rod.
  - Prices include double boss-head.
  - Each.
  - 372 —For tubes up to i|- in. in diameter 5/-
  - 373 .—For tubes up to 3 in. in diameter .. 6/6
  - 374 .—For tubes up to 4 in. in diameter .. 8/6
  - 375.—Special
  - Condenser Clamp, oxidized brass, for condensers of all sizes, and to fit any size retort stand rod.
  - Each
  - 6/6
  - 376.—Nivoc Laboratory Clamp. Brass with
  - iron boss-head. We recommend this particular pattern as an engineering product and an example of high-class British manufacture. It has been specially designed and manufactured by us to obviate those little annoyances which are familiar to the user. The elliptical opening of the jaws ensure a perfect grip, and the arrangement of the opening screw is such that it is impossible for the threads to bind or stick.
  - To take tubes up to 2,\ in, diameter. Price, including double boss-head................ ................each 4/6
  - 377.—The “Students” Brass
  - Clamp. Small size, to take tubes up to i\ in. diam. Price, including double boss-head .. .. each 3/9
  - 379.—The “ Science
  - School” Clamp.
  - Strongly made of iron; small size, to take tubes up to tl\ in. diam., etc.- Price, including double boss-head, .each 3/9
  - 378.—The “Stu-
  - dents” Brass
  - Clamp. Large size, to take tubes up to 3| in. diam. Price, including double boss-head each 5/6
  - 380.—The “ Science
  - School” Clamp.
  - Strongly made of iron; medium size, to take tubes up to 2 J in. diam. Price, including double boss-head each 4/6
  - 381.—The “Science School ” Clamp.
  - Strongly made of iron; large size, to take tubes up to 3! in. diameter. Price, including double boss-head .. .. 5/6
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.38 - vue 46/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 39
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TRIPODS AND LABORATORY STANDS
  - 382.—Tripods, stout iron, of side 5 in., height 7 in.
  - 382/5
  - 383. —Tripods.
  - height 7 in.
  - 384. —Tripods.
  - in., height 8 in.
  - 385. —Tripods.
  - in., height 9! in.
  - triangular. Length .. each 1 /-Length of side 6 in., .. each 1/3
  - Length of side 7^ .. .. each 1/6
  - Length of side 10 .. each 2/-
  - 386.—-Tripods, stout iron, round. Diameter
  - of top 4 in., height 7 in. .. each 1/-
  - 386/8
  - 387. —Tripods.
  - in., height 8 in.
  - 388. —Tripods.
  - in., height 10 in.
  - Diameter of top 6 .. each 1 /3
  - Diameter of top 8 .. each 1 /9
  - WIRE GAUZE
  - -tj+ in pi. Si r
  - jfjft -Pr qDDqijqqidr T^irTl
  - :jrj:j:j=|4qq: -P'-
  - # iftni EFjrjEj
  - rH- -ft~- pftif 3Tn * -f-
  - ft k b“fcfcp: :jqj3o;d:j±rqr
  - - ^ 1 jlllllff if 4t “IT ± fn! i-REp- m -i+g 1
  - T mm
  - ffllfflltfltlTH- '1 :i: Pm! Hi ft
  - 389/392
  - 389. —Iron Wire Gauze, in squares, 10 holes to the inch.
  - A. 3X3 in. per doz. 10d. C. 5x5 in. per doz. 1/9
  - B. 4x4 in. „ 1/- D. 6x6 in. „ 2/3
  - 390. —Iron Wire Gauze, in squares, 20 holes to
  - the inch.
  - A. 3x3 in. per doz. 1/3 C. 5x5 in. per doz. 2/3
  - B. 4x4 in. ,, 1/4 D. 6x6 in. ,, 3/-
  - 391. —Iron Wire Gauze, in squares, 30 holes to
  - the inch.
  - A. 3X3 in. per doz. 1/6 C. 5x5 in. per doz. 3/-
  - B. 4x4 in. ,, 1/8 D. 6x6 in. ,, 3/10
  - 392.—Iron Wire Gauze, as above, but not
  - cut up.
  - A. Holes to the lineal inch, 10 price per sq. ft. 9d.
  - B. „ 20 1/2
  - C. „ 30 1/4
  - D. „ 40 2/6
  - 393.—Rising Table. —This is a small table having a cast-iron base provided with a small mahogany table, 6 in. X 4 in., fixed to an iron rod, which works in a heavy socket on the base. It can be clamped at any height by means of a strong clamping screw, and can be used over a range of some 6 in. Very useful as a table for a small motor.
  - Price ...........................£1 12 6
  - 394. — Laboratory Stands, superior quality and finish, for lecture table work. The base, which is extra heavy and has a perfectly even surface, carries a polished steel rod, which is screwed into it. We stock the following sizes .—
  - Diam. of Base 18 23 30 cm.
  - Height of Rod 35 75 100 ,,
  - Diam. of Rod 12 16 25 mm.
  - Price, each.. 5/-* 7/9 11/6
  - 395. —-Special large size boss-
  - heads and clamps for above stands.............8/6
  - REFER TO OUR CHEMICAL APPARATUS CATALOGUE FOR ANY ITEMS NOT INCLUDED IN THIS SMALL MISCELLANEOUS SECTION.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory. »
- p.39 - vue 47/555
- - 4-0 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - For
  - INDIA RUBBER TUBING, see next page.
  - GLASS TUBING
  - Soft Soda Glass, in 5-ft. Lengths.
  - Illustrations are shown full size.
  - oo
  - °°ooooOOO
  - A B C D E
  - 396.—Glass
  - Size
  - Outside diameter
  - P 0 N
  - |, best quality soft soda glass, for blowpipe work, etc. Guaranteed free from i
  - - A ' B C D E F G H J K
  - 3 to 4 4 to 5 6 7 9 10 12 14 16 19
  - 2/6 • 2/6 1/8 1/8 1/8 1/8 1/8 1/8 1/9 1/9
  - L
  - 22 mm.
  - 1/9
  - Size
  - Outside diameter Per lb. ..
  - M
  - 23
  - 1/9
  - N
  - 25
  - 2/1
  - 0
  - 30
  - 2/1
  - P
  - 35
  - 2/6
  - Q
  - 40
  - 2/6
  - R
  - 45
  - 3/-
  - S
  - 50 mm.
  - 3/6
  - We can draw glass tubing up to about 70 mm. outside diameter. Prices on application.
  - GLASS ROD
  - Illustrations are shown full size.
  - • • • • 4
  - A B C D E
  - 397.—Glass Rod, soft soda glass.
  - Sizes C, D and E.. .. per lb. 1 /9
  - „ A and B .. .. „ 2/-
  - F, G and H
  - 2/9
  - THERMOMETER & BAROMETER TUBING, Etc.
  - •0000000OO
  - A B C
  - 398. -
  - Soft
  - 399.
  - Soft
  - 400. -
  - Soft
  - 401;
  - Soft
  - 402. -
  - Soft
  - 403.
  - Soft
  - 404.
  - Soft
  - D
  - H
  - -Thermometer Tubing.
  - soda glass, size A (as illustrated)
  - -Thermometer Tubing.
  - soda glass, size B (as illustrated) ..
  - -Thermometer Tubing.
  - soda glass, size C (as illustrated)
  - -Barometer Tubing.
  - soda glass, size D (as illustrated)
  - -Barometer Tubing.
  - soda glass, size E (as illustrated)
  - -Glass Tubing, Thick Walled.
  - soda glass, sizes F, G, H and J (as illustrated)
  - -Glass Tubing, Thick Walled.
  - soda glass, size K (as illustrated)
  - K
  - .. per lb. 2/9
  - „ 2/9
  - ' » 2/9
  - 2/3 „ 2/3
  - 2/9 2/9
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the » Leading Scientific Press.
- p.40 - vue 48/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C-1. 41
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RUBBER TUBING
  - Guaranteed Finest London Make.
  - {Prices are subject to fluctuations of the market.)
  - ____ If desired we can supply rubber tubing of cheaper quality, but we would
  - point out that the tubing listed below is the best quality and is the only kind we can conscientiously recommend for Chemical work.
  - 405. —Black Cut Sheet Rubber Tubing, guaranteed made of best selected rubber, for chemical work. Illustrations are shown actual size. Size D is the most suitable for Bunsen burners.
  - Size .................................A B C D E F G H J K
  - Inside diameter i tV i jfr t . £ f i i I inch.
  - Price, per foot.........................2d. ^ 3|d. 5d. 6|d. 9d. 1/2 1/9 2/10 4/- 4/6
  - 406. —Red Rubber Tubing, guaranteed made of best selected rubber, for chemical work. Illustrations are shown actual size.
  - Size .................................A B C D E F G H J K
  - Inside diameter.........................| & J f | f | £ i inch.
  - Price, per foot.........................2d. 3|d. 5d. 8d. 9d. 1/5 1/9 2/10 4/- 4/6
  - 407. —Bunsen Burner Tubing, special quality and thicker walled.
  - Price, per foot ........................... .. .. .................................. ...................7d.
  - In coils of 6o ft., per foot .... .. .. .. .. .... .. .. .. .. .. 6d.
  - We have been supplying this quality for some time to many Educational Institutions and now list it by special request.
  - W For Flexible Metallic Tubing with rubber ends see Index. W
  - A
  - B C
  - 408.—Extra Thick-walled Rubber Tubing for Pressure, best quality.
  - Size .. .... A B C D E
  - Outside diameter f \ \ £ £ in.
  - Inside diameter • • i i fV & -h »
  - Price, per foot .. 8d. 1/- 1/2 1/6 2/6
  - 409.—Canvas Lined Rubber Pressure Tubing. Guaranteed best quality. This tubing, although not so flexible as ordinary pressure tubing, will withstand a much higher pressure.
  - Outside diameter .. .. \ | f in.
  - Inside diameter .. I ^
  - Price, per foot . . .. 1 /6 1/2 2/9
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.41 - vue 49/555
- - 42 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SQUAT PATTERN RUBBER CORKS
  - Guaranteed Finest London Make.
  - FOR PRICES SEE PAGE 45
  - FOR PRICES SEE PAGE 46
  - Illustrations are shown full size. Fop prices, see page 45, No. 410.
  - TALL PATTERN RUBBER CORKS.
  - Guaranteed Finest London Make.
  - Illustrations are shown full size. For prices, see page 45, No. 411.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.42 - vue 50/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 43
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - FOR PRICES SEE PAGE 45
  - SQUAT PATTERN RUBBER BUNGS
  - Illustrations are shown full size. For prices, see page 45, No. 412.
  - FOR PRICES SEE PAGE 45
- p.43 - vue 51/555
- - 44 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - FOR PRICES SEE PAGE 45
  - TALL PATTERN RUBBER BUNGS
  - Illustrations are shown full size. For prices, see page 45, No. 413.
  - FOR PRICES SEE PAGE 45
  - FOR PRICES SHALLOW RUBBER BUNGS FOR PRICES
  - SEE PAGE 45 For Steam Jackets, etc. SEE PAGE 45
  - Illustrations are shown full size. For prices, see page 45, No. 414.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.44 - vue 52/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 45
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RUBBER CORKS
  - For full-size illustrations, see pages 42, 43 and 44.
  - 410.—Squat Pattern Rubber Corks, best quality, solid, one or two holes. Finest London make. (For
  - full-size illustrations, see page 42.)
  - Diameter of narrow end ft i ft 1 ft f ft 1 ft 1 in.
  - Each .. 3d. 3d. 3d. 3d. 4d. 4d. 5d. 5d. 7d. 7d-
  - Per dozen •• 2/- 2/- 2/6 2/6 3/6 3/6 4/6 4/6 6/- 6/-
  - Diameter of narrow end .. • • ft ft if t\ if in.
  - Each ' .. .. 8d. nd. 1/1 i/4 1/6
  - Per dozen .. 7/- 10/- 12/- 15/- 15/6
  - 411.—Tall Pattern Rubber Corks, best quality, solid, one or two holes. Finest London make. (For full-
  - size illustrations,' see page 42.)
  - Diameter of narrow end ft i ft t ft h ft f ft in-
  - Each .. .. • ftd. ftd. 2d. 2d. 2jd. 3d. 4d. 5d. 6d.
  - Per dozen • v- 1/3 1/6 1/9 2/- 2/9 3/6 4/3 5/3
  - Diameter of narrow end j \ ft 1 1 i| in.
  - Each . . yd. 9d. iod. nd. 1/2
  - Per dozen .6/6 7/6 9/- 10/- 13/6
  - 412.—Squat Pattern Rubber Bungs, best quality, solid, one or two holes. Finest London make. (For
  - full-size illustrations, see page 43.) Diameter of narrow end if ft 2 2l 2| 2f 2f 2| 3 in.
  - Each i/9 2/6 2/8 3/4 4/- 6/- 6/6 7/- 8/-
  - Per dozen .. 20/- 29/- 30/- 38/- 46/- 71 /- 77/- 83/- 93/-
  - 413.—Tall Pattern Rubber Bungs, best quality, solid, one or two holes. Finest London make. (For full-
  - size illustrations, see page 44.) Diameter of narrow end . .. ft ft ft if if 2 in.
  - Each .. i/n 2/5 3/5 4/" 4/3 6/8
  - Per dozen .. .. 22/- 28/- 40/- 46/- 48/- 77/-
  - 414.—Shallow Rubber Bungs, for steam jackets, etc., best quality, solid. Finest London make. (For fun-
  - size illustrations, see page 44.) -
  - Diameter of narrow end H Mm H i| 2 21 in.
  - Each .. " . 2/3 2/6 3/- 3/6 4/6
  - Per dozen . . 26/- 29/- 35/- 40/- 53/-
  - The prices of all rubber goods are subject to the fluctuations of the rubber market
  - FOR PRICES OF
  - BARK CORKS SEE PAGE 34
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.45 - vue 53/555
- - 46 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. St J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SUNDRIES
  - 415. —Set of 12 Geometrical Figures, made
  - of cardboard, for finding areas by direct measurement and weighing.......... per set in box 1/9
  - 416. —Ditto, of metal .. .. .. per set 2/6
  - 417. —-Tin Foil (Composition) in sheets, per lb. 2/6
  - 418. —Tin Foil, Pure, in sheets .. ,, 5/-
  - 419. —Aluminium Foil, in sheets per lb.
  - 420. —Cardboard, 40 X 28 in. per sheet
  - 421. —Emery Cloth, assorted per quire
  - 422. —Lead Shot, per lb., 10d.; 14 lb., per lb.
  - 423. —Lead Sheet per lb.
  - 424. —Hog’s Bristles .. .. per bundle
  - 425. —Knitting Needles per doz.
  - 426. —Blanket Pins per gross, 2 in.
  - „ in.
  - 427. —Ordinary Pins .. .. per packet
  - 428. —Cardboard Pill Boxes ..per doz.
  - 429. —Indiarubber Bands, assorted, per box
  - 430. —Thread .......... per reel
  - 431. —Tape per skein
  - 432. —Sand Paper, assorted .. per quire
  - 6/-
  - 3d.
  - 3/6
  - 9d.
  - V-
  - 6d.
  - 6d.
  - 2/-
  - 3/“
  - 2d.
  - 4d.
  - 1/3
  - 4d.
  - 3d.
  - 2/3
  - CHEMICALS
  - (Complete List sent Post Free on Application.)
  - 433. —Wax, soft red .. .. .. per lb. 4/-
  - 434. —Wax (White Beeswax) . . .. per lb. 3/6
  - 435. —Wax, Paraffin (White) .. .. per lb. 10d.
  - 7 lb., per lb. 9d.
  - 436. —Wax (Yellow Beeswax) .. per lb. 2/6
  - 437. —Methylated Spirit .. per gallon 5/3
  - 438. —Turpentine ...................per lb. 2/2
  - W. qts., per lb. 2/-
  - 439. —Olive Oil .....................per lb. 3/3
  - 440. —Glycerine per lb., 1/8; W. qts., per lb. 1/6
  - 441. —Mercury Metal, Pure Redistilled.
  - per lb., 7/- ; 7 lb., per lb. 6/9 ; 14 lb., per lb. 6/7
  - 442. —Mercury Metal, Ordinary., per lb. 5/-
  - 7 lb., per lb. 4/9 ; 14 lb., per lb. 4/7
  - 443. —Copper Sulphate, Crystals per lb. 7d.
  - 14 lb., per lb. 6d.
  - 444. —Dutch Metal, leaf, in books each 9d.
  - dozen 8/-
  - 445. —Gold Leaf, in books each, 3/- ; dozen 34/-
  - 446. —Aluminium Leaf, in books each 8d.
  - dozen 7 /-
  - 447. —Silver Leaf, in books each, 1/-; dozen 11/-
  - 448. —Salammoniac for batteries . . per lb. 8d.
  - 14 lb., per lb. 6£d.; 28 lb., per lb. 6d.
  - 449. —Potassium Bichromate, Crystals.
  - per lb., 1/-; 14 lb., per lb. 10d.
  - 450. —Marble Chips...........per lb. 2d.
  - 28 lb., per lb. 1 £d.
  - 451. —Vaseline, Yellow .. 1 lb. tins, each 3/-
  - 452. —Vaseline, White .. 1 lb. tins, each 4/-
  - 453. —Oi Ied Silk, for repairing air pump valves 1 /6
  - 454. —Sand, Silver...........per lb. 3d.
  - 455. —Shellac Flakes (best orange) per lb. 5/-
  - 456. —Shellac, Bleached.. . per lb. 5/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.46 - vue 54/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 47
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - A FEW TOOLS FOR USE IN THE LABORATORY
  - 457. —Tool Cabinets, large size, con-
  - taining : 2 hammers, hatchet, mallet, hand saw, pincers, pliers, 2-ft. rule, square, spokeshave, plane, 2 gimlets, 2 bradawls, compasses, 2 turn-screws, tackclaw, cold chisel, brad punch, 2 files, rasp, 2 chisels, gouge, oil stone, oil can, glue pot and brush, nails, etc... .. £5 5 0
  - 458. —Ditto, largest size, strongly made, con-
  - taining : 2 hammers, mallet, hatchet, hand saw, tenon saw, saw pad and saw, hand vice, pincers, cutting pliers, 2-ft. rule, bevel, square, spokeshave, smoothing plane, 4 gimlets, 4 bradawls, compasses, 2 tumscrews, 2 files, rasp, 4 chisels, 2 gouges, 2 brad punches, striking knife, drawing knife, brace and bits, scraper, movable spanner, spirit level, oil stone, oil can, glue pot and brush, nails, etc. .............£9 15 0
  - ASSORTMENT OF
  - SIX USEFUL FILES
  - FIRST QUALITY
  - 462.—Assortment of Six Useful 3| in.
  - Files, first quality, on cards. Series 1, as illustrated, comprises : |-round, 3-square, flat, knife, square and round. Series 2 comprises : oval, slitting, flat, 3-square, pillow and ridge back.
  - Price, either series .. .. .. .. each 4/6
  - IIJ 1 —Hil^- II L , | |ji||l
  - 459.— Firmer Chisel, cast steel, with box-
  - handles.
  - Width .. tV i A i At'** t t in.
  - Price V- 1/3 1 /5 each.
  - Width .. i- 1 ii ii if i| in.
  - Price .. 1/6 1/8 1/10 2/- 2/3 2/6 each.
  - 460.—Hand Forged Chisels for Metal,
  - best English manufacture.
  - Diameter ..
  - Length
  - Price
  - I £ t
  - 6 8 10
  - 10d. 1/2 1/6
  - | in. 10 in. 2/-
  - 461.—File Cleaner or Wire Brush. No. 1,
  - ordinary, as illustrated.
  - Each ........................................9d.
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed w4th the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.47 - vue 55/555
- - 48 F, E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LABORATORY
  - TOOLS
  - 463.—Improved Breast Drill, two speeds, nickel plated, rosewood handles, steel jaws, malleable-iron stock and breast-plate, with two pairs of jaws, cut gears, ball thrust. Price ......................................................27/6
  - 463A.—Archimedean Drill, with spring head and ebonised handle ; length, io in. .. .. .. .. .. 3/-
  - 464.—Superior Sheffield Braces, perfect alignment, steel sweeps, steel ratchet wheels, ball-bearing heads, with hardened and tempered steel ball races, octagonal grip, drop-forged steel jaws, self-opening spring jaws, interchangeable parts, highest possible finish, best English product.
  - First Sheffield quality—lignum head, rosewood handle, nickel-plated.
  - 466. — Bench Drill. This is a nicely-finished and substantial little machine, with solid iron frame, cut gears, steel feed-screw and adjustable table, all well made and nicely fitted. It has a 3-jaw chuck — o to l in.,®|* eight nicelyfluted drills 1%. |
  - —iV to in. Height from table to feed-wheel is 13 in. Packed in box, size i6|xiox6| in. Gross weight, n lb. Price ....................................35/-
  - 467.—Bench Grinder. This has machine cut wheels, the bearings are accurately made. Height, 10 in.; width, 8 in. ; depth, 6 in. The clamp will fit on to a 2 in. bench. It carries rests for right and left hand. It is supplied with an emery wheel, 4x1 in. Diameter of spindles | in. Net weight, 8 lb.
  - 8 in. sweep, plain 9/6 ; with ratchet 10 in. „ 11/6; „
  - .. 14/-.. 15/6
  - Price.......................... ..£2 7 6
  - each
  - 468.—Best Canterbury Hammers,
  - 2/6
  - oval handles, strongly made, medium size,
  - each
  - 3/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.48 - vue 56/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 49
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LABORATORY TOOLS
  - 469.—Nail Puller, English manufacture.
  - Small, 16 in. Medium, ig| in. Large, 28 in.
  - 14/6 18/- 27/6
  - These are most useful tools for the laboratory. With one a box can be opened in half the time, and with hardly any labour. The nails are drawn out without breaking or bending them, and the box and lid remain sound for future use.
  - 470.—Case Openers, best English make, forged steel.
  - Length.............10 12 14 16 in.
  - Price, each .. ..5/6 7/- 7/6 8/-
  - 471.—Turnscrews, cast steel, beech handles.
  - 3 4 5 6
  - 10d. 1/- 1/3 1/9
  - 7 8 in.
  - 2/- 2/3 each.
  - 9
  - 2/8
  - 10 n 12 m.
  - 3/- 3/6 4/3 each.
  - 472.—Turnscrews, spindle.
  - 6 7 8 10 in.
  - 1/2 1/5 1/6 1/8 each.
  - 12 14 16 18 20 in.
  - 1/10 2/- 2/3 2/6 3/3 each.
  - 474.—Pincers, guaranteed best make.
  - Length .. .. 6 7 8 9 in.
  - Price, each .. .. 1/6 2/- 2/6 3/-
  - Price, each .. . . 2/- 2/6 3/3 4/- 4/9 6/6
  - 476.—Pipe Wrench Pliers, best quality.
  - Length .. ..6 7 9 12 14 16 in.
  - Price, each .. ..1/9 2/3 3/- 4/6 6/9 10/-
  - 477.—Combination Pliers, containing wire
  - cutter, flat nose pliers, screw driver, wrench and gas pliers—gripping pipes from J to i£ in. diameter. Length, 6£ in.
  - Each ..................................3/6
  - 473.—Gem Spanner, wrought steel bar, thoroughly well made and gun-hardened. Each .................................2/9
  - Oup Balances and Weights have' achieved World-wide Reputation: vide Opinions of the
  - Leading Scientific Press.
  - E
- p.49 - vue 57/555
- - 50 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - LABORATORY TOOLS
  - 478.—Cutting Pliers, new improved pattern* Solid cast steel, made by machinery, and of very superior quality. Wherever wire is used these pliers will be found invaluable.
  - Each ..............................3/6
  - 480.—Round Nose PI iers, solid cast steel, best quality ..................each 2/3
  - 481. —Flat Nose Pliers, solid cast steel, best
  - quality ............................each 2/3
  - 482. — Cutting
  - Nippers, very powerful.
  - Per pair .. .. 5/-
  - 483. —Ditto, cheaper, but good quality per pair 3/9
  - 479.—Metallurgical Shears, large, for fixing in block on table, very useful for shearing thick metal. Each .. .. .. .. .. .. .. 32/6
  - 484.—Shears, best
  - quality, for cutting metal, wire gauze, etc. Length .. 7
  - Each .. .. 2/9 3/
  - (If fitted tvith spring, each extra 10d.)
  - 485.—Complete Soldering Outfit, in polished wood case. Box, 11 x 6 X 2| in. Containing lamp, soldering iron, three-square file, bottle of solution, brush, stick of solder, and piece of sal-ammoniac.
  - Price .............................................11/-
  - 486 .—Ditto. Box, 11 X 6 x 21 in. As illustrated, containing lamp, two soldering irons, half-round file, three-square scraper, bottle of solution, brush, stick of solder, and piece of sal-ammoniac.
  - Price .. .. .. .. .. .. .. .. .. 15/-
  - 487.—Soldering Irons, best make.
  - Weight of Copper Head i * f lb.
  - Price, each .. 2/6 3/- 4/-
  - Weight of Copper Head. 1 i* lb.
  - Price, each .. 5/- 6/6 7/6
  - 488.—Gas Burner and Oven, for small light soldering bolts. This will heat one bit and keep another nearly ready for use, so that the two can be used in succession.
  - Price, without bits.................................9/6
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.50 - vue 58/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 51
  - W. & J. 'GEORGE (LONDON), Ltd., PROPRIETORS.
  - LABORATORY TOOLS
  - 489.—Parallel Bench Vices.
  - Extra strong. Guaranteed finest make and finish.
  - Size No. 00 0 1 2
  - Weight about 5 7 11 20 lb.
  - Jaws 2& 2| 3 3|in.
  - Opens .. 2| 3 3i 4i »
  - Each 12/6 13/6 15/6 24/-
  - Size No... 3 4 5 6
  - Weight about 30 45 67 89 lb.
  - Jaws 4 4* 5 6 in.
  - Opens .. 5 5* 6 7 »
  - Each 33/6 37/6 55/- 70/-
  - 490.
  - Bench Vice,
  - very strongly made, of solid wrought steel.
  - Each .. 12/6
  - 491.
  - Clamps,
  - malleable iron, with machine - turned screw, best make.
  - 3 in... each 3/9
  - 4 in... ,, 4/6
  - 5 in... „ 5/6
  - 6 in... „ 6/-
  - 492.—Hand Vice, nicely nickel plated, for holding small articles steadily in the hand.
  - Each.............3/6
  - 493.— Hand Vice,
  - solid wrought steel, best quality.
  - Each .. .. 3/9
  - 494.—Hand Saws, excellent quality, cast steel, beech handles, polished edges, three screws. A first-rate cheap saw, excellent finish.
  - 10 12 14 16 18 in.
  - 3/- 3/6 3/9 4/- 4/6
  - — 20 22 24 26 in.
  - — 5/- 5/6 6/- 6/6
  - students’ use .. .. each 7/6
  - 496.— Goniometer, steel, nickel- plated ; diameter of scale 6 in., length of slide 12 in. '
  - Each .. 17/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
  - E*
- p.51 - vue 59/555
- - 52
  - SECTION 2.
  - 501 .—Snap Pocket
  - Case, containing plain - pointed bow compasses, with adjustable pen, pencil and divider points; holder (for converting pen point into a ruling pen and divider point into a pricker) ; case for reserve leads, drawing-pins and compass key. Brass instruments.
  - Each ....................................5/-
  - INSTRUMENTS
  - 500.—Students’ Set of Mathematical
  - Instruments in tin pocket case, containing solid cast brass pencil compass, 4-in. solid cast brass divider, one each tinned steel set squares, 6o° and 45°, tinned steel protractor, 6-in. hardwood rule and pencil.
  - Each.......................... .. 2/3
  - Per dozen .. .. .. .. .. .. 24/-
  - 502.—“ Science School ” Set of Math ematical Instruments, in
  - elegant snap case, containing double steel sector-jointed bow compasses with " bolt and nut ” needle point, pen and pencil points and lengthening bar, sector-jointed divider, ruling pen, case for leads, and drawing pins.
  - Each ..................................11/6
  - 503.—“ Technical School ” Set in elegant snap case, containing double-jointed needle-pointed bow compasses, with adjustable pen and pencil points and lengthening bar ; improved pattern divider; drawing pen with unbreakable white celluloid handle; case for reserve leads and needles ; drawing pins and compass key ; steel-jointed throughout. Brass instruments.
  - Each .. .. ..... .. .. .. .. .. 17/6
  - 504 .—Ditto, ditto, electrum instruments ... .. each 21/-
  - 505 .—Ditto, but both pens with hinged nib. Brass instruments.
  - Each............................................. •. 25/-
  - 503-4
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.52 - vue 60/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 53
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DRAWING INSTRUMENTS
  - 506.—The “ School ” Set Geometrical
  - Instruments, in handsome magazine case (polished, slide lid, etc.), containing plain-pointed bow compasses with adjustable pen, pencil and divider points; holder (for forming capital ruling pen and pricker); case for reserve leads; pair of superior pearwood set squares (7" 6o° and 4" 45°) ; 6-in. boxwood rule with inches and TVths, millimetres, etc. ; 4-in. brass protractor; pencil; eraser; pencil
  - sharpening block ; drawing pins and compass key. Brass instruments.
  - Each .........................................6/6
  - 507. —3fin. Brass Dividers
  - each 6d.
  - 508. —4 in. Brass Dividers
  - each 9d.
  - 510. —4-in. Brass Pencil Compass, to take
  - any size pencil .. each, 9d. ; per doz., 9/-
  - 511. —Ditto, ditto, with bow head
  - each, 10d. ; per doz., 10/-
  - 512.—3£-in. Brass Pencil Compass. The 509. —Beam Com passes, " Helix-Fawkes ” reversible point takes any size pencil student’s pattern. each, 1/1 ; per doz., 12/6
  - Price, including lath ..
  - 6/-
  - 513.—Blackboard Compasses, hardwood.
  - A. 16 in. long...................... .. each
  - B. Ditto, best quality .. .. ..
  - 2/6
  - 6/6
  - 514. —3-in. Stout Brass Semicircular Protractor, 1 row of figures .. per doz. 6/-
  - 515. —3-in. Brass Semi-Circular Protractors, two rows of figures .. per doz. 7/-
  - 516. —4-in. ditto, ditto, one row of figures
  - per doz. 8/-
  - 517. —4-in. Stout Brass ditto, two rows of
  - figures .. .. .. .. .. per doz. 9/-
  - 518.—4-in. Celluloid Semicircular,
  - divided to degrees............per doz. 6/-
  - 519. —6-in. ditto, ditto, divided to half degrees
  - per doz. 17/6
  - 520. —6-in. ditto, ditto, divided to half degrees
  - per doz. 20/-
  - 514/7
  - Our stock of pure Chemicals and Acids is very considerable.; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.53 - vue 61/555
- - 54 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DRAWING INSTRUMENTS
  - 521.—6-in. Pupil’s Metric Protractors, with
  - scale of inches and |ths, TVths, and TVths, and lines of centimetres and chords. Boxwood.
  - Each........................................11 d.
  - Per dozen .. .. .. .. . . .. .. 10/6
  - 5SI
  - VI •i «l ’I «l »| 1 •I ’1 «l *1 «l"»
  - V. «1 *1 ~
  - */4 ^ I ^ ' *1 ' *1
  - INCH * *1 2 *1
  - Cl IO_ ' llo I «|° 1 4(0 1 g|o 1 e|o i 7|o 1 e|o , p| e
  - ill r l I Is. I I I I I I I iJ UJ !.l I. 111 |E| 11111111 111 111111 j Pi 1 mTi
  - 522.—6-in. 4-Scale Protractors, with line of centimetres. Boxwood.
  - Each Per doz.
  - 11d.
  - 11/
  - 523.—Circular Protractor for dividing circles, brass arm and silvered dial.
  - Each ......................£15 0
  - 524.—Ebony Bar Parallel Rules.
  - 6 9 12 15
  - A. School quality, solid bars each 9d. 2/- 3/- 3/6
  - - B. Best quality, open bars ,, 1/6 2/6 4/- 4/6
  - A. 4to Imperial, full size 16 X n| in. . each 4/-
  - B. | Imperial 19 X 13! in. . 5/6
  - C. \ Imperial, full size 23 X 16 in. . • „ 7/-
  - D. Royal 22 X 17 in. . • „ 7/-
  - E. l Double Elephant .. d o\ H tJ- • „ 9/-
  - F. Imperial 28 X 19 in. . „ 10/6
  - G. Imperial, full size .. 31 X 23 in. . „ 14/6
  - 525.—Clamped Deal
  - Drawing Boards,
  - best make and finish.
  - 526. —T Sq uares, French shape (as illustrated).
  - Length of blade 12 15 18 21 24 32 inches.
  - Each .. 11d. 1/- 1/2 1/4 1/7 1/10
  - 527. —T Squares, English shape (as illustrated).
  - Length of blade . 24 32 42 inches.
  - A. Polished beech wood . 3/3 4/- 5/- each.
  - B. Pear wood . 2/6 3/- 3/6 „
  - C. Mahogany, edged with ebony . . 6/- 8/- 12/- „
  - 527 English Shape.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.54 - vue 62/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 55
  - W. & J. 'GEORGE (LONDON), Ltd., PROPRIETORS.
  - DRAWING INSTRUMENTS
  - 45 DEGREES. 60 DEGREES.
  - 528.—Set Squares, best red pear wood.
  - 468
  - A. 45 degrees .., .. .. 2/- 3/3 5/3
  - B. 6o degrees........— 2/- 3/3
  - io inch.
  - — per dozen.
  - 5/3 per dozen.
  - 529 .—Transparent Celluloid Set Squares. 530.—Framed Set Squares, polished ma-
  - 45 degrees. 60 degrees. hogany with ebony edges.
  - A. 4 inches each 1 /- each 8d. 45 degrees. 60 degrees.
  - B. 6 „ „ 1/9 » v- A. 6 inches each 2/6 each —
  - C. 8 „ „ 2/6 „ 1/9 B. 8 „ „ 3/- .. „ 2/6
  - D. 10 „ 3/9 „ 2/6 C. 10 ,, 3/6 » 3/-
  - E. 12 „ 5/3 „ 3/9 D. 12 „ — „ 3/6
  - DRAWING PINS
  - THESE ILLUSTRATIONS ARE THE EXACT SIZES OF THE DRAWING PINS.
  - 531.—English-made Drawing Pins
  - (Highest Quality and Finish).
  - Per gross.
  - A. Brass .. .. .. .. .. 3/-
  - B. 3/-
  - C. 3/6
  - J. „ long points......... 7/6
  - T. Steel, with 3 points .. .. 2/9
  - X. Brass .. .. .. .. 4/-
  - No. 1. Brass ............... 7/-
  - „ 2L. „ 7/6
  - „ 16. „ 12/-
  - ,, 21. Brassed Drawing Pins, small 1/4
  - ,, 22. „ „ „ medium 1/6
  - „ 23. „ „ „ large 1/8
  - „ 43. Albata.................,, 18/-
  - ,, 52. Brass .. .. .. ,, 10/6
  - „55- „....................... „ 8/6
  - 532.—“ Best of All ” Drawing Pins (Patent).
  - Brass. No. 1 (large) .. .. .. per gross 18/-
  - „ No. 2 (medium)....................... „ 15/6
  - „ , No. 3 (small) .. „ 14/6
  - 533 —Neat round Metal Boxes containing three dozen large Brassed Drawing Pins, with long points.
  - Per box .. .. .. .. .. 6d.
  - The other sizes of drawing pins as illustrated are not now manufactured.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.55 - vue 63/555
- - 56 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PLAN I METER
  - 534. —Planimeter, Amsler’s, arranged for measuring areas in either of several units (English and Metric) or scales to a range of 24 in. in diameter. Complete in lined case.
  - Price ......£6 5 0
  - PANTOGRAPHS
  - For enlarging or reducing and copying Photographs, Maps, etc.
  - 535. —Beechwood Pantograph, enlarges only .. each 1/3
  - 536. —Superior quality ditto .. .. .. .. .. .. „ 1/6
  - 537. —Superior Beechwood Pantograph, with sliding fittings
  - and closely divided, enlarges and reduces .. .. .. .. each 5/6
  - BLACKBOARDS, Etc.
  - 538.—Blackboards.
  - 24 X 18 36 X 24 42 X 30 48 X 36 in.
  - 17/6 34/- 42/6 60/- each.
  - 539.—T Squares for Blackboards.
  - Beechwood, 36 in., with handles .. .. each 5/-
  - „ 42 in. „ .. .. „ 6/-
  - 540.—Set Squares for Blackboards, beechwood, with handles—
  - A. 18 in., 45 degrees......... .. each 5/-
  - B. 18 in., 60 degrees .. . .. .. „ 5/-
  - 541.—Easel for Blackboard, double sided, with pegs both sides deal, 6 ft., .. each 30/-
  - 542.—Compasses for Blackboards.
  - A. Hardwood, 16 in .. each 2/6
  - B. Superior quality, 16 in. .. „ 6/6
  - 543.—Chalk Holders :. .. each 9d.
  - 544.—Sponges .. each 1 /-
  - 545.—Lecturers’ or Blackboard Chalks,
  - also suitable for free-arm drawing.
  - A. ROUND WHITE, wooden boxes of 1 gross each 1 /6
  - Card boxes of 1 dozen .. .. .. ,, 5d.
  - B. ROUND COLOURED, 6 colours—
  - Wooden box of 1 gross, assorted .. „ 3/-
  - Card boxes of 1 dozen, assorted .. „8d.
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.56 - vue 64/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 57
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - “NIVOC” PATENT MATHEMATICAL STENCIL
  - Designed by C. Pask Matthews, B.Sc. Hons. Lond., F.I.C., F.C.S.
  - The need of a rapid method of constructing figures to illustrate problems in the Conic Sections has long been felt by students of mathematics. This stencil is designed to provide a simple solution of this difficulty, and does away with the labour involved in the usual methods of obtaining a curve even approximating to the true form. By means of it all the diagrams required in the study of the subject may be accurately drawn in a few seconds.
  - CONIC SECTIONS, PARABOLAS, HYPERBOLAS, AND
  - ELLIPSES CAN BE DRAWN EASILY, RAPIDLY AND ACCURATELY.
  - Catalogue No. 546. Price
  - each 1 /6
  - Directions for use.
  - To the student conversant with the geometry of the conic, no directions are necessary, but for those who are not we give the following constructions :—
  - The Parabola.—The outer edge of the stencil at Px P2 and P3 represents parabolas of differing focal length, and to draw the curve the pencil is pressed well against the edge and passed round the one required. A dot is next made where the line Px P2 or P3 meets the curve, thus giving the vertex, and finally the pencil is passed through the corresponding hole px pz or pz to make a dot, which is the focus. The axis is obtained by joining the two dots, and producing, the directrix being a line at right angles to it at a distance from the vertex equal to the focus.
  - The Ellipse.—The pencil is passed round within the cut-out E of the stencil and dots made where the lines e1 e2 e3 ei meet the curve. The axes are given by joining ex e2 and ez eit and the foci by striking arcs with a compass across the major axis from centre es with radius equal to half the major axis.
  - The Hyperbola.—The rectangular hyperbola is given by marking round the curved portion of the cut-out H. Dots are also made through the holes at hx h2 h3, and one also at the focus ki. By joining these as shown on the stencil, the directrix, axis and asymptotes are obtained.
  - The outlining of the curve H represents an hyperbola of eccentricity 2, and by making dots through h\ h\ h'z and at the focus h\, the directrix, etc., are given on joining, the lines being shown on the stencil.
  - The rightward curve of H" is the hyperbola conjugate to the last, and requires dots to be made through h"x h'\ h's for the directrix, etc.
  - The figures A and A x give the useful angles of 30, 45, 60 and 90 degrees ; a scale in eighths of inches is also attached.
  - N.B.—Use a sharp-pointed pencil.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.57 - vue 65/555
- - 58 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.,
  - CALCULATING RULES
  - 547.—New Metal “ Students’ ” Slide Rule,
  - n-inch, transp. cursor ; contains Scales A, B, C, and D ; sine, tangent, log and log-log scales ; special electricians’ “ Dynamo-Motor ” and “ Volt-Loss ” scales ; simple and very accurate ; a mathematical education in itself ; a rule for students, for working engineers useful for hot climates.
  - Price, in case .. .. .. .. each 5/-
  - Students’ Slide Rule, constructed entirely of metal, with the addition of an unbreakable Transparent Free-view Cursor, and eminently suited for withstanding the most extreme climatic conditions. Warping, shrinking, and breaking are eliminated.
  - The provision of an extra Slide enables the new “ Students’ ” Slide Rule to combine within itself the principal distinctive features of nearly all the best-known modern Slide Rules, so that the expert possessing it has at his disposal (in a large measure) the same resources as would be furnished by a whole collection of Rules, comprising, say, the standard “ Gravet ” or “ Mannheim,” the “Fix,” “ Rietz,” “ Jackson Log-log,” " Perry,” “ Faber,” “ Electrician,” and “ C.E.M.” Slide Rules ; and the student who gives himself the real pleasure of thoroughly mastering its principles and capabilities will know pretty nearly all there is to know about the underlying principles of the nine Rules named, and be in a fair way, with practice, to becoming a Slide Rule expert himself.
  - 548.—Students’ Slide Rules (useful for learning the principles ; to be replaced later by a best quality rule for real work). 6-in. cardboard slide rule, with metal cursor.
  - Each.............................2/6
  - (Price includes neat paper case.)
  - 549/369 (Actual size).
  - 549/369.—Faber’s Pocket Precision Calculating Rule, 6 in. long, with white celluloid surface and ordinary aluminium cursor with glass. Similar to rule 551/360 in arrangement, see next page. (Book of Instructions, 3/- extra.)
  - Each
  - 14/-
  - 550/361 (Reduced size).
  - 550/361 .—Faber’s Students’ Precision Calculating Rule, n in. long, with white celluloid surface and ORDINARY aluminium cursor with glass. On the face of the rule are the two usual logarithmic scales with decimal figuring 1. 1,1. 1,2. 1,3. for multiplication and division, squaring and cubing, together with the extraction of square and cube roots.
  - On the upper bevelled edge is a centimeter scale and at the bottom an inch scale. (Book of Instructions, 3/- extra.) THIS RULE IS SPECIALLY SUITABLE FOR USE IN INTERMEDIATE AND TECHNICAL SCHOOLS. Each ....................... ..........................................................................................15/9
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.58 - vue 66/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 59
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CALCULATING RULES
  - 77777777777777J777777777777777777777777777777777777777
  - 90 100
  - v 80 90 WO
  - Quot
  - 360 *A.W. FABER WCASZECC'^ |fe
  - 0R.PATENT. MS 206428
  - 55i/36o (Reduced size).
  - 551/360.—Faber’s Precision Calculating Rule, II in. long, with white celluloid surface and ordinary aluminium cursor with glass. On the upper face of the rule are the two usual logarithmic scales for multiplication and division, squaring and cubing, and the extraction of square and cube roots. On the under side of the slide are the sine and tangent scales, SS and TT, for carrying out trigonometrical calculations, and the logarithmic scale LL, by means of which higher powers and roots can easily be determined.
  - This is a very important rule, which is of great service for technical and commercial calculations. It appeals to the Architect, the Constructional Engineer, the Mechanical Engineer, the Electrical Engineer, the Physicist and the Chemist.
  - Each .........................................................................£110
  - iminiifiiiiiiiii}j;iiiuuiiiiiiiuiiiuiiiinfT]uni^tiiimm\ yimijummiQuuimr:
  - '0 , '80 • 90
  - Dynamo
  - Quot.
  - -1 •
  - 552/378 (Reduced size).
  - 552/378.—Faber’s Precision Calculating Rule, ii|- in. long, with white celluloid surface and ordinary aluminium cursor with glass. In addition to the same scales as on rule No. 551/360, this carries three other logarithmic scales, by means of which powers and roots of the form ax and -\/a can be calculated, where a; may be fractional. The length of the rule imposes a limit to the scale, and having regard to the most usual values required, it is arranged to extend from i-i to 100,000. Further, the efficiency of a dynamo or motor can be determined by a single setting of the slide, while the cross section of an electrical copper conductor for continuous or alternating current, free from induction, can be obtained by two settings of the slide, the other necessary data being given.
  - This special slide rule, for Electrical and Mechanical Engineers, has been very extensively adopted in professional circles owing to its practical utility and simplicity of operation. It is an indispensable aid not only to the Special Engineer, but also to the Manufacturer and Works Manager.
  - Each ..........................................................................£116
  - 553/367 (Reduced size).
  - 553/367.—Faber’s Precision Calculating Rule, 11 in. long, with white celluloid surface and digit registering aluminium cursor with glass. Similar to rule No. 360 in arrangement, but with indication marks on the stock.
  - Each ................ ...............................................£16 3
  - 554 —Book giving full instructions for the uses of above rules .. .. .. .. .. .. each 3/-
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.59 - vue 67/555
- - 60 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WATCH FORM CALCULATOR
  - Price complete with manual containing all data and formulae explanatory of the uses of the Watch Form Calculator .. .. .. 21 /-
  - 555.—Watch Form Calculating
  - Rule, an invaluable and indispensable instrument superseding the older types of slide rule, combining all the advantages of the Slide Rule with those of the Pocket Calculator.
  - Being only J in. thick, and is very neat and compact, and is always at hand, being carried in the waistcoat pocket without the slightest inconvenience.
  - Being in a circular form, the reading is continuous without any break or end.
  - The Cursor Lines are very fine and very close to the Dial, and ensure great accuracy in reading.
  - Most calculations are made with only one setting.
  - It gives a great range of proportions at each setting.
  - If the accuracy of the setting is doubtful, it can be tested at any time.
  - The scales for inverse proportions are close together and can be set and read without the Cursor.
  - “NIVOC” LABORATORY NOTE-BOOKS
  - Ruling guaranteed accurate.
  - Cat. No. Size without Margin. Divided into Remarks. Number of Pages. Price, each.
  - 556 8 X 6 in. 2 mm. squares Thickened line every 2 cm. 120 2/-
  - 557 8 x 6 in. 2 mm. 60 1/3
  - 558 8 X 6 in. 1 mm. ,, Thickened line every f, 1 and 5 cm. 120 2/6
  - 559 8 x 6 in. 1 mm. 60 1/6
  - 560 8 X 6 in. 1/10 in. Thickened line every \ and 1 inch. 120 2/6
  - 561 8 X 6 in. 1/10 in. ,, 60 1/6
  - “ Nivoc ” Sectional Paper and Note Books are unrivalled for accuracy and clearness of printing. They are printed in non-fading inks, and in all cases have wide margins for notes.
  - “NIVOC” ACCURATE SQUARED PAPER
  - No. Size, without margin. Divided into Prices, Per quire.
  - 562 20 X 15 cm. 2 mm. squares 1/3
  - 563 8 X 6 in. TVr in. squares V-
  - 564 15 X 10 in. -2\y in. squares 2/6
  - 565 15 X 10 in. TV in. squares 2/-
  - 566 15 X 10 in. | in. squares 2/-
  - Note.—Thickened lines same as paper above. All books are ruled with squares on one side only, the other side being ruled ordinary note.
  - " O
  - 567.—Squared Paper, finest quality, guaranteed accurate, ruled in mm.'s and cm.’s, size of sheets 56 x 43
  - cm. .. .. .. .. .. .. per sheet 5d.
  - 568 .—Ditto .. .. .. .. .. per quire 6/-
  - irH
  - Eirr
  - 569.—Logarithm Paper,
  - special ruling 25 X 25 cm. Price, per quire . .. 4/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.60 - vue 68/555
- - *
  - OPEN HERE
- p.n.n. - vue 69/555
- - CERTIFICATE
  - ---OF-----
  - EXAMINATION
  - Of
  - A CHEMICAL BALANCE.
  - Marked:- 5.1^ 47616*
  - By:- Messrs* F.E* Becker & Company*
  - The component parts of this balance have’been examined and assembled at the National Physical Laboratory, Teddington, Middlesex, and found to be in good condition and working order.
  - The agate knife edges and planes are satisfactory.
  - Variation in Sensitiveness and Period of Swing obtained by
  - altering the Position of the Sensitivity Nut on the Beam*
  - The range allowed for the adjustment of the sensitivity nut gives ample variation of sensitiveness to the balance*
  - Observations have been made with the sensitivity nut in three different positions, the approximate results being set out in the following table* 'the sensitivity should be re-determined when the balance Is finally set up*
  - Date :
  - 8th August, 1919.
  - R,fmnee ; M*W
  - 69*964
  - Table/
  - £ * .
  - Director.
  - Wt. P423 Im-6-18 W F P
  - N P h 86b
- p.n.n. - vue 70/555
- - We received an order from the Chemical Laboratories of the Royal Arsenal, Woolwich, withj the request that the Balances be certified by the NATIONAL PHYSICAL LABORATORY. The
  - Balances were taken at random from our stock and sent to Teddington. A copy of the certificate is shewn on other side. Also see copy of unsolicited testimonial on next folder.
  - OPEN HERE
- p.n.n. - vue 71/555
- - CONTINUATION. OP CERTIFICATE OF EXAMINATION OF A CHEMICAL BALANCE.
  - (f£ 47616)
  - Position of Sensitivity Nut • Height of nut above lower end of pointer * Load Criterion of Sensitiveness of Balance (value of 1 division of white scale) Period of complete (to and fro) Swing of Balance«
  - Low 6.1 inches 0 grammes 0*003 gramme 8 seconds
  - Low u ii 100 ii 0.003 " 12 ii
  - Low II it 200 ti 0*003 " 16 ii
  - Mean 7.3 ii 0 grammes 0*0010 gramme 14 seconds
  - Mean ti ii 100 ii 0-0010 " 22 it
  - Mean ti it 200 n 0.0010 " 28 ii
  - High 7 .7 11 0 grammes 0*0002 gramme 30 seconds
  - High ii n 100 ii 0*0002 " 45 n
  - High it it 200 it 0*0002 56 it
  - * The position of the nut is defined "by the distance between the middle groove of the nut and the lower end of the pointer.
  - NOTE :-
  - The value given in the fourth column of the above table is the/mass required to be added to one pan of the balance in order to change the rest point by one division of the white scale. The smaller the value given, the more sensitive is the balance*
  - Reference'- M*W.69«96* Date:- 8th August, 1919.
  - Range/
  - Wt 86899 lM ll-20 WFP Ltd NPL 88a
- p.n.n. - vue 72/555
- - CONTINUATION. OF CERTIFICATE OF EXAMINATION OF A CHEMICAL BALANCE.
  - (te 47616)
  - Range of Load *
  - The balance was found to take loads up to 200 grammes
  - satisfactorily.
  - There was a slight creep in the rest point of the order of
  - 0*8 division of the white scale during observations made with loads ranging from 0 grammes to 200 grammes. This, however, only occurred in the condition of maximum sensitivity. Continued application of a 200 gramme load caused a further creep of the rest point and it is therefore inadvisable to maintain such a load for any considerable length of time*
  - Graduation of the Rider Bar.
  - The graduations on the rider bar are satisfactory, the zero
  - and the M10M lines being found, with sufficient accuracy, vertically over the fulcrum and terminal knife edges respectively.
  - Director•
  - Reference: M*W. 69.96.
  - Date: 8th August, 1919.
  - Wt 26399 Im-U-20 WFP Ltd NPL 88a
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- p.n.n. - vue 74/555
- - COPY OP UNSOLICITED TESTIMONIAL
  - Taunton's School, SOUTHAMPTON.
  - March 13th, 1922.
  - TO : - P. E. BECKER & CO. ,
  - Dear Sirs,
  - The apparatus and chemicals have all arrived in very good condition, and give every satisfaction.
  - I am sending you on separate sheet a short account of a test I have made with the Balance, which you are at liberty to use. The zero point is constant to one-tenth of a division. The sensibility with a load of 10 gm. on each pan is about 4.1 scale divisions. With a load of 10 gm. in each pan, the balance gives results which only differ by a unit or two in the fifth decimal place, i.e., by one or two-hundredths of a milligramme.--Yours faithfully
  - (Signed) Arthur W. Warrington.
  - March 13th, 1922.
  - I have examined the Balance you have sent to the Taunton’s School.
  - (a) The zero point was constant. I made the following six determinations with different loads. The centre of the scale was taken as 10.
  - (1) 9.7, 9.8, 9.8 9.9. (4) 9.3, 9.4, 9.6
  - (2) 13.6, 13.6, 13.6. (5) 5.0, 5.0, 5.1.
  - (3) 5.3, 5.4, 5.6. (6) 13.3, 13.2, 13.3.
  - Prom these figures it will be seen that the zero point is constant to
  - one-tenth of a scale division.
  - (b) The deflection for one milligramme extra load was very constant. The following six determinations in scale divisions give the effect of an extra load of one milligramme:-
  - 4.14, 4.16, 4.07, 4.12, 4.03, 4.08.
  - (c) I compared the values of the two ten-gramme weights in one of your boxes, with the following results:-
  - (1) 10-gm. = 10-gm. -f- 0.000055 mg.
  - (2) 10-gm. = 10-gm. -f 0.000049 mg.
  - (3) 10-gm. = 10-gm. -f 0.000030 mg.
  - It is clear that with a load of ten grammes and weighing by vibrations
  - and using Gauss’ method the balance gives results accurate to the hundredth of a milligramme.--Yours faithfully,
  - (Signed) Arthur W. Warrington.
  - Pormerly assistant lecturer and demonstrator in Chemistry at the University College of Wales, Aberystwyth, and sometime Professor of Natural Philosophy at the Imperial University, T'ai Yuan Pu, China, and now Chemistry Teacher at the Taunton’s School, Southampton.
  - The writer of the testimonial and report on our Analytical Balance in a further letter dated March 28th, 1922, says "I could not refrain from giving your work a spontaneous approval. I am returning the copy of the National Physical Laboratory Certificate which at least shows that the sensibility of your balance does not vary with the weight. All that' Chemists require in ordinary Research Work is a balance with a constant zero point, which is sufficiently sensitive to give without too long a period of vibration, res'ults reliable to 0.0001 gramme. These requirements your balance perfectly fulfils."
  - OPEN HERE
- p.n.n. - vue 75/555
- - CERTIFICATE
  - ----OF-----
  - EXAMINATION
  - OF
  - A SET. 03? WEIGHTS.
  - Sent by MessrsJT.E*Becker & Company.
  - Material:- 50 grammes to 1 gramme.................Brass.
  - 500 milligrammes -to 50 milligrammes... .Gold.
  - 20 milligrammes to 1 milligramme.....Aluminium,
  - Two Riders............................Aluminium.
  - Box markedN? 50339.
  - Distinguishing mark or form of weight.
  - re so G 20 10 10 5 2 2 1
  - 500 M G
  - Date:
  - Reference ;
  - Density.
  - 3.29 (determined)
  - Mass (to Class B accuracy),
  - 50.000 grammes
  - ,29 (assumed) 20.000 ii
  - 11 t» 10,000 u
  - II it 10,000 u
  - II u 5,000 ii
  - ll ii 2.000 ii
  - It 2.000 ti
  - II it 1.000 tt
  - 19.3 (assumed)
  - 0.5000 gramme
  - May 17, 1921. M.W. 98. 102.
  - Wt P408 SM-6-18 WFP
- p.n.n. - vue 76/555
- - CONTINUATION. of Certificate of Examination of a Set of Weights. Box marked:- N? 50339.
  - Mass (to "Class B
  - Distinguishing mark or form of weight.
  - accuracy).
  - Density
  - 0.2000 gramme 0.1000 "
  - 0.1000 u
  - 19.3 (assumed)
  - 0.0200
  - 2.7 (assumed)
  - 0.0100
  - 0.0100
  - 0.0020
  - 0.0020
  - 0,0010
  - 0.0010
  - 0.0100
  - 2.7 (assumed)
  - 0.0100
  - The above values may be taken as accurate to
  - -0,001 gramme in the Case of weights of 1 gramme and upwards 'io.0001 gramme in the case of fractional weights.
  - Within
  - Date:-
  - Reference:- M.W, 98. 102.
  - Director.
- p.n.n. - vue 77/555
- - We received an order from the Chemical Laboratories of the Royal Arsenal, Woolwich, with the request that the Balances be certified at the NATIONAL PHYSICAL LABORATORY. The Balances were taken at random from our stock and S£nt to Teddington. A copy of the N.P.L. certificate is shown on accompanying folder. Also see copy of unsolicited testimonial on other side of this folder.
- p.n.n. - vue 78/555
- - 61
  - BALANCES & WEIGHTS
  - We still hold the unique position of being the Leading House in the Trade for Balances and Weights
  - See copy of National Physical Laboratory Certificate on flyleaf herein. Also copy of unsolicited testimonial.
  - Our Balances and Weights hâve achieved World-wide Réputation : vide Opinions of the Leading
  - Scientific Press
  - F. E. BECKER & Co.’s ANALYTICAL BALANCE
  - Capacity : 200 grammes in each pan. Sensitivity : milligramme when carrying full load.
  - Price - £16 : O : O
  - 570.—F. E. BECKER & Co.’s ANALYTICAL BALANCE. Désignée! particularly to meet the demand for a high quality reliable Analytical Balance at a moderate price. The Beam, which is free from ail complicated adjustments, is graduated along its entire length and being black with white graduations is easily read. The rider apparatus is of new design specially constructed for rapid manipulation traversing whole length of beam. The knife-edges and planes are of the best quality agate throughout. The case is of superior polished mahogany with glass top, two side glass doors and sliding counterpoised front window, the whole being mounted on a heavy thick black glass base with massive brass levelling screws and spirit level.
- p.61 - vue 79/555
- - 62
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL,“ LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s SHORT BEAM BALANCE
  - (BUNGE’S SYSTEM)
  - ^ '11 '
  - 571. —F. E. BECKER & Co.’s SHORT BEAM BALANCE, to carry 250 grammes in each pan ; sensitive
  - to the tenth part of a milligramme when loaded with its maximum charge. Beam and pillar richly gilt. Platinised pans. Beam is notched, each notch being equal to one-tenth of a milligramme and 100 notches to a centigramme. Arrestments for beam, stirrups, and pans. Rider apparatus.
  - In polished mahogany case (mounted on black plate glass base) with counterpoised sliding front and glass doors at sides. Spirit level and levelling screws.
  - Capacity : 250 grammes. Sensitivity : -jg milligramme.
  - Price - £15 : O : O
  - 572. —Ditto, as above but in polished hardwood case.
  - Capacity : 250 grammes. Sensitivity : TV milligramme.
  - Price - £13 : lO : O
  - Every requisite for Chemical, Physical and Bacteriological work supplied, from a test tube to the complete
  - furnishing of the largest laboratory
- p.62 - vue 80/555
- - 63
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD. PROPRIETORS
  - F. E. BECKER & Co.’s ANALYTICAL BALANCE
  - “Triangular Beam” Pattern
  - 573.—F. E. BECKER & Co.’s SHORT BEAM BALANCE (Bunge’s system), in elegant mahogany case with front and back sliding doors and two side doors. Bottom of case made of black plate glass. Agate knife-edges and planes. The beam, which is in one piece and richly gilt, is divided into 100 parts. The pans are platinised, and provided with compensation hangers. Rider apparatus is of the latest design. Arrestments for beam, pan supports, and pans.
  - Capacity : 250 grammes. Sensitivity : To milligramme.
  - Price - £18 : O : O
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. See comprehensive list at end of Chemical Apparatus Catalogue
- p.63 - vue 81/555
- - 64
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s ANALYTICAL BALANCE
  - “ Circular Beam ” Pattern
  - 574
  - 574.—F. E. BECKER & Co.’s “ CIRCULAR BEAM” BALANCE.—Extremely sensitive; latest construction, with agate knife-edges working on agate planes. Beam is fitted with a long and quick-working pointer. Beam and pan supports richly gilt, platinised pans, arrestments for beam, stirrups and pans ; plumb bob, rider apparatus, and scale. Fitted in elegant mahogany case with counterpoised sliding door, mounted on black plate glass base with screws for levelling.
  - Capacity : 250 grammes. Sensitivity : yu milligramme.
  - Price - £19 : O : O
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory
- p.64 - vue 82/555
- - 65
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s ANALYTICAL BALANCE
  - New Design for Advanced Work
  - 575.—F. E. BECKER & Co.’s ANALYTICAL BALANCE. New design for advanced work.
  - The beam is manufactured by a spécial process, making same immune from any variations of température, and is graduated along its entire length engraved in white on a black background, making same easily readable. The rider apparatus is of simple design, and the knife-edges and planes are of best quality agate throughout. The case is of superior polished mahogany with glass sliding front and hinged side doors mounted on heavy black glass base with massive brass levelling screws and spirit level.
  - Capacity : 200 grammes in each pan. Sensitivity : milligramme when carrying Jull load.
  - Price - £12 : 15 : O
  - Our Balances and Weights hâve achieved World-wide Réputation : vide Opinions of the
  - Scientific Press
  - Leading
- p.65 - vue 83/555
- - 66
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s ANALYTICAL BALANCE
  - Several of these Balances are in use in Woolwich Arsenal, the Government Laboratories, National Physical Laboratory, etc.
  - 576.— F. E. BECKER & Co.’s ANALYTICAL BALANCE, agate knife-edges and planes throughout;
  - richly gilt beam graduated along its entire length and rider apparatus of new construction ; extra wide pans ; double hooks and wooden bridge for specific gravity work. Highest quality workmanship and finish, in elegant polished case, with front counterpoised sliding window and side doors ; all mounted on heavy, thick, black plate glass base provided with levelling screws and spirit level.
  - Capacity : 200 grammes. Sensitivity : TV milligramme.
  - Price - £21 : O : O
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory
- p.66 - vue 84/555
- - 67
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s
  - NEW SHORT BEAM ANALYTICAL BALANCE
  - 577—F. E. BECKER & Co.’s NEW SHORT BEAM ANALYTICAL BALANCE, for quick and accurate weighing. The Beam is of new design, with white graduations along its entire length and manufactured by a spécial process from a métal which is not influenced in any way by température variations and is also particularly designed to prevent stresses, etc. The rider apparatus traversing the whole length of the beam is of an improved, simple but efficient type, spécial attention having been given towards minimising the risk of riders falling during operations. The knife-edges and planes are of best quality agate throughout, the knife-edges being fitted with our patent mountings thus ensurmg easy replacement should occasion arise. The case is extra large and roomy of superior polished mahogany with glass top, two side glass doors and sliding counterpoised front window, the whole being mounted on a heavy thick black glass base with massive brass levelling screws and spirit level.
  - Capacity : 200 grammes in each pan. Sensitivity : Tü milligramme when carrying full load.
  - Price - £14 : ÎO : O
  - Our Balances and Weights hâve achieved World-wide Réputation : vide Opinions of the Leading
  - Scientific Press
- p.67 - vue 85/555
- - 68
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s PATENT “RESEARCH” BALANCE
  - SENSITIVE TO THE TWENTIETH PART OF A MILLIGRAMME
  - 578
  - 578.—F. E. BECKER & Co.’s PATENT “RESEARCH” BALANCE, for work requiring the utmost possible ^accuracy. The beam of this Balance is made of magnahum, its special feature being great lightness combined with absolute stability. The end supports are outside the end knife-edges, thus giving absolute rigidity to the beam. The rider scale is graduated from left to right, beginning at zero, thus avoiding all errors in + or — calculations. On placing a 5-milligramme rider on the zero point of rider scale, the pointer will set at zero.
  - This Balance is eminently adapted for use m research laboratories, and we can recommend it with every confidence. It is of handsome appearance, and provided with agate knife-edges and planes ; compensating suspenders which transfer the load to the centre of the knife-edges, platinised pans, rider apparatus of latest construction which lifts rider vertically, arrestments for beam, pan supports, and pans ; in nicely finished mahogany case opening at front, back, and both sides, and mounted on black plate glass base, provided with levelling screws and plumb bob.
  - To carry ............................. 120 250 grammes.
  - Sensitive to ......................... & A milligramme.
  - Price - - - £19 : 15 : O £22 : lO : O
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. See comprehensive list at end of Chemical Apparatus Catalogue.
- p.68 - vue 86/555
- - 69
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s ANALYTICAL BALANCE
  - “ South Kensington ” Pattern
  - 579
  - 579.—F. E. BECKER & Co.’s “ OPEN BEAM ” ANALYTICAL BALANCE, “ South Kensington ” pattern with beam graduated along its entire length. Agate knife-edges and planes. No steel used in its construction. Arrestments for beam and suspenders. Rider apparatus works on both sides of the beam. Plumb bob, levelling screws, double hooks for specific gravity experiments. In highly finished polished case with drawer, glass sides and sliding door, as illustrated. Guaranteed highest-quality workmanship and finish throughout.
  - Several of these Balances are in use in the Imperial College of Science and Technology, South Kensington; Government College, Lahore; Central College, Bangalore, etc.
  - Capacity 250 grammes, and sensitive to j milligramme.
  - Price - £10 : lO : O
  - Our Balances and Weights have achieved World-wide Reputation: vide Opinions of the Leading
  - Scientific Press
- p.69 - vue 87/555
- - 70
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complété furnishing of the largest laboratory
  - F. E. BECKER & Co.’s SHORT BEAM BALANCE
  - “ Ni voc ” Pattern (BUNGE SYSTEM)
  - 580.—F. E. BECKER & Co.’s SHORT BEAM BALANCE. “ Nivoc ” Pattern. Capacity, 100 grammes, and sensitive to ï^th milligramme. Agate knife-edges and planes. Divided beam and spécial rider apparatus. Six agate centres, resting in six agate cups, form the beam and stirrup arrestment. A great feature is the method of lowering the arrestment from the Beam to put the Balance in action. In superior polished mahogany case, with black plate glass base, sliding front and glass doors at sides.
  - Price - £16 : 16 : O
- p.70 - vue 88/555
- - 71
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. &. J GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s CHEMICAL BALANCE
  - “ George Green ” Pattern
  - Copy of unsolicited Testimonial received from the Senior Science Master of the George Green School, East India Dock
  - Road, Poplar, E.
  - To Messrs. F. E. Becker & Co.
  - Gentlemen,—On the occasion of the completion of our equipment order, I beg to cordially thank you and your staff for the courtesy, care, and despatch which have been uniformly observed throughout its execution.
  - The quality of the goods supplied is of a high order, and especially is this so in regard to the Chemical Balances.
  - They are handsome in appearance, simple in construction, and that they are eminently adapted to students’ use is abundantly shown by the daily results obtained by our students.
  - They are simple enough for beginners, and they are sensitive and accurate enough for Honours Students.
  - I shall always feel it is simply your due that anyone you may wish to send should be allowed to inspect your work here.
  - Without Rider Apparatus With Rider Apparatus
  - 581.—F. E. BECKER & Co.’s CHEMICAL BALANCE (“ George Green ’’ pattern). Extra strongly made for students’ use ; cannot possibly get out of order ; cannot be knocked over; absolutely dust-proof beam cannot be knocked off its support. No steel used m its construction.
  - This balance was especially made by us (m quickest time on record) for the George Green School, Poplar, and was made exactly to their specification.
  - It is extra strongly made, and will therefore stand any quantity of rough handling without getting out of order.
  - The beam is of the “ open ” pattern, and is graduated to show the principle of the Rider Apparatus. It rests on a special support and cannot be shaken from its place. When beam is at rest its links and middle knife-edge are out of action. The original pattern was made by us to specification without rider apparatus, but if rider apparatus is required it can be supplied at small extra cost---see note below.
  - When loaded with 100 grammes in each pan, the balance is sensitive to half a milligramme.
  - The Balance is provided with agate knife-edges and bearings, special beam support, double hook for specific gravity experiments, and plumb bob. It is mounted in a highly finished polished mahogany case, provided with counterpoised sliding door in front, sliding door at back, and three strong levelling screws on heavy base.
  - A. —100 gramme size , sensitiveness, i milligramme............................ £6 ; 10 : 0
  - B. —250 „ ., 1-2 „ ........................... 7 : 10 • 0
  - The above prices are for Balances without Rider Apparatus. If required with Rider Apparatus the extra cost per Balance is 19/6. When ordering please state clearly whether 100 gramme or 250 gramme size is required, and if with or without Rider Apparatus.
  - Our Balances and Weights have achieved World-wide Reputation: vide Opinions of the Leading
  - Scientific Press
- p.71 - vue 89/555
- - 72
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s “SCIENCE SCHOOL” BALANCE
  - 582. —F. E. BECKER & Co.’s “ SCIENCE SCHOOL ”
  - BALANCE. Best quality workmanship and finish ; movable pans, agate knife-edges and layers, beam support, plumb bob, levelling screws, double hooks for specific gravity work ; in nicely finished polished mahogany case, with drawer and counterpoised sliding door. Guaranteed highest quality and finish. No steel used in its construction.
  - Capacity 100 grammes, and sensitive to \ milligramme. Price £7 : 12 : 6
  - 583. —F. E. BECKER & Co.’s “ SCIENCE SCHOOL ”
  - BALANCE. Specification as above, but to carry 250 grammes in each pan, and sensitive to 1-2 milligrammes. Diameter of pans, 10 cms.
  - Price £8 :17 : 6
  - F. E. BECKER & Co.’s “ Munitions Pattern ” BALANCE
  - 584.—F. E. BECKER & Co.’s PRECISION BALANCE.
  - Specially made by us for Cartridge Filling and Munitions Factories. Elegant, well-finished polished case, with drawer and counterpoised sliding front, to carry 50 grammes in each pan, and sensitive to \ milligramme. Loose brass pans, each with handle for quickly emptying weighed material ; levelling screws and pendulum ; agate knife-edges and bearings, with improved stops to take weight off knife-edges when not in use.
  - Price - £5 : 17 : 6
  - Every requisite for Chemical, Physical and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory
  - For Sets of Grain Weights suitable for this Balance, see page 84
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  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s
  - WESTPHAL SPECIFIC GRAVITY BALANCE
  - 585—F. E. BECKER & Co.’s WESTPHAL SPECIFIC GRAVITY BALANCE. For the rapid and
  - accurate determination of the specific gravity of liquids.
  - With this balance the specific gravity of liquids heavier or lighter than water can be rapidly and accurately determined, only a small quantity of the liquid being required. The right arm of the beam is divided into 10 equal parts, grooved to carry the riders, and adjustable to any convenient height. The support for the beam is easily fixed to the top of the box by means of two milled screws. The polished box is partitioned to take the various parts of the balance, thus making it portable.
  - 585
  - Price
  - Complete
  - £2:15:0
  - The balance consists of :—
  - 585a
  - Extra Plummets with
  - Platinum Wire each 15s.
  - A thermometer plummet, suspended by means of a platinum wire, and having a displacement of 5 grammes of distilled water at 15° C.
  - A trial jar with a capacity of about 60 ccs.
  - A double set of rider weights, which may be called D, E, F and G.
  - A conveniently partitioned highly-finished polished box.
  - The largest rider D is equal to the weight of the quantity of distilled water (5 grammes weighed at a temperature of 15° C.) displaced by the plummet. Rider E is equal to ^ of D, rider F is equal to of E and of D, rider G is equal to jV of F and xjjp of E or xoVo °f D. When the balance is set up and plummet immersed in distilled water at 15° C. the equilibrium is immediately upset, but is restored by placing rider D on the hook of the stirrup from which the plummet hangs.
  - To determine the specific gravity of a liquid LIGHTER than water.
  - The liquid of which the specific gravity is to be determined must be poured into the trial glass and the plunger entirely immersed in it, after which rider D is placed in one of the grooves of the right arm, which exactly readjusts the equilibrium, but when this occurs at some point between two grooves on the beam, say between 8 and 9, the rider D is placed on the lower number (8) and rider E is used for the second decimal place. For example, if rider E readjusts the equilibrium at 5, the specific gravity would be 0'85. If rider E falls also between 5 and 6, the rider F (and if necessary rider G) is used in the same way to get the third and fourth decimal places, so that if rider F must be placed between 5 and 4, and rider G between 4 and 3, the specific gravity would be 0'8543. If it happens that two riders must be placed in the same groove, the smaller of the two is hooked into the larger, and so we get two same decimal-ciphers. For further example, if rider F must be placed at 4, and rider G in the same groove, the specific gravity would be 0‘8544.
  - To determine the specific gravity of a liquid HEAVIER than water.
  - In this case one of the large riders D is placed on the hook of the stirrup of the right arm above the plunger, and the decimals are found in the same manner as above.
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. See comprehensive list at end of Chemical Apparatus Catalogue
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  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s BALANCE SETS FOR STUDENTS
  - Either with “ Solid ” graduated beam or “ Open graduated beam, agate knife-edges and planes.
  - 586/589
  - NOTE:—The Balance supplied with these Sels has a graduated beam of latest design No. 592, and the Case has a glass top giving maximum light on Balance during Weighing operations.
  - 586. —F. E. BECKER & Co.’s “ BALANCE SET”
  - FOR STUDENTS, consisting of Balance 100 grammes with graduated beam, agate knife-edges and planes as No. 592. Case with sliding front and glass top, mahogany stool, and glass vessel for specific gravity work and set of weights 100 grammes to 1 milligramme in polished box with lid as No. 603.
  - Price for the complete set .. £3 : 19 : 6
  - 587. —Ditto, exactly as Specification No. 586, but
  - Balance with “ OPEN ” BEAM, agate knife-edges and planes, 100 gramme size as No. 596.
  - Price for the complete set .. £3 : 19 : 6
  - 588. —F. E. BECKER & Co.’s “ BALANCE SET ”
  - FOR STUDENTS, as No. 586, but larger size. Balance will carry 250 grammes in each pan as No. 593, and weights go from 1 milligramme to 200 grammes.
  - Price for the complete set £4:8:6
  - 589. —Ditto, exactly as Specification No. 587, but
  - Balance with “ OPEN ” BEAM, agate knife-edges and planes, 250 gramme size, as No. 597.
  - Price for the complete set £4:8:6
  - Balance Cases
  - 590.—Balance Cases to take Students’ Balances. White wood stained to resemble mahogany. Glass all sides and glass top. The front glass sliding door is provided with stops to keep it at required height for weighing.
  - To take Balances 100 250 500 grammes.
  - Each .. .. 23/- 24/6 35/-
  - 590 A.—Ditto, best quality, polished mahogany. To take Balances 100 250 500 grammes.
  - Each .. .. 30/- 33/6 40/-
  - Cheap Balance for Elementary Work
  - WiWiI
  - 591.—F. E. BECKER & Co.’s CHEAP BALANCE
  - for elementary work
  - Specification.—Balance, cheap pattern, brass beam having knife-edge in middle and hook suspender at each end, beam support, movable brass pans, plumb bob, levelling screws, mounted on polished base. Capacity 250 grammes, and sensitive to 5 to 8 milligrammes.
  - Price • • • • • • .. £1 : 9 : 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory
- p.74 - vue 92/555
- - 75
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s STUDENTS’ BALANCES
  - “ Solid Beam ” Pattern, Agate Knife-edges and Planes
  - 592/595
  - 592. —F. E. BECKER & Co.’s STUDENTS’ BALANCE.
  - “ Solid Beam ” pattern, agate knife-edges and planes. Knives are mounted in hard brass (as in the finer-made analytical balances) to avoid chipping. Graduated beam for showing principle of the rider apparatus, beam support, plumb bob, levelling screws, stirrup-shaped suspenders, double hooks for specific gravity experiments. Mounted on handsomely finished base. Capacity 100 grammes, and sensitive to 1 milligramme . . • • Price . . £2:7 : 6
  - 593. —F. E. BECKER & Co.’s STUDENTS’ BALANCE.
  - “ Solid Beam ” pattern, as above, but capacity
  - 250 grammes, and sensitive to 2 milligrammes.
  - Price . . £2 : 12 : 6
  - 594. —F. E. BECKER & Co.’s STUDENTS’ BALANCE.
  - “ Solid Beam ” pattern, as above, but capacity
  - 500 grammes, and sensitive to 8 milligrammes.
  - Price . £3 : 15 : 0
  - 595. —F. E. BECKER & Co.’s STUDENTS’ BALANCE.
  - “ Solid Beam ” pattern, as above, but capacity
  - 1,000 grammes, and sensitive to 15 milligrammes
  - Price .. £4:7 : 6
  - F. E. BECKER & Co.’s STUDENTS’ BALANCES
  - “ Open Beam 99 Pattern, Agate Knife-edges and Planes
  - 596.—F. E. BECKER & Co.’s STUDENTS’ BALANCE. “ Open Beam ” pattern, of improved construction, agate knife-edges and planes, arrestments for stirrup suspenders, beam support, plumb bob, and levelling screws. The stirrup-shaped suspenders are fitted with double hooks for specific gravity experiments. Beam is graduated for showing principle of the rider apparatus, and when at rest on its support its links and middle knife-edge are out of action. Mounted on handsomely finished base.
  - Capacity 100 grammes, and sensitive to 1 milligramme .. .. .. Price £2:7:6
  - This enlarged illustration shows the action of the improved arrestments and supports for the stirrup suspenders in Balance
  - -t. Hi. JdUv-JVEjK & L-O. S J3 1 UUH.IN 1 O DftLfiliGti.
  - “ Open Beam ” pattern, as above, but capacity 250 grammes, and sensitive to 2 milligrammes.
  - Price . • £2 : 12 : 6
  - Balances with Steel Knife-edges can be supplied, if specially required, at somewhat lower prices. We do not recommend them as the method of mounting our Agates has any advantage which steel may possess without any of its disadvantages.
  - h-
  - Our Balances and Weights have achieved World-wide Reputation: vide Opinions of the Leading
  - Scientific Press
- p.75 - vue 93/555
- - STUDENTS' BALANCES WITH GRADUATED BEAM are now in general use to enable students to become familiar with the principle of the Rider Apparatus and for that reason we have discontinued supplying the plain beam unless specially required.
  - All Balances on this page can be supplied with Beams Not Graduated at 5/- LESS per balance. The same remarks apply to our special Balance Sets on page 74, i.e., SI- LESS per set if required WITHOUT GRADUATED BEAM.
  - 38190—STUDENTS’ MAQNALIUM BALANCES. “Solid Beam” pattern (Beam not graduated), capacity 250 grammes. Agate knife edges and planes. Each £2 3 o.
  - 38590—STUDENTS’ MAQNALIUM BALANCES. “ Open Beam ” pattern (Beam not graduated), capacity 350 grammes. Agate knife edges and planes. Each £2 10 o.
- p.n.n. - vue 94/555
- - 76
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s
  - LECTURE DEMONSTRATION BALANCE WITH
  - DOUBLE POINTER
  - 598.—F. E. BECKER & Co.’s “ DOUBLE POINTER ” BALANCE of special design, provided with pointer and scale on both sides, thus enabling students to observe weighing operations carried out by the lecturer at the demonstration bench.
  - This Balance is of the “ Open Beam ” type, and is provided with agate knife-edges and planes. When beam is at rest its links and middle knife-edge are out of action.
  - Capacity : 300 grammes, and sensitivity 3 to 4 milligrammes
  - Price ----- £3 : 7 : 6
  - (Short Pan, if required, extra .. .. .. • • • • 7s. 6d.)
  - Our Balances and Weights have achieved World-wide Reputation: vide Opinions of the Leading
  - Scientific Press
- p.76 - vue 95/555
- - 77
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s LECTURE DEMONSTRATION BALANCE
  - “ Tall Form,, with Pointer and Scale on Both Sides
  - 599.—F. E. BECKER & Co.’s LECTURE DEMONSTRATION BALANCE WITH DOUBLE POINTER,
  - “ Tall Form.” The Balance is provided with pointer and scale on both sides. The beam is made of hard brass nicely lacquered and is furnished with specially hardened steel knife-edges and bearings. The total height of the Balance is 24in. The pans, which are 5^in. in diameter, will take a boiling flask of nearly 2 litres capacity.
  - The distance from suspender to inside of long pan is 17^in. The distance from the hook at bottom of the short pan to the base of balance is lOJin. The base, is made of mahogany and nicely polished, measures 20in. X 11 in.
  - The whole Balance is soundly constructed and will be found very serviceable for lectures.
  - Its carrying capacity is 1,000 grammes and when thus loaded is sensitive to 12 milligrammes.
  - Price - £4 : 17 : 6
  - Complete with two long pans and one short pan as figured
  - Every requisite for Chemical, Physical and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory
- p.77 - vue 96/555
- - 78
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s STUDENTS’ PHYSICAL BALANCE
  - <-...............38 cms...........-....>
  - Fig. C.—Ready for Ordinary Weighings.
  - II—a"
  - Fig. B.—Front View.
  - Fig. D.—Enlarged View of Pointer and Scale.
  - 600
  - Fig. A.—Back View.
  - 600—F. E. BECKER & Co.’s STUDENTS’ PHYSICAL BALANCE, as Illustrated (see Figs. A, B, C, and D).
  - To weigh to 250 grammes in each pan, and sensitive to 2 milligrammes when loaded with its maximum charge. Beam can be raised to desired height and rigidly held there by means of a thumb-screw. Can be used for ordinary chemical laboratory weighings as well as for Physical Laboratory Experiments.
  - A. Price of Balance only, including short pan (as Fig. C.)
  - £1:8:6
  - B. Price, including short pan, bucket and cylinder, a" and a" (to prove Archimedes Law)
  - glass jar, C, and set of weights, B (200 grammes to 1 milligramme in box with lid and fractions under glass slab)
  - £2:5:0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. See comprehensive list at end of Chemical Apparatus Catalogue
- p.78 - vue 97/555
- - 79
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s PHYSICAL BALANCE
  - “ Science School ” Pattern
  - Height
  - Capacity
  - 36 inches.
  - Pans 6£ inches
  - Sensitivity
  - 50 milligrammes
  - when fully
  - Beam
  - loaded.
  - 14 inches long.
  - 601.—F. E. BECKER & Co.’s NEW PHYSICAL BALANCE “SCIENCE SCHOOL” PATTERN.
  - When loaded with 1,000 grammes in each pan will turn with 50 milligrammes.
  - This Balance is of the same design as the Students’ Physical Balance figured on page 78, and can be used for ordinary Chemical weighings as well as for Physical Laboratory experiments.
  - The illustration above shows balance beam raised to its maximum height, where it is kept rigidly in position by a thumb-screw fixed behind sliding rod.
  - A. —Price of Balance only, including short pan .. .......................... £2:17:6
  - B. Price, including set of weights, 1,000 grammes to 1 milligramme (fractions in
  - separate compartments under glass slab), forceps, glass vessel, bucket and
  - cylinder for Archimedes’ experiment, and short pan .............. £3:12:6
  - Our Balances and Weights have achieved World-Wide Reputation: vide Opinions of the Leading
  - Scientific Press
- p.79 - vue 98/555
- - 80
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s PHYSICAL BALANCE
  - “ College ” Pattern
  - 602
  - 602.—F. E. BECKER & Co.’s “COLLEGE” PATTERN PHYSICAL BALANCE. Length of beam, 19^in. ; height of brass pillar, 18in. ; diameter of pans, 6in. This balance will carry 1,200 grammes in each pan and turn with 10 milligrammes. Steel knife-edges and planes ; beam support; plumb bob ; short pan for specific gravity work, bucket and cylinder to prove Archimedes’ Law, glass jar, etc.
  - A. Price of Balance only, including short pan
  - £4:15:O
  - B. Price, including bucket and cylinder and glass jar as figured
  - £4:19:6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory
- p.80 - vue 99/555
- - 81
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s SETS OF GRAMME WEIGHTS
  - 603.—F. E. Becker & Co.’s Sets of Gramme Weights for Students, in polished box with hinged lid and forceps. The fractions are of nickel silver and aluminium covered by a glass slab.
  - A. 100 grammes to 1 milligramme
  - per set 7/6
  - B. 200 grammes to 1 milligramme
  - per set 10/6
  - 604.—F. E. Becker & Co.’s Sets of Gramme Weights, without fractions or forceps, in polished box, as illustrated.
  - A. 1 gramme to 100 grammes . . 6/-
  - B. 1 gramme to 200 grammes • . 9/-
  - C. 1 gramme to 500 grammes • . 13/—
  - D. 1 gramme to 1,000 grammes • . 20/—
  - 604
  - 605.—F. E. Becker & Co.’s Special Set of Gramme Weights, at a very low price, yet made accurate enough for all ordinary work. As seen by the illustration, the weights total up to 300 grammes and are enclosed in a nicely polished box with forceps. The fractions are made of aluminium, and go from 10 milligrammes to 500 milligrammes.
  - Price • • • • • • 15/—
  - _______________________________ 6l)5
  - Every requisite for Chemical, Physical and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory
- p.81 - vue 100/555
- - 82
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s ANALYTICAL WEIGHTS
  - 606/607
  - 608
  - 608.—F. E. BECKER & Co.’s SETS OF ANALYTICAL
  - WEIGHTS in polished mahogany velvet lined box with fractions under glass cover and forceps. The weights from 1 gramme upwards are highly nickel plated and the fractions are of nickel-silver and aluminium.
  - 606.—F. E. Becker & Co.’s Sets of Analytical Weights in polished mahogany velvet lined box, fractions and two riders under glass cover with fine ivory tipped forceps. The weights from 1 gramme upwards gold plated and fractions of pure nickel and aluminium.
  - A. B.
  - 50 100 grammes to x\r milligramme.
  - 32/6 37/6 per set.
  - 607.—F. E. Becker & Co.’s Sets of Analytical Weights in polished mahogany velvet lined box, fractions and two riders under glass cover with fine ivory tipped forceps. The weights from 1 gramme upwards lacquered and fractions of nickel and aluminium.
  - A. B.
  - 50 100 grammes to x^y milligramme.
  - 29/6 35/- per set.
  - A. B. C.
  - 50 100 200 grammes to 1 milligramme.
  - £1:2:6 £1:5:0 £1 : 12 : 6 per set.
  - 609.—F. E. BECKER & Co.’s SETS OF GRAMME WEIGHTS, in polished mahogany box, with forceps. The fractions are made of aluminium. These weights have been specially introduced to meet the increasing demand for an accurate box of weights at a low price.
  - A. 50 grammes to 1 milligramme (total 100 grammes) .. 18/0
  - B. 100 grammes to 1 milligramme (total 200 grammes) .. 19/6
  - C. 200 grammes to 1 milligramme (total 500 grammes) •. 27/6
  - Every requisite for Chemical, Physical ' and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory
- p.82 - vue 101/555
- - 83
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s ANALYTICAL WEIGHTS
  - Best
  - Sent by. Material '
  - CERTIFICATE
  - — OF------------
  - EXAMIN ATION
  - OF
  - A Set of Gramme Weights.
  - Messrs. F. E. Becker & Co.. Hatton Wall, London.
  - 60 grammes to 1 gramme ... 3rasr..
  - 500 milligrammes to 50 milligrammes, Gold.
  - 20 milligrammes to 1 milligramme. Aluminium. Z Ririers ... ...... Aluminium.
  - Box marked: « 33399.
  - iÈÜ*
  - te 5C G « 20 te îo te io*
  - Ocnsity.
  - 8.32 (deternined! 8.32 (assimori)
  - B.33 8.32
  - 8.32 •
  - 8.32 “
  - 8.32 *
  - 8.32
  - Mass jn vacuo. 50.000 Gréâmes. 20.000 *
  - 10.000 •
  - 10.000 •
  - 5.000 11
  - 2.000 "
  - 2.000 •
  - 1.000
  - February lôth, 1917. M.W. XXXV. 106.
  - QPy'
  - National Physical Laboratory Cer-tificate for any of these sets of Weights, extra .. .. .. £2:7:6
  - The Set of Weights to which this Certificate attaches was one of a hatch of 50 sets taken absolutely at random and sent to the N.P.L. The Certificate speaf^s for itself.
  - Quality
  - 610
  - 610. —F. E. BECKER & Co.’s SETS OF ANALYTICAL
  - WEIGHTS, in polished mahogany box, each weight inlaid in velvet, fractions and two riders under glass cover, with fine ivory-pointed forceps, and the large fractions made of Solid 18-ct. gold.
  - A. B.
  - 50 100 grammes to y?, mdligramme.
  - £2:2:0 £2 :10 :0 per set.
  - 611. —F. E. BECKER & Co.’s SETS OF ANALYTICAL
  - WEIGHTS, in polished mahogany box, each weight inlaid in velvet ; the weights from 1 gramme upwards gold plated ; fractions and two riders under glass cover, with fine ivory-pointed forceps and the large fractions made of Solid 18-ct. gold.
  - A. B.
  - 50 100 grammes to Ay milligramme.
  - £2:7:6 £2 :12 :6 per set.
  - 612. —F. E. BECKER & Co.’s SETS OF ANALYTICAL
  - WEIGHTS, in polished mahogany box, each weight inlaid in velvet, the weights from 1 gramme upwards gold plated ; fractions and two riders under glass cover, with fine ivory-pointed forceps and the large fractions made of Platinum.
  - A. B.
  - 50 100 grammes to milligramme.
  - £3:5:0 £3 :12 :6 per set.
  - Our Balances and Weights hâve achieved World-wide Réputation : vide Opinions of the Leading
  - Scientific Press
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  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. &. J. GEORGE (LONDON), LTD., PROPRIETORS
  - F. E. BECKER & Co.’s SETS OF GRAIN WEIGHTS
  - 613
  - 613.—F. E. BECKER & Co.’s SETS OF GRAIN
  - WEIGHTS, accurately adjusted. In elegantly finished polished mahogany box, with velvet-lined lid. Aluminium fractions under glass slab, with polished brass forceps. 1,000 Grains to ycrt Grain.
  - As supplied by us to Government Munition
  - Factories, etc. . • • • per set £1 : 12 : 6
  - 614
  - 614. —F. E. BECKER & Co.’s SETS OF GRAIN
  - WEIGHTS, in polished box, with forceps. 500 Grains to Grain .. per set £1:5:0
  - 615. -F. E. BECKER & Co.’s SETS OF GRAIN
  - WEIGHTS, in mahogany block with forceps, each weight fitted separately; 10 grains and downwards are made of aluminium and covered with a glass slab. From Aj grain to 2,000 5,000 10,000 20,000 grains.
  - Per set 18/- 22/6 27/6 39/6
  - LOOSE GRAMME WEIGHTS
  - 616.—Gramme Weights, polished brass, flat form, as used in sets No. 603, page 81.
  - Size 1 72 5 10 20 50 100 200 500 1,000 grammes,
  - Each 2d. [2d. 3d. 4d. 5d. 9d. 1/4 2/- 4/6 7/- each.
  - Per dozen .. 1/2 1/6 2/- 3/- 4/- 8/- 14/- — — —
  - Size ......................... 2 5 10 kilos.
  - Each ......................... 13/6 .. 28/6 .. 52/6 each.
  - 617.—GRAMME WEIGHTS, polished brass, tall form, as used in set 609, page 82.
  - Size' 2 5
  - Price 2d. 2d. 3d.
  - Size 50 100 200
  - Price 1/- 1/5 2/4
  - 10 20 grammes.
  - 4d. 6d. each.
  - 500 1,000 grammes • 5/- 8/- each.
  - Our Balances and Weights have achieved ^World-wide ^Reputation : vide Opinions of the Leading
  - Scientific Press
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  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. &. J. GEORGE (LONDON), LTD., PROPRIETORS
  - FRACTIONAL WEIGHTS, RIDERS, Etc.
  - 618
  - 618.—NIVOC FRACTIONAL WEIGHTS; accurately
  - adjusted. Size Per gross •. 7/-.. 500 200 100 50 milligrammes
  - Per dozen . .. 8d. 8d. Sd. 8d.
  - Size .' 20 10 5 2 1 milligrammes
  - Per dozen . . 8d. 8d. 8d. 8d. 8d.
  - 619.—NIVOC FRACTIONAL WEIGHTS, as No. 406,
  - in turned wooden box, each box containing 1 dozen weights, 500 to 1 milligrammes, the 200, 20 and 2 milligramme weights being duplicated.
  - Per set .. . . . . . . . . . . .. 8d.
  - Per dozen sets • • • • 7/- Per gross sets .. 80/-
  - 620.—ALUMINIUM FRACTIONS, “ Bent-up ” pattern.
  - Size Best finish. ..1,000 500 200 100 50 milligrammes. Size Best finish. ..1,000 500 200 100
  - Price .. 6d. 4d. 4d. 4d. 4d. each. Price .. 6d. 4d. 4d. 4d.
  - Size .. 20 10 5 2 1 milligrammes. Size .. 20 10 5 2
  - Price .. 4d. 4d. 4d. 4d. 4d. each. Price .. 4d. 4d. 4d. 4d.
  - 621.—ALUMINIUM FRACTIONS,“ Concave ” pattern.
  - 4d. each.
  - 1 milligrammes. 4d. each.
  - 622
  - 622.—ALUMINIUM WIRE FRACTIONS, Spiral pattern. Size . . 500 200 100 50 20 milligrammes.
  - Price .. 6d. 6d. 6d. 5d. 5d. each.
  - Size . . . . 10 5 2 1 milligrammes.
  - Price .. 5d. 5d. 5d. 5d. each.
  - 623
  - 623.—ALUMINIUM GRAIN WEIGHTS.
  - Size ..10 5 2 1 0*5 0*2 grain.
  - Price .. 6d. 5d. 5d. 5d. 5d. 5d. each.
  - Size .................. 0*1 0*05 0*02 0*01 grain.
  - Price .. 5d. 5d. 5d. 5d. each.
  - \
  - 624
  - 624. BALANCE RIDERS, made of aluminium wire.
  - Sjze 1 centi- 1 milli- 2 milli- 5 milli- 12 milli- 1 l-10th
  - _ . gramme, gramme, grammes, grammes, grammes, grain, grain.
  - Price .. 6d. 6d. 6d. 6d. 6d. 6d. 6d.
  - 625
  - 625.—PLATINUM FRACTIONS, guaranteed accurate and finest finish—
  - Gramme .. *001 *002 *005 *01 *02
  - Price .. 5d. 5d. 5d. 3/- 3/8 each.
  - Gramme .. *05 * 1 *2 *5
  - Price .. 5/- 6/- 8/- 16/- each.
  - Prices vary according to the market price of platinum.
  - Every requisite for Chemical, Physical and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory
- p.85 - vue 104/555
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  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - 626
  - 626.—BLACK POLISHED BLOCK, for fractions 0*01 to 0‘5 gramme.
  - Price not including fractions .. . . . . 1/6
  - 626 A
  - 626 A.—POLISHED BOX, with glass sliding lid, complete with fractions.
  - 1-500 milligrammes, as figured . . . . each 3/6
  - 626 B
  - 626 B.—OPAL SLABS FOR PLACING INSIDE BALANCE CASES.
  - The eight circular cavities are made shallow so that fractions can easily be taken hold of by means of forceps.
  - The black, figures show up well and any shortage of Weights is quickly observed.
  - The slabs are 84mm. long by 44mm. wide, and have polished edges.
  - A. Price, each 1/9
  - B. Price, per dozen......................19/6
  - 626 D
  - 626 C.—F. E. BECKER & Co.’s SETS OF HOOKED PHYSICAL WEIGHTS, very convenient for experiments with pulleys. Made of brass and lacquered, each weight being fitted with a hook. Price, complete in box :
  - Set consisting of eight weights, viz. :—one each . .
  - 1, 2, 5, 10, 20, 50, 100 and 200 grammes.
  - Per set .. 15/—
  - 626 D.—Set consisting of ten weights, viz.:—1, 2, 2, 5, 10, 20, 20, 50, 100 and 200 grammes.
  - Per set . . 18/6
  - 626 E
  - 626 E.-SET OF GRAMME WEIGHTS, in polished
  - circular boxes with forceps on cover, from 10 milligrammes upwards, all the 2’s being in duplicate. From 10 milligrammes to 50 100 grammes.
  - Price, per set • • • • • • 5/6 .. 6/6
  - 626 F.—Brass Hand Scales,
  - with horn pans on silk cords.
  - Length of
  - beam--- 12 17 19 eras,
  - Capacity 25 50 100 grammes
  - Each ... 5/6 n- 8/-
  - Length of beam 30 35 cms.
  - Capacity 250 500 grammes
  - Each - 12/- 15/-
  - Our Balances and Weights have achieved World-wide Reputation: vide Opinions
  - Scientific Press
  - of the Leading
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  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - BALANCE ACCESSORIES
  - 627 A
  - 627 A.—Spirit Level, brass, best quality. Length, 3J in.
  - Each ........................ 2/6
  - Per dozen .. .. .. .. 27/6
  - 627>D
  - 627 D.—Brass Forceps—
  - Ivory points
  - each 2/6
  - 627 E
  - 627 E.—Forceps, for balances, nickel-plated .. 6/- per dozen ; each 7d.
  - 627 H
  - 627 H. — Feet for protecting benches and tables from indentations caused by the adjusting of levelling screws ; each 9d.
  - 627 B
  - 627 B.—Circular Cross Spirit Levels, best quality. Nickel-plated . . each 5/6
  - 627 F
  - 627 F.—Triangular Desiccators, polished on all sides, for placing inside balance cases.
  - 2in. by Ifin. .. each 1/3
  - 3&in. by 2£in. .. each 1/6
  - 627 C
  - 627 C.—Circular Spirit Levels
  - best quality.
  - A. lin. diameter. . each 4/9
  - B. liin „ .. „ 5/9
  - C. 2in......... „ 6/9
  - 627 G
  - 627 G.—Powerful Lens, on
  - metal foot, for magnifying the divisions of index scales on analytical balances ;
  - each 8/6
  - 627 K.—Mahogany Stools,
  - best quality for specific gravity work. These may be used with 100 gramme or 250 gramme size balances ; each 1/-
  - 627 J
  - 627 J. - G 1 a s s Vessels for Specific Gravity work.
  - Each.. .. 1/-
  - Per dozen .. 11/—
  - 627 L
  - 627 L.—Camel Hair Brushes for dusting balance pans ;
  - each 6d.
  - Every requisite for Chemical, Physical and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory
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- - 88
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - GRIMLEY’S PROSPECTOR’S BALANCE
  - For Alluvial Tin Concentrates.
  - Value of sample in lbs. per cubic yard read direct from the beam. Also weight of sample can be ascertained, enabling specific gravity to be taken, and tin
  - contents to be estimated.
  - Reprinted from “The Mining Magazine” for October, 1921.
  - F. E. Becker & Co. (Proprietors, W. and J. George, Limited), of 17-29, Hatton Wall, London, E.C. 1, are putting on the market a prospecting balance for use in connection with alluvial tin estimations, invented by Philip Grimley, Assoc.Inst.M.M. This balance, which is on the lines of a steelyard, is designed so that if the concentrates resulting from washing \ cu. ft. of ground be weighed on it, the value of that sample in pounds per cubic yard can be read from the beam, which is divided into 10 units, each of which is sub-divided into tenths. In addition the weight of the concentrates can be easily ascertained. Two large and three small sliding weights are supplied. Each of the small weights has a Value of 4.2 grammes.
  - That is, if concentrates
  - weighing 4.2 grammes are placed in the pan, the beam will be horizontal when one of the small weights is at 1, or, if the weight of the concentrates be 42.0 grammes, the beam will be horizontal when the weight is at 10. One quarter of a cubic foot = 1/108 cub. yd., and 4.201 grammes = 1/108 lb. So,
  - for example, if J cu. ft. of ground be washed up and when the resulting concentrates are put in the pan the beam is horizontal with one of the small weights at, say, 3.2, the value of the sample is 3.2 lb. per cu. yd. and the weight of the concentrates is 3.2 X 4.2
  - Cat. No. 628.
  - grammes. If only one of the small weights be used, concentrates of a higher value than 10 lb. per cu. yd. have to be weighed in two or more portions, and the beam readings must be added together. But with, for example, one small weight at the mark 10 on the beam, and another of the small weights at 4, a value of 10 plus 4= 14 lb. per cu. yd. can be read. Similarly, with the medium weight (which is twice as heavy as one of the small weights) at 10, and a small weight at 3 (as illustrated), a value of 2 X 10 plus 3 = 23 lb. per cu. yd. can be read; or, with the largest weight at 10 and one of the small weights at 3, a value of 3 X 10 plus 3 = 33 lb. per cu. yd. can be read. In all the above cases the value in lb. per cu. yd. X 4.2 = weight of concentrates in grammes. Further, should it, at times, be desirable to wash samples of i cu. ft., then the medium-sized weight at, say, the mark 7, would indicate a value of 7 lb. per cu. yd. (Should any of the small weights be used when samples of i cu. ft. are washed, its beam reading must be halved.) When i cu. ft. samples are taken, the weight of concentrates in grammes = value in lb. per cu. yd. X 8.4. The apparatus is simple and not likely to get out of order when taken on a prospecting expedition. It weighs, in its wooden box, only li lb., and the dimensions of the box are Min. by 4|in. by Igin. One advantage of the instrument is that it can be carried while prospecting so that the samples can be immediately tested, thus obviating error and misadventure, and giving the required information promptly.
  - Price, complete in case, £3:3:0
  - 629/1
  - 629/1.—F. E. BECKER & Co.’s PRECISION BALANCE (M.V.l),
  - Load 60 grammes ; sensitive to 8 milligrammes ; lacquered brass beam carrying needle-pointer swinging in front of an ivorine scale ; middle knife-edge made of hardened steel ; pillar, suspenders, and pans made of brass nicely lacquered. All the parts can be quickly taken to pieces and placed in drawer of box. The beam is raised by means of the eccentric lever. The box is made of polished mahogany. Movable pans. Price £1 : 5 : 0
  - 629/2.—F. E. BECKER & Co.’s PRECISION BALANCE (M.V.2).
  - Specification as (M.V.l), but weighing to 120 grammes and sensitive to 9 milligrammes • • • • • • Price £1 : 8 : 6
  - 629/3.—F. E. BECKER & Co.’s PRECISION BALANCE (M.V.3).
  - Specification as (M.V.l), but weighing to 250 grammes and sensitive to 10 milligrammes . • • Price £1 : 12 : 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the Leading
  - Scientific Press
- p.88 - vue 107/555
- - 89
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - 630.—LABORATORY SCALES, superior quality and finish. Suitable for weighing chemicals, etc. ; double beam ; mounted on nicely finished walnut box ; with white marble top, and provided with two movable brass pans.
  - To weigh ••• ... 1 2 5 10 kilos.
  - Diameter of pans ••• 16 18 20 22 cms.
  - Each ................. 42/6 50/- 75/- 92/6
  - 631.—F. E. BECKER & Co.’s LARGE LECTURE BALANCE.—This balance is fitted with double-handled eccentric for raising or lowering, a pair each of long and short suspenders with pans, a rider-scale, and flat centre plane. The beam has two pointers, each of them oscillating on a sextant, the one facing the lecturer, the other the audience. The short suspenders may be used in the place of the long ones.
  - Sensitive to 10 milligrammes when loaded with 5,000 grammes in each pan.
  - The balance may be used also for ordinary purposes and the following instructive experiments :
  - Uniform knife-edges and such, in the proportion of 1 : 2.
  - Long or short pointers.
  - Elongation of lever.
  - Moving the level of plane up or down.
  - Alteration of the point of gravity.
  - Weighing with the rider-scale.
  - Specific gravity experiments.
  - Price complete
  - £17 : 0 : 0
  - 631/1.—SETS OF LARGE DEMONSTRATION GRAMME WEIGHTS, in fine polished box, lid lined with velvet. With fork for lifting out the large weights and brass forceps for use with small weights. The 2, 20, 200, and 2,000 gramme weights in duplicate—
  - Set of I gramme to 2 kilogrammes 5 kilogrammes. Price £3 s 0 : 0 £4 : 12 : 6
  - 10 kilogrammes.
  - £7 : 10 : 0
  - 631/2.—SETS OF FLAT BRASS WEIGHTS.
  - A. %oz. to £lb. per set 4/6
  - B. ^oz. to 11b. „ 7/6
  - C. ^oz. to 21b. „ 14/—
  - D. ioz.to41b. 26/6
  - 631/2
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- - 90
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - OTHER MAKES OF BALANCES AND WEIGHTS
  - SARTORIUS ANALYTICAL BALANCE “U.S.A. MODEL,” agate
  - knife-edges and planes, triangular aluminium graduated beam, gdt compensated suspensions, circular movement for releasing and arresting the beam, adjustable pan supports, rider apoaratus. In oak glazed case with counterpoised sliding front window. Mounted on black glass base with levelling screws. Capacity 200 grammes and sensitivity 1/10th milligramme.
  - Price ... £14 : 10 s 0
  - = - ~ ,,'
  - SARTORIUS ANALYTICAL BALANCE No. 5, with straight aluminium beam 14cms. long, agate knife-edges and planes, improved rider apparatus, circular movement for releasing and arresting the beam. In polished oak glass case with counterpoised front sliding m/Mint-prl nn Klarlf crlass base with levelling screws.
  - Price ••• £25 : 0 : 0
  - OERTLING ANALYTICAL WEIGHTS in mahogany
  - boxes with forceps and fractions under glass slab.
  - A. 200 grammes to '001 and riders • • per set
  - B. 100 grammes to '001 and riders • • per set
  - C. 50 grammes to '001 and riders •. per set
  - D. Platinum fractions '5 to '01 gramme for
  - any of the above sets • • • • extra
  - E. 10,000 grains to '01 grain and riders, per set
  - F. 6,000 grains to '01 grain and riders, per set
  - £4 : 15 : 0 £4 : 0:0 £3 : 5:0
  - £1 : 10 : 0 £7: 0:0 £6 : 5:0
  - Every requisite for Chemical, Physical and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory
- p.90 - vue 109/555
- - 91
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.l
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - OTHER MAKES OF BALANCES
  - OERTLING BALANCE No. 34, with 8in. beam
  - divided into 100 parts, to carry 200 grammes in each pan and sensitive to 0'2 milligramme ; agate knife-edges and planes, instead of bearings ; single rider-shde traversing total length of beam ; adjustable pan supports, 4-in. concave pans, polished mahogany glass case fitted with counterpoise weights to front slide and with levelling screws and plummet
  - Price £15 : 15 : 0
  - OERTLING BALANCE No. 38, with 6in. horizontal beam divided into 100 parts, to carry 200 grammes in each pan and turn with O’ 1 milligramme ; agate knife-edges working on agate planes ; single rider-slide traversing total length of beam ; pansupports ; 4in. concave pans ; plummet; polished mahogany glass case fitted with counterpoise weights to front slide and with levelling screws.
  - Price .. £18 : 10 : 0
  - OERTLING BALANCE No. 31 A, with
  - 13 cm. gun-metal beam to carry 100 grammes in each pan and turn with O’ 1 milligramme ; agate knife-edges working on agate planes ; pan supports ; rider-slide which traverses the entire length of the beam ; plate-glass to bottom of case ; polished mahogany glass case with counterpoise weights to front slide, and with levelling screws and plummet. This balance is fitted with side-action.
  - Price .. £25 : 0 : 0
  - OERTLING BALANCE No. 36, made of aluminium-alloy, with 5in. triangular beam to carry 200 grammes in each pan and turn with 0’ 1 milligramme ; agate knife-edges working on agate planes ; vertical rider-slide ; plummet; pan supports ; rider bar on same plane as knife-edges and serrated into 100 parts, “ 0 ” in centre to “10 ” at each end ; the pointer is of angle aluminium in order to decrease the effect of surrounding vibrations; pans gold-plated 2fin. plates, and 5fin. between wires at base ; black plate-glass base to bottom of case ; polished mahogany glass case fitted with counterpoise weights to front slide and with levelling screws.
  - Price .. £30 : 0 : 0
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.91 - vue 110/555
- - 92
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C. 1
  - W. & J. GEORGE (LONDON), LTD., PROPRIETORS
  - OTHER MAKES OF BALANCES
  - Oertling Balance, No. 1 S.B • with 8in. beam (20cm.) to carry 100 grammes in each pan, and turn with 0' 1 milligramme; the beam is constructed with agate knife-edges working on agate planes, and divided for the use of the rider ; rider-slide ; pan supports ; polished mahogany glass case with counterpoise weights fitted to front slide.
  - Price £30 : 0 t 0
  - Plate glass to bottom of case Extra £2:5:0
  - Oertling Balance, No. 2 S.B. with 6in. beam (15’2cm.) to carry 200 grammes in each pan, and turn with O' 1 milligramme ; agate knife-edges working on agate planes ; rider-slide, which traverses the entire length of the beam ; plate-glass to bottom of case ; pan supports ; polished mahogany glass case with counterpoise weights fitted to front slide.
  - Price .. £40 : 0 : 0
  - Assay Balance, Oertling No. 39, with 5in. triangular beam, to carry 2 grammes in each pan and turn with 0'01 milligramme. Agate knife-edges and planes ; rider-bar, divided into 100 parts, on same plane as knife-edges ; vertical rider-slide; pan supports, polished mahogany and glass case fitted with counterpoise weights to front slide.
  - Price .. £35 : 0 : 0
  - Assay Balance, Oertling No. 12 S.B.A., with 6in.
  - horizontal beam, divided into 100 parts ; to carry 2 grammes in each pan and turn with 0*01 milligramme. The beam is constructed with agate knife-edges working on agate planes, which are all relieved when not in use. Double rider-slide, plate-glass to bottom of case, polished mahogany glass case with counterpoise weights fitted to front slide.
  - Price .. £50 : 0 : 0
  - Other Oertling Balances not \ included in this list, supplied ; at maker s current list prices. \
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory
  - H. a K., LTD., LONDON. S.E.1
- p.92 - vue 111/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 93
  - W. St J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - The “NIVOC” MICROSCOPE
  - Built to the specification of the British Science Guild this Instrument will be found excellent for every form of Laboratory work.
  - Of first quality throughout, the stand is of BRASS with diagonal rack coarse adjustment and horizontal lever fine adjustment, one complete rotation of which moves the body 0-125 mm.
  - The stage, measuring 3^ X 3f inches, is covered completely with ebonite and will carry a 6 inch Petri dish. The limb can be inclined to the horizontal. Plane and concave mirrors of plain understage fitting are included.
  - PRICES.
  - A “Nivoc” Microscope. Stand only B ,, ,, Fitted oak carrying case
  - £6 10 0 1 2 6
  - COMPLETE OUTFITS.
  - C “Nivoc” Microscope, with objectives 3 and 6, 1 eyepiece, either X 6, X 8, X 10. Case..................................................£11 10 0
  - D “Nivoc” Microscope, with spiral focussing screw and oak case, dustproof double nosepiece, 1 eyepiece, either X 6, X 8, X 10, objectives 3 and 6, simplified Abbe condenser .. .. .. .. .. .. .. .. .. £14 12 6
  - ACCESSORIES FOR THE “NIVOC” MICROSCOPE.
  - E Nosepiece dustproof pattern, double ..........................
  - F ,, ,, ,, triple
  - G Simplified Abbe condenser H Sleeve pattern iris diaphragm J tV in. oil immersion objective, N.A. 1-28 ..
  - K Attachable mechanical stage L Spiral focussing screw..
  - NOTE.—If a case is not required deduct from the above prices of sets
  - £12 6 15 0 1 10 0 0 15 0 7 10 0 7 0 0 12 6 £12 6
  - FOR ALL OTHER
  - MICROSCOPES & ACCESSORIES
  - REFER TO PAGES 47 TO 76 OF OUR
  - CHEMICAL APPARATUS CATALOGUE
  - 23rd EDITION.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory. f
- p.93 - vue 112/555
- - 04
  - SECTION 4
  - METEOROLOGY, ETC.
  - 634. —DEMONSTRATION SET OF THERMOMETERS AND SCREEN, designed for the •use of observers who have not the convenience for setting up the ordinary full-size Stevenson’s Screen. As will be seen, the apparatus is easily fixed upon a wall or post. The thermometers are specially made of standard accuracy. The Screen is designed to allow of the correct observation of shade temperatures. It is well made and painted white. Illustration shows the front raised and supported by the arm on the left side for taking readings, but when let down, the front entirely covers and protects the thermometers.
  - A. Screen
  - B. Wet and Dry Bulb Thermometer
  - C. National Physical Laboratory Certificate
  - D. Maximum Thermometer
  - E. National Physical Laboratory Certificate
  - F. Minimum Thermometer
  - G. National Physical Laboratory Certificate
  - 635. —Stevenson’s Thermometer Screen, double louvred and painted white, arranged to contain maximum and minimum, and wet and dry bulb thermometers.
  - Each .. .. ..............................................................£5 5 0
  - 2 2 0 0 5 0 110 0 3 6 110 0 3 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.94 - vue 113/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 95
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - THE “SCIENCE SCHOOL” SET OF STANDARD METEOROLOGICAL INSTRUMENTS
  - comprising a set of Standard Instruments of the finest quality, making a complete Meteorological Station suitable for Schools, Colleges, etc. Any of the instruments may, however, be had separately (Catalogue No. 636).
  - Standard Barometer. 636 A.
  - "Snowden” Rain Gauge. 636 c.
  - Maximum Thermometer. 636 g.
  - 636.—
  - A. Standard Barometer, as Specification on page 96
  - B. National Physical Laboratory Certificate ................. ................
  - C. Standard 5-in. “ Snowdon ” Rain Gauge, in stout copper, with Camden Measure
  - D. National Physical Laboratory Certificate ..................................
  - E. Standard Wet and Dry Thermometer...........................................
  - F. National Physical Laboratory Certificate ..................................
  - G. Standard Maximum Thermometer
  - H. National Physical Laboratory Certificate ..................................
  - J. Standard Minimum Thermometer ..............................................
  - K. National Physical Laboratory Certificate
  - L. Register for one year
  - £7 15 0 2 2 0 2 2 0 0 6 0 2 2 0 0 5 0 110 0 3 6 110 0 3 6 0 2 0
  - Any of the above instruments can be had separately.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.95 - vue 114/555
- - 96 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - FORTIN’S STANDARD BAROMETERS
  - SPECIAL NOTE.—For export orders the only tolerably safe way to send Barometers is in care of one of the Ship’s Officers. When this is done, however, it is necessary for customers to arrange to take personal delivery at the Port of discharge. We guarantee the instruments to be in perfect condition when they leave our Warehouse, but we cannot accept responsibility for damage during transit. For Home orders we can arrange to send in care of the guard of any specified train, provided customers arrange to meet the train on its arrival.
  - 637. —Fortin’s Standard Barometer, large size, diameter of tube 0-5 in., with double vernier reading to ^ny^th of an inch, and jVth of a millimetre ; mounted on handsomely finished mahogany board,
  - with opal glass reflectors, adjusting screws, etc. .. .. ..............................£18 10 0
  - 638. —Fortin’s Standard Barometer. This instrument has been designed to meet the requirements of those who find the need of a Barometer which will give exact reading and cost but a moderate sum, and is used for Demonstration purposes in all the principal Science and Technical Laboratories.
  - We wish to emphasize that this is a Standard Barometer, made on the same principle as the larger Fortin’s Barometer, and gives readings to o-oi in. and o-i millimetre and is recommended for use as a
  - “ Standard ” in Colleges, Schools and private Observatories.
  - Price, mounted on polished mahogany board and complete with standard thermometer .. .. £7 15 0
  - A. National Physical Laboratory Certificate ........................................ .. .. extra 2 2 0
  - B. Glazed Oak or Mahogany Case to contain above .. .. .. .. .. .. .. .. 440
  - 639.—Fortin’s Standard Barometer, as No. 637, but in elegantly finished case with lock and key 22 14 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.96 - vue 115/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 97
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BAROMETERS
  - These Instruments have been specially designed for use in science classes as, on account of their construction, the working of the tubes can be observed without dismantling the Instruments.
  - 640. —Standard “ Direct Reading ” Barometer. The scale of this Instrument is compensated to allow for the rise or fall of the mercury in the cistern, and thus gives direct readings and obviates the addition necessary in the Syphon pattern. The scale which can be either inches or millimetres is divided and etched on the glass tube, and reads to -05 inch or 1 millimetre. Mounted on polished oak
  - or mahogany board with reflector .. .. .. ........... ...........................£2 10 0
  - 641. —Demonstration Wheel Barometer. The 8-in. engraved and silvered metal dial is divided to T<xirth in. from 28 to 31 inches, thus giving a very open range showing slight variations in atmospheric pressure. The spindle is hardened and polished steel and works without friction. The tube is provided with a glass stopcock so that at any time it is required to shift the position of the barometer, the mercury can be run up to the top of the tube and the tap turned, thus making it quite safe for carrying about. This Instrument is mounted in a well-made fumed and polished oak frame with strong brass bevel with domed glass and index, framed glass over top part of tube and hinged door to lower end, thus making it dust proof.
  - Price £3 10 0
  - 642. —Standard “Syphon ,f Barometer. The scales are divided and etched on the tube in
  - millimetres, mounted on polished oak or mahogany board with reflectors .. .. .. .. .. £2 10 0
  - 643. —A Thermometer (divided and figured on the stem) can be attached to either of No. 640 or 642 Barometers at an extra charge of 5/-.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
  - G
- p.97 - vue 116/555
- - 98 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BAROMETERS
  - 644.—Fitzroy Barometer, best quality
  - 645. —Bunsen’s Syphon Barometer, white enamelled back, graduated in millimetres, mounted on nicely
  - polished mahogany board .. .. .. .. .. .. .. .. .. .. .. ..£2120
  - 646. —Bunsen’s Syphon Barometer, filled and graduated in millimetres, on white enamelled back, mounted
  - on strong iron support with clamp .. .. .. .. .. .. .. .. .. .. ., £2 2 0
  - 647. —Ditto, but not mounted..................... ...................... ................£1 10 0
  - 648. —Bunsen’s Syphon Barometer, empty tube only......................................... 12 6
  - 649. —Wheel Pattern Mercurial Barometer, 8-in. dial, opal plates, with mirror, damp detector and level,
  - in oak, walnut, or mahogany, as figured .. .. .. .. .. .. .. .. .. .. £2100
  - 650. —Model Barometer, best quality, ivory scale, with thermometer, sliding vernier, portable screw and polished
  - mahogany frame.. .. .. .. .. .. .. .. .. .. .. .. .. .. £2100
  - dHI
  - 651.—Barometer Tubes.
  - A. Plain, thick-walled .. .. each 1 /2
  - B.
  - B. Bulb pattern .. .. .. ,, 2/3
  - C. Syphon pattern .. .. ,, 2/3
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.98 - vue 117/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 99
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CARVED WOOD FRAME ANEROID BAROMETERS
  - 652. Solid Oak Pendant Frame Barometer,
  - best make and finish, with thermometer and closed porcelain dial in., length of frame 28 in.
  - Each...............£3 3 0
  - 653. —Ditto, with dial 8 in.,
  - length of frame 35 in.
  - Each.. .. .. £3 7 6
  - 654.—“ Yacht ” Pattern Barometer,
  - in metal frame, with closed porcelain dial. Each............. ..£2 5 0
  - 655.—A neroid Barometer, very neatly carved, dogtooth circle, open dial, light or dark oak.
  - A. 5-in. dial ............. .. 39/6
  - B. 6|-in. „ .. . . .. .. 45/-
  - C. 8-in. „ .. ...........57/6
  - 656. Solid Oak Pendant Frame Barometer,
  - best make and finish, with thermometer, and closed porcelain dial 6| in., length of frame 30 in.
  - Each .. .. £3 3 0
  - 657 .—Ditto, with dial 8 in., length of frame 35 in.
  - Each.. .. .. £3 7 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.99 - vue 118/555
- - 100 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BOXWOOD SCALE THERMOMETERS
  - 658. — Thermometers, square-edged boxwood scale, for hanging on walls.
  - Each .. .. 1/6
  - 659. — Double Scale Thermometers, highly finished, bevelled boxwood, with both Centigrade and Fahrenheit scales.
  - Each .. .. 3/6
  - 660.—Set of 3 Ther-mometers, Centigrade, Fahrenheit, and Reaumur scales respectively, mounted on polished boxwood back for hanging on wall.
  - Each..................12/6
  - 661.—Set of 3 Thermometers, cheaper make, showing Centigrade, Fahrenheit and Reaumur scales, mounted.
  - Each .. .. .. 6/6
  - 66i
  - MAXIMUM THERMOMETERS
  - ' (For Minimum Thermometers, see next Page.)
  - The self-registering maximum thermometer is used by observers to register the extreme heat during the day. It is usually placed in a Stevenson’s screen, together with the minimum thermometer and the hygrometer. If a screen is not available, a board with a sloping top, to screen from sun and rain, will be found useful. The observation is usually taken at 9 a.m. every morning, when the thermometer is also reset. To reset, hold the top of the thermometer by the right hand and give it two or three gentle swings of the arm, which will cause the column of mercury to descend to its starting point.
  - 662. —Thermometers, maximum, self-registering,
  - boxwood scale, 8 in. .. .. .. each 3/-
  - 663. —Ditto, io in. .. .. .. ,, 3/9
  - 666.—Standard Maximum Thermometer,
  - self-registering, engine-divided on stem, and figured on opal scale, mounted polished mahogany or oak back.
  - £110
  - 664.—Maximum Thermometer, better
  - quality, boxwood scale, 8 in. ... .. each 6/-
  - 665 .—Ditto, io in................... ,, 7/6
  - 667.—Maximum Thermometer, self-registering, engine-divided on stem, and figured on opal scale, mounted on polished mahogany frame, as No. 666, but smaller size ............... * 15/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.100 - vue 119/555
- - F. E. BECKER <& CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 101
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MINIMUM THERMOMETERS
  - The self-registering minimum thermometer is used by observers to obtain the extreme of cold during the night. It is usually suspended with the bulb end, slightly inclined downwards, in the Stevenson’s screen, with the maximum and the hygrometer. If a screen is not available it may be suspended on a board with sloping top to shelter from sun and rain.
  - The observation is usually taken at 9 a.m. every morning, and the index is reset at the same time. To reset the index, lift the bulb end of the thermometer and allow it to run to edge of the spirit in the tube ; thus set, the instrument may be replaced in its horizontal position.
  - 668.—Thermometer, minimum, self-registering, boxwood scale, 8 in., as figured .. .. each 2/9
  - 669 .—Ditto, 10 in............ ,, 3/6
  - ffTTj*. I I M , I M 1 , M I M , ,1 M I
  - 210 1I0
  - 670.—Thermometer, minimum, better quality, boxwood scale, 8 in. as figured .. .. each 4/6
  - 671 .—Ditto, 10 in. .. .. .. .. „ 7/-
  - 672.—Standard Minimum Thermometers,
  - self-registering, engine-divided on stem, and figured on opal scale, mounted on polished mahogany or oak back................................£110
  - 673.—Minimum Thermometer, standard pattern, self-registering, engine-divided on stem, and figured on opal scale, mounted on polished mahogany frame, as No. 672, but cheaper make .. 15/-
  - COMBINED MAXIMUM AND MINIMUM THERMOMETERS
  - 10 I 20 i 30 140 150 160 I 70 1.80 I 90 I 1001 1101 1201 130114
  - FREEZING g£CK£R haTTON WALL, LONDON.
  - , , **' ’ FREEZING
  - iiiiiiiiiiiiiiiiiiiiiiiiniiiiiiiiiiini
  - 674.—Thermometer, combined maximum and minimum, io in. scales .. .. .. each 17/6
  - 675.—10 in. Window or Bracket Six’s Thermometer, mounted on oak or mahogany board, opal scale and plain figures, with magnet.
  - Each ......... ..£17 6
  - 676.—Six’s Self-Reg istering Maximum and Minimum, boxwood, in well-finished japanned tin frame, complete with grooved magnet, 8 in.
  - Each .. ..6/6
  - 677.—Ditto, io in. Each
  - 9/6
  - 678. — Combined Standard Maximum and Minimum Thermometers, self-registering,
  - Six’s principle, engine-divided on stems, and clearly figured on opal scale, in white metal case with magnet, verified at Kew, io in., £1 17s. 6d. ; 12 in., as illustration, £2 17s. 6d.
  - For HYGROMETERS, DIFFERENTIAL AIR THERMOMETERS, BECKMANN’S and OTHER THERMOMETERS, see INDEX.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.101 - vue 120/555
- - 102 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1
  - & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SOLAR RADIATION THERMOMETERS, Etc.
  - 3
  - m
  - FOR OTHER THERMOMETERS SEE INDEX.
  - ¥
  - I
  - 686
  - 689. — Earth Thermo-meter, Symon’s Pattern, with chain and cap suspender and pointed steel tube. To penetrate the earth.
  - 1 ft.
  - 2 ft.
  - 3 ft.
  - 4 ft.
  - .. 30/-.. 32/6 .. 35/-.. 37/6
  - 689A.— National Physical Laboratory Certificate .. 3/-
  - 679.—Standard Solar Radiation Thermometer for showing the true temperature of the Solar Rays. Self registering maximum, with black bulb in vacuo .. .. .. .. .. .. £110 0
  - 680 .—Ditto, bright bulb in vacuo .. .. .. .. 1100
  - 681. —National Physical Laboratory Certificate .. .. 0 7 0
  - 682. —Standard Solar Radiation Thermometer for showing
  - the temperature of Solar Rays in open air, self registering maximum, black bulb.........................................£110
  - 683 .—National Physical Laboratory Certificate .. .. 0 7 0
  - 684.—Standard Terrestrial Radiation or Grass Mini-mum Thermometer ..................................... 110
  - 685 .—National Physical Laboratory Certificate .. .. 0 3 6
  - 686 .—Ditto, ditto, with specially sensitive loop bulb .. 15 0
  - 687 .—National Physical Laboratory Certificate .. .. 0 3 6
  - 688 and 690
  - 688.—Brass Stand to hold Nos. 679 and 681 Thermometers .. 10/-
  - 690 .—Ditto, for Nos. 682, 684 or 686 Thermometers .. 10/-
  - 691.—Wood Stand to hold Nos. 679 and 681 Solar Thermometers, 6 ft. high, painted white .. .. 12/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.102 - vue 121/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 103
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - HYGROMETERS
  - 692. — Mason’s Wet and Dry Bulb Hygrometer, on boxwood Scale, enclosed in well-finished japanned tin case.
  - Each .. .. 9/6
  - 693.—Daniell’s Hygrometer, on well-polished stand.
  - 694. — Standard Hygrometer, wet
  - and dry bulb, Mason’s pattern, for ascertaining the dew point and amount of humidity in the air. The tubes are engine-divided on stem, and figured on opal slips on brass backs ; neatly mounted on a polished mahogany board.
  - Each
  - 17/6
  - Complete..
  - £2 10 0
  - 695.—Standard Hygrometer, after
  - the style of No. 694, but cheaper make, smaller size .. ..£220
  - 696.—Dine’s Hygrometer, best make and finish.
  - proved pattern, with aspirator, etc.
  - £2 19 6
  - Complete, as figured..
  - £3 10 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.103 - vue 122/555
- - 104 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - WATCH FORM ANEROIDS
  - 699.—Best Flat Watch
  - Aneroid, heavily gilt case, revolving altitude scale, with silvered dial, raised ring and thermometer, in morocco snap case £4 4 0
  - 700.—Gilt Watch Aneroid,
  - compensated, revolving altitude scale, 8,ooo ft., in morocco snap case
  - £3 17 6
  - 701.—Watch Aneroid, with
  - revolving altitude scale, compensated, with detachable Singer’s day and night compass on reverse side.
  - £5 5 0
  - 702. —Damp Detector,
  - silvered dial and gilt case. Will easily detect the slightest moisture
  - 19/6
  - 703. —Ditto, cheaper quality .. 8/6
  - BAROGRAPHS AND THERMOGRAPHS
  - 704.—Barograph, in fumed oak or mahogany frame, with glass sides and top, and with eight large vacuum chambers (illustration shows instrument with six vacuum chambers only), complete with one year’s supply of charts. This instrument was specially designed by us to meet the requirements of educational establishments, schools, laboratories, etc., and providing a thoroughly accurate self-recording instrument at a moderate cost.
  - Each ...................£11 11 0
  - 705.—Barograph, in strong polished copper case, hinged cover, with glass front, hooks, and handle on top; carefully tested and highly finished. Complete, with a year’s supply of charts .. .. £12 12 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.104 - vue 123/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 105
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - THERMOGRAPHS AND BARO-THERMOGRAPH
  - 707.—Combined Barograph and Thermograph.
  - This Instrument combines in one the Barograph and Thermograph, and records accurately on one chart the variations in barometric pressure and changes of temperature during the week. The two pens being filled with different coloured inks, the records are quite distinct and the pens being specially shaped, work with only one hour space (XV in.) between them.
  - The instrument is fitted with all the latest improvements in the movements and is mounted on a strong japanned metal base, with polished copper cover which has a perforated brass panel to allow the temperature to have access to the thermostatic coil.
  - Price complete, with charts and ink for one year £10 10 0
  - Size, ii in. X 5^ in. x in.
  - Size ii in. x 5 in. x 7% in.
  - 708. —T her rrfo graph, extra strong construction, mounted on a cast-iron base with hinged copper cover, having perforated brass panels back and front to allow the air to circulate round the thermostatic coil.
  - Price complete, with charts ranging 0-120, 30-150 or 100-200° F. or 0-1000 C. £8 0 0
  - 709. —Spare Set of Charts for Thermographs .. .. .. .. .. 5/-
  - It is important when ordering new sets of charts to see that they are exactly the same as the ones originally supplied with the Instrument, as otherwise the^indications recorded may be incorrect.
  - 710.—Light Pattern Thermograph with pen
  - working directly off the Thermostatic coil. Mounted on cast aluminium base with hinged copper cover, as illustration. Ranges usually stocked are 0-120, 30-150 F., or — 20 + 50° C.
  - Price, complete with charts and ink .. £7 0 0
  - 711.—Thermograph, exactly as above, but with hinged japanned iron cover £6 15 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.105 - vue 124/555
- - 106 F. E. BECKER <& CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RAIN GAUGES
  - 712/3
  - 712.
  - Standard 5 in. “ Snowdon ” Gauge,
  - as used by the Meteorolog ical Office. Complete with inside glass receiver, engine divided “ Camden ” Measure.
  - In strong copper with heavy ' brass ring .. £2 2 0
  - 713. —-Ditto, in
  - galvanized iron, with heavy brass ring .. £116 0
  - 714. — National Physical Laboratory Certificate 6/-
  - 715__“ Cam
  - den” Measure
  - showing *005 in.
  - 10/6
  - Also supplied reading to -i mm.
  - 718
  - 718.—The “ Observatory ” Self-Recording Rain Gauge, in japanned iron case. Records the
  - 716.—8 in. “Snowdon ” Pattern Rain Gauge, as
  - used by the Meteorological Office, with engine divided measure, in strong copper, with heavy brass ring .. £4 4 0
  - 717 .—Ditto, in galvanized iron, with heavy brass
  - ring.. £3 10 0
  - 716/7
  - 719.—The Wilson Self-registering Dial Rain Gauge. 8-inch square receiver with dial showing up to 10 inches.
  - A. In copper .. .. .. .. .. £12 12 0
  - B. In zinc .. .. .. .. .. 10 10 0
  - rainfall on a weekly chart, and indicates on a dial.
  - A. To indicate up to 10 inches .. .. £20 0 0
  - B. To indicate up to 200 inches .. .. 21 0 0
  - Complete with a year’s supply of charts and ink.
  - 720 .—Ditto, with 10-inch square receiver, with dial showing up to 25 inches.
  - A. In copper case .. .. .. .. £21 0 0
  - B. In polished zinc case .. .. .. 17 10 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.106 - vue 125/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON. E.C.1. 107
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 721/2
  - 721.—S y m o n s’ Rain Gauge, British Association pattern, complete with measure, 5-in. diameter, japanned tin, brass rim.
  - 16/-
  - 722 .—Ditto, ditto, made of copper with brass rim.. ..£176
  - SUN DIALS
  - RAIN GAUGES
  - 723.—H o w a r d 1 s Rain Gauge, japanned funnel with brass ring, glass bottle and measure, 5 in. diameter .. .. 10/6
  - 724 .—Ditto, ditto, copper funnel with brass ring, glass bottle and measure.
  - 725.—G I a i s h e r’s Rain Gauge, japanned, with glass measure, 8 in. size .. £110 0
  - 726 .—Ditto, ditto, copper, with glass measure, 8 in. size .. £2 12 6
  - 15/-
  - WIND VANES
  - 727.—Antique Design Sundial in Brass, as illustration, divided to 5 minutes.
  - A. 8-in. diameter .. £3 0 0
  - B. 9-in. ,, 3 7 6
  - C. 10-in. 3 19 6
  - D. 12-in. „ 5 15 0
  - Mottoes extra.
  - 728. — Weather Vane, plain zinc, 42 in. high, with a socket 6 in. x 4J in. for fixing into a pole, etc... £3 15 0
  - 729 .—Ditto, plainer kind, but more serviceable and effective for meteorological purposes .. .. .. £3 19 6
  - The vanes are not painted, but the colours are left to the option of the purchaser.
  - The arrow should be well balanced, and move freely and easily horizontally.
  - The vane should be placed as high as practicable. The arm N. & S. should be adjusted to true north—not magnetic N. The wind direction should be observed to 16 points of the compass and the indication entered in capital block letters in the Register.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.107 - vue 126/555
- - 108 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Lid., PROPRIETORS.
  - SUNSHINE RECORDER, ANEMOMETERS, Etc.
  - 730. —Sunshine Recorder, Campbell
  - Stokes, for recording the duration of bright sunshine. On Polished slate base with adjustment for any latitude, complete with a year’s supply of charts £21 0 0
  - 731. —Extra Charts, per set (400) .. .. 2 10 0
  - 733.—Improved Robinson’s Anemometer,
  - to show up to 500 miles. In cast-iron frame, with wind vane working on ball bearings, and four fixed points'.
  - £21 0 0
  - 732. — Evaporation Gauge, for determining the amount of terrestrial evaporation. Copper dish, galvanized iron wire cage, and graduated measure:
  - £2 2 0
  - 734.—Improved Robinson’s Anemometor,
  - as above, without wind vane .. .. £12 12 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.108 - vue 127/555
- - 109
  - SECTION 5
  - MECHANICS
  - (PRACTICAL AND APPLIED)
  - Hydrostatics • Pneumatics • Steam and the Steam Engine
  - SETS OF
  - “NIVOC” INTERCHANGEABLE APPARATUS FOR EXPERIMENTS IN MECHANICS
  - The important feature of this apparatus lies in the fact that the parts, being interchangeable, are easily and quickly adapted for a large number of experiments. A reference to the illustrations, which are actual photographs, will make this quite clear.
  - Besides being strong and durable, the apparatus is simple, easy to manipulate, and for the small initial cost of £8 a wide range of experiments can be carried out, whilst at a small additional cost, the number and variety of experiments may be almost indefinitely extended.
  - The illustrations themselves are almost sufficient to show the exact functions of every part. The special screw clamp holder is perhaps the most useful device, as it can be used in many ways and is necessary for every experiment.
  - Apparatus for demonstrating parallelo gram of forces by means of pulleys.
  - Apparatus for demonstrating parallelo-
  - gram of forces by means of spring balances and heavy iron ring weights.
  - The weights on the bases of the tripod stands ensure stability.
- p.109 - vue 128/555
- - 110 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - “NIVOC” INTERCHANGEABLE APPARATUS
  - FOR MECHANICS
  - See page 112 for full Details and Prices.
  - Apparatus for parallelogram of forces,
  - fitted up to demonstrate rectangular components.
  - ..."
  - t!^.....................1
  - Apparatus for demonstrating parallelogram of forces by the horizontal method.
  - See Note on page 115.
  - Balance Lever and Moments Apparatus.
  - Lever Apparatus,
  - showing suspension at the fulcrum by means of a knife edge, demonstrating the principle of the lever and pressure on the point of - suspension.
  - Apparatus for demonstrating the three orders Of levers. The third order is illustrated.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.110 - vue 129/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 111
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - “ NIVOC ” INTERCHANGEABLE APPARATUS FOR MECHANICS
  - See Next Page for full Details and Prices,
  - Apparatus to demonstrate pressure between an inclined plane and the body resting on it.
  - Inclined Plane Apparatus with force at any angle.
  - to demonstrate forces when at
  - Apparatus moments of angles.
  - The metal peg with steel pin should be used for centre support of boxwood rule and plummet.
  - Apparatus to demonstrate parallel forces and the
  - reactions of the supports of a beam.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.111 - vue 130/555
- - 112 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Lid., PROPRIETORS.
  - SPECIFICATION AND DETAILS OF
  - COMPLETE SETS OF APPARATUS
  - For carrying: out the Experiments illustrated on pages 109, 110, and 111.
  - 735.—The set Of apparatus for carrying out the eleven experiments, as described on pages 109, no and m, consists of 3 tripod stands, 3 special screw clamp holders with all necessary brass screws, 1 drawing board, 1 wooden crosspiece for keeping tripod stands rigid for certain experiments, 2 aluminium pulleys, with rod for fitting into scre\^ clamp holder, 1 metal peg with steel pin, 1 metal peg with knife edge, 2 tubular spring balances, 1 strong graduated boxwood lever 100 cm. long with brass fulcrum, 2 brass scale pans, 1 inclined plane, 1 brass roller, 15 brass slotted weights, each 1/10 lb. ; 5 brass slotted weights, each 1/20 lb. ; 5 brass slotted weights, each 1/100 lb. ; 3 brass hangers for slotted weights, 1 double-hooked brass hanger (each hanger weighs 1/10 lb.), set of square iron ring weights, J, 1, 2 and 4 lb.; 1 ball of special twine for pulley and other work, polished box with hinged lid to hold the various parts, and a useful selection of hooks, cords, etc., with plumb bob.
  - Price of complete set, £8 O O.
  - 736.—For a class of 16 Students working in pairs (and some at different experiments from others), the following parts are required for the experiments :—20 tripod stands, 20 special screw clamp holders with all necessary screws, 12 aluminium pulleys in frame, with rod for fitting into brass clamp ; 4 drawing boards, 4 wooden stays to keep tripod stands rigid for certain experiments, 8 metal pegs with steel pin, 8 metal pegs with knife edge, 8 tubular spring balances, 8 strong graduated boxwood levers 100 cm. long, each with brass fulcrum; 8 boxwood scales for lever and physical balance experiments, 16 brass scale pans, 4 inclined planes, 4 brass rollers, 80 brass slotted weights, each 1/10 lb. ; 20 brass slotted weights, each 1/20 lb. ; 20 brass slotted weights, each 1/100 lb. ; 12 brass hangers for slotted weights, each 1/10 lb.; 8 double-hooked brass hangers (each hanger weighs 1/10 lb.), 8 sets of square iron ring weights, \ to 4 lb., 4 balls of special twine for pulley and other work, boxes with hinged lids to hold the various parts, and a useful selection of hooks, cords, etc., with 4 plumb bobs.
  - Price of complete set for a class of 16 Students, £45 O O.
  - The tripod stands, special screw clamp holders, spring balances, boxwood scales and iron ring weights of the above sets are necessary for the following experiments which may be carried out at a small extra cost for the additional parts as shown in the illustrations.
  - 737.—Physical Balance.
  - Additional parts per set
  - 8/6
  - 738.—Apparatus to demonstrate screw. Price of additional part
  - efficiency of a
  - .. 19/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.112 - vue 131/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 113
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - “NIVOC” INTERCHANGEABLE APPARATUS
  - FOR MECHANICS
  - See page 112 for full Specification of Complete Sets.
  - k
  - 739.—Wheel and Axle.
  - Price of additional part ., 15/-
  - 740.—Apparatus to verify Law of Moments of Forces
  - Price of additional part ,. 7/6
  - 741.—Roman Steel-
  - yard 13/6
  - 742.—Two V-shaped Grooved Planes, with one steel ball and one boxwood ball, two wood blocks for varying the angle .. .. .. .. 19/6
  - 743. Inclinometer, showing method of use for measuring the angle of an inclined plane. Additional part, consisting of varnished scale mounted on wooden back, with plumb-bob .. .. 7/-
  - 744.—Wedge Apparatus. The top
  - crossbar keeps the tripod stands quite rigid. Additional parts ..........23/6
  - H
- p.113 - vue 132/555
- - 114 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - “NIVOC” INTERCHANGEABLE APPARATUS FOR MECHANICS
  - See Page 112 for full Specification and Prices.
  - 745.—Jib Crane, for demonstrating triangle of forces.
  - Price of additional parts .. .. .. .. 23/6
  - 746.—Apparatus for Determination of
  - sisting of pendulum with heavy bob.
  - Price of additional parts .. 16/6
  - 747. — Set of Irregular Shaped Figures, with eyelet holes for suspending from steel pin ..........................7/6
  - 748.—Compound Wheel and Axle.
  - Price of additional parts, including wooden pulleys .. .. 18/6
  - 749.—Single Movable Pulley Block.
  - For prices and details of pulleys, see page 115.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.114 - vue 133/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 115
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - <( NIVOC ” INTERCHANGEABLE APPARATUS
  - FOR MECHANICS
  - See Page 112 for full Specification of Complete Sets.
  - 750. —Set of 4 “Single " Pattern Pulleys, aluminium .. 12/- per set.
  - 751. —Set of 2 “ Double ” Pattern Pulleys, aluminium .. 11/6 per set.
  - 752. —Set of 2 “ Triple One Row ” Pattern Pulleys, aluminium.
  - 17/- per set.
  - 753. —Set of 2 “ Triple Long ” Pattern Pulleys .. 17/6 per set.
  - For details of Large Pulleys for heavy weights see page 125.
  - For prices and details of all other “ Nivoc ” Pulleys see page 124.
  - 754. —Set of 3 Pendulum Bobs, with
  - Cord ..........................3/6
  - 755. — Pulley Block Apparatus.
  - Apart from the pulleys the only additional piece required is a wooden cross-bar with hooks as shown in the illustration. The price of this cross-bar is 5/- only, and it is suitable for pendulum experiments as shown. If the tripod stands cannot be arranged between two tables, then stools should be used.
  - Price of stools .. .. .. each 13/6
  - See page 112 for full details and specification of the complete sets of apparatus for carrying out the experi-
  - 756.—Apparatus for sliding friction,
  - consisting of board with 2 sliding blocks and brass hooks.
  - Price of additional parts .. ... 4/9
  - ments illustrated on pages 109, 110 and 111.
  - For apparatus for demonstrating parallelogram of forces by the horizontal method, as illustrated on page no, it is assumed that more than one complete set will be ordered, otherwise one extra tripod stand with special screw clamp holder, etc., are required.
  - The irregular shaped board, as in apparatus to verify law of moments of forces,; No. 740, page 113, is suitable for the experiment.
  - 757 .—Price of three steel balls.
  - 3/- per set.
  - 758.—Screw Jack for
  - demonstrating mechanical efficiency. Complete with circular table, cord, pulley and hook .. £3 10 0
- p.115 - vue 134/555
- - 116 F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - * W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 759. — Inclined Plane, 20 in. long, polished mahogany, with heavy brass roller weighing i lb., and wooden block1700 . . . . .. .. 25/-
  - 760 .-—-Ditto, but cheaper make and rougher finish 1701
  - 16/6
  - 761.—Inclined Plane, 24 in. long, 4 in. wide, hinged at one end, with graduation to show angle, and fitted with adjustable pulleys for transmitting force. 1703
  - Price, including brass roller and scale pan £4 17 6 See Perry’s “ Applied Mechanics,” 1909 Edition, pages 99 and 104.
  - PLANES
  - 762.—Inclined Plane, 20 in. long, provided with ball-bearing detachable pulley, heavy brass roller, and thin plate-glass plate. Pulley, being detachable, may be used for other experiments 1702 .. .. £1 15 0
  - 763.—Wedge and Divided Block of Hard
  - Wood. Price, complete with two rubber bands as figured 1704 ..................... 7/6
  - 764.—Inclined Plane and Brass Roller, provided with aluminium pulleys running in centres, so that pull may be parallel with the plane or base as desired. 1705
  - A. Price for best make, not including weights or scale pan .. .. . . .. .. . . .. £110 0
  - B. Ditto, including scale pan and necessary weights .. .. . . . . .. .. .. .. £1 15 0
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.116 - vue 135/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 117
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - INCLINED PLANES
  - 765.—Inclined Plane and Friction Apparatus of superior make and finish. Length 36 in., width 7 in., provided with 8 sliders of hard and soft woods, metals, leather, glass, etc. The plane may be placed horizontally or set at any angle. Angle and length measurements may be taken by means of arc and scale fitted to the apparatus. The upright rod carries an arrangement for supporting the inclined plane at any angle ; also provided with fine adjusting screw.
  - Price, complete with ball-bearing aluminium pulley 1711
  - £7 15 0
  - 766.—Heavy Truck on ball-bearings, for use with the above1712.. .. .. .. extra £2 2 0
  - 767.—Inclined Plane, 24 m. long, having scales on plane and base board. The graduated arc is slotted so that plane can be fixed at desired height.
  - Price, complete with aluminium pulley and brass roller 1714
  - £17 6
  - 768.—Improved Inclined Plane, 24 in. long, with adjustable angle for sliding friction experiments, etc. The framework and base are made of iron, and the plane of oak, well finished and smooth. The ballbearing aluminium pulley can be moved along the groove, so that forces parallel or inclined to the plane may be shown.
  - Price, including heavy brass roller and set of weights, as figured1713 .. . . ...........£3 10 0
  - 769.—Bertram's Inclined Plane. Superior
  - construction and finish. Framework of iron. Pulley can be adjusted at various angles. Edges of plane and base are graduated.
  - Price, complete as figured1715 .. .. £7 15 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.117 - vue 136/555
- - 118 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SLIDING FRICTION APPARATUS, ETC.
  - :
  - 770. —Apparatus for determination of friction by finding the angles of repose ; also for determining sliding
  - friction. Price, including 8 sliders (pine, mahogany, teak and oak, with and across the grain), scale pan, and small bracket with pulley 1709 .. .. .. .. .. .. .. .. .. .. .. .. .. .. £5 5 0
  - 771. —Iron sliders (planed) for ditto1710 ....................................................each, 12/6
  - 772.—Apparatus for Sliding Friction,
  - consisting of oak board, about 30 in. long and 7 in. wide, having a highly finished and smooth surface ; two sliders measuring 9 in. X 6 in. and 6 in. X 4^ in. respectively. One side of each slider is planed up as true and smooth as possible, and the underside is cut out so that the under surface equals half the top surface. See Wells' " Practical Mechanics.” 1707
  - Price, including pulley and two sliders .. .. 21 /-
  - 773.—Apparatus to find the conditions of equilibrium of a body resting upon an inclined plane, the body and plane being supposed smooth. This apparatus consists of a board about 30 in. long, 7 in. wide, 1 in. thick, having one of its faces covered with a sheet of glass. One end of the board is hinged to a stout base board, and the other is raised to desired height, by a hinged stay fixed in any position on the base board by a simple screw. The upright stay is clamped to the base board, so that a small aluminium pulley can be clamped to it at desired height, the groove of the pulley coinciding with the centre line of the board. A small wood box about 7i ln- X 5 in., and just large enough inside to contain a 7 lb. weight, is provided, with three aluminium wheels. (See Wells' " Practical Mechanics ”) 1708 .. £2 17 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.118 - vue 137/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 119
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - APPARATUS FOR “G”
  - 774.—Apparatus, for the determination of “ g,n as used at the Birmingham Municipal Technical School. This apparatus consists of a plain teak board fitted with a flat wooden strip to which is fixed a heavy lead weight. 1718 (See Gregory and Simmons, page 164) .. 23/6
  - Instructions for Use.—The pendulum is bushed, and is fitted on steel spindle, and is adjusted so that the face, when vertical, touches the equator of the bob. Pull the pendulum a little out of the vertical as shown in the diagram, measure the height in feet of the equator of the bob above any convenient base below the pendulum. Then burn the thread at a point just above the bottom pulley. The pendulum is thus released, and the instant it reaches the vertical line it strikes the sharp equator of the falling bob, and a mark is thereby made upon it. Measure the distance in feet from the base to the top of this mark when the pendulum has come to rest. The difference gives the space passed through by the bob in one-quarter of a complete swing-swang. Determine the time taken by ten or twenty to-and-fro vibrations of the rod swinging freely, and calculate from it the time (t) of one-quarter of a vibration. The value of the force of gravity (g) can then be determined from the simple formula: so that
  - $ = £gt2 so that g =
  - (b) Repeat the experiment by varying the rate of vibration of the pendulum, and making the measurements in centimetres.
  - 775.—Apparatus for determination of “ g ” (another pattern) mounted on heavy iron base1719..............................................£1 19 6
  - 776.— Apparatus FOR THE
  - DETERMINATION OF “ G.” This consists of an improved form of inclined plane, 12 ft. long (made of mahogany, and highly polished), in which a very accurately turned billiard ball is used as the moving body. The inclination can be varied and exactly measured. The usual relations of force, acceleration, velocity, and space can be determined as with the Attwood’s machine, and as the friction is practically nil, “ g ” can be found with great exactness. The apparatus can be raised or lowered by means of a hand-wheel and screw .. .. £10 10 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 120 F. E. BECKER & CO.> NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ATWOOD’S MACHINES
  - GEORGE’S NEW ATWOOD’S MACHINE (PATENT)
  - Pneumatic Release—therefore no vibration.
  - No Electrical Connections or Coils—therefore no residual magnetism. No Dropping Platform—No Interference with Dropping Weight—therefore
  - more accurate results.
  - Instantaneous Release—therefore more accurate results.
  - No Swing given to Weight or Over-Weight—therefore more accurate results.
  - That this machine will give more accurate results than other makes is obvious for the above-mentioned reasons.
  - We have received several letters from science teachers testifying to the general excellence of George’s New Atwood’s Machines. One Professor goes so far as to state that it will supersede all other makes, especially those electrically worked.
  - The height of the machine is 8 ft., and it is provided with an aluminium wheel 5 in. diameter (accurately adjusted and balanced) running in agate bearings, graduated rod, two sliding platforms, weights and overweights, patent pneumatic release, plumb bob, and special wall-brackets.
  - Each machine is carefully tested before leaving our manufactory, and a certificate showing results sent per post.
  - GENERAL DESCRIPTION.
  - George’s Atwood’s Machine is much used in Physical Laboratories by teachers and students, to prove by experiment the laws and formulae for the relation between time, distance, velocity and acceleration.
  - It is provided with both vertical and horizontal adjustments for the scale and plumb bob, and may be fixed to the wall of a class room by its brackets. The graduated brass upright is 8 ft. long, and carries on its upper end a light, accurately adjusted and balanced aluminium wheel, which runs freely in agate bearings to minimise the friction. The inertia of this wheel is equivalent to that of a known mass situated at its circumference. Two sliding platforms, one of which is a sliding ring ; a fine strong flexible silk thread; cylindrical weights with circular over-weights of the same diameter n, and riders S0S[9E£SI are a^s0 supplied.
  - The release of the left-hand weight is gently effected by aid of a pneumatic pipe and ball, as shown at the foot of the figure. This permits the other right-hand weight with its rider fSHnEIES t0 s^art falling freely without either jerk, swing, or vibration. A correction for the friction of the wheel bearings may be made by putting a little fine wire on the descending weight when two equal cylindrical weights are used, until no slowing down is observable after setting these weights in motion. The weight of the cord or thread passing over the pulley may be balanced by a length of the same kind and size, attached to the bottoms of the right and left weights : or by hanging therefrom loose vertical lengths of such thread. Either of these plans enables the experimenter to raise and lower the weights into position for adjustment or starting an experiment.
  - (Continued on next page.)
  - Every' requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 121
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ATWOOD’S MACHINES
  - GEORGE’S NEW ATWOOD’S MACHINE (PATENT)
  - (Continued from previous page.)
  - Method of Using the Machine.—If the two weights attached to the ends of the cord are equal, then no motion will ensue, since the downward force of gravity acting upon one weight, balances its downward force upon the other through their tensions on the connecting thread. The balanced wheel is unaffected by the action of gravity. But, if the right-hand weight be made heavier than the left-hand weight, by placing a very small wire weight to balance the friction of the wheel bearings, plus a rider upon it, then it will be set in
  - motion, solely due to the action of gravity upon the rider, until the rider is caught by the ring. The ring, although intercepting the rider, permits the weight with the little wire weight to pass clear through it without touching. The stop-stand may be clamped at any desired position on the vertical scale.
  - Now, referring to the two following figures, let us suppose that only a rider be placed on the right-hand weight, whose bottom is level with
  - the zero of scale, and top level with A on the line diagram. Then if the ring intercepts this rider at B one second after the weights have begun moving, the motion during that time has been uniformly accelerated, and the velocity is represented to scale by line B E. But, when the right-hand weight passes the ring, its motion will thereafter be uniform until its base is arrested by the stop-stand, with the velocity which it had acquired when its top just passed through the ring, viz., C D which is equal to B E. We may thus find the velocity gained in the first second, and, by changing the mass of the weights and riders, the positions of the ring of the stop-stand, we can try the following and other experiments, wherein the rider may be replaced by one or other of the circular overweights which pass clear through the ring, and cause uniform acceleration until they come to the stop-stand.
  - (See Jamieson’s " Elementary Manual on Applied Mechanics.”)
  - 777.—George’s New Atwood’s Machine (Patent) 1720, see
  - figure 777 .. .. .. .. .. .. .. .. ..£900
  - 778.—George’s New Atwood’s Machine (Patent). As No. 777,
  - but superior make and finish. Provided with sensitive friction wheels, mounted in elegantly finished magohany case. Complete with wall brackets, as figured on page 126 1721 .. .. .. .. .. .. .. .. £21 0 0
  - METRONOMES, STOP-WATCHES, Etc.
  - 779
  - 779. — Metron omes, best
  - make 1723 .. ... each 17/6
  - 780. —Ditto, with bell1724 „ 21/-
  - 781. —Stop-Watch, very reliable, jewelled movement, guaranteed accurate, with start, stop, and flyback action 1725 .. .. 35/-
  - 782. — Seconds Clocks. 1727
  - each 27/6
  - 783 .—Ditto, better make and more accurate, fitted in square-shaped polished mahogany case.1728
  - each £2 0 0
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- - 122 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - FLETCHER’S TROLLEY APPARATUS
  - 784 Q
  - 784.—Fletcher’s Trolley Apparatus.—For determining the relations between space, velocity, acceleration, and mass.
  - A trolley which may be variably loaded runs freely on a horizontal plane. A cord attached passes ovey a pulley at end and carries a scale pan. Weights placed in the latter set the trolley in motion. A vibrating spring supported in clamp is set in motion, a brush or marker then tracing a sinuous line on trolley or paper carried by it. A small metal block is provided which is affixed to the edge of the trolley with the steel pin fitted into it, when the trolley moves this releases the brush which traces the vibrations. From the known time of vibration of spring, and the number of waves recorded, the space moved in different times is found, and from this the velocity and acceleration are easily calculated by the usual formulae. By varying the weight of trolley and weights in pan, the relations between the foregoing and mass can be shown 1722 .. .. .. .. .. .. .. .. .. .. .. £4 17 6
  - The Scale Pan shown in the illustration has now been replaced by a more suitable wash leather bag.
  - BALLISTIC BALANCE o
  - 785.—-Ballistic Balance, for determining the velocity and momentum of falling bodies. Consists of a heavy frame moving on a central knife edge, and provided with cups on end knife edges, a pointer moving over a graduated scale, and movable gravity bob for adjusting the centre of gravity. Accompanied by a tall stand, from which the weights are let fall, and suitable balance weights. May also be used for experiments on the theory of the balance, determination of periodic times of oscillation, and for determining moments of inertia 1745 ..£915 0
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 123
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BALLISTIC BALANCES, PERCUSSION APPARATUS, Etc.
  - / 786
  - 786.—Hick’s Ballistic Balance,
  - height about 3! ft. Price for best make, giving good results1743 ..£217 6
  - 788. —Percussion Apparatus, for
  - demonstrating wave motion, consisting of ten balls suspended from a polished mahogany framework, as figured. 1735/4730
  - Price ................£110
  - 789. —Ditto, fitted with 5 balls £0 15 0
  - . 787.—Glazebrook’s Apparatus, for demonstrating the movement of a body projected horizontally and falling freely— thus describing a parabolic curve. Arranged for fixing to wall.1742
  - £6 0 0
  - 790.—Tyndall’s Percussion
  - figured 1734/4729
  - Apparatus, about 40 in. long, with ten balls and three levelling screws, as
  - .................................................. .. 27/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - 124 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ALUMINIUM AND BRASS
  - 791.—“Screw Stem” pattern, aluminium pulleys with Ball Bearings .. .. each 5/6
  - 792 .—Ditto, Brass . . ,, 5/6
  - 793. —“ Bicycle ” pattern,
  - aluminium pulleys with Ball Bearings .. .. each 5/6
  - 794. —Ditto, Brass .. ,, 5/6
  - PULLEYS
  - 795. —“ Blackboard ” pat-
  - tern, aluminium pulleys with Ball Bearings .. .. each 5/6
  - 796. —Ditto, Brass .. ,, 5/6
  - 797.—“ Inclined Plane ” pattern, aluminium pulleys each 2/-
  - 798 —Ditto, Brass, each 2/-
  - 805. —“ Girder ” pattern, aluminium pulleys .. each 12/-
  - 806. —D i 11 o , Brass,
  - each 12/-
  - 799.—“ Single” patter n, aluminium pulleys, each 3/-800—Ditto, Brass, each 3/-
  - 801.—“Double”
  - pattern, aluminium pulleys, each 5/9
  - 802 .—Ditto, Brass, each 5/9
  - 9
  - 803. — “Triple one row ” pattern, aluminium pulleys each 8/6
  - 804. —Ditto, Brass,
  - each 8/6
  - 814. — “ Triple
  - Long ” pattern, aluminium pulleys each 8/6 815.—Ditto, Brass.
  - each 8/6
  - 807.—
  - “Up right Screw ” pattern, aluminium pulleys,
  - each 5/-
  - 808. —Ditto, Brass, each 5/-
  - 809. —“Atwood’s Machine”
  - pattern, large size aluminium pulleys .. .. each 15/-
  - 810. —“ Bench ” pattern,
  - aluminium pulleys with Ball Bearings .. .. each 11/6
  - 811. —Ditto, Brass ,, 11/6
  - 812 .—As above, but with pivoted
  - bearings .. .. each 7/6
  - 813.—Ditto, Brass ,, 7/6
  - 818.—“ Clamp” pattern, aluminium pulleys each 4/6
  - 819 .—Ditto, Brass, each 4/6
  - 816. —“Retort Stand ” pattern, aluminium pulleys each 3/9
  - 817. —Ditto, Brass .. „ 3/9
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 125
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LARGE BRASS PULLEYS, Etc.
  - Large size, specially designed for use in ENGINEERING CLASSES.
  - 820. —Single Brass Pulley,
  - large size, accurately and substantially made, for use in engineering classes. Wheel about 3! in. diam with groove taking \ in. cotton rope 1759 .. .. each 19/6
  - 821. —Double Brass Pulley,
  - large size, accurately and substantially made, for use in engineering classes. Wheels about 3^ in. diam. with groove taking J in. cotton rope 1760 .. .. each 25/-
  - 822. —Triple Brass Pulley,
  - large size, accurately and substantially made, for use in engineering classes. Wheels about 3^ in. diam. with groove taking £ in. cotton each 30/-
  - 822
  - rope J
  - 823. — Weston Differential Pulley Blocks.1763
  - With Chain Guides.
  - The length of chain required is four times the height of lift, plus about 4 ft. in the £, and f-ton sizes ; about 6 ft. in the 1 and i|-ton sizes ; and about 8 ft. in the 2, 3, and 4-ton sizes.
  - The weights specified are those to which each respective set of blocks and chain is tested, but a size must always be selected which gives ample margin above the load to be lifted.
  - Prices.
  - Tested to 1 \ f ton
  - Distances between inside of hooks when drawn close up .. 18 23 23 in.
  - Block and chain for 6 ft. lift 28/6 32/- 37/-
  - For 10 ft. lift .. 36/6 40/- 47/6
  - For 16 ft. lift .. 48/6 52/- 63/6
  - For 20 ft lift .. 56/6 60/- 74/6
  - 824.—Set of Strong Teakwood Pulleys. Large
  - size, for heavy weights. The set consists of three pairs (“ single,” “ double,” and “ triple one row ”), as illustrated. Per set of six, complete with necessary rope .. £3 0 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc,, see Chemical Apparatus Catalogue.
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- - 126 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PULLEYS, Etc.
  - 825.—Single Boxwood Pulleys
  - 826. —Double Boxwood Pulleys. 1768
  - each 2/-
  - 827. —Triple Boxwood Pulleys. 1769
  - each 2/9
  - 828. — Triple Boxwood Pulleys,
  - long pattern 1770 .. .. .. . • each 2/9
  - 831. —Iron Brackets, for screwing
  - to boards. Very useful for pulley experiments, etc. 1774 .. .. each 2/6
  - 832. —Ditto, larger and much stronger1775
  - each 4/6
  - 829. —Set of Boxwood Pulleys,
  - complete with pulley frame as figured. Price does not include the weights. 1771
  - £3 0 0
  - 830. —Pulley frame only,
  - polished wood 1772 .. each £2 2 6
  - 833.—Cheap Quality Cabinet of Mechanical Powers,
  - with explanatory handbook, containing experiments to illustrate the simple principles of mechanics, by Professor R. A. Gregory, F.R.A.S. Price complete, containing 23 pieces of apparatus, packed in strong wooden box, with descriptive pamphlet. Cheap quality for students.
  - 1776
  - £3 12 6
  - 834.—Screws and IMuts.316
  - Per dozen 2/-
  - 835.—Wooden Model of Screw and Nut, large
  - 9/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 127
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WHEELS AND AXLES, Etc.
  - 837.—Set of Mechanical Powers, better quality, polished mahogany. Complete as figured, and including Inclined Plane and Wedge 1777 ...............£9 15 0
  - 838
  - 838.—C o m p o u n d Wheel and Axle,
  - made of hard wood and mounted in cast-iron frame. Diameter of wheel 6 in. Diameter of axle 3 in. and 1^ in., with steel rod centred into steel centres. 1784
  - £1 12 6
  - 839. — C o m -pound Wheel and Axle,
  - made specially for Engineering Classes. Constructed entirely of metal. Diameter of wheel about 14 in. Ball Bearings. Price, including brass pulley. 1785
  - £7 10 0
  - 840.—Wheel and Axle,
  - simple; diam. of large wheel 6 in., diam. of small wheel, 3 in. 1779 .. .. each 3/6
  - 841. — Compound Wheel and Axle,
  - in bracket, best make and finish.1780
  - each 21 /-
  - 840
  - 842.—W o o d e n Screw, in
  - bracket, with sliding rod, as figured.
  - Price for best make 842
  - and finish 1782 .. .......each 27/6
  - 843.—Compound Wheel and Axle,
  - superior make, provided with iron brackets for fixing to wall, steel shafting, bearing, woodwork of solid teak, total length about 18 in., diameter of. teak wheel about 12 in., steel axis about l in, diam.; the bearings are carefully machined.
  - Price, not including pulley or weights 1786
  - £3 15 O
  - 839
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 128 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS..
  - SCREW EFFICIENCY AND FRICTION
  - 845.—Screw Jack for demonstrating mechanical efficiency. Complete with circular table, cord, pulley and hook.
  - £3 10 0
  - 844.—Worm and Wheel. All
  - machine-cut gear. All castings truly machined. This apparatus is self-contained for fixing to wall. The wheel, which is about io in. in diameter, is provided with correctly cut teeth gears, with a square threaded screw fixed on a shaft carrying a flanged wheel. Weights can be attached by suitable cords so that the friction, velocity ratio, and mechanical efficiency can be readily ascertained. 1788
  - Price, not including weight or Scale
  - Pan ..............£11 5 0
  - 846.—Apparatus to show
  - Efficiency of Screw. Square threaded screw on frame (steel nut) to which weights can be attached ; force applied by cords passing over two guide pulleys, to the periphery of a double grooved wheel (about 9 in. diam.), on end of screw. Height overall, about 25 in.
  - This apparatus is provided with two " Nivoc ” aluminium ball-bearing guide pulleys, and two scale pans. 1789
  - Price complete, as figured
  - £13 15 0
  - COMBINED SCREW AND
  - WORM WHEEL JACK.
  - Large Size.
  - 847.—Combined Screw and Worm Wheel Jack, large size, for Engineering Classes. Machine-cut Worm and Gears. Screw and worm wheel can be used separately or together.
  - The whole apparatus of superior construction and finish, self-contained, and mounted on tall stand 1791 £18 15 0
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 129
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - JIB CRANES
  - 848.—Wall Crane, large
  - size 1795 .. each £3 5 0
  - 849.—Apparatus to show relations of Forces in Braced Frames (Jib Crane). Height about 4 ft. Consists of three parts—post, jib, and tie-rod, the two latter fitted with balances to record pull and thrust. The jib and tie-rod can be adjusted to various angles. 1796 £5 7 6
  - 850.—Jib Crane, after the style of No. 849, but with upright post working in strong cast-iron bracket.
  - The Pull on the upright post is measured by means of two spring balances which are attached by two guide ropes 1797 .. .. .. £6 15 0
  - 851.—Model Crane, large size.
  - Height over all about 5 ft. SPECIFICATION.
  - Geared for three speeds, the turning effect being applied by a cord or grooved wheel which can be placed on any axle. Diameter of grooved wheel about 10 in.
  - Tie-rods readily adjustable by means of lugs and thumb screws.
  - All gear wheels are machine cut. All shafts are truly turned.
  - Steel castings are accurately machined.
  - The whole apparatus is well finished and mounted on clamped wooden base. 1798
  - Price .................................................. .. £19 10 0
  - Every requisite for Chemical, Physical, [and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - 130 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - w. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ROOF TRUSSES,
  - Etc.
  - 852.—Simple Roof Truss. This
  - apparatus is useful for finding the forces acting in the different members of a simple triangular roof truss, and is provided with one spring balance and loop for suspending weight. 1799
  - Price.........................18/6
  - 853.—Model of Sheer Legs
  - with balances showing tension and compression of the different members. Complete, with adjustable stand.1801
  - £4 15 0
  - See Duncan s “ Applied Mechanics for Beginners.”
  - 855.—Roof TruSS, superior quality. This form is provided with two compression spring balances and one extension spring balance. The two supports are made telescopic, so that the pull and the thrust may be measured. One arm is provided with small wheels to lessen friction ; total length about 4 ft. 1800 .. .. . . £4 17 6
  - See Duncan’s “ Applied Mechanics for Beginners”
  - 856.—Adhesion Plates, 4 in. diameter, without handles. 1740
  - per pair, 5/-
  - 857 .—Ditto, with brass handles, 3 in. diameter 1741 .. „ 17/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.130 - vue 149/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 131
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TESTING APPARATUS
  - INCLUDING DEFLECTION OF BEAMS AND SPRINGS, YOUNG’S MODULUS, TORSION, FRICTION, Etc.
  - 858.—Strong Cast Iron Brackets. These brackets are provided with knife-edges, and will be found exceedingly useful for determining the stiffness and strength of beams.1802 Per pair................................................................................................................12/-
  - 859. —Apparatus for determining the stiffness and strength of wooden and metal rods.
  - Constructed entirely of metal. Length 36 in., can easily be fixed to wall. Furnished with case-hardened knife-edges, which can be moved along the two metal shafts at desired distances, and rigidly fixed there by means of clamping screws. Price, without rods and weights 1807 .. .. .. .. .. .. .. .. .. ...... £2 10 0
  - 860. —Mirror Scale for measuring the slope of the elastic curve 1808 .. .. .. .. .. .12/6
  - 861.—Apparatus for determining the reactions of the supports Of a beam. This apparatus consists of two circular spring balances, each weighing up to 20 lb. and provided with necessary hooks, beam one metre long, and wooden framework.1809
  - 862. — Knife-Edges.—These consist of two strong iron brackets, each 10 X 10 in., which can be screwed to the wall in desired position. The top surface of each bracket is provided with a hardened steel knife-edge, 5 in. long.1817
  - Price, not including the weights
  - £5 12 6
  - Price 12/6 per pair.
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For prices, etc., see Chemical Apparatus Catalogue.
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- - 132 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TESTING APPARATUS
  - 863.—Apparatus, as No. 861, but cheaper make and finish, provided with two spring balances, each weighing up to 15 lb., and three simple form hook suspenders. 1810
  - 866.
  - Apparatus for showing B reakin g Stress of Steel Wires,
  - fitted with crab and winder and steelyard; height of apparatus about 4 ft. 1821
  - Price, complete
  - £11 10 0
  - £2 10 0
  - 864. —Set of 6 Wooden Laths, planed deal, consisting of one each Lath, 36 x 2 X ^in.,36 X 1 X ljrin.,36 X 1 X £ in., 24 X \ X | in., 18 x 1 X J in., and 4 X 1 X i in. 1812
  - Per set .. .. ...........................2/-
  - 865. —Wooden Laths, planed deal, 24 X \ X \ in. 1813
  - Per dozen .. .. .. .. .. .. .. .. 3/6
  - 867.—Experimental Model of an Arch, best make 1811 £5 10 0
  - 868. —Wooden Laths, different sections. Prices on application. 1815
  - 869. —Sets of Planks, strapped together, for bending. Prices on application. 1816
  - 870. —Metal Laths, different sections. Prices on application. 1814
  - 871.—Lathe Bed Apparatus, for determining the stiffness and strength of rods, the measurement of Young’s Modulus by bending, and other experiments.
  - “ University ” Pattern, see Ewing’s “ Strength of Materials,” page 86, 1906 edition.
  - This apparatus is furnished with a Reading Microscope and Mirror Scale, and is fully described on page 222 of our Physical Apparatus Catalogue, 1913 edition.
  - Price, including wooden and steel rods of various breadths, depths and lengths1818 .. .. .. £24 0 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.132 - vue 151/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 133
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - EXTENSION AND COMPRESSION OF SPRINGS
  - 872.—Apparatus for determining the Compression of Springs. Improved pattern. Made entirely of metal, highly finished and machined. Loads are applied direct, and the compression read by means of a silvered scale and vernier. 1823
  - Price, including four powerful springs of different strengths,
  - £6 5 0
  - 873.—Apparatus for determining the Extension and Compression of Springs.
  - Improved pattern. Made entirely of metal, highly finished and machined.
  - Illustration shows a powerful spring fixed in frame ready for extension experiments.
  - “ For “ compression ” experiments, spring must be fixed below as shown in figure 872.
  - Price, including six springs (3 for extension and 3 for compression experiments). 1824
  - £6 17 6
  - 874. — Apparatus for demonstrating the comparative relation of Compression and Extension of Springs. 1826
  - £1 10 0
  - The above apparatus carries one compression spring balance and one extension spring balance.
  - 875.—Heavy Steel Springs for use in Engineering Classes. These springs vary from 25 to 50 mm. in diameter, and are about 30 cm. in length. Square section of wire about 6 mm. 1827
  - 5/- to 8/6 each, according to size.
  - 876.—Spiral Springs,
  - dynamometers, etc.1828 Each
  - Per dozen
  - 12 in. X l in. for small
  - ......... .. .. 8d.
  - ....................7/-
  - 877.—Rubber Cord, square section. Prices subject to fluctuations of the market. 1829 A. ^-.in................................ .. per ounce
  - i >>
  - ie >> ........................
  - 1 .. .............................,
  - Larger sizes to order.
  - B.
  - C.
  - D.
  - 1/2
  - 1/4
  - 1/6
  - 1/8
  - 878.—Rubber Cord, round section, fluctuations of the market. 1830
  - Prices subject to
  - A.
  - B.
  - C.
  - i m.
  - per ounce
  - Larger sizes to order.
  - 1/4
  - 1/6
  - 1/8
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.133 - vue 152/555
- - 134 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - YOUNG’S
  - 879
  - MODULUS, Etc.
  - 879. —Young’s Modulus of Wires Apparatus.
  - This is a simple form of apparatus for measuring the elongation of a wire under the influence of a stretching force. It consists of a scale vernier, reading to -^ths of a mm. on the scale, 2 hooks for screwing into beam or ceiling, brass clamp with 2 nuts for keeping wires parallel, scale pan, and weight to keep one of the wires taut and free from kinks. 1831
  - Price, complete in box .. .. .. .. .. • • 28/6
  - 880. —Wires for use with Young’s Modulus of Wires
  - 'Uljjjh Apparatus.1833
  - ^ Gauge No. .. .. 18 20 22 24 26 28
  - A. Steel Wire .. per lb. 2/10 2/10 3/2 4/4 5/6 7/6
  - = B. Brass Wire .. „ 2/10 2/10 3/- 3/2 3/6 3/9
  - C. Copper Wire.. „ 2/8 2/10 2/10 3/- 3/- 3/3
  - 881.—Scale and Vernier, reading to ^ths of a millimetre for Young’s Modulus of Wires Apparatus 1832 .. .. .. . • .. 14/6
  - to
  - Enlarged View of Scale and Vernier.
  - 882
  - «.
  - 882. —Wells’ Apparatus for investigating the behaviour of a length of fine wire when loaded until it breaks.
  - This apparatus consists of a length of ordinary metal wire about 0*05 in. or ^Vin. diameter, free from twists or kinks, which pulls apart with a load of 120 to 160 lb.
  - A strong metal hook, rigidly fixed to some convenient post or bracket about 6 ft. from the floor. A vernier gauge for measuring the extension of the wire, reading to the I1TV<yth part of an inch, and with screws for fixing to the wire at points exactly 10 in. apart, so that the extension is measured on a length of 10 in. 1834
  - Price, including bracket and hook and strong scale pan for heavy loads .. .. 23/6
  - 883. —Young’s Modulus of Wires Apparatus, improved pattern with special clips for gripping wires. 1835
  - Per set, without weights .. .. 38/6
  - 884 .—Ditto, heavier type, for engineering laboratories, and made for testing thicker wires. 1836
  - Per set, without weights .. .. 57/6
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the
  - utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.134 - vue 153/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1. 135
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - YOUNG’S MODULUS, Etc.
  - 885.—Young’s Modulus of Wires Apparatus,
  - improved pattern, and made in accordance with the suggestions contained in a paper read by G. F. C. Searle, Esq., F.R.S., at the Cambridge Philosophical Society, on March 29, 1900. In this paper, Mr. Searle points out that when using apparatus of the usual types, consisting of a movable scale and vernier, it is impossible to avoid errors arising from the yielding of the support, and from change of length, due to rise of temperature.
  - The latter may cause a large error, for a difference of 2 per cent, will produce a difference of 1/10 mm. in length in a copper wire three metres long. Both errors are practically eliminated in this modified apparatus.
  - Instead of measuring extension of the lower end of a long wire in relation to a fixed mark, one observes the extension of the end of the wire, relative to the lower end of a second Wire of same material, hanging from same support, stretched by a constant weight, and used as a standard of comparison, assuming the coefficients of expansion in both cases to be the same, although the wires are subject to different stresses.
  - The description of instrument and method of using are as follows.
  - The two circular brass frames support the two ends of a very sensitive spirit level.
  - One end of the level is pivoted to the frame, the other end rests on the point of a vertical screw working in a nut. The wires for use with the instrument are fixed in small brass swivels, one to pass through the top, and one through bottom of each frame. The swivels permit the wires to hang always free from torsion, and the frame being rigid, the wires hang always in a vertical plane. The screw has 1 mm. pitch, and the head is divided in 100 parts. The wires provided . should be fixed at top of instrument. In order to do this, the level can be removed. The ends of these long wires are fixed in the usual way to a beam. The instrument is then hanging freely. The two shorter wires must now be passed through the two lower holes in the brass frame in the same way. The level is then replaced. To one short wire is attached the fixed weight. Before making the experiment, the micrometer screw is adjusted, so that the bubble is at its fiducial mark.
  - After stretching, the extension is measured by bringing the bubble back by means of the micrometer, and the distance is the difference between the two readings.
  - The level is sensitive enough to enable a reading to be made to b of a division, that is 1 /1000 mm. 1837
  - Price.......................................................................£3 17 6
  - 886.—Modulus of Torsion in rods. This apparatus can be used with rods up to 25 mm. diameter, and 65 cm. long. Two reading telescopes and mirrors are provided. The whole is fixed on a wooden frame to fasten on the wall; an assortment of rods with hanger and weights are provided. 1838
  - Described in Ewing’s “ Strength of Materials."
  - Price...................................£27 10 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.135 - vue 154/555
- - 136 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RIGIDITY APPARATUS
  - 887. — Modulus of Rigidity Apparatus.
  - This apparatus consists of a large block of rubber, about 14 X 4| X i in., mounted on a polished mahogany base. A strip of metal is fixed firmly to the upper edge of the rubber, and, by means of the cord passing over pulley, pulling forces of varying magnitude can be applied. The distortion of the rubber is measured by the movement of a vernier over a fixed graduated scale1844 .. . . • • • • £4 15 0
  - 888.—Searle’s Apparatus, for proving that the Angle of Torsion in a Rod is proportional to its length and that different materials have different rigidities.
  - In this apparatus the front pulley carries a cord with known weights suspended from it. The spindle of this pulley moves in ball bearings, and carries at its inner end a three-jaw chuck. This chuck is for holding one end of the rod under test, whilst the other end is for tightly clamping it to the back bracket of the machine. The torsional couple is applied by means of weights hung from the aforementioned cord, and the torsion in degrees is read off on the dials.
  - To eliminate errors, the weights should be hung first on one side of pulley, then on the other side, and the mean of the two readings taken. It will be noticed that both the pointers and the scales can be readily moved to any distance from the fixed end of the rod 1845 .. £5 0 0
  - (See Jamieson’s “ Elementary Manual on Applied Mechanics.” )
  - 889.—Lathe Bed Apparatus,
  - for proving that the angle of torsion in a rod is proportional to its length and that different materials have different rigidities.
  - This apparatus is of substantial make and highly finished. It consists of a Lathe Bed about 8 ft. long, fitted with five cast-iron sliders, which can be clamped at various distances, three graduated dials, three pointers, each with clamping screw, and accurately turned pulley wheel.1846
  - Price, complete as figured £25 0 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.136 - vue 155/555
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TORSION APPARATUS
  - 890.—Apparatus for demonstrating that the torsion in a rod is proportional to its length.
  - This apparatus is composed of a square brass supporting rod, i in. square section arranged to be attached to the wall.
  - One side of the rod is graduated in centimetres, so that the length of the wire under examination can be easily measured. The sliders carry divided circles, each bearing a pointer which clips the wire; these sliders can be adjusted in any position on the rod, and form an easy means of measuring the length of the wire examined. The graduated circle on each dial is protected by ground glass, on which any observations made can be written.
  - The apparatus is provided with a double grooved wheel, two “ frictionless ” pulleys, and two scale pans for weights. 1847
  - Price, complete as figured .. £8 10 0
  - 891.—Torsion of Wire Apparatus.
  - New form, fitted on heavy tripod'foot and provided with levelling screws, three reading dials, which can be adjusted, and pointers. Height over all, about 4 ft. 2641
  - Price, complete .. ' . . .. £7 15 0
  - 892.—Searle’s Rigidity Apparatus. Consisting'of a piece of wire, 30 cm. long, the ends of which are soldered into holes drilled axially into cheese-headed screws, the two screws being slipped into holes bored in the middle of two brass rods, A B and C D, and are clamped by means of small nuts N N. The wires enter the screw heads exactly on the axes of the rods A B and C D. The rods are about 30 cm. long by 1-5 cm. diameter, and are suspended by means of thin silk fibres so that the rods and the wire which connects them lie in the same horizontal plane.
  - For full details of experiments which may be carried out with this apparatus, refer to Edser’s “ General Physics for Students,” 1922 {Macmillan 6- Co.).
  - Price, complete as above . . .. .. .. .. .. .. - .. .. 17/6
  - Searle’s Apparatus. {Perspective view above, sectional plan below.)
  - Our stock of pure Chemicals and Acids is very considerable \ hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.137 - vue 156/555
- - 138 F. E. BECKER & CO., IMIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TORSION
  - 893.—Maxwell’s Needle for Experiments on the Torsion of Wires.
  - Price .. .. .. .. .. .. .. £3 15 0
  - This is a particularly convenient oscillator for use in measuring the modulus of rigidity of wires.
  - It consists (Fig. 43) of a tube into which four equal short pieces of tube can be slipped, each of the short pieces being one-fourth of the length of the long tube. Two of the short pieces are empty, and two are filled with lead.
  - By placing the tubes as shown in Figs. 43 and 43a, the moment of inertia of the system can have two values given to it : I x and 12, of which Ix (corresponding to Fig. 43) is considerably the greater.
  - To express the change in moment of inertia, or Ix — I2, let a be the half-length of the long tube, mx the mass of each of the two short tubes that are filled with lead, and m2 the mass of each of the empty short tubes.
  - Then the system is changed by shifting two masses, each equal to mx — m2, so that the distance of the centre of gravity of each from the axis changes from §a to \a.
  - Hence I, — I2 = 2 (mx — m2) (T9G«2 — TV«2) = {mx — m2)a2.
  - Let tx and t2 be the observed periods of oscillation in the two cases respectively,
  - tl = h
  - i 2 T ‘'2 -* 2
  - / 2 T T
  - X1 ___ X1
  - OF WIRES
  - Then
  - / 2_______f
  - ‘'1
  - Ii — la («i“ Ij. _ (wi w2)a2 t\ — tz
  - m2)a2
  - and hence we obtain, without calculating I, the following equation for C,
  - r _ 128nl _ (mx — m2)a2 tx2-12
  - See Ewing’s “ Strength of Materials,” pages 91-93, 1906 edition.
  - COMPRESSION BALANCES
  - TUBULAR PATTERN. FOR EXPERIMENTS ON MECHANICS.
  - 894. —Tubular Compression Balances for Experiments on Mechanics.
  - ABODE To indicate 6 lb. X J lb. 10 lb. X J lb. 6 lb. x \ lb. 10 lb. x \ lb. 20 lb. x \ lb.
  - Each .. .. 12/- 17/- 11/6 12/- 17/6
  - 895. —Tubular Compression Balances, as No. 894, but graduated in kilogrammes.
  - A B C D E F
  - To indicate .. 5 kilos. X TV 8 kilos, x rV 10 kilos, x ro I2 kilos. X\ 15 kilos, x \ 20 kilos. X £
  - Each........ 17/- 22/6 27/- 24/- 27/9 31/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.138 - vue 157/555
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SPRING BALANCES
  - 896. —Spring Balances, reading in grammes.
  - To weigh up to .. 50 50 50 100 100 150 250 500 500 1000 grammes
  - Divided into .. z\ 5 1 5 1 5 5 5 10 10 grammes
  - Price, with hook .. 1/2 1/2 1/6 1/6 4/- 3/3 4/6 8/- 6/- 8/- each.
  - 897. —Spring Balances, in kilogrammes.
  - To weigh up to .. .. 5 10 12 15 20 20 25 30 40 50 kilos.
  - Divided into .. • • tV tV £ £ £ £ £ £ £ £ kilo.
  - A. Price, with hook only, as
  - figured .. .. 1/3 5/9 1/3 2/4 3/9 2/4 2/9 3/9 4/9 8/-each.
  - B. Price, with hook and
  - scale pan .. ..3/- 7/9 3/- 4/6 6/6 5/- 6/- 7/- 9/-13/-each.
  - 898. —Spring Balances, graduated in lb. and oz.
  - To weigh up to .. 12 15 20 25 25 30 40 50 60 75 100 lb. Divided into ..£££££££ £ £ iilb.
  - A. Price, with hook
  - only, as figured 1/3 2/4 3/9 5/9 1/3 2/4 3/9 5/9 8/- 4/9 8/- each.
  - B. Price, with hook
  - and scale pan 3/- 4/6 6/6 9/3 3/- 4/6 6/6 10/- 12/- 8/9 13/-each.
  - ..liiiiiii
  - SPRINC
  - ibal
  - !£i
  - 899.—Spring Balances, tube pattern, improved shape, IN KILOGRAMMES.
  - Range 3 X nr kilo. 4x t<t kilo. 5 X tV kilo. 6 x tV kilo. 8 X A kilo.
  - Each 3/9 4 /- 4/6 5/- 6/-
  - Range 5 X £ kilo. 10 X £ kilo. 12 X £ kilo. 15 X £ kilo. 20 X £ kilo.
  - Each 3/6 4/- 4/9 5/- 6/-
  - 900.—Spring Balances, tube pattern, similar to No. 899, but IN LB.
  - AND IOZ.
  - Range 12 lb. XI oz.. 4 lb. xi oz. 8 lb. X 2 oz.
  - Each */- 5/- 6/3
  - Range 6 lb. x£ lb. 8 lb. x £ lb. 10 lb. x £ lb. 15 lb. x£ lb. 20 lb. x £ lb.
  - Each 3/6 3/9 4/- 5/- 6/-
  - Range 12 lb. X £ lb. 20 lb. x£lb. 25 lb. x £ lb.
  - Each \ 3/6 4/- 4/6
  - Range 30 lb. x £ lb. 40 lb. X £ lb. 50 lb. X £ lb. 60 lb. x£ lb.
  - Each 5/- 6/- 11/3 17/-
  - 896, 897 and 898
  - 901. —Laboratory Com press ion
  - Balance, with enamelled dial and round scale pan. .
  - 7 lb. X J oz......15/-
  - 14 lb. X1 oz......16/—
  - 251b. xi oz.......24/—
  - 28 1b.X2oz........18/6
  - 50 lb, x 2 oz. .. 27/6
  - Our Balances and Weights have achieved World-wide Reputation]]: vide Opinions of the
  - Leading Scientific Press.
- p.139 - vue 158/555
- - 140 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SPRING BALANCES
  - 902.—New Patent Circular Balances, with hook only or with hook and scale pan.
  - To weigh up to 10 15 20 25 30 40 50 60 kilos
  - Divided into 50 50 50 50 50 100 100 100 grammes
  - A. Price, with hook
  - only.. 13/6 14/6 19/6 21/- 27/6 28/6 30/- 32/6 each
  - B. Price, with hook
  - and scale pan 18/- 19/6 25/- 26/- 32/6 33/6 35/- 41/- each
  - With Hook and Scale Pan.
  - IRON WEIGHTS
  - 903
  - 903. —Set of Iron Kilo Weights, with hanger, consisting of seven weights,
  - |, 1, 2, 5, 10 kilos, as illustrated. 1872
  - Price, complete .. £2 5 0
  - 904. —Set of Four Iron Weights, with hanger, consisting of three 10 lb. weights, and one 20 lb. weight. 1873
  - Price, complete .. £2 7 6
  - f
  - 905. —Set of Slotted Weights, consisting of one hanger weighing 500 grammes, and the following loose weights : 1 of 500 grammes, 2 of 200 grammes, and 1 of 100 grammes. 1874
  - Price, complete .. .. .. .. 10/-
  - 906. —Slotted Weights, 1000 grammes,
  - to fit hanger 905 1875 .. .. each 2/-
  - 907. —Set of Slotted Weights, consisting of one hanger weighing 1 lb. and the following loose weights : 1 lb., 0-5 lb., 0-5 lb., 0-2 lb., g-2 lb., o-i lb., o-o3 lb., 0-02 lb., 0-02 lb., o-oi lb.1876
  - Price, for complete set .. .. .. 18/6
  - 908.—Slotted Weights, to fit hanger 907
  - A. 2 lb. ..................each 2/-
  - B. 4 lb........................ 3/6
  - 909.—Set of Nine Slotted Weights with Hanger,
  - totalling 500 grammes. 1878
  - Price, per set .. ... 8/-
  - For Brass Slotted Weights, see page 143.
  - 905
  - 910.—Kilo Weights in Sets.
  - 200 grammes down to 50 grammes, 2/- per set.
  - 500 grammes down to 50 grammes, 3/3 per Set.
  - 1 kilo down to 50 grammes, 5/- per set.
  - 10 kilos down to 50 grammes, 27/6 per set.
  - 2 kilos down to 50 grammes, 8/- per set.
  - 20 kilos down to 50 grammes, 35/- per set.
  - 5 kilos down to 50 grammes, 14/6 per set.
  - 911.—Single Kilo Weights, shape as No. 910.
  - Size .. .. 50 100 200 500 grammes. Size .. .. 1 2 5 10 20 kilos.
  - Price .. ... 7d. 8d. 10d. 1/3 each. Price .. -.2/- 3/- 6/- 10/6 19/-each.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.140 - vue 159/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 141
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - IRON WEIGHTS
  - 912.—Iron Kilo Weights, roughly adjusted, from i kilo to io grammes.1881
  - 5/-
  - 913.—Set of Kilo Weights, roughly adjusted, as No. 912, but from 1 kilo to 1 gramme, the 5, 2, and 1 gramme weights being made of brass. 1882
  - 6/- per set.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.141 - vue 160/555
- - 142 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - APPARATUS FOR MOMENTS AND LEVERS
  - 917.—Lever and Wedge-shaped Fulcrum,
  - cheap make 1888 .. .. .. .. .. 3/9
  - 918.—Lever and Wedge-shaped Fulcrum,
  - lever 48 X 2 X f in., fitted with brass eyes, fulcrum 6 in. high. 1889
  - Made of polished mahogany .. .. .. each 9/-
  - 919.—Lever, “ Lecture Table ” pattern, superior make and finish. 1894
  - Price, complete with 16 slotted weights, each TVth of a lb.
  - 32/6
  - 920.—Apparatus for determining the meaning of the “ moment of a force.”
  - This apparatus consists of a beam of hard wood, 60 in. long, i| in. deep and f in. thick, with the upper edge divided into lengths of 1 in., a slight saw-cut being made at every inch, to form a nick. A piece of \ in. square steel bar is driven through the centre of the beam, the ends being drilled slightly hollow and conical, to form centres, about which the beam will turn as an axis. A wooden bracket from the wall carries a plate-iron bracket, in which are screwed two set screws with hardened conical ends, to fit into the centres of the axis of the beam. Two pieces of iron bar fixed on one side of the bracket act as stops to keep the beam in place. 1893
  - Price..........................................................................................22/6
  - See Wells’ “ Practical Mechanics.”
  - 922.—Lever for Suspension,
  - length 36 in., divided into 20 parts, fitted with 8 brass eyes, hole drilled through each division. 1890
  - 921.—Simple Lever, in the form of a graduated rule, one metre long, with movable fulcrum, and two riders, which can be fixed through holes at various distances. Holes are 2 cm. apart.1892 ...... .......... 5/9
  - A. Made of polished mahogany
  - each 6/-
  - B. Made of ebonised wood ,, 5/-
  - O__ Q O
  - m—
  - 922
  - 923—Lever Apparatus, consisting of a rule fitted into a pivoted stirrup. 1891
  - A. Price, including brass slotted weights
  - B. Ditto, without weights
  - 8/9
  - 6/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.142 - vue 161/555
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SLOTTED WEIGHTS, STEELYARDS, Etc.
  - 924.—Set of 16 Brass Slotted
  - Weights (four of which have rods bent at right angles and provided with knife-edges) each TVth of a lb. and accurately adjusted 1896
  - Per set .. .. ' .. .. 12/6
  - 925.—Set of 16 Brass Slotted Weights, as 924, but with four of them in the form of hanging carriers with brass hook. 1897
  - Per set .. .. .. .. 12/6
  - 926.—Hanging Carrier, with
  - brass hook, total weight TVth lb. 1898 Per dozen .. .. .. 15/-
  - 927.
  - 928.
  - 929.
  - Brass Slotted Weights,
  - TV lb. size.. sV lb. size..
  - , ,, ,, t<tct lb* size..
  - (These weights fit carriers Nos. 924 and 925.)
  - 9/- per dozen. 9/- „
  - 9/- „
  - FOR
  - IRON SLOTTED WEIGHTS, SEE PAGE 140
  - 930.—Danish Steelyard, with
  - movable fulcrum 1906 .. 11/6
  - 931.—Model of Roman Steelyard, made of hardwood 1905 .. 8/- each.
  - 932.—Roman Steelyard, strong and highly polished 1902 .......... 25/-
  - 933 —Ditto, smaller size and rougher finish.1903
  - 15/-
  - 934—Law Of Moments. Apparatus to verify. This apparatus is fully described in Schuster and Lee’s “ Intermediate Course of Practical Physics,” and consists of a balanced disc of wood capable of rotating about its centre. Weights can be suspended from holes bored in the disc.
  - Price, including glass scale, plumb bob and two scale pans, as figured 1913
  - 27/6
  - 934
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.143 - vue 162/555
- - 144 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - APPARATUS FOR MOMENTS, LEVERS, Etc.
  - W5JGE0RCELT0.
  - 935
  - 935.—Apparatus for measuring the period of an oscillating body,
  - by the eye and ear method comparison of moments of inertia. This apparatus consists of a light metal cradle (a), suspended by a phosphor bronze wire, and having a mirror (m) attached, by means of which an image of a scale is reflected into a telescope. The upper end of the suspension wire is soldered to a metal rod, which is itself firmly clamped to a cross-bar that rests in two V's, attached to an upright tube (c), which is itself carried by a box with glass sides. This box serves to protect the suspended part of the apparatus from draughts. Metal cylinders of various shapes are provided, which can be placed in the V’s of the cradle. The object of the experiment is to determine the period of the cradle alone, and also when it carries each of the metal cylinders in succession. From these periods it is possible to compare the moments of inertia of the cylinders, and also, if we know the moment of inertia of one of the cylinders, determine the torsional rigidity of the suspension wire. 1909
  - Price................................................................19/6
  - See Watson’s " Text Book of Practical Physics,” p. 107, 1906 edition.
  - 936.—Bell Crank Lever, consisting of wooden lever centred at the end with long arm, the length of which is about 30 in. A spring balance is attached to the short arm, the other end of the former being fixed to a hook screwed in the upright pillar. 1911 Price .. .. .. ..£150
  - 937.—Lecture Apparatus, for
  - experiments on Moments, Levers, etc. ; frame 36 in. high, fitted with bracket for carrying lever. Price, including boxwood lever, two “ Nivoc ” clamping pulleys, and three scale pans. 1908 Price.................£2 10 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.144 - vue 163/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 145
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CAMS
  - reciprocating and circular motion.
  - 938.—Apparatus to find the difference in the motion produced by a cam, with a small and large roller, assuming the cam to rotate with uniform angular velocity, consisting of Eccentric Cam, Involute Cam, Heart Cam, Heart and Circle Cam. Stout board, on feet, with scale and pointer. 1915
  - £4 5 0
  - See Wells’ “ Practical Mechanics.”
  - 938
  - 939.—Apparatus to investigate the
  - motion of a connecting rod and crank, and to find the effect of using connecting rods of different lengths. The motion of the crank is supposed uniform.1916
  - £4 17 6
  - See Weils’ “ Practical Mechanics.”
  - 939
  - 940
  - 940.—Apparatus as No. 939, but piston and pump rod in one piece (as used in small vertical engines and pumps), with slotted bar, in which the slot is at right angles to the rod, and the crank pin moves to and fro in the slot.1917
  - 941.—Apparatus
  - to find by experiment and graphically the forces acting at the crosshead of a steam engine, and the crank effect for different positions of the crank, supposing the pressure on the piston to be constant.1918
  - £3 5 0
  - See Wells’
  - “Practical Mechanics.”
  - £4 17 6
  - W.ft.d.GEORGE.L7“
  - 941
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
  - K
- p.145 - vue 164/555
- - 146 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ENERGY OF
  - 942. — Experimental Fly-Wheel, about 20 cm. in diameter, and 4! cm. thick, mounted on a horizontal shaft. Constructed entirely of metal. All working parts truly machined and turned. The balanced wheel is marked, and a pointer is fixed to the bracket, as figured. 1919
  - Price complete .. . . .. .. ..£376
  - 943.—Perry’s Experimental Fly-Wheel.
  - This apparatus, which is constructed entirely of metal, consists of a nicely balanced massive wheel, 15 in. diameter, and weighing about 80 lb. Mounted on a self-contained iron bracket. All the working parts are truly machined and turned. The shaft is 2 in. in diameter, and works in ball-bearing races. A ballbearing pulley, mounted on separate iron bracket, carries a rope for attaching to shaft, and a pointer is fixed to framework for facilitating the counting of the revolutions of the fly-wheel. See Perry’s " Applied Mechanics.” 1920
  - Price ........................£12 10 0
  - FLY-WHEELS
  - 944.—Apparatus to show friction of a pulley, superior make and finish, all parts accurately machined and turned. The wheel, which is 12 in. in diameter, is carried in journals and supported on cast-iron brackets. Shaft 1 in. in diameter. 1928
  - Price .........................£3 17 6
  - 945.—Rope Brake and Dynamometer, consisting of a V-grooved wheel about 18 in. in diameter with steel shaft working in journals, the whole fitted to frame complete as figured. 1929 Price £5 10 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.146 - vue 165/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 147
  - W. * J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - COIL FRICTION APPARATUS, Etc.
  - 946. — Apparatus to show Coil Friction of Rope and Belt. Consists of massive iron base with upright and strong circular board divided into degrees or angles. The Apparatus is provided with two sets of pulleys for use with the rope or belt. The lap of the coil may be varied by adjusting the circular board at different angles. All the working parts are carefully machined and accurate. 2640
  - Price, complete .. .. .. .. .. ..£6150
  - 947.—Apparatus for Coil Friction, complete
  - with spring balance and pulleys. This apparatus is worked by means of a handle. The pulleys can be placed in different positions, thus enabling the arc of contact to be varied. The large pulley can be fixed in position, or moved by a handle so that it can be used as a dynamometer. 1934 Price ........................... £2 10 0
  - 948.—Coil Friction Apparatus, consisting of 4 in. brass drum and three aluminium pulleys, giving £, f and full circumference of contact, mounted on board measuring about 30 in. x 24 in. 1933 Price, complete with cord and two scale pans £2 10 0
  - 949.—Apparatus for proving Law of« Work, consisting of; train of wheels enclosed ? in box, with projecting > shafts provided with pulleys and complete with scale pans. All gear wheels are machine cut, and other parts accurately machined. 1932 £4 17 6
  - For full description of this apparatus and instructions for use, see Perry’s “ Applied Mechanics.”
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.147 - vue 166/555
- - 148 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 950
  - FRICTION
  - 951.—Train of Gear Wheels, cheaper pattern and small size for students’ use • .. 12/6
  - 950.—Train of Gear Wheels, with large pulley for explaining and demonstrating the great mechanical advantage gained by the combination of toothed wheels of varying sizes ; as will be seen by the illustration 2 lb. raises 56 lb.
  - Price, not including weights .. .. .. £6 15 0
  - 953.—Apparatus for investigating sliding friction at various speeds and testing lubricants. 1935
  - £7 15 0
  - See Perry’s “ Applied Mechanics,” Fig. 27.
  - APPARATUS
  - D W.S.J.GEORGE.L!? Q
  - 952.—Fluid Friction Apparatus. This consists of a hollow cylindrical body F supported so that it cannot be moved sidewise, and yet so that its only resistance to turning is due to the twist it would give the suspension wire A. C C is water or other liquid, filling the annular space between the cylindrical surfaces D D and E E, and wetting both sides of F. When the vessel D D, E E is rotated, the liquid moving past the surfaces of F tends to make F turn round, and this frictional torque is resisted by the twist which is given to the wire. The amount of twist in the wire gives us then a measurement of the viscosity of liquids, and investigations may be made under very different conditions. 1938
  - Price, without Whirling Table .. .. £5 10 0
  - For further details, see Perry’s “Applied Mechanics,” also “Proceedings of Physical Society,” March, 1893.
  - 954. — Apparatus for investigating sliding friction at various speeds and testing lubricants. 1936 £19 10 0
  - See Perry’s “ Applied Mechanics,” Fig. 28.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.148 - vue 167/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1. 149
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - rm
  - PENDULUMS
  - 955.—Simple Pendu-
  - lum, with one suspended lead ball. 1940
  - Each,
  - 3/9
  - 956 —Ditto, with 3 balls, brass, wood, and lead. 1941
  - Each
  - 9/6
  - 956
  - 958.—Lead Balls with
  - hooks for making simple pendulums. 1943
  - Each .. .. .. 4d.
  - Per dozen .. .. 3/6
  - 959
  - 960
  - 960.—Kater’s Reversible Pendulum
  - 957
  - 959.—Simple Pendulum, consisting of a heavy iron ball suspended by steel wire, and clamp for altering length of same, hardened steel knife-edge and brass bracket with hardened steel bearings, for fixing to wall or shelf. 1946
  - Price, complete .. 15/-
  - This pendulum consists of a vertical bar carrying a brass weight near each end, together with two similar boxwood weights between the brass weights, which are so attached as to compensate for the air displacement of the brass ones. The pendulum may be hung from one or. other of two movable steel knife-edges working on agate planes. 1944 See Jamieson’s “ Elementary Manual on Applied Mechanics.” Price, complete as figured,
  - 961. — Schuster and Lee’s Pendulum,
  - consisting of a lead bullet suspended by means of a cord in front of two glass mirror scales 1939 Complete, mounted on stand.
  - Price .. .. 17/6
  - £8 5 0
  - 957.—Simple Pendulum. Polished Mahogany, with 4 balls and clamps. 1942
  - Each.. .. .. 32/6
  - 962
  - 962.—Kater’s Reversible Pendulum,
  - Wall pattern, consisting of two sets of hardened steel knife-edges (movable), two sets of weights, brass bar of suitable length, and brass bracket for fixing to wall.1946
  - As figured .. £3 5 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.149 - vue 168/555
- - 150 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PARALLELOGRAM OF FORCES
  - 963. — Gravesande’s Apparatus for verifying the parallelogram of forces, consisting of two uprights mounted on polished mahogany board, two brass " clamp ” pulleys, and a set of weights. 1952
  - 964.—Glazebrook’s Apparatus for
  - verifying the parallelogram of forces. Complete with weight and pulleys, but without drawing board. 1958
  - For full details, see Glazebrook’s “ Mechanics and Hydrostatics,” page 46, 1902 edition.
  - Price
  - 27/6
  - Price
  - 35/-
  - 965.—Frick’s Parallelogram of Forces Apparatus. Price for superior make, including 3 balanced scale pans 1956
  - £2 5 0
  - 966.—Parallelogram of Forces Apparatus,
  - consisting of a blackboard with two aluminium " Clamp Pattern ” pulleys and two wall brackets. Illustration shows a piece of drawing paper pinned on to the blackboard 1959 .......................... 30/-
  - 967.—Polygon of Forces Apparatus, with four pulleys 1960 .. .. .. .. .. 37/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.150 - vue 169/555
- - F. E. BECKER <ft CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 151
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PARALLELOGRAM OF FORCES
  - Fig. A
  - Fig. D
  - Fig. C
  - 968.—Parallelogram of Forces Apparatus, Dulwich College Pattern. This apparatus can be used for the following experiments :—
  - Verification of Parallelogram or Triangle of Forces.
  - Verification of Polygon of Forces (five forces). See Fig. B.
  - Verification of the Moment Theorem (general case for 4 forces). See Fig. C. The perpendiculars to the lines of action of the forces can easily be measured by means of a couple of scales, or the angles by a protractor and the perpendiculars calculated.
  - The weights in pans and the position of pulleys must be adjusted so that scale hangs vertically (between two lines marked on board).
  - To verify the position and magnitude of resultant of two parallel forces. See Fig. D. The scale being suspended instead of turning about the pivot.
  - Arrange horizontal pulls P, Q and P Q at A, B, and C, so that P X AC = Q X BC, then scale hangs in equilibrium. A scale pan is provided of double the mass of the others.
  - GENERAL ADVANTAGES.
  - 1. Simple method of attaching to table. See Fig. A.
  - 2. The use of the vertical lever instead of the usual horizontal type.
  - 3. The strings of pans from the upper pulleys are kept clear from the pulleys in the slots.
  - 4. Greater stability and sensitiveness.
  - The above apparatus is strongly made, and consists of a board clamped at top and bottom, and provided with iron slot on each side, and a metal rod at top for supporting the graduated lever.
  - Price, complete with 4 ball-bearing “ frictionless ” pulleys, and 4 scale pans 1961 .......... .. £2 17 6
  - V
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 152 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 969.—Apparatus to illustrate Centre Of Gravity, consisting of an irregular board, with lines drawn upon one face. 1962 Each.........2/-
  - CENTRE OF GRAVITY
  - 970.—Set of 3 Zinc Figures, of triangular, quadrilateral, and circular shapes respectively, with lines showing how the centre of gravity is constructed. Each plate has two holes for strings for demonstrating that the centre of gravity is represented by the point where the two plumb lines intersect each other-
  - Price for complete set, including pointed support for carrying the figures in the centre of gravity 1963 ..........................£2 5 0
  - 971. —Apparatus to illustrate Centre Of Gravity, consisting of two parallelepipeds of hard wood, 5| X 4 x 2. 1964
  - Per pair . . .. 5/6
  - 972. —L e a n i n g Towers. 1965
  - Each...........4/6
  - 973.
  - Plumb Bobs.1966 Each .. 9d.
  - 974.—Plumb Lines. 1967
  - Each .. • • 11/6
  - 975. — Lever and Wedge-shaped Fulcrum, cheap make 1975 .. each 3/9
  - !
  - i
  - 976. — Gyroscope, small size, for students’ use. 1947
  - Each.........................2/6
  - 977. —Gyroscope, medium size, for lecture table use. 1948
  - Each
  - £1 15 0
  - 978.—Gyroscope, “ University ” pattern, of heavy make, complete with accessories, in box, as figured 1949b £6 15 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 153
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CENTRE OF GRAVITY
  - 979.—Equilibrium Apparatus, consists of an iron pivot loaded with two balls, and balancing by means of its point on an upright support, showing the state of equilibrium. To show unstable equilibrium loosen screw which fixes wire stirrup in the iron pivot. 1968
  - Price .. .. .. .. 8/-
  - 980.—Centre of Gravity
  - Apparatus, consisting of a semicircular piece of metal balanced on a pointed support. 1969
  - Each ................19/6
  - 981.—Double Cone and Inclined Plane.1974
  - Each ................11/6
  - WHIRLING TABLES
  - 982.—Whirling Table, of bronzed iron, for horizontal and vertical positions 1981 .. .. .. £2 10 0
  - 984.—Whirling Table,
  - large size, for horizontal and vertical positions, Worked
  - by motor. 1983
  - Price .. .. £11 17 6
  - When ordering, please state voltage.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.153 - vue 172/555
- - 154 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WHIRLING TABLES AND ACCESSORIES
  - 985.—Whirling Table, strongly made, with large driving wheel which can be moved along a groove and rigidly kept in position by means of a fly-nut underneath, when it is necessary to tighten up pulley band. Adapted for use in horizontal or vertical position and suitable for all the following accessories. 4905 Price.................« ............................................£2 10 0
  - 986.—Rings to illustrate spheroidal form of the earth 1984 .. 10/6
  - 990.—Semi-circular Ring and Ball,1988 9/6
  - 988.—Support, with two
  - 989.
  - 987.—Foucault’s Pendulum. 1985 17/-
  - tubes.
  - 1986
  - 10/6
  - Glass Globe,
  - 10/6
  - 1987
  - The small copper tube is fixed on a small wheel. The tube, three parts full of water, is closed by a cork, and is pressed between a pair of oak boards, while the wheel is rotated very rapidly. The water quickly becomes heated by the friction, and its temperature soon exceeding the boiling point, the cork is projected to a height of several yards by the pressure of the steam.
  - Price, without Whirling Table 8/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.154 - vue 173/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 155
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CENTRIFUGAL FORCE MACHINE
  - 995. —Centrifugal Force Machine.
  - Improved pattern, fitted with recording counting apparatus and ball bearings, etc. 1977
  - £13 10 0
  - 996. —Handwheel for ditto 1978 £1 17 6
  - BALANCING MACHINE
  - 997.—George’s New Balancing
  - Machine. An iron frame suspended from three points by stranded wires. .It carries a shaft with six discs, which can be driven by an electric motor, also fixed on the frame, so that the apparatus is self-contained.
  - This larger form of Balancing Machine contains, in addition to the discs fitted with balance weights, provision for the examination of reciprocating movement.
  - Three cranks are arranged on the shaft, and are connected to three sliding pieces. As the weight of these can be varied, and one or more may be disconnected, a complete examination of the influence of varying masses, crank angles, and number of reciprocating pieces, can be made.
  - Price......................£22 10 0
  - DYNAMOMETER
  - 998. —Rintoul JS Spring dynamometer. This Spring Dynamometer is by far the cheapest and best pattern in the market. It may be used for a dozen or more experiments—for full details see “ An Introduction to Practical Physics,” by D. Rintoul, pages 114 to 147. It consists of the usual form of spring resting in a groove, with hook for cord, etc. A cross-bar enables the reading on the scale (which is graduated in grammes) to be made with a fair degree of accuracy. It is also provided with an adjustment at the top by which the spring can be re-set should it become permanently elongated. 1993
  - Each .. .! .............4/6 Per dozen ..................52/-
  - 999. —Scale Pans, with silk cords and brass hook, suitable for use with above Dynamometer. 1994
  - Each .. .. .. .. .. .. 11d. Per dozen .. .. .. .. .. 10/-
  - Our stock of pure Chemicals and Acids is very considerablej hence ail orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.155 - vue 174/555
- - 156 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - FLUIDS
  - MECHANICS OF
  - 1000.—Apparatus for studying the flow of water through orifices of different shapes and over notches of different gauges.
  - This apparatus consists of a vertical tank nearly 4 feet high, standing upon a strong support. At the bottom of this trough is fixed a rotating brass diaphragm, by means of which orifices of various shapes may be used, and which can be readily adjusted so that water can flow freely or be stopped as desired. Baffle plates are placed in the tank at different heights to still down all eddies.
  - A long vertical gauge glass serves for reading off the head of water.
  - A shallow sloping trough is provided to carry the water away to a large horizontal trough, which measures about 54 X 18 X 10 inches. The latter is fitted with baffle plates to prevent eddies, and its distant end is made to take rectangular and V gauge notches.
  - The measurement of the head of water above the lower edge of the notch, is effected by means of a hook gauge.
  - The water now flows into a vertical measuring and receiving tank, which is divided into two compartments so that the flow may be readily changed to either side as desired. Two water gauges, with scales marked in cubic feet, are fixed to this tank for determining the quantity of water collected. 2015
  - A. Price without stands .. . . . . • • • • • • • • • • • • • ®22 10 0
  - B. Stands extra .. .. .. . . . . • • • • • • • • • • • • • • • • • • £8 0 0
  - See Perry’s “ Applied Mechanics.”
  - HYDROSTATIC PRESSES
  - IOOI 1002
  - 1001. —Hydrostatic Press, apparatus to show the principle
  - of 2033 ...........................each £2 15 0
  - 1002. —Ditto, smaller size and cheaper make 2034 ,, £17 6
  - 1003.—New Model Hydrostatic Press, of simple construction. This machine is very powerful and easy to work.
  - It is provided with an arrangement for breaking bars of iron and also a table, as shown in illustration, for placing heavy weights upon. The large piston is provided with a self-releasing valve, which practically makes it impossible to have an accident with the machine, whatever weight is placed upon the table. 2035
  - Price, complete
  - £4 17 6
  - 1003
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.156 - vue 175/555
- - F. E. BECKER & CO., NIVOC HOUSE HATTON WALL, LONDON, E.C.1. 157
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MODELS OF PUMPS
  - 1004.—Lift Pump Model, all glass.2017
  - Each .. ..2/6
  - N
  - 1008. — Force Pump Model,
  - all glass. 2021
  - Each .. .. 4/-
  - 1012.
  - Fire Engine Model, all glass. 2029 Each .. .. 4/-
  - 1005.—Lift Pump Model, mounted on support, including zinc trough and rubber tubing. 2018
  - Each .. .. 12/6
  - 1006.—Lift Pump,
  - large size, height overall 56 cm. Of metal and glass, and made to withstand a great deal of wear and tear. 2019 35/-
  - 1009. -r- F o r c e Pump Model,
  - mounted on support, including zinc trough and rubber tubing. 2022
  - Each .. .. 13/6
  - 1010. — Force
  - Pu mp, large size, height overall 60 cm., metal and glass, and made to withstand a great deal of wear and tear 2023 .. 37/6
  - 1013.—Fire Engine Model, mounted on support, including zinc trough and rubber tubing2030 .. ... 13/6
  - 1007.—Bramah’s Press Model, mounted on support, including zinc trough and rubber tubing 2026 1 3/6
  - 1011.—Bramah’s Press Model, all glass. 2025 Each............4/6
  - 1014.—F ire Engine Model, superior quality, glass and metal.2031
  - Each.............£1 17 6
  - X)ur Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.157 - vue 176/555
- - 158 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. * J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - HERO’S FOUNTAINS, Etc.
  - 1015.—Hero’s Fountain of Glass,
  - simple form. 2038 Each .. .. .. 5/-
  - mounted. 2039
  - Each..............8/6
  - 1020.—IVIodel of Hydraulic Ram. 2043 Each...........9/6
  - 1017.—Hero’sFoun-tain of Glass,
  - superior construction. 2040 Each .. .. £5 17 6
  - 1021.—A p p a r atus
  - on Stand, for showing expansion of gases. 2044
  - Each .. £1 10 0
  - 1018.—Apparatus to
  - show pressure of fluids. Each...........5/-
  - 1019.—Apparatus to
  - show pressure of gas in all directions.
  - Each............7/6
  - 1022.—Models of a Set of Water Wheels,
  - overshot and undershot, made of japanned tinplate, consisting of an overshot-wheel, an undershot-wheel, a water cistern, a frame to support the whole in acting position, and a pan to receive the spent water.2047 The complete set .. .. .. ..£250
  - 1023 .—Ditto, undershot only, mounted on stand. 2048 Each ...............................£17 6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.158 - vue 177/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 159
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SPIRIT LEVELS
  - 1024.—Spirit Levels, cheap quality, walnut case, metal top.2049
  - Length .. 4 6 8 inches.
  - Price, each .. 10d. 1/- 1/3
  - 1025.—Circular Spirit Levels, best quality.2050
  - A. 1 in. diameter each 4/9
  - B. in. „ „ 5/9
  - C. 2 in. ,, ,, 6/9
  - 1026.—T riangular Table, fitted with 3 levelling screws for levelling a given plane surface with a spirit level 2051 .. .. 12/6
  - 1027.—Circular Cross Spirit Levels, best quality. 2054
  - Nickel-plated .. each 5/6
  - 1028.—Small Brass Pocket Level,
  - in wooden case. 2052
  - Each ........................2/3
  - Per dozen .. . . .. .. .. 24/-
  - 1029.—Spirit Level,
  - brass, best quality. 2053 Length, in.
  - Each ................2/6
  - Per dozen............27/6
  - LEVEL OF WATER, Etc.
  - 1030.—Apparatus to
  - show level of water, glass.2060
  - 1031.—A pparatus,
  - mounted on support. 2061
  - 1032.—A pparatus,
  - consisting of glass tube with five branches. 2062
  - Each
  - 1/6
  - Each
  - .. 2/6
  - Each
  - .. 6/6
  - 1033.
  - B a r k e r’s IVl i I I , made of japanned tinplate. 2064
  - Each .. 13/6
  - 1034.
  - Capillary PI a t e s ,
  - in japanned zinc frame. 2069
  - 1035. — Set of 6 Capillary Tubes,
  - in japanned zinc frame, with trough. 2068
  - 1036.—Glass Vessel, with
  - five capillary tubes. 2067
  - Per set
  - 3/6
  - Per set
  - 4/-
  - Each
  - 3/-
  - 1037.
  - Manometer,
  - mounted on board, with sliding scale, 2059
  - 10/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.159 - vue 178/555
- - 160 F. E. BECKER & CO., IMIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PRESSURE OF LIQUIDS, Etc.
  - 1038.—Apparatus to show that there is greater velocity wherever a pipe is contracted, and that greater velocity means greater kinetic energy, etc., etc. 2016
  - £4 0 0
  - 1039.—Apparatus to show decrease of pressure in cylindrical tubes. 2075
  - See Perry’s “ Applied Mechanics.”
  - Each
  - £1 17 6
  - 1041.—C artesian
  - Figures, best quality. 2097
  - Each........4d.
  - 1042.—C artesian Figure, in glass jar 12 in. high, and a piece of india-rubber sheet. 2098
  - 1040. — Pascal’s
  - Apparatus, for
  - showing that the pressure of liquids depends upon their height and the surface of the bottom of the columns, and not upon the capacities of the vessels; mounted on brass, with polished wood stand.
  - Price, including three vessels of different shapes.2081
  - £4 5 0
  - 1043.—Cartesian
  - Diver, in jar as figured, best quality.2099
  - 1044.—Pascal’s Apparatus, large size, superior make, provided with vessels of four different shapes. 2083
  - Each..........................£4 15 0
  - 1045.—Cold Water Float, made of brass.2088 Each........12/6
  - 1047.—S pouting
  - Cylinder, of
  - japanned tin. 2074
  - Per set
  - 3/-
  - Each ..
  - .. £1
  - 7 6
  - 1046.—Ditto, glass 2089
  - made of 6/-
  - Each ..
  - •• 7/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.160 - vue 179/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1. 161
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PRESSURE OF WATER, Etc.
  - 1048. — Plateau’s E q u a l-weight Wire Figures,
  - set of five 2094 12/-
  - 1049.
  - Apparatus for
  - showing the upward pressure of water, consisting of a glass cylinder, metal disc, and glass jar. 2063
  - Per set .. 5/-
  - 1049
  - 1050.—Glass Syphons,
  - with suction tube and bulb.
  - Length .. 8 10 15 in.
  - Each .. 2/3 2/6 3/3
  - Length .. — 20 30 in.
  - Each — 3/9 6/-
  - 1051 •—Ditto, plain, without suction tube.
  - Length .. 12 15 18 30 in.
  - Each..............1/- 1/4 1/9 2/3
  - AIR PUMPS
  - 1052.—Double Barrelled Air Pump, with lever handle, and brass stopcock, mounted on polished mahogany stand with plate 8 in. dia. Price .....£11 10 0
  - 1052
  - 1053. —Double Barrelled Air
  - Pump, with lever handle, stopcocks, and 8-in. plate, mounted on raised platform with polished mahogany base .. .. £15 10 0
  - 1054. —Ditto, with 10-inch plate.
  - £16 10 0
  - 1053/4
  - 1055.—The “ Nivoc ” Vacuum Foot Pump (Registered Design). Works with the ease of a motor pump, and a good vacuum can be obtained with very little exertion. Specially suitable for use by junior students and ladies.
  - A. Price of pump, complete with pressure tubing and connections .. .. .. .. .. each £17 0
  - B. Air pump plate for same .. .. .. .. • • . • .... .. .. .. ,, 0186
  - Our stock of pure Chemicals and Acids is very considerable j hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.161 - vue 180/555
- - 162 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. QEORQE (LONDON), Ltd., PROPRIETORS.
  - AIR PUMPS
  - 1056 .—Diameter of plate, 4J in. ..
  - 1057. „ „ 5 „
  - 1058. „ „ 5|„
  - 1059. „ „ 7 ,,
  - Air Pump,
  - single barrel, on polished ma-
  - hogany base, with stopcock.
  - Each.
  - .. £2 2 6 2 7 6 2 12 6 2 17 6
  - 1060.
  - Air Pump Plate,
  - on stand, diameter of plate 10 in.
  - Each .. £2 17 6
  - 1061. — Pres-sureTubing to
  - fit ditto.
  - 1 /6 per foot.
  - 1062. — Exhausting Syringe, length of barrel, 5 in. .. 12/-
  - 1063. —Ditto, length of barrel, 8 in. .. .. 22/6
  - 1064. —Condensing Syringe, 5 in. barrel 12/-
  - 1065. —Ditto, 8 in barrel .. .. .. 22/6
  - 1066.—Tate’s Air Pump, fitted on heavy iron base for screwing to table. Length of barrel, 16 in., diameter of plate, 7 in.......each £5 10 0
  - 1067 .—Ditto, but fitted with plate, 8 in. diameter.
  - £5 15 0
  - 1068. —Tate’s Air Pump, plate 7 in. diameter, as No. 1066, but fitted with strong clamp to fix to table.
  - £5 5 0
  - 1069. —Ditto, but fitted with 8-in. plate.. £5 10 0
  - 1070. — Exhausting and Condensing Syringe,
  - with strong clamps for fixing to bench. The barrel is 8 in. long, and ij in. diam.
  - £1 18 6
  - 1071.—Exhausting and n
  - Condensing Syringe, n-cn- ............
  - length of barrel, 6 in. 16/6 ^ L
  - 1072 .—Ditto, length of barrel, 8 in. .. .. 27/-
  - GERYK VACUUM PUMPS (Fleuss’ Patents)
  - THE “GERYK” PUMP.
  - 1073.—Small Portable Geryk Pump, designed to meet the demand among Schools, Laboratories, etc., for a cheap efficient vacuum pump. The pump is precisely the same as that of the well-known No. o “ Geryk ” Patent Vacuum Pump, and is capable of giving the same vacuum, i.e., one fiftieth of a millimetre off perfect. Owing to the vertical pull, these pumps are quite easy to work. They are extremely light and portable, these advantages being effected by dispensing with the more elaborate rotary motion of the original “ Geryk.’'
  - A. No. 5 size with i| in. diameter cylinder by 4 in. stroke, including spare charge of
  - oil .......................................................£7 0 0
  - B. No. 6 size with longer stroke to make the pump double size, including spare charge
  - of oil .. .. .. .. .. .. .. .. .. £8 0 0
  - C. 7 in. brass vacuum plate fitted with screw plug for regulating the admission of
  - air, length of india-rubber tube for connection to pump, and removable brass tube for connection to apparatus other than a bell jar. All mounted on cast iron stand.. ..................... ......................£2 17 0
  - D. 8 in. ditto ditto .. . . . . .. .; . . . . .. £3 2 0
  - E. g in. ditto ditto.. .. .. .. .. .. ..£450
  - F. Oil sealed stopcock fitted to inlet of either of the above-mentioned vacuum plates
  - £17 6
  - G. Glass bell jar with ground flanged rim and knob at top, suitable for 7 im vacuum
  - plate .. .. .. .. .. .. .. .. ..£096
  - H. For 8. in. ditto .. .. .. .. .. .. .. .. 0 10 6
  - J. For 9 in. ditto .. .. .. ... ... .. .. ..0126
  - K. “ U ” mercury gauge mounted on wooden stand .. .. .. 0 5 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.162 - vue 181/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 163
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GERYK PATENT VACUUM PUMPS
  - 1074. —Geryk Patent Air Pump, No. o size with 7 in. plate and vacuum gauge, suitable for schools, elementary classes, etc., with new patented improvements. Fast running type.
  - Diameter of cylinder r| in.
  - Stroke .. .. .. 4 in.
  - A. Price, without plate
  - and gauge .. £7 5-6
  - B. Price, with plate and
  - gauge.. .. £9 12 6
  - With this pump, all the ordinary phenomena can be produced, such as freezing water by evaporation, etc. Vacuum obtained within -3 of 1 millimetre less than perfect vacuum, as registered by the McLeod gauge.
  - 1075. — Geryk Patent Air Pump, No. o size as above, but motor driven. Complete with Electric Motor (continuous current up to 250 volts) and suitable Reduction Gear, mounted on same baseplate, including Single Acting Starting Switch. Also fitted with 7 in. Plate and Vacuum Gauge.
  - (When ordering please state voltage.)
  - Price.................... ......................£28 0 0
  - 1076.—Geryk Patent Air Pump, No. 1 size as illustrated, with new patented improvements. Fast running type.
  - Diameter of cylinder 2 in. Stroke .. .. .. 4 in.
  - Price..............£9 12 6
  - This pump is specially designed for hard work in laboratories. It is of larger diameter than the No. o, and consequently exhausts more rapidly. It is so frictionless that a boy can readily work it; it is always ready for use, even if put away for any length of time.
  - 1077 —Ditto, but motor driven as No. 1075 .. .. £29 15 0
  - 1078.—Geryk Air Pump,
  - as above, but larger. No. 2 size. Diameter of cylinder 2 in.
  - Stroke .. .. .. 10 in.
  - Price..................£14 0 0
  - 1079 —Ditto, but motor driven as ioj6 No. 1075 .. .. £36 15 0
  - 1083. —Geryk Patent Air Pump.
  - Duplex A .. £35 0 0
  - This pump has 2 in. cylinders by 5 in. stroke.
  - Special vacuum stopcock, fitted with screw plug for regulating admission of air 26/6 This pump van be worked by hand if required.
  - 1084. —Geryk Patent Air Pump.
  - Duplex B, with 2\ in. cylinders by 5 in. stroke..........£43 15 0
  - Stopcock .. .. extra £115 0
  - 1085. —Geryk Patent Air Pump.
  - Duplex C, with 3 in. cylinders by 7 in. stroke .. .. .. £70 0 0
  - Stopcock .. .. extra £2 12 6
  - 1Q86.—Geryk Patent Air Pump. Duplex D, with 31 in. cylinders by 7 in. stroke .. .. .. £87 10 0
  - Stopcock .. .. extra £3 13
  - ACCESSORIES FOR GERYK PUMPS.
  - 1080. — Air Pump Plate, on
  - stand, diameter of plate 10 in.
  - Each........... .. £2 17 6
  - 1081. —Pressure Tubing, to fit
  - ditto .. .. .. per foot 1/6
  - 1082. —Special Oil, eminently suitable for high vacua for use with Geryk pumps .. per pint 2/6
  - 1087.^Geryk Patent Air Pump, Duplex No. 1, extra powerful, for the rapid production of very high vacua, with new patented improvements. Fast running type.
  - This pump has been used and tested by well-known scientists who have found it invaluable. The vacuum "obtained is comparable with that given by a Sprengel Pump and the exhaustion of air is, of course, infinitely more rapid.
  - Diameter of cylinders 2 in. Stroke .. .. 5 in.
  - Price .. .. £27 2
- p.163 - vue 182/555
- - 164 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - APPARATUS FOR USE WITH AIR PUMPS
  - 1088.—Bell Jars, open at top, and well-ground flange at bottom for air pump work, etc.
  - 7 8 8 9 in.
  - 5 4 5 6 in.
  - .. 5/- 5/- 6/- 7/-
  - 1088
  - 1089.—Bell Jars, with knob
  - and well-ground flange.
  - 5678 in. 5 6 7 8 in.
  - 3/9 5/6 7/6 8/6
  - Height Diameter Each..
  - 1089
  - Height .. 9 10 12 12 in.
  - Diameter .. 6\ 8 6 8 in.
  - Each ..8/6 9/6 9/- 12/-
  - 1090.—Syphon Gauges for screwing into plates of Air Pumps.
  - ' Each.......................6/-
  - 1091 .—Ditto, on wooden base. Each
  - .. 3/6
  - 1092.—Indiarubber Bladders for showing the elasticity of air by their expansion in an exhausted receher.2163 ,
  - Per dozen .. :. .. .. .. .. 1/-
  - 1093. — Bell Jars, stoppered with well-ground flange, for air pump work, etc.
  - Height 6 6 8 8 9 in.
  - Diameter 3 4 4 6 6 in.
  - Each .. 3/6 3/9 5/9 8/- 8/6
  - Height 10 10 10 12 12 in.
  - Diameter 5 7 8 6 8 in.
  - Each .. 8/- 12/6 14/- 12/6 19/6
  - 1093
  - 1094.—Receivers, best white crystal glass, height 36 in., for Torricellian experiments. 2150
  - Each
  - 15/-
  - The flange is accurately ground to fit Air Pump Plate.
  - 1094
  - 1095.—Flask of very Light
  - GI aSS, to show that air has weight, fitted with brass tap, extra screw and one hook; size of flask about 4i in. 2163
  - Each
  - 10/6
  - 1095
  - 1096. —Bladder Glasses.2162
  - Each
  - 1/9
  - 1097.—Flask of very Light Glass, another form. 2155
  - Each.
  - A. 1,000 c.c. capacity. 14/-
  - B. 2,000 c.c. 16/-
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.164 - vue 183/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 165
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - APPARATUS FOR USE WITH AIR PUMPS
  - 1098. —G u i n e a and Feather Apparatus,
  - two falls, price not including tall jar. 2156
  - Each .. ..£15 0
  - 1099. —Tall Glass Jar
  - for ditto 2157 .. each 10/6
  - 1100. —G u i n e a and Feather Apparatus,
  - three falls. 2158
  - Each .. £1 10 0
  - 1101. —Tall Glass Receiver for ditto. 2159
  - Each .. 10/6
  - 1102. — Magdeburg Hemispheres, best quality brass. Diameter in.
  - Per pair .. £116
  - 1103. — Baroscope,
  - with ball and weight, for showing the buoyancy of the air. 2167
  - Each...........10/6
  - 1104.—B ladder, Frame, and
  - Weights for
  - showing the elasticity of air when relieved from pressure, without receiver, best quality. 2164
  - Each..........15/-
  - 1105. —Pressure of Air Apparatus, consisting of glass cylinder* covered by very thin rubber, which bursts as cylinder is exhausted. 2161
  - Each .. .. .. 3/6
  - 1106. —Thin Rubber Sheeting for above experiment. 2162
  - Per square foot .. 2/6
  - 1107. — Barometer
  - Tube, fitted with strong brass cap and stuffing box. 2171
  - Each............10/6
  - H
  - i (i
  - 1108. —Fountain in Vacuo Apparatus,
  - superior make and finish. Total height, 120 cm. 2178 Each .. .. £3 7 6
  - 1109. —Ditto, cheaper make, height 40 cm.2179
  - Each .. .. £1 15 0
  - 1110.—Rotating Glass Ball, for placing under the receiver of air pump ; the ball begins to rotate immediately the pump is worked.2163
  - 1111.— Apple Cutter, made of brass.
  - Each
  - 10/6
  - Each
  - 4 /-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.165 - vue 184/555
- - 166 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 1112. —M e r-cury Shower Apparatus,
  - superior quality, double form. In this pattern the mercury remains in the tube, and is therefore always ready for use. 2173
  - £2 7 6
  - 1117.—Glaze-brook’sTins
  - for placing over boiling flasks for determining boiling point of water.2213
  - Each .. 2/3
  - AIR PUMP APPARATUS, Etc.
  - 1113.—IVI e r-cury Shower Apparatus,
  - cheap pattern.2172 Each .. 5/6
  - 1114.
  - Tantalus Cup. 2096 Each .. 2/-
  - 1115.—Glass Breaking Squares.2169
  - Each ..............1 /-
  - Per dozen .. .. 10/-
  - 1118.—Water Hammers
  - best quality. 2174
  - Each
  - 2 /-
  - 1119. —Water Hammers,
  - double pattern, best quality 2176 .. 3/-
  - 1120. —Ditto, one exhausted and the other not, to show the different working. 2177
  - Per pair .. 4/-
  - 1116.—Bourdon’s Ring
  - for attaching to air pump for explaining the working of Bourdon’s Gauge and Aneroid Barometers. This apparatus may be exhausted to show higher exterior pressure, or placed under receiver of air pump to show higher interior pressure. 2182
  - Each...........£3 5
  - j h
  - 1121 . — Wollas-
  - ton’s Steam
  - Piston. 2207
  - Price, including metal
  - holder .. each 5/-
  - 1122.—H e r o ’s Steam Engine,
  - mounted on support. 2208
  - Price, including spirit lamp .. .. 7/6
  - 1123.—Apparatus to show the pressure of the atmosphere, consisting of a thin cylindrical vessel of tinplate, fitted with cork, large size, 23 cm. x 8 cm.2184
  - Each...............1/3
  - 1124.—L a r g e Sectional Working Model of a Steam Engine, with graduated brass circle, etc. A very instructive model for demonstration purposes. On heavy wooden base,about 36 inches long by 12 inches wide.
  - Each £5 15 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.166 - vue 185/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 167
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DAVY SAFETY LAMP, Etc.
  - FOR OTHER MINING APPARATUS, REFER TO SECTION 6, PAGES 294-322, OF THE 1913 EDITION OF OUR PHYSICAL APPARATUS CATALOGUE. PRICES ON APPLICATION.
  - 1125.—Ventilation Apparatus to prove that, both by law and circumstance, it is necessary to produce sufficient ventilation in a mine to dilute and render harmless the noxious gases. This apparatus consists of a large airtight box 16 x io X 7 in., fitted with two perforated discs carrying glass tubes A and B. On
  - 1126.—A ction of Wire Gauze on Flame, and to
  - show that a combustible substance will not burn, even in presence of air or hydrogen, unless it is raised to a certain temperature, which is called the “ temperature of ignition ” of the particular substance. For details of several experiments, see “ Heat, Light and Sound,” by D. E. Jones, B.Sc. (Lond.), published by Macmillan & Co., Ltd. 6299
  - A. Iron wire gauze, of very fine mesh,
  - for flame experiments.
  - per square foot 4/6
  - B. Bunsen burners .. each 1 /6
  - 1127
  - lighting candle in A, air will pass down tube B. A piece of smouldering brown paper held over B serves for showing the circulation of air in a mine. Close up B with a rubber stopper, and candle goes out. 2372
  - A. Price complete, as figured .. .. .. 15/-
  - 1127. — Davy Safety Lamp, after first pattern. This lamp is so well known that a detailed description is unnecessary. 6300 ............................... 12/-
  - For full details regarding other forms of Miners’ Lamps, see Section 6, pages 304 to 307 of the 1913 edition of our Physical Apparatus Catalogue.
  - 1128.—Apparatus to show how a Blown-out Shot may force the flame of a Miner's Lamp through the gauze, thereby causing the gas in a mine to ignite and set up an explosion. This apparatus consists of a long metal tube, 10 ft. in length and 3 to 4 in. in diameter (having a flexible diaphragm in centre), mounted on three metal supports, as figured. The Special Stand for holding lamp is fitted with two ring burners and one supporting hook, all of which are adjustable. A pistol (charged with Blank shot) fired up the tube forces flame through gauze, thereby causing the gas escaping from the rings surrounding the lamp to become ignited.
  - A. Price, complete as figured .. .. . . . . . . . . . . . . . . . . . . .. £2 10 0
  - B. ,, without Miner’s Lamp .. .. .. .. .. .. .... .. .... 1 17 6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.167 - vue 186/555
- - 168
  - SECTION 7.
  - SURVEYING AND PHYSICAL GEOGRAPHY
  - 1129.—The “ IMivoc ” Improved IVlodel Theodolite. For Instruction in Surveying and Physical Geography. This instrument is SPECIALLY DESIGNED FOR USE IN SCHOOLS, but is sufficiently accurate for small land-surveying, and has been used by engineers with the very best results. The Horizontal Circle (which is 5 in. diameter) is accurately divided in degrees, and is provided with a vernier reading to four minutes. The Vertical Circle is graduated from o° to 90°, and is also provided with a vernier. The Telescope is fitted with erect and inverting eye-pieces, and can be focussed from about 3 metres to infinity. The whole instrument is mounted in brass and furnished with levelling screws. The divided circles are silvered, and all the brass parts of stand and telescope are finished in dead black. The Theodolite is fitted with a compass and spirit level, and a new form of clamping arrangement which allows a complete revolution of the instrument.2500
  - Price ....................................................................................................£7 10 0
  - Stand, extra .. .. .. .. .. .. .. .. .. .. .. .... .. 126
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.168 - vue 187/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 169
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ANGLEMETERS AND SEXTANT
  - 1130.—The Anglemeter. Dr. J. Erskine-Murray’s Patent. The only practical instrument at a low price for actual Surveying. Invaluable to Teachers of Surveying, Practical Geography, Practical Mathematics, etc. 2501
  - Price, including pamphlet .. .. .. .. 8/6
  - 1131.—The Anglemeter. D. J. Erskine-
  - Murray’s Patent. Superior quality, stronger make, and fitted with vernier. 2502
  - Price, complete in velvet-lined case .. 17/6
  - 1132.—Becker’s Registered Model Sextant for use in Schools. Aluminium Frame ; Vernier reading to iVjths. ; Sighter arranged to take piece of smoked glass for use with artificial horizon ; Mirror, and half-mirror, the latter being readily adjustable to zero; Handle for holding, etc. 2557
  - Price, complete in box, as figured
  - £2 7 6
  - REFER ALSO TO SECTION 7 OF THE 1913 EDITION OF OUR PHYSICAL APPARATUS CATALOGUE. PRICES ON APPLICATION.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific ^Press.
- p.169 - vue 188/555
- - 170 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CHEAP SCHOOL APPARATUS FOR USE IN PHYSICAL GEOGRAPHY CLASSES
  - 1133. — Inclinometer, Students’ Pattern.
  - Varnished paper scale, mounted on polished mahogany back, with metal bob. 2628
  - Each ....................................4/6
  - 1136. —Sighting Rule, 12 in. long, Students' •Pattern, bevelled edge, divided into inches, eighths, and sixteenths. Made of hardened aluminium, and fitted with blackened folding sights, and a pivoting eye. 2631 Each..................................................13/6
  - 1134.—Combined Inclinometer and Compass. Malvern Pattern. 2629 Each ..........................8/6
  - 1135.—Combined Inclinometer and Sighting Rule. Better make andfinish, and made entirely of metal. 2630 .
  - Each ............... 'J .. £1 17 6
  - 1137.—Trough Compass, comprising nicely balanced magnetic needle (agate centre), 4-inch long, mounted in a hardened aluminium box having bevelled ruling edge and celluloid cover as figured.2633
  - Each ...............................15/-
  - 1138 .—Ditto, cheaper make, needle mounted in polished teak trough, with device by means of which needle may be thrown out of action. 2634
  - Each......................................7/6
  - 1139.—P rismatic
  - Compass, plain card dial, jewelled cap and stop, in morocco leather sling case. 2576
  - Size 3 3h in.
  - Each .. 67/6 72/-
  - Size 4 4\ in.
  - Each .. 76/6 81/-
  - 1140.—Cross Spirit Level,,; for use with plane tables, strongly made of polished teak, with brass top. Each limb measures 4 X f X f in.
  - Each .............................3/-
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.170 - vue 189/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 171
  - W. & J. GEORGE (LONDON),- Ltd., PROPRIETORS.
  - LUCY’S “ METRANGLE ”
  - (Patent applied for.)
  - A COMPOSITE SURVEYING INSTRUMENT.
  - Measures bearings in any plane, and also angles of elevation and depression with the horizontal directly, without the aid of an artificial horizon.
  - T T is generally realized that the teaching of Elementary Trigonometry and Geography has been considerably handicapped
  - by the lack of an accurate Surveying Instrument which can be produced at a price such that each pupil of a class may possess one.
  - Lucy’s “ Metrangle ” will appeal to progressive teachers of these subjects, since it is possible to carry out all practical work with its aid. Full Descriptive Circular on application.
  - In the one instrument are combined facilities for measuring bearings in any plane and for measuring angles of elevation and depression with the horizontal directly, without the aid of an artificial horizon. Moreover the school instrument is so designed that it can be used as an ordinary alidade for plane table work.
  - The principle of the instrument can be taught in a single lesson, since it involves only an elementary law of plane mirrors, and pupils can then proceed to take their own measurements, thus making their work interesting and real. Being a hand instrument, no tripod is required except, perhaps, for plane table work.
  - 1141.—Model “A.”
  - Angles can be read by vernier correct to three minutes; also with this model it is possible to see at once when a sighting plane is horizontal—a new feature in Surveying Instruments.
  - Price .. ,. each 257-
  - Full Descriptive Circular on Application.
  - 1142.—Model “ B.”
  - On the same principle as Model “A,” but without vernier and spirit level.
  - Each .. ................................................15/-
  - Per dozen .. .. .. .. .. .. .. .. .. 155/-
  - Manufactured by us to the specification of the inventor, Mr. A. W. Lucy, M.A. (Oxon), Headmaster of Sir Joseph Williamson’s Mathematical School, Rochester: author of “ Laboratory Mathematics ” (Oxford Press), and of the Essay on Mathematics in “ The Modern Teacher” (Methuen).
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory. :i'
- p.171 - vue 190/555
- - 172 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 1145.—Land Chains, made of Best Iron Wire, with two oval rings, brass swivel handles and tallies. The 2- and 4-pole chains are divided into links, and tallied at every ten links. The 50 and 100 feet chains are divided into feet, and tallied at every ten feet.
  - 2 poles .. each 12/- 50 feet .. each 13/-
  - 4 poles .. ,, 18/- 100 feet .. ,, 21/-
  - 1146. —Ranging Poles or Pickets,
  - with wrought-iron shoes, light but very strong. Poles well-seasoned, painted red, white and black.
  - Size . . .. 6 7 8 10 ft.
  - Per dozen.. .. 60/- 70/- 77/6 115/-
  - 1147. —Off-set Rod.
  - 10-link, shod .. .. .. .. 7/6
  - With hook for chain .. .. .. 10/6
  - 1148. —Picket Flags, 6x 4| in., red
  - or white.
  - Per dozen .. .. .. .. .. 19/6
  - LAND CHAINS AND RANGING POLES
  - PLANE TABLES
  - 1149.—Plane Table, cheap school pattern,
  - into which is set a circular spirit level, with tripod stand, each leg of which can be lengthened or shortened as required. The table revolves on the stand, and, when desired position is obtained, it may be tightly clamped by means of a screw and socket.
  - Price, complete............... ,. £2 5 0
  - 1150.—Sequoia Plane Table, with mahogany
  - slotted battens, brass slot plates, and § in. Whitworth boss nut. Size of table 18 X 16 in., with teak tripod, having bronzed metal top, including 12 in. boxwood sight rule alidade and 4 in. boxwood trough compass, waterproof canvas case for board, with pocket to take alidade and compass, waterproof canvas case for tripod.
  - Price, complete .. .. .. .. .. £4 10 0
  - 1151 .—Ditto, board 24 X 18 in..... 5 5 0
  - 1152 .—Ditto, board 30 X 24 in. .. .. 6 0 0
  - 1153 .—Boxwood alidade can be supplied separately.
  - Each ....................................19/6
  - 1154. —Mahogany Snap Case, for ditto.
  - Extra. .. .. .. .. • • • . • • • 5/-
  - 1155. —Polished Boxwood Trough Compass ..................... •• each 10/6
- p.172 - vue 191/555
- - 173
  - SECTIONS 8 & 9.
  - MAGNETISM AND ELECTRICITY
  - 1156. — Lodestone,
  - quality, small size 2700 .
  - ordinary each 2/-
  - 1157. — Ditto, medium size, strongly magnetic 2701 . .each 5/6
  - 1158. —Ditto, extra large and specially selected 2702 .. each 8/6
  - 1159.—Piece of Lodestone, specially selected, mounted in metal frame, having hooks and armature. 2704
  - Price, complete .. .. .. 30/-
  - 1160. —Horseshoe Magnets, with armature.2706
  - Length 2 3 4 6 8 9 10 12 in.
  - Price .. 5d. 5d. 6d. 1/- 2/- 4/6 5/9 7/6 11/6 each.
  - 1161. —Compound Horseshoe Magnets, strongly magnetised, complete with hooks and armature. 2707
  - Length ............3 5 6 9 12 in.
  - Number of bars .... 2 3 3 5 6
  - Price....................4/9 14/- 16/- 45/- 101 /-each.
  - 1162. — Bar Magnets, strongly magnetised, complete with armatures. 2708
  - Length 3 4 6 8 10 12 in.
  - Price .. 1/3 1/6 2/3 3/9 5/9 6/9 per pair.
  - 1163.—Wooden Cases, hinged, for holding one pair of bar magnets. 2709
  - Size of bar magnets .. 4 6 8 10 12 in.
  - Each.................. 1/9 2/3 2/6 3/- 3/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 174 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MAGNETS
  - 1165.—Bar Magnets, for use with magnetometers, complete with armatures. 2711
  - 1164. — Bar Magnet, extra strong magnetized, with hole in centre for suspending. Length io in. 2710
  - A.
  - B.
  - Each .............................4/9
  - 2 in. long 4 in. long
  - per pair
  - 10d.
  - 1/6
  - Fig. 2.
  - 1166.—Robison’s Ball-ended Magnets and Searle’s Vibration Magnetometer 2712 (see Proceedings Cambridge Phil. Soc., Vol. XII., Part i).
  - Searle’s Vibration Magnetometer.—This apparatus consists of a small cylindrical magnet, fixed in a brass bob of a special shape and size, and is used for comparing accurately magnetic fields up to 4'o C.G.S. units.
  - In the lower part thereof is fixed the magnet, which is 15 mm. in length, and below the magnet is fixed a thin aluminium pointer, 5 cm. in length. The centre of the magnet lies in a vertical line through the lower point of the bob (Fig. 1). This makes it easily possible to locate the centre of the magnet over any required point in a sheet of paper.
  - This Magnetometer is suspended by a silk fibre about 15 cm. long, from a torsion head on a small stand.
  - The aluminium pointer allows the time of vibration to be accurately observed. Where great accuracy is required a correction must be made for torsion.
  - This Magnetometer is very suitable for use in connection with Robison’s Ball-ended Magnets, described below:
  - Robison’s Ball-ended Magnets.—These magnets (see Fig. 2) were devised by Dr. John Robison, Professor of Natural Philosophy in Edinburgh, at the end of the eighteenth century. Dr. Robison, writing on Magnetism in the “ Encyclopaedia Britannica,” states :—
  - “ The force of each pole seemed to reside almost in the centre of the ball. This was our object in giving them this shape. It reduced the examination both of the attraction and of the direction power to a very easy computation; the result was that the force of each pole varied in the inverse duplicate ratio of the distance. The error of this hypothesis in no case amounted to TVth of the whole. In computing for the phenomenon of the directive power, the irregularities and deviations from this ratio were much smaller.”
  - G. F. C. Searle, Esq., in a paper read before the Philosophical Society, at Cambridge, says “ I argued that if a sufficiently easy inlet and outlet were provided by which the magnetic induction might flow into and out of the ends of the magnet, it would be content to flow in and out there, and would consequently not enter or leave the magnet at intermediate points. There would then be no free magnetism, except at the ends of the magnet. I also hoped that this flow of induction would be nearly uniform over the surface of each sphere. In this case the magnet would act like an ideal magnet, with its poles at the centres of the spheres. The expectations which I had formed have been very closely verified, and, in practice, the students at the Cavendish Laboratory obtain very definite results with the Robison Magnets.”
  - We are making the Robison Magnets in three sizes, viz. :—
  - A. 20 cm. long
  - B. 30 „ „ .............. ...................
  - C. 40. „ ..................................
  - D. The Vibration Magnetometer, with Aluminium pointer
  - E. Stand with Torsion Head for use with above
  - per pair 3/6
  - „ 3/9
  - 4/-
  - each 2/6
  - ,, 13/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.174 - vue 193/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 175
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MAGNETS
  - 1167.—Magnetic Magazines,
  - Coulomb’s. 2713 Size A. With 3 bars. Each .. £2 5 0
  - Size B. With 6 bars. Each .. £3 15 0
  - 1168.—Cylindrical Bar Magnets, polished.2714
  - Length 4 6 8 12 20 in.
  - Diameter Price ..
  - 3 3 3 3
  - S' ¥ ¥ "S'
  - 1/- 1/8 2/6 3/3
  - h „
  - 5/- each.
  - 1173.—Combinations of Magnets, for projecting horizontally in the Science Lantern. These consist of small magnets fixed to glass slides 4^ x 3^ in., to demonstrate with iron filings the magnetic field surrounding the magnets. 2719
  - A. Single magnet each 2/6
  - B. Two magnets (N facing S) „ 2/6
  - C. „ „ (N „ N) ,, 2/6
  - D. » (S „ S) „ 2/6
  - E. ,, ,, (N ,, S) with piece of
  - soft iron in the magnetic field „ 2/6
  - 1174.—Bar Magnet,
  - neutral line, length 6 in.
  - bored a
  - Price, including special stand 2720 5/9
  - 1169.—Pair of Cylindrical Bar Nagnets,
  - length 8 in., with armatures, complete in polished box with lid2715.. .. . . .. .. per set 9/6
  - 1170. —Set of 16 Bar Magnets, each on a
  - separate support, for showing distribution of magnetism 2716................per set £2 5 0
  - 1171. —Ditto, but with set of 24 magnets 2717
  - per set £2 17 6
  - 1172.—Set of 3 Bars,
  - Antimony, Bismuth, and Nickel, 3 in. X | in. x /V in., complete in box. 2718
  - 1176.—Hibbert’s Patent Magnetic Balance.
  - This instrument is the invention of W. Hibbert, Esq., of the Regent Street Polytechnic, London. 27223
  - Per set
  - 7/6
  - “ Agate Knife Edge ”
  - pattern
  - £2 10 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 176 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MAGNETISM
  - 1177.—12 Small Bars of Soft Iron inbox.
  - Per set .. .. . . . . .. .. 1 /3
  - 1178.—Soft Iron Bars, 8 x i| x | in.2724 Each .............................1/3
  - 1179.—Soft Sheet Iron Discs 2725 per doz. 4/-
  - 1180. —Steel Knitting Needles, best quality.2726
  - per doz. 6d.
  - 1181. —Steel Sewing Needles per packet 2727 4d.
  - 1185.—Steel Clock Springs, broken pieces 2731
  - per doz. 2/6
  - 1186 —Ditto, complete springs, as figured 2732
  - per doz. 10/-
  - 1187.— Iron Filings, extra
  - fine, for showing lines of force
  - per i lb. bottle 1/-
  - 1188 • —Ditto, ordinary quality
  - per lb. 8d.
  - 1189.—Steel Filings
  - per lb. 1/-
  - 1190.—S ieve for use
  - with iron filings. 2736
  - Each.............2/6
  - 1182.—Unmagnetised Steel Bar, 272
  - 8 x i X tit in. each
  - 8d.
  - 1183. — S t e e I Watch Springs,
  - broken pieces. 2729 Per dozen .. 1/3
  - 1184. —Ditto, complete springs, as figured. 2730
  - Per dozen.. .. 8/-
  - 1191.—Glass Tube, closed at both ends, and filled with very fine filings, as used at Owen's College, Manchester 2738 .. .. each 2/6
  - On passing an electro-magnet over the tube, it is converted into a magnet for the time being, and if suspended in a stirrup will set itself in the magnetic meridian. If after this the tube is taken out and the filings shaken up in the bulb, it will be found' | to have lost its magnetism.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 177
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MAGNETIC NEEDLES, COMPASSES, Etc.
  - 1192.—Magnetic Needles,
  - well magnetized, brass centres,
  - best quality.
  - 2739
  - Length 1 1 2 3 4 6 8 in.
  - Price.. 9d. 11d. 1/1 1/3 1/6 2/- 3/3 each.
  - 1193.—Ditto, with Length .. $ agate centres, best quality. 2740 i 1 2 3 4 6 8 in.
  - Price .. 1/3 1/3 1/4 1/6 1/9 2/- 2/10 3/9 each.
  - 1194.—Brass Supports, with fine steel point, for use with magnetic needles. 2741
  - A. Superior quality, heavy brass .. each 3/9
  - B. Cheap quality, light brass .. ,, 1/6
  - C. Ditto (wooden base and pillar with needle
  - point) .....................each 9d.
  - 1195.—Sensitive Magnetic Needle,
  - with aluminium pointer, as used in the best quality magnetometers and compass boxes. This needle is fitted with agate centre, and is nicely balanced. To those requiring a sensitive needle at a fair price, we can recommend it with every confidence. 2744 Each.............................4/6
  - 1196.—Brass Compass BOX, best quality, 4| in. diameter, fitted with anti-parallax mirror and sensitive magnetic needle with jewelled centre No. 1195. A good magnetometer when used in conjunction with two ordinary metre rules. 2745 Each.................19/6
  - 1197.—Astatic Pair, with
  - coil, mounted on polished mahogany base, with brass support 2747 ..........12/6
  - 1198. — Cheap Compass, for
  - tracing lines of force; glass one side only. 2748 Each .. 6d. Per dozen .. 4/6
  - 1199. —Cheap C o m p a ss,
  - for tracing lines of force; glass both sides. 2749 Per dozen .. 8/6
  - 1200. — Compasses, for
  - tracing lines of force, superior make and finish, jewelled centre, glass top and bottom, with pointer at right angles. This compass is furnished with extra sensitive needle, and never fails to give every satisfaction. 2760 Each...........................7/-
  - 1201.—Mariner’s Compass, brass bowl, in gimbals, complete in oak box, with lid. 2751
  - Size of Box .... 4 5 6 8 10 12 in.
  - Price............ 12/6 13/6 17/6 23/6 35/6 39/6
  - 1202.—Compass Card, best
  - quality 2752 .. .. each 1/-
  - 1203.—Ditto,
  - quality 2753..
  - on thin paper, cheaper .. each 6d.
  - 1202
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a* test tube to the
  - complete furnishing of the largest laboratory.
  - M
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- - 178 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DIP NEEDLES
  - 1204.—Azimuth Compass
  - Box, with sights and wooden supports 2754 .. .. .. 12/6
  - 1205.—Dip Needle, with graduated arc and base 2755 .. .. .. each 11/6
  - 1206 •—Ditto, cheap student’s pattern, without graduated arc 2756.. .. .. each 6/6
  - 1207. — Stewart & Gee’s Dip Needle. Best Quality. This instrument is fitted with a graduated silvered dial, 6 in. diameter, an anti-parallax mirror and two needles with jewelled centres, one magnetized and the other unmagnetized 2757 .. .. .. .. . . .. .. .. each £115 0
  - 1208 —Ditto, smaller size 2758
  - 12 6
  - JfC?EJL HATTON WALL
  - STANDARD DIP CIRCLE
  - 1209.—Standard Pattern Dip Circle, “ Nivoc ”
  - Pattern. Superior Quality and Finish. This instrument is provided with a needle rolling on agate knife edges, and is furnished with a means of raising the needle when not in action on V supports by means of a milled head at the side. The vertical circle is divided in half degrees and can be rotated in the horizontal plane. The lower graduated circle can be read by a vernier to one-tenth degree. All working parts are in brass and the whole is enclosed in a highly finished mahogany case, glass front and back, and is furnished with a spirit •level and supported on three levelling screws. The instrument is very carefully made and perfectly adjusted, and is put to severe tests before being sent out. We are confident that it will prove of
  - great value, as a reliable dip needle and will furnish accurate results.
  - / .
  - The needles are accurately adjusted and their axis of rotation coincides
  - 3i!:- i
  - with their centre of gravity, so that reversing the face of the needle' and reversal of its magnetism give the same readings.2769
  - I
  - Price .. .. .. .. .~ .'. .. ~£8 10 0
  - Our Balances and Weights havei achieved World-wide"Reputation
  - '• :i Leading Scientific Press.
  - vide Opinions of the
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 179
  - W. & J, GEOROE (LONDON), Ltd., PROPRIETORS.
  - MAGNETOMETERS
  - 1210.—Deflection Magnetometer, Stewart & Gee’s, with two magnets, polished mahogany box, bar needle
  - with agate centre, and optically true mirror glass to prevent parallax. Diameter of dial, 6 in. 2762 £2' 7 6
  - 1211 —Ditto, smaller size, cheaper make 2763 £1 1 0
  - 1213.—Comparison Mag-
  - netometer,. Stewart & Gee’s, as figured, including pair of bar magnets and a pair of soft iron bars, same size. 2766
  - Price, complete ".. .. £2 10 0
  - 1215.—Glazebrook & Shaw’s Apparatus for demonstrating Gauss’s verification of the law of magnetic force. 2773
  - Complete, as figured .. . . .. £1 12 6
  - (See Glazebrook & Shaw’s “ Practical Physics.”)
  - Complete as figured
  - £1 7
  - 1212. — Deflection Magnetometer,
  - Schuster & Lees' pattern. 2769
  - 1214. —Magnetometer, S t e w a r t & Gee’s, with suspended mirror in a brass damping space, fixed to substantial base provided with 3 levelling screws. Price, including boxwood metre scale, magnet and magnet holder 2770
  - £1 17 6 (See Stewart & Gee’s “ Elementary Practical Physics.”)
  - 1216.—Vibration Magnetometer, Stewart & Gee’s, of polished mahogany of superior make and finish.
  - Price, including one each bar magnets, 2 in. and 4 in. long.2767
  - £1 1 0
  - Our stock of pure Chemicals and Acids is very considerable j. hence all.orders are executed with the j utmost despatch. For Prices, etc., see Chemical Apparatu^ Catalogue.
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ... ..................* ' ' ......................................
  - MAGNETOMETERS, ELECTRO MAGNETS, Etc.
  - 1220.—Iron U Tubes. 2785
  - A. Limbs 4 in. X \ in. .. each 1 /6
  - B. „ 5 „ X f „ „ 2/3
  - C. „ . 6 „ x f „ CVI
  - D. ,, 10 „ X I „ „ 5/6
  - 1217.—S p r i n g Magnetometer, best quality. 2776
  - Each ...................£1 17 6
  - 1' 1218.—Magnetoscope, simple form. 2774
  - Each........3/6
  - 1219. — Magneto-
  - SCO pe , Owen’S College pattern. 2776
  - Each .. ..3/6
  - 1221.—Electro - Magnets,
  - connecting screws. 2786
  - A. 3 in. long, -fa in. core
  - B. 4 „ „ * „ „
  - C. 6 „ „ f „ „
  - D. io ,, ,, i „
  - 1222. — Electro - Magnets, superior quality, wire (double cotton covered) wound on wooden bobbins. 2787
  - A. 4 in. long, | in. core . each 10/6
  - B. 5 1, „ f „ „ • • „ 14/-
  - C. 6 „ „ i „ • • „ 17/-
  - D. 7 » ,, 1 ,, ,, • „ 25/-
  - 1223.—Electro-Magnet, lecture table pattern, on polished mahogany frame, 3 ft. high, magnet 9 in. long by i| in. core, and very powerful. We can thoroughly recommend this apparatus. 2788
  - Price, without weights .. .. £6 15 0
  - 1224 .—Ditto, smaller size, electro-magnet 6 in. X 1 in. 278i>
  - Price £4 17 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.180 - vue 199/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 181
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ELECTRO MAGNETS
  - 1225. — Electro-Magnet, heavy
  - type, with removable coils 8 in. high, and soft iron cores i in. in diameter, two pole pieces ; the whole mounted on polished mahogany base, as figured. 2790
  - Complete .. .. .. £5 10 0
  - 1226.—E lectro-
  - Magnet, limbs are fixed on strong iron plate, which acts as base if magnet is used with the two poles upwards. 2792
  - Price, with armature
  - 1227.—Set of Dia-magnetic Apparatus, for use with electromagnet No. 1226, consisting of two iron armatures for the poles, hollow cube of glass, hollow glass rod, and solid rods of bismuth, copper, and glass which contains iron.
  - Price, including suspension apparatus. 2793
  - £2 19 6
  - £2 2 0
  - 1228. — Du Bois Magnet. The total height is about 30 in., the diameter of the base 28 in., and the diameter of coil holders 6 in.
  - The base is a heavy iron casting provided with four massive steel levelling screws. It is furnished with slots through which two supporting pieces for the magnet arms are fixed by means of the slots and clamping screws. The position of either or both arms of the magnet can be adjusted in the horizontal plane.
  - There are also slots in the limbs through which bolts are passed, so that any desired angle or distance can be arrived at.
  - When the pole pieces are in position, a distance of 140 mm. can be obtained, and without the pole pieces, 180 mm.
  - Two pairs of pole pieces are provided, one conical, and one cylindrical. They are fastened on very easily by means of bayonet catches.
  - The limbs of the magnet are bored through in a line parallel with the base for optical experiments.
  - A small table, as shown, can be adjusted at various heights between the limbs of the magnet, or at various distances in the same horizontal plane.
  - When all coils are in series it has a total resistance of about 3-5 ohms.
  - There are 2,000 turns of wire, which will carry a maximum current of 20 amperes ; with the conical pole pieces and with air gap 1 mm. long, and 40,000 ampere turns, a field of 41,000 C.G.S. can be obtained.
  - The total weight is between 4 cwt. and 5 cwt. 2795
  - Price ........................................................................ .........................£95 0 0
  - Note.—We also supply all the optical accessories required. Prices on application.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ELECTRO
  - 1229.—Faraday’s Apparatus, for dia magnetic experiments, best make, latest pattern. 2798
  - £67 10 0
  - MAGNETS
  - 1230.—Soft Iron Ring, for demonstrating that the space within a soft iron cylinder is perfectly screened from the effects of a neighbouring magnet. 2794 Price of Ring only .. .. .. .. ... 5/-
  - APPARATUS FOR PROVING AMPERE, FARADAY
  - AND OTHER LAWS
  - 1231.—Pair of Flat Spirals,
  - on boards, -for illustrating induced currents. 2804
  - 1233.—Ampere’s Apparatus
  - to demonstrate that successive portions of the same rectilinear current repel one another. Price, complete, with two terminals (not shown in figure) 2842 .. .. .. 15/6
  - Per pair ..
  - 11/6
  - 1232.—Pair of Flat Spirals*
  - having coils 6 in. in diameter, mounted on rods 7 in. high, fixed in heavy bases 4 in. square. 2805 Price, per pair .. .. £115 0
  - (See Silvanus P. Thompson’s “ Elementary Lessons in Electricity and Magnetism.”)
  - 1234.—Complete set of Apparatus for illustrating Induced Currents, consisting of strong bar magnet, soft iron bar with handle, bundle of thin iron rods in handle, 2 pairs of conducting cords and interrupting wheel, the whole packed in box.2809
  - Price, complete .. .. .. .. •• £4 17 6
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - INDUCED CURRENTS APPARATUS
  - 1235.—Apparatus for showing Induced Currents, superior make and finish. Price, complete, with soft iron core (not shown in illustration) 2807 .. £110
  - 1236.—Apparatus for showing Induced Currents, as used by Professor Poynting of the Birmingham University. The primary and secondary coils are strongly made. Mounted on polished mahogany base fitted with two terminals. 2808
  - Price, complete, with soft iron core £115 0
  - 1237.—Weinhold’s Induction Coil, for
  - explaining induced currents. Complete with two coils mounted on stand and handle respectively as illustration.
  - Price .. 18/6
  - 1238. — Solenoid,
  - for converting a bar of soft iron into a magnet. 2810
  - Each
  - 4/6
  - 1239. — Solenoid,
  - for suspending by silk thread. Price, including mercury cup with terminals2813 .. 8/6
  - 1240 .—Ditto, without mercury cup 2814 7/3
  - 1241.—Ampere’s Parallelogram, for
  - suspending by silk thread. Price, including mercury cup with terminals 2811 .. ‘ .. 2/9
  - 1242. —Ditto, without
  - mercury cup
  - 1/6
  - 1243.
  - F I o a ting B a 11 ery,
  - with solenoid. 2815
  - Each .. 8/-
  - 1244.
  - F I o ating B a 11 ery,
  - with ring of coiled wire.2816
  - Each .. 8/-
  - 1245.—Ampere’s Apparatus,
  - action of the earth on solenoids. 2822. Price, complete with stand..
  - for showing the directive
  - £1 8 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - 184 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - INDUCED CURRENTS APPARATUS
  - 1246.—Earth Inductor, or Delezenne’s
  - Circle. This consists of a wooden ring wound with insulated copper wire. The square frame can be turned about a horizontal axis. The ring also rotates. It is used to show that the magnet-\ ism of the earth induces currents in metallic bodies in motion, the current disappearing when the angle of the circle is parallel with angle of dip. 2818
  - £5 5 0
  - {See Stewart & Gee’s “ Practical Physics.”)
  - 1247.—A m pore’s
  - Apparatus, with solenoid, circle, and rectangle, to demonstrate the action of magnets on currents. 2819 £117 6
  - i
  - ^sr\
  - 1248.—Ampere's Apparatus, superior quality, with all latest improvements and accessories 2821 .. £5 5 0
  - (See Ganot’s “ Physics.”)
  - 1249.—Arago's Apparatus,
  - for illustrating induced currents, consisting of copper disc for rotating and a magnetic needle. 2825 Price, for best quality .. £3 17 6
  - 1250.—Faraday's Apparatus,
  - to show that currents are produced in a copper disc rotated between poles of a magnet. 2827
  - Price, for best make .. £3 10 0
  - 1251. —St u rgeon's
  - Disc. Current is conveyed to the axis by brass support, and to the edge of disc by small mercury trough in which the disc revolves when current is passing. 2826 17/6
  - 1252.—Barlow’s Wheel, large
  - size,guaranteed best make and finish.2828
  - £2 2 0
  - 1253 «—Ditto, without magnet, smaller size 2829 .. .. .. .. 16/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.184 - vue 203/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 185
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - VOLTAIC ELECTRICITY APPARATUS
  - 1254.—O ersted’s Apparatus, simple, with 3 in. needle and two mercury cups. 2830
  - 7/6
  - 1255.—Oersted’s Apparatus;
  - superior quality, with copper strip and three needles, mounted on nicely polished base 2831 .. .. .. .. 30/-
  - 1256.—De La Rive’s Apparatus, of white glass, to show the action of a magnet on the electric discharge in rarefied gases. 2843 Price, complete .. £110 0
  - 1257 —Ditto, but the vacuum tube made of uranium glass. Price, complete .. £117 6
  - Note.—The thread of light produced rotates in the same direction as the current which runs through the coil.
  - 1258. — Apparatus to
  - show that continuous rotation can be produced between a magnet and a circuit, or between two parts of one circuit, provided that one part of the circuit can move while another part remains fixed, or that the current in one q part can be reversed. 2837
  - Price .. .. .. 6/6
  - S (See Silvanus P. Thompson’s
  - “ Elementary Lessons in Magnetism and Electricity.”)
  - 1259.—R o g e t’s Jumping Spiral,
  - large size, superior make and finish 16/6
  - 1260.—Lecture Apparatus, superior make, for showing rotation of a movable current round a magnet; of a magnet round a fixed current; of a magnet on its own axis under the influence of a current, and rotation of a current under the influence of another current 2834 .. .. . . £7 15 0
  - 1261. —Apparatus
  - to demonstrate rotation of a current round the pole of an electromagnet. Mounted on three legs as figured.2836
  - £15 0
  - 1262.—Apparatus
  - to demonstrate rotation of a current round the pole of a magnet. 2835
  - £1 15 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.185 - vue 204/555
- - 186 F. E. BECKER & CO., NIVOC HOUSE, HATTOIV WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - FRICTIONAL ELECTRICITY
  - 1265.—Glass Tubes, closed both ends, one half roughened, 24 in. x 1 in. 2852 .. .. each 3/- 111 V7-;: 1268.—Rods, half Glass and half Brass 2856 each 2/9
  - 1266.—Rods of Sulphur, with handle 2854 each 3/- 1269.—Rods of Brass, rounded ends 2857 each 2/9
  - 1267.—Rods of Sealing Wax, about 12 in. long X 1 in. diameter 2855 .. .. .. each 1/3 1270.—Rods of Shellac, about 12 in. long X 1 in. diameter 2858 .. .. .. .. .. each 1 /9
  - 1271.—Rods of Vulcanite, best quality, polished. 2859
  - Length .. 6 8 Diameter. . f\ i Price .. 4d. 5d.
  - 8 9 io io
  - tiff
  - 10d. 1/5 1/- 1/9
  - 12 12 14 in.
  - tV I I y,
  - 6d. 2/3 2/9 each
  - 1272.—Rods, Brass 2860 .
  - half Vulcanite,
  - each
  - 1275. —Flannel Rubbers
  - 1276. —Silk Rubbers . ;
  - each 1 /-each 1 /6
  - 1273.—Rods of Gutta Percha, about
  - 1277.—Catskin Rubbers,
  - 12 in. long x 1 in. diameter 2861 each 4/-
  - whole skin as figured each 4/-
  - 1274.—Amber
  - piece 2863
  - Specimens
  - , selected each 1 /-
  - 1278.—Ditto, selected skin,
  - Each L. .. .. .. 5/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.'
- p.186 - vue 205/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 187
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - FRICTIONAL ELECTRICITY APPARATUS
  - 1279.—Fox-tail Rubbers, best quality 2870 .. .. .. each 9/6
  - 1280.—Electric Amalgam in bottle. 2871 Per ounce .. .. 1/3
  - 1283.—Tin Ovens
  - for warming and drying rubbers, glass tubes, etc. 2875
  - Price, not including gas burner .. .. 6/6
  - 1281. —Bent Stirrups,
  - rods, etc. 2873
  - 1282. —Ditto, size 2874
  - Wire
  - for glass each 6d.
  - small each 4d.
  - 1284.—Electrophorus,
  - student’s size, diameter of base 4 in., handle made of vulcanite. 2876
  - Each ..............3/6
  - ELECTROPHORUS, PROOF PLANES, Etc.
  - 1285.—Electrophorus, ebonite base in tin sole, glass handle, fixed in brass cover, best make and finish. 2877
  - Size A. Diameter of ebonite base, 5 in.
  - „ B. „ „ „ 6 „
  - „ C. „ „ „ 8 „
  - ,, D. ,, ,, ,, 10 ,,
  - each 8/-„ 11/-,, 15/-
  - „ 17/6
  - 1286.—Vulcanite Discs,
  - quality. 2879
  - Size A. Diameter 4 in.
  - „ B. „ 6 „ ..
  - ,, C. „ 8 „ ..
  - ,, D. ,, 10 ,, ..
  - I in. thick, polished on both sides, guaranteed best
  - each 3/6 » 7/-
  - „ 12/-„ 16/-
  - 1287. —Proof Plane, consisting of an ebonite rod with a brass ball at end. 2914
  - each 1 /-i
  - 1288. —Proof Plane, consisting of an ebonite rod with brass disc at end. 2915
  - each 1 /-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the . r t Leading Scientific Press,
- p.187 - vue 206/555
- - 188 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LEYDEN JARS
  - Q
  - 1289.—Leyden Jars, improved pattern,
  - well insulated and provided with ebonite covers. These jars work better than all the other forms on the market, and never fail to give every satisfaction. Prices for best make and finish are as follows:— 2880
  - Size A. \ pint each 6/6
  - „ B. i pint .. •• „ 7/6
  - „ c. 2 pints.. „ 12/6
  - „ D. 4 pints.. .. •• „ 16/-
  - 1290. — Leyden Jar, with movable coatings made of tin. 2883
  - A. \ pint size 8/-
  - B. i „ „ 9/6
  - C. 2 „ „ 13/6
  - 1291.—Leyden Jar Batteries, best
  - make and finish, in polished mahogany trays. 2881
  - A. Battery consisting of 4 jars, each pint size, £2 7 6
  - B. „ „ 4 - ,, 2 pint size, £3 0 0
  - C. 6 „ ,, 1 pint size, £3 15 0
  - D. 6 „ ,, 2 pint size, £4 10 0
  - 1292.
  - “ Diamond ” Leyden
  - Jars, for
  - showing effect of discharge. 2882
  - A. Pint size
  - each 12/-
  - B. Quart size
  - each 15/-
  - DISCHARGERS
  - 1293.—Henley’s Universal Discharger, superior make and finish, large size 2891 .. .. .. each £2 10 0
  - 1294.—Discharger, small size, with fixed limbs. 2887
  - Each .. .. .. ..3/6
  - 1295.—Discharger, medium size, with jointed arms, glass handle. 2888 Each.............. .. 10/6
  - 1296.—Unit Jar,
  - for administering measured charges of electricity. 2894 Price for best make and finish .. £110 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.188 - vue 207/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 189
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - STATICAL ELECTRICITY APPARATUS
  - 1297.—Brass Sphere,
  - 6 in. diameter, with hole at top, i| in. diameter, for inserting proof planes. Price for best make and finish 2912
  - £17 6
  - 1298 .—Ditto, smaller size and cheaper finish 2913 .. 13/6
  - 1299. —Faraday's Ice Pails. 2902
  - Set of four .. .. .. .. ... .. 12/-
  - 1300. —Ditto, set of two, small size 2903 .. .. 6/-
  - Apparatus,
  - with
  - horizontal brass cylinder, mounted on well-insulated base, best make and finish .. 19/6
  - 1302.
  - K i n ne r-s I e y’s Thermometer, best make and finish. 2920
  - 1303. — Gunpowder Cup, for setting fire to gunpowder, alcohol ether, etc.2924
  - Each.............13/6
  - 27/6
  - 1304. Faraday's Butterfly Net, best quality. 2910 Each .. 6/6
  - 1305.—Orrery, an apparatus by means of which the rotation of the moon round the earth, and the earth and moon round the sun, can be electrically illustrated, best make and finish.2917 .. .. 13/6
  - 1306.—Roll Of Tinfoil, on polished mahogany table, superior make and finish. 2899
  - Price, including Henley’s Quadrant Electrometer .. .. £4 17 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.189 - vue 208/555
- - 190 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - STATICAL ELECTRICITY APPARATUS
  - 1308. —Pith Balls,
  - small size. 2926 Per box of 12 .. .. 1 /-
  - 1309. —Ditto, large size.292 7
  - Per box of 12 .. .. 1/3
  - 1310.—Pith Figures,
  - best quality. 2928 Each.............1/6
  - 1313.—Electrical Pistol,
  - for exploding mixed gases by the electric spark, best make and finish 2922 .. .. 13/6
  - 1314. — Electrical Cannon, for exploding mixed gases by the electric spark, made of solid brass castings, well finished 2923 .. 30/-
  - 1311.—Pith Figure Plates, mounted on polished mahogany base, large size. Top plate adjustable2919 .. 14/6
  - 1312.—Pith Ball A P pa rat US,-consisting of glaSs ’ cylinder, with wooden cover, wooden base. 2925 Price including 12 pith balls .. .. 10/-
  - 1315.—Head of Hair, best make
  - and finish 2952 .. .. .. 6/6
  - 1316."—Apparatus, best
  - make and finish, to demonstrate the action of electricity on points 2950 .. each 19/6 Note.—If the point be directed towards a charged jar or conductor, it will silently draw off the charge, (which can be seen to pass in small sparks) to the lowerball.
  - 1318.—Luminous Pane, made of ebonite, mounted on stand No. 1341. Price, including special holder No. 1342
  - Each.. .. .. 15/6
  - 1319 .-"-Ditto, without stand and holder. Each .. . • • .. - . . 8/-
  - Our Balances arid Weights have achieved World-Wide Reputation.: vide Opinions of the ^ ..
  - Leading Scientific Press.
- p.190 - vue 209/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 191
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CONDUCTORS
  - 1320. —Spherical Conductor,
  - 5 in. diameter, made of wood, and covered with tinfoil 2933 each 10/-
  - 1321. -Ditto, diameter 3 in. ,, 4/-
  - 1322. - -Insulated stand for ditto 2934
  - i; . each 3/6
  - 1323. —Spherical Conductor,
  - brass, 5 in. diameter, on thick vulcanite rod fixed to heavy mahogany base293 5 .. •• each 21/-
  - 1324. —Ditto, small size, for students; diameter of ball 3 in. 2936
  - each 10/6
  - 1325.—Cylindrical Conductor, 10 in. long x 3 in. diameter, made of wood and covered with tinfoil 2937.. .. each 8/6
  - 1326 .—Ditto, 7 in. long x 3 in. diam.
  - each 4/6
  - 1327. —Insulated stand for ditto 3/6
  - 1328. —Cylindrical Con-
  - ductor, same dimensions as above, made of brass, and mounted on thick vulcanite rod fixed to heavy mahogany foot 2939 .. £15 0
  - 1333.—Induction Apparatus to
  - demonstrate that the + and —, separated by induction, are equal in'quantity ; best make, brass semi-cylinders and ebonite fittings 2945 ... ... .. £2 17 6
  - 1334.—Brass Spheres,
  - on vulcanite uprights fixed to mahogany bases.2943
  - Per pair.............10/6
  - 1329.—Conical Conductor,
  - 10 in. long x 4 in. diameter at wide end, made of wood and covered with tinfoil 2940 .. each 8/6
  - 1330 • —-Ditto, 7 in. long x 3 in. diam.
  - each 4/6
  - 1331. —Insulated Stand for ditto
  - each 3/6
  - 1332. —Conical Conductor,
  - same dimensions as above, made of brass, and mounted on thick vulcanite rod fixed to heavy mahogany base 2942.. .. £1 15 0
  - 1335.—Biot’s Apparatus,
  - large size, to demonstrate that electricity resides only on the surface of bodies; best make and finish 2931 .. £1 10 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Priices, etc., see Chemical Apparatus Catalogue.
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- - 192 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - INSULATING STANDS, Etc.
  - 1336.—Insulating Stools,
  - polished mahogany top, 12 in-square, with four ebonite legs. 2953
  - Each.................16/6
  - 1337-
  - 1337. —Insulating Stand, polished mahogany table on thick vulcanite pillar fixed in mahogany foot. Best make and finish. 2955
  - Each .. .. 15/-
  - 1338. —Insulating Stand, small
  - size, comprising table-top on glass rod, sliding in metal tube; adjustable heights. 2957
  - Each.....................15/-
  - 1338
  - 1339.—Luminous Tubes,
  - best make, for hanging on conductors of electrical machines. 2960
  - Each .. .. 9/6
  - 1340.—L u m i n o u s
  - Tube
  - smaller size, for fixing on top of Insulated Stand, No.
  - Each ..
  - \
  - 1339
  - 1341.—Insulating Stand,
  - suitable for all the accessories mentioned on this and the following page. 2963
  - Each.................5/-
  - &
  - w
  - 1342.-Brass ^ Holders, for
  - luminous panes, vacuum tubes, etc. 2964
  - Each .. 2/6
  - (ThisJits on top of stand No. 1341.)
  - 1343.—Ind ia Rubber, Sheets, 12 in. square, for insulating purposes. 2958 Each.. .. .. .. 3/-
  - 1344.
  - Fulminating Panes, large size, with silk handles. 3007
  - Each .. .. 6/-
  - 1345.—F rank lin’s Fulminating
  - Pane, mounted on well-finished insulating stand. 3008
  - Each .. .. £110
  - 1346. —Set of Electric Chimes, best make and finish, mounted on stand No. 1341.
  - Each .. .. 17/6
  - 1347. —Ditto, without stand 2966., each 12/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - Complete furnishing of the largest laboratory.
- p.192 - vue 211/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1. 193
  - W. & J. DEORGE (LONDON), Ltd., PROPRIETORS.
  - STATICAL ELECTRICITY APPARATUS
  - 1348. —Apparatus for Vacuum Tubes.
  - Price, including stand No. 1341, holder No. 1342, and vacuum tube 2969 .. 9/6
  - 1349. —Ditto, Holder
  - only (see No. 1342)
  - each 2/6
  - 1350. —Ditto, Stand
  - only (see No. 1341)
  - each 5/-
  - FOR VACUUM TUBES See Index.
  - 1353.—Electric Motor 2975 .. each 13/6
  - 1354 .—Ditto, mounted on stand No. 1341 ,, 18/6
  - 1355.—Pith Ball Apparatus 2977
  - each 8/-
  - 1356 .—Ditto, mounted on stand No. 1341 .........each 13/-
  - Condensation Apparatus 2979
  - each 8/-
  - 1358.—Ditto, mounted on stand No. 1341 .. ,, 13/-
  - 1357
  - t
  - 1359.
  - Paper Brush. 2981
  - Each .............2/-
  - 1360 .—Ditto, mounted on stand No. 1341 each 7/-
  - 1361.—R otat i n g Glass Ball (Electrical Circus) 2983
  - each 7/-1362 .—Ditto, mounted
  - on stand No. 1341
  - each 12/-
  - 1363.—A pparatus
  - for the puncture of glass by the electric discharge2985.. each 7/6
  - 1364 .—Ditto, mounted on stand No. 1341
  - each 12/6
  - 1351.—Electric Whirl,
  - as figured 2973 .. each 5/-
  - 1352 .—Ditto, , mounted on stand No. 1341.. each 10/-
  - 1365.—Brass Chain for
  - making connections to various electrical accessories.2987
  - Per yard.. .. .. .. 4d.
  - 1366.—Electric Whirl, mounted on mahogany foot 2988 .. .......... ./ each 4/6
  - 1366
  - Oup Balances and Weights have achieved World-wide Reputation : vide Opinions of the'
  - Leading Scientific Press. n
- p.193 - vue 212/555
- - 194 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - STATICAL ELECTRICITY APPARATUS
  - 1367.—Brass Balls, with Hook.
  - Diameter
  - Each
  - 5d.
  - 9d.
  - i m.
  - 1/3
  - 1368.—Brass Balls, hollow, without Hooks. 2991
  - Diameter .. .. ..........\ I i
  - Each .........................4d. 8d. 1/2
  - 1369.—Bucket and Syphon, best make, for suspending from conductors of electric machines 2992 .. .. .. each 7/6
  - 1370 .—Ditto, small size 2993 .. .. .. .. ,, 4/-
  - 1371. Henley’s Quadrant Electrometer, best make. 3002 Each .. 13/6
  - 1372. —Pith Ball Electrometers 3017
  - each 2/-
  - 1373. —Ditto, superior quality, and larger size 3018
  - each 4/6
  - 1374.—S moke Condensation Apparatus, as
  - described by Sir Oliver Lodge in his various papers on Smoke Condensation. 2996
  - Price, complete, best make and finish.. .. £2 10 0
  - 1375.
  - Tin Vessels, with
  - vulcanite handles, as described by Stewart & Gee. 3006
  - Per pair
  - 2/6
  - CONDENSERS
  - 1376.—Condenser, simple form, with glass plate and two sliding brass plates, each provided with vulcanite handle ; mounted on. polished mahogany base. 3010
  - £17 6
  - 1377.—Sliding Condenser, with two 4-in.
  - plates mounted on ebonite rods sliding in strong wooden base having a millimetre scale on one side, as figured. 3011 Price, complete .. ........... .. £18 6
- p.194 - vue 213/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 195
  - _________________W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CONDENSERS, Etc.
  - 1378.—“ Nivoc ” Condenser, im
  - proved pattern (registered). As will be seen by the illustrations, the plates of this condenser can be used for either vertical or horizontal positions, so that various dielectrics such as sulphur, paraffin wax, liquid solutions, etc., may be conveniently inserted. The base is made of polished mahogany and is provided with a graduated boxwood scale on one side. 3012
  - Price, complete
  - £4 7 6
  - Plates vertical.
  - Plates horizontal
  - 1379.—Wire Gauze Cylinder, open
  - at top, for showing that electricity only resides on the surface of bodies. 3005
  - Price, not including insulating stand 6/-
  - 1380.—Wire Cage, for showing that electricity only resides on the surface of bodies. 3004 Each ........................£17 6
  - ELECTROSCOPES
  - 1381
  - 1381.—“ M.V.T.” Electroscope, the ideal electroscope for students’ use ; retains its charge for a whole day. Glass can be removed for cleaning or renewal when required. Provided with two small holes—one in metal disc and the other near bottom of case—for attaching wires. 3020 Each .. .. . .. .. .. .. •. .. 10/6
  - This Electroscope measures 6 x 3J X in.
  - Prof. D. Robertson of the Merchant Venturers Technical College, Bristol, writes :—" I have now been able to test the Electroscope and find it very satisfactory. It will keep a charge for about a day. Please make'me eighteen more.”
  - 1382.—Bennett’s Gold Leaf Electroscopes, guaranteed best make and finish. 3021
  - A. ’Pint size .. .. each £0 18 6
  - B. Quart size .. .. • • ,, 1 5 0
  - N.B.—The point A is screwed on to plate when it is'required to -show that electricity escapes off points.
  - 1382
  - Every requisite 5for -Chemical, Physical, and, Bacteriological., work supplied, from a test tiibe to the
  - complete furnishing of t|ie largest laboratory.
- p.195 - vue 214/555
- - 196 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ELECTROSCOPES AND ELECTROMETERS
  - 1383.—E I ect rose o p e, polished mahogany case, glass back and front, vulcanite fittings and adjustable brass side-plates. Complete as figured. 3025
  - Each .. £1 1 0
  - 1385.—Ayrton’s Gold Leaf Electroscope.
  - The glass shade is covered inside with narrow bands of tinfoil, which are joined at the bottom to a brass ring or collar. The supports for the rod to which the gold leaves are attached consist of an insulated structure. Inside the shade is a receptacle for sulphuric acid and pumice stone. 3031
  - Each .. .. £1 17 6
  - See Ayrton’s “ Practical Electricity.”
  - 1384.—Volta’s Electroscope. 3028
  - A. One pint size .. 22/6
  - B. Two „ „ .. 27/6
  - (Prices include condenser).
  - 1386.—Coulomb’s T orsion Balance, for Electrical Experiments. Large Size. " University ” Type, 1911 Pattern, complete with all accessories for experiments in Magnetism and Electricity 3041 .. £6 0 0
  - 1387.
  - Stewart & Gee’s Quadrant Electrometer 3038 £4 7 6
  - Ouf* Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.196 - vue 215/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 197
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DOLEZALEK’S ELECTROMETER
  - 1388.—Dolezalek’s Quadrant Electrometer. (1911
  - Pattern.) Guaranteed Best Make. Price, including four spare Quartz Suspensions 3037 .. . . .. .. .. £11 17 6
  - Professor Watson, in his Text-Book of Practical Physics states :—
  - “ The original Kelvin pattern quadrant electrometer was a very elaborate instrument, troublesome to set up, and difficult to keep in adjustment. Of recent years, however, a more simple form of quadrant electrometer has been found just as accurate, and very much easier to use. The best known pattern of quadrant electrometer of this more simple form is that designed by Dolezalek. The needle is made of two pieces of silvered paper attached to a thin stem of aluminium, which also carries a mirror. The needle system is suspended by a thin strip of phosphor bronze or a quartz fibre, rendered conducting by being smeared with a solution of calcium chloride, or coated with a thin layer of platinum.
  - " The needle should be charged to between ioo and 200 volts, and for this purpose it is connected to one pole of a battery of about eighty small accumulators, the other pole of the battery, as well as the outside case of the instrument, being earthed by being joined to the gas or water pipes.”
  - ELECTRICAL MACHINES
  - (See also page 198.)
  - 1391. — Cuthbert-son’s Plate Electrical Machines,
  - on polished mahogany stand, fitted with brass bow conductors. 3050
  - Size A. Diameter of plate, 30 cm. .. each £5 10 0 „ B. „ „ 40 „ „ 6 5 0
  - 1389.—Wimshurst Machines, F; E. Becker
  - & Co.’s new improved form, original construction ; do not require any initial charge ; will work in all weathers; do not require warming. These machines are guaranteed to give the very best results. 3055 Size A. Diameter of plates, 26 cm., approximate
  - length of spark, 9 to 13 cm. .. each £3 19 6 ,, B. Diameterof plates, 31 cm., approximate
  - length of spark, 10 to 15 cm. . . each 5 7 6
  - 1390.—Wimshurst Machines, F. E. Becker
  - & Co.’s new improved construction. 3056
  - A. Diameter of plates, 40 cm. ; approximate
  - length of spark, 13 to 20 cm. .. each £10 10 0
  - Diameter of plates, 50 cm.; approximate
  - length of spark, 15 to 25 cm. .. each £12 15 0
  - Diameter of plates, 60 cm. ; approximate length of spark, 20 to 30 cm.
  - B.
  - C.
  - each £15 0 0
  - We have discontinued making Wimshurst Machines with Ebonite Plates as they were found to be unsatisfactory, as the plates “ warp ” arter a time.
  - Oup stock of pure Chemicals and Acids is very considerable; hence all orders are executed with ithe utmost despatch For Prices, etc., see Chemical Apparatus Catalogue.
- p.197 - vue 216/555
- - 198 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ELECTRICAL MACHINES
  - (See also previous page.)
  - 1392.—Electrical Machines, cylinder form, English glass cylinder mounted on polished mahogany stand, with brass conductor, etc. 3049
  - Size A. With cylinder measuring 20 cm. x 15 cm.
  - Each ...............................£4 17 6
  - 1393.—Wimshurst Machines, in glass case
  - with mahogany framework. 3057
  - A. 2 glass plates, 14 in. diameter, with 2 Leyden jars
  - fitted................................ .. £17 10 0
  - B. 4 glass plates, 14 in. diameter, with 4 Leyden jars
  - fitted ,................ .. .. £21 0 0
  - C. 6 glass plates, 14 in. diameter, with 4 Leyden jars
  - fitted..............................£27 15 0
  - D. 8 glass plates, 26 in. diameter.. .. £65 0 0
  - E. 12 glass plates, 26 in. diameter .. £78 0 0
  - 1394.—Demonstration Set of Instruments for Experiments in Frictional Electricity, comprising: Leyden jar; set of chimes, having five bells of different tones ; electric whirl; pith ball electrometer; Geissler’s vacuum tube; paper brush; electric circus; luminous plate; luminous tube; discharger for Leyden jar; condensation of smoke apparatus ; jumping pith ball apparatus ; insulated support for all the apparatus ; holder from which to hang vacuum tube, etc. ; pair of handles for use with Wimshurst machines ; small quantity of chain. 3064
  - Complete in cardboard box .. .. .. £3 10 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.198 - vue 217/555
- - F. E. BECKER <& CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 199
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - VOLTAIC ELECTRICITY
  - BICHROMATE
  - 1395
  - 1395.—Bichromate Battery, Lecture Table
  - pattern, with arrangement for lifting and lowering, 5-pint size glass cells ; zinc plates, which are amalgamated ready for use, measure 6 in. x 3 in. .. £3 15 0
  - A. Extra Carbons for above.. .. .. each 1/9
  - B. Extra Amalgamated Zincs for above .. each 2/-
  - C. Complete set of Carbons and Zincs, with clamps,
  - terminals and wires ready for connecting up the five cells .. .. .. ..£220
  - BATTERIES
  - 1396. — Bichromate Battery, bottle form, with arrangement for raising and lowering the zinc.
  - A. Capacity 250 c.c. each 4/6
  - B. ,, 500 ,, ,, 6/-
  - C. „ 800 „ „ 7/6
  - D. ,, 2,000 ,, „ 10/6
  - 1397.—Students* Bichromate Battery Elements, packed in cardboard box .. .. each 2/3
  - 1398.—Spare Cylindrical Zincs, for above]
  - Each .. .. .. 6d. Per dozen .. .. 5/-
  - Improved Low-Resistance Mercury Bichromate Battery.—This battery is well adapted for driving small motors, charging accumulators, small lights, and various, uses in the laboratory.
  - For full specifications and directions for use, see page 446 of our Physical Apparatus Catalogue, 1913 Edition.
  - Batteries complete with Tray and Lifting Arrangements for Amalgam Plates.
  - 3-Cell Battery. 6-Cell Battery. 10-Cell Battery.
  - 3-pint size Cells 10-pint size Cells 1399 £3 0 0 | 1401 £5 10 0 1400 ! 5 10 0 i 1402 j 8 15 0 ! I I 1403 |£750
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.199 - vue 218/555
- - 200 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BUNSEN’S CELLS
  - 1404.—Bunsen’s Cells, best make,
  - complete with carbon block and terminal, zinc cylinder and terminal, porous pot and outer stoneware vessel.
  - A. Pint size . . .. .. each 6/-
  - B. Quart size .. .. .. ,, 8/6
  - I4°4
  - 1405 and 1407
  - 1405. —Set of 4 Bunsen’s Cells, pint size, fitted in teak tray, as figured
  - 1406. —Set of 6 Bunsen’s Cells,
  - 1407. —Set of 4 Bunsen’s Cells, quart size, fitted in teak tray, as figured
  - 1408. —Set of 6 Bunsen’s Cells,
  - per set £1 17 6
  - „ 2 10 0
  - „ 2 7 6
  - „ 2 17 6
  - 1409
  - DAN I ELL’S CELLS
  - 1409.—Daniel I’s Cells, zinc rod with mahogany cap and terminal, porous pot, outer copper vessel with terminal. 3121 ,
  - A. -|-pint size
  - B. 1
  - C. 2
  - D. 3
  - each 6/3
  - V-
  - 8/-
  - 10/-
  - 1410c
  - 1410.—Sets of Daniel I’s Cel ls, as No.
  - 1409, but fitted in -strong teak trays with handles, as figured. 3122 ‘ :
  - As Set of 3 cells, 1 pint size, in tray, complete.
  - Per set .. .. .. .. .. £112 6
  - B. Set of 4 cells, 1 pint size, in tray, complete.
  - Per set .... .. ..' ..£240
  - C. Set of 6 cells, 1 pint size, in tray, complete.
  - Per set .. .. .. .. . • £3 2 6
  - Our stock of pure Chemicals and Acids is very considerable; Hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.200 - vue 219/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 201
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DAN I ELL’S CELLS
  - Complete Cells. Coppers Zincs. Porous Pots. Glass Cells.
  - No. 1411.—3-Pint Gravity Daniell Each. Each. Each. Each. Each.
  - Element 3116 1 No. 1412.—3-Quart Gravity Daniell 5/6 1 V- 3/6 — 1/9
  - Element3117 No. 1414.—3-Pint Quantity Daniell Element (Colonial Government j 9/6 1/9 5/- 3/3
  - Pattern)3119 5/- i V- 1/9 10d. 1/6
  - 1411
  - 1414
  - 1415
  - GROVES’ CELLS
  - 1415. —Groves’ Cells, best make. Price varies according to the market price of platinum. Size of outer glass cell 5j X 3| X 2| in. Size of platinum plate required 5 x 2 in. 3125
  - Price, without platinum plate .. .. .. .. .. .. .. .. .. each 9/-
  - 1416. —Platinum Plates for Groves’ Cells, 5 in. x 2 in. Price varies according to market price of Platinum.
  - 1417. —Groves’ Battery, consisting of four
  - cells as No. 1415, in teak tray. Price, not including platinum plates 3126 .. .. £118 0
  - 1418. —Groves’ Battery, consisting of six
  - cells as No. 1415, in teak tray. Price, not including platinum plates3128 .. .. £2 15 0
  - SMEE’S CELLS
  - 1419. —Smee’s Cells, consisting of a platinised silver plate between two zinc plates, fixed
  - to a wooden top with terminals 3130 .. .. .. .. •• .. each 12/6
  - 1420. —Glass Jars for Smee’s Cells .. .. ,, 2/3
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - 202 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LECLANCHE CELLS
  - 1421. — Leclanch6 Cells, ordinary pattern, complete with porous pot (charged), zinc rod, and outer glass vessel. Prices for best make.
  - A. 2-pint size each 2/2 | B. 3-pint ,, ,, 3/-
  - 1421
  - 1422. — Leclanch6
  - Cells, “ Carporous ” pattern, complete with combined porous pot containing the depolarising mixture. (For full details see Physical Apparatus Catalogue, 1913 Edition.)
  - A. 2-pint size each 2/3
  - B. 3-pint ,, ,, 3/6
  - 1422
  - 1423.—Leclanche Cells, “Agglomerate Block" pattern. This is a modified form of the Leclanche cell, specially designed to avoid the necessity of using a porous pot, thereby considerably decreasing the internal resistance of the cell, and producing a heavier current output. The negative element consists of a carbon capped plate, against which two agglomerate blocks, composed of manganese and carbon moulded into convenient shape under pressure, are held tightly by means of two indiarubber rings ; the indiarubber rings are provided with loops for the zinc rods.
  - Prices for best make—•
  - A. i-pint • size . . .. .. .. .. each 2/6
  - B. 2-pint ,, • • • • »3/-
  - C. 3-pint ,, 4/-
  - 1423
  - MINOTTI CELLS
  - E.M.F. Internal Resistance.
  - Volts. 1-08 1-08 Ohms. 9-0 9'° 1424. —i^-pint size, Ebonite Cel], complete .. 1425. —i|-pint size, Glass Cell .. 6/6 7/6
  - Coppers. Zincs. Outer Cells. Sulphate of Copper.
  - 1424.-For Cells 10d. 2/9 2/9 6d.
  - 1425.- „ „ 10d. 2/9 3/9 6d.
  - The elements in this battery consist of copper and zinc discs, one placed at the bottom of the cell and the other at the top. Materials for charging—copper sulphate crystals—sulphuric acid 1 to 10 parts of water. A layer of sand previously soaked in sulphate of zinc intervenes between the copper and zinc elements.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 203
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - STANDARD CADMIUM CELLS
  - 1426
  - 1426. —The Normal Weston Cadmium
  - Cell (for full report, see “ The National Physical Laboratory: Collected Researches.” Vol. IV., 1908, pp. 85-119). Recommended by the International Conference on Electrical Units and Standards as a standard of electric pressure for the measurement of both E.M.F. and current.
  - Price ............................£3 17 6
  - (N.P.L. Certificate extra, if required.)
  - 1427. —Normal Weston Cadmium
  - Cell, double pattern
  - Price complete .. .. .. .. £6 15 0
  - (N.P.L. Certificate extra.)
  - 1428. —Glass “ H ” Tubes, as used for making up Normal Weston Cadmium Cells
  - Each ................................. 7/6
  - SECTIONAL VIEW.
  - A—Mercury. B—Mercurous Sulphate Paste. C—Cadmium Sulphate Crystals. D—Cadmium Sulphate (Saturated Solution). E— Cadmium Amalgam.
  - 1429.—Normal Weston Cadmium Cell with Combined External Resistance. This compact arrangement includes three resistance coils, 10,000, 1,000 and 100 ohms respectively, which are in series with the cell, and enables it to be used with the minimum of risk of short circuiting. Starting with the 10,000 ohms, it can be adjusted down by three stages to the zero point. Resistance of coils correct to 0-05 per cent.
  - Price complete ................................... .. £5 12 6
  - 1430.—Volta’s Pile, consisting of 80 pairs of copper and zinc plates, 2 in. diameter, having felt discs in between ; mounted in frame as figured.3192
  - £2 2 6
  - 1431—Zinc and Copper Plates,
  - with wires attached, for making simple cells. 3146
  - Per pair .. .. .. .. .. 1 /-
  - 1432.—Zinc and Copper Plates,
  - as above, but thicker metal. 3147 Per pair.....................1/3
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 204 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SPARE PARTS F
  - 1433.—Zincs, for Leclanche Cells. 3165
  - A. i-pt. size each 3d.
  - B. 2-pt. ,, ,, 4d.
  - ; C. 3-pt. „ „ 5d.
  - 1434.—Zincs, for Daniell’s Cells, ready
  - I tapped for terminals. 3166
  - 1 A. i-pt. size each 1 /-
  - I B. 2-pt. ,, » VC
  - 1 C. 3-pt. „ • • „ 2 h
  - 1435.—Zincs, for Daniell’s Cells, fitted with mahogany caps and terminals. 3167
  - A. i-pt. size
  - B. 2-pt. ,,
  - C. 3-pt. „
  - each 2/-
  - „ 2/6
  - » 3/-
  - 1436.—Zincs, for bichromate batteries bottle form (see illustration No. 1396), hole drilled and tapped ready for use. 3168
  - For 250 c.c. 500 c.c. 800 c.c. 2,000 c.c.
  - 5d. 6d. 8d. 1 /-
  - 1437.—Zincs, for Groves’ Cells, amalgamated ready for use. 3163
  - Each .. .. .. .. .. 3/-
  - Per dozen .. .. .. .. 35/-
  - 1438.—Zi nCS, thick, for Bunsen’s Cells. 3164
  - A. Pint size
  - B. Quart ,,
  - each 1 /6 » 2/-
  - 1439.—Carbon Blocks, for Bunsen's batteries. 3171
  - A. For pint size batteries. 5 in. long X 1 in. X f in.
  - each 9d.
  - B. For quart size batteries. 6^ in. long X ij in. X f in.
  - each 1 /-
  - <1440.—Carbon Plates, for bichromate bottle batteries. 3172
  - For 250 c.c. Battery .. .. .. .. each
  - ,, 500 c.c. /K
  - ,, 800 c.c. ,, .. • • • • • • >>
  - ,, 2,000 c.c. ,, .. • • • • • • 11
  - See page 199 for Bichromate Bottle Batteries.
  - 5d.
  - 6d.
  - 8d.
  - 1/2
  - 1441, — Battery Cells, round, stoneware, for Bunsen’s batteries. 3173
  - A. Pint size .. • • • • • • • • each 1 /-
  - B. Quart ,, .. . . • • .... ,, 1/6
  - 1442.—Rectangular Glass Jars, for Groves’ Cells. 3175
  - A. 12 X 8 X 4% cm..............each 2/-
  - B. I2| x 9 X 7 „ 2/3
  - C. 15 X 9 X 6 „ 2/3
  - D. 20 XI2|X7 ,, •• .. .. ,, 3/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 205
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BATTERY JARS, CELLS, Etc.
  - 1443.—Glass Jars, for Bunsen’s batteries. 3174
  - Height 10 13 15 16 20 20 26 cm.
  - Diameter •• 7\ 9 10 12 10 12 15 „
  - Price, each . . 9d. 11d. 1/2 1/4 1/6 1/10 3/-
  - Price, per dozen .. 7/- 9/- 11/- 13/- 16/- 18/- 30/-
  - *1444.—Battery Cells, round, porous ware. 3176
  - Length 3 in., diam. 1 in. .. each 6d.
  - „ 3 > y ) > i£ „ >> 6d.
  - „ 4 ) > y y if „ . . ,, 8d.
  - 4b >t > > 2 ,, 10d.
  - cSHHiiS it—liliiiiiim S ” 5 tt tt 2 ,, V-
  - „ 5i >t 11 „ • • tt V-
  - ,, 6 11 ft i| ,, • • tt V-
  - „ 6 tt 11 2 ,, • • 11 1/-
  - ,, 5f i t tt 21 „ • • it 1/3
  - „ 6* it it 2f „ • • it 1/3
  - „ 7 tt tt 2 ,, 1/3
  - ,, 8 tt tt 2| „ * • it 1/5
  - P „ 9i 2i ,, 1/6
  - „ ioi 2i • • tt 1/9
  - ,, I2 a it 3i ,, * • it 2/6
  - H H wjw it a 4i .. • • it 3/-
  - 1445—Battery Cells, fiat, porous ware. 3177
  - Height 4\ in., , width 2| in., depth | in. each 1 /3
  - >> 4t »» „ 21 „ „ 1 „ .. „ 1/6
  - » 4t ,, „ 3l „ „ 1 „ •• „ 1/3
  - » 5t „ ,, 3t >> >> 1 >. „ 1/3
  - » 7 » Other sizes to order. „ 1/6
  - SUNDRIES
  - SHEET EBONITE
  - 1446.—Pure Para Rubber Strip, 22 B.W.G.,
  - in \ in., § in., or 1 in. widths .. .. per oz. 1/-
  - 1447. —India-rubber Prepared Tape for
  - binding wire joints .. .. .. per oz. 6d.
  - 1448. —India-rubber Solution, in collapsible
  - tubes. - Contains \ lb. solution .. .. each 1 /3
  - 1449. —Chatter ton Compound in Sticks. Contains a high percentage of rubber. Easily melted. Much used by electricians. In 2-oz. sticks each 1/3
  - 1450. —Wire Solder for making electrical connec-
  - . tions ... .. .. .. .. per lb. 2/9
  - 1451.—Sheet Ebonite, smooth bright surface, any thickness from | in. to i in. inclusive. Good quality
  - for all ordinary purposes.. .. .. per lb. 5/6
  - 1452. —Sheet Ebonite, smooth bright surface,
  - in thick sheets, 1 in. to ij in. .. per lb. 7/6
  - 1453. —Sheet Ebonite, over i£ in. up to 2 in.
  - thick.............................per lb. 8/-
  - EBONITE ROD
  - 1454.—Ebonite Rod, polished, good quality for all ordinary purposes.
  - Diameter ..................| and tg sV to 2
  - Price .. .. .. per lb. 9/6 10/- 7/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the ? Leading Scientific Press.
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- - 206 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TERMINALS
  - Best English Make, Cut from Solid Straight-drawn Metal. Screw Threads according to the
  - British Association Standard Dimensions.
  - 68 69 70 7I 72 73 '
  - 1455.—Terminals, for screwing into wood. Illustrations are shown actual size.
  - Size.......................................... 68 69 70 71 72 73 74
  - Per dozen .. .............. 3/- 3/3 3/6 4/- 4/3 5/8 5/10
  - 478
  - 1457.—Terminals for electric light fittings, etc. Illustrations are shown actual size.
  - Size v .. .. .476 477 478
  - Per dozen .. 4/9 6/- 18/6
  - 1458.—Terminals, for batteries. Illustrations are
  - shown actual size.
  - Size .. .. .. .. 1 2 3 4
  - Per dozen .. ... .. 2/3 2/7' 3/- 3/6
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.206 - vue 225/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 207
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TERMINALS
  - 1459.—Terminals, various. Illustrations are shown actual size.
  - Size .. .. .. .. .. .. .. .... .... 24 25 26 27
  - Per dozen .. .. .. .. .. .. .. .. .. .. .. 4/3 3/7 5/10 5/-
  - 13 14 96
  - 2/3 2/6 7/-
  - 1461.—Terminals, various. Illustrations are shown actual size.
  - Size .........................................7 8
  - Per dozen . . , . . .. .. .. .. 3/6 2/7
  - 9
  - 2/2
  - 10 18 19
  - 2/- 2/7 3/8
  - 1462.
  - Terminals.
  - Size .. 28 29
  - Per dozen 2/4 2/2
  - 1463.—Terminals, single
  - pattern, for Groves’ batteries.
  - Each .............. 1/3
  - Per dozen .. .. 12/-
  - 1464. — Terminals, double pattern for Groves’ batteries.
  - Each .. .. 1/8
  - Per doz. ' .. 18/-
  - Every requisite for Chemical/ Physical, and Bacteriological work supplied, from, a test tube to the
  - complete furnishing of the largest laboratory.
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- - 208 F. E. BECKER <& CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TERMINALS
  - 1465.—Terminals, for Carbons, etc. Illustrations are shown actual size,
  - 2I2
  - Size .............................................224 219 214 209 205 211 212
  - Per dozen .. .. 9/- 9/6 11/- 13/- 16/- • 8/6 12/6
  - 1466.—Terminals, for Carbons, etc. Illustrations are shown
  - Size .. .. .. .. .. •. . • • • 206 (
  - Per dozen .. .. .. .. .... .. 15/-
  - actual size.
  - 210 215 220 217
  - 14/- 10/- 10/- 10/
  - 222
  - 9/-
  - Our Balances and Weights ^have achieved World-wide Reputation : vide Opinions of the j
  - Leading Scientific Press.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 209
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TERMINALS
  - 226 225
  - 1467.—Brass Terminals, highest finish for best
  - quality instruments and other work. Illustrations are shown actual size.
  - Size................ ..................228 227 226 225
  - Per dozen................. .. 8/- 12/- 16/6 25/-
  - 1468.—Double Connector, for joining two, three, or four wires.
  - Per dozen .. .. .. 10/-
  - 1469.—Special Terminal, suitable for the reception of hook, wire, or pin end.
  - Per dozen .. .. . . 4/-
  - 1470.—Con nectors. Illustrations are shown actual size.
  - Size .. .. .. 53 54 55
  - Per dozen .....................4/- 3/3 2/6
  - (No. 55 is size most frequently ordered.)
  - THE “SPRINGCLIP” TERMINAL (Patent).
  - These terminals are rapidly replacing other types of binding screws for batteries, coils, etc. They hold most tenaciously, and yet at the same time the wire can be removed immediately upon pressure by the thumb. Illustrations are shown actual size.
  - 1471. —Large Double, to take
  - two wires.
  - Per dozen .. .. .. .. 9/6
  - Fixing screws not included.
  - 1472. —Large Single.
  - Per dozen .. .. .. .. 6/-
  - Fixing screws not included.
  - 1473. —Small Single.
  - Per dozen .. .. .. .. 2/-
  - Fixing screws not included.
  - 1473
  - 1472
  - 1471
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.209 - vue 228/555
- - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
  - RESISTANCE WIRES
  - Approximate Resistance at 60° F. (15-5° C.) per 1,000 yards and Carrying Capacity.
  - Size of Wire. Eureka. Nickel-Chrome. Nickel Silver (German Silver), Manganin. Platinoid.
  - S.W.G. Diam. in Diam. in Milli- Ohms per Amps, at Ohms per Amps. at Ohms per Amps, at Ohms per Amps, at Ohms per Amps, at
  - inches. metres. i,ooo yards. ioo° C. i,ooo yards. ioo° C. i,qoo yards. ioo° C. 1,000 yards. ioo° C. 1,000 yards. ioo° C.
  - 8 •160 4-06 33-5 33-o 65-8 23 16-5 31 28-8 40 28-8 37
  - 10 •128 3*25 52-3 22-8 103 16 257 26-5 45*o 26 45 24
  - 12 •104 2-64 79*3 16-8 156 II 39-2 21 68-3 20 68-2 18
  - 14 •080 2-03 133*9 9-5 264 6*5 66 13 115 12 ii5*4 II
  - 16 •064 1-62 209-4 6-o 412 4-2 103 8-3 179 7 180-3 6-5
  - 18 •048 I-2I 371-8 4-3 732 3-o 179 6-o 320 5 320-6 4-8
  - 20 •036 •91 661-3 3-0 1301 2-1 326 4'3 570 3-5 569-9 3-2
  - 22 •028 •71 1093 2-2 2152 i-6 54i 3'i 946 2'5 942-2 2-4
  - 24 •022 •55 1770 i-5 3486 i-o 876 2-0 1530 i-6 1526 i-4
  - 26 •Ol8 *45 2645 1-0 5206 •70 1311 1-5 2288 i-3 2279 i-o
  - 28 •OI48 •37 3914 •76 7704 •53 2006 I-I 35oo •89 3372 •86
  - 30 •0124 •3i 5575 *59 10969 •44 2752 •83 4801 •68 4803 •65
  - 32 •0108 •27 7350 •47 3^464 •33 3539 •64 6315 •55 6332 •5o
  - 34 •OO92 •23 10128 •37 19932 •26 5046 •53 8805 •44 8727 •41
  - 36 •OO76 •19 14840 •28 29213 •19 7400 •40 12910 •32 12789 •30
  - 38 *006 •i5 23808 •19 46873 •13 11895 •26 20755 •21 20518 •18
  - 40 •OO48 •12 37i84 •15 73100 •10 18502 •20 32285 •17 32060 •15
  - CHARACTERISTICS OF RESISTANCE WIRES.
  - Eureka. Nickel Chrome. Nickel Silver (German Silver). Manganin. Platinoid.
  - Temperature Co-efficient Specific Resistance in Microhms per ccm. Specific Gravity Melting Point Comparative Resistance Times Copper. . Tensile Strength, tons per square inch Weight per cubic inch •00022° C. 48 8-9 1,250° C. 28 40 •32 lb. •00042° C. 100 8-15 i,55o° C. 58 47-12 •29 lb. •00038° C. 23-5 8-77 1,000° C. 14 29 •32 lb. •000017° C. 41 8-89 1,150° c. 24 29 •32 lb. •00025° C. 43 878 1,100° C. 24 29 •32 lb.
  - 8 < 8 O 3 o
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  - £ 1 ? >
  - a "1
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- p.210 - vue 229/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 211
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ELECTRICAL WIRES ON REELS
  - (See also pages 212 and 213)
  - PRICES INCLUDE
  - COST OF REEL
  - AND WINDING
  - ON SAME.
  - COPPER WIRE.
  - 4. Weight Standard Wire Gauge and Price per Reel.
  - Cat. of Wire Description.
  - No/ on Reel. 14 16 18 20 22 24 26 28 30 32 34 36 38 40
  - 1474 I lb. Bare 1/1 1/1 1/1 1/2 1/2 1/2 1/3 1/4 1/6 1/6 1/7 1/7 1/11 2/2
  - 1475 i lb. jj 2/2 2/2 2/2 2/3 2/4 2/4 2/6 2/7 3/- 3/- 3/2 3/2 3/9 4/3
  - 1476 i lb- Enamelled .. 9d. 9d. 10d. 11d. 11d. 1/1 1/2 1/3 1/5 1/8 1/10 2/2 2/5 3/3
  - 1477 h lb. jj 1/4 1/4 1/5 1/6 1/9 1/10 2/- 2/2 2/4 2/9 3/2 3/11 4/2 «/-
  - 1478 i lb. jj 2/2 2/2 2/3 2/5 2/9 3/- 3/3 3/6 3/9 4/6 5/6 7/- 7/6 11/-
  - Double
  - 1479 i lb- Cotton Covered 9d. 9d. 10d. 1/- 1/1 1/3 1/5 1/6 1/9 2/- 2/3 2/9 3/4 4/6
  - 1480 I lb. i > 1/4 1/4 1/5 1/8 1/10 2/2 2/5 2/6 3/- 3/7 4/2 5/3 6/3 8/9
  - 1481 i lb. jj 2/2 2/2 2/3 2/8 3/- 3/6 4/- 4/9 5/2 6/3 7/3 9/3 11/6 16/6
  - Double
  - 1482 i lb- Silk Covered 1/3 1/3 1/3 1/9 1/10 1/11 2/2 2/4 2/8 3/- 3/6 4/- 5/6 6/5
  - 1483 | lb. j> 2/3 2/3 2/3 2/11 3/3 3/5 4/- 4/5 5/- 5/8 6/8 7/5 10/6 12/6
  - 1484 i lb. jj 4/2 4/2 4/2 5/3 5/9 6/3 7/3 8/3 9/3 10/9 12/6 14/6 20/- 24/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.211 - vue 230/555
- - 212 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ELECTRICAL WIRES ON REELS
  - EUREKA WIRE.—A high resistance alloy with a temperature co-efficient practically nil.
  - Cat. No. Weight of Wire onReel. Description. Standard Wire Gauge and Price per Reel.
  - 14 16 18 20 22 24 26 28 30 32 34 36 38 40
  - 1485 1486 1487 i lb. 1 lb. i lb. Bare a • • • • ,, 1/1 2/1 3/6 1/2 2/2 3/9 1/3 2/3 4/- 1/4 2/6 4/3 1/6 2/9 4/9 1/7 2/11 5/3 1/9 3/3 6/- 2/- 3/8 6/6 2/2 3/10 7/3 2/4 4/5' 8/- 2/8 5/1 9/3 3/- 5/8 10/6 3/5 6/8 12/6 4/3 8/3 15/6
  - 1488 1489 1490 i lb. i lb. i lb. Double Silk Covered JJ n 1/10 3/5 6/3 1/11 3/6 6/6 2/2 4/- 7/3 2/4 4/6 8/6 2/8 5/- 9/- 3/- 5/8 10/6 3/2 5/9 11/3 3/10 7/6 14/- 5/- 9/9 18/6 5/5 10/6 20/- 6/4 12/- 23/- 7/5 14/5 28/- 9/6 18/6 36/- 12/- 23/6 46/-
  - NICKEL SILVER WIRE (German Silver).—A low resistance alloy. Temperature co-efficient -00044 approximate per degree Centigrade.
  - Cat. No. Weight of Wire on Reel. Description. Standard Wire Gauge and Price per Reel.
  - 14 16 18 20 22 24 26 28 30 32 34 36 38 40
  - 1491 1492 1493 i lb. i lb. 1 lb. Bare ,, ,, 1/3 2/4 4/3 1/4 2/5 4/6 1/6 2/8 4/9 1/7 2/10 5/- 1/8 3/1 5/6 1/10 3/6 6/3 2/- 3/9 6/9 2/3 4/2 8/- 2/8 5/- 9/9 3/3 6/3 12/- 3/10 7/5 14/- 4/9 9/3 17/6 5/9 11/3 22/6 6/6 12/9 25/6
  - 1494 1495 1496 i lb. i lb. 1 lb. Double Silk Covered >j 2/3 4/4 8/3 2/4 4/5 8/6 2/5 4/8 9/- 2/9 5/3 10/- 3/- 5/10 11/- 3/6 6/7 12/6 3/10 7/4 14/- 4/6 8/10 17/- 5/6 10/9 21/- 6/6 12/9 25/- 7/9 15/- 29/6 9/3 18/- 35/6 11/9 23/6 46/- 15/5 30/4 60/-
  - NICKEL-CHROME WIRE.—A high resistance alloy for heating elements.
  - Cat. No. Weight of Wire on Reel. Description. Standard Wire Gauge and Price per Reel.
  - 14 16 18 20 22 24 26 28 30 32 34 36 38 40
  - 1497 1498 1499 i lb. h lb. 1 lb. Bare ,, ,, 4/10 9/3 17/6 5/- 9/9 18/6 5/4 10/3 19/6 5/10 11/3 21/6 7/- 13/3 25/6 7/8 14/9 28/6 »/- 17/3 33/6 9/10 19/3 37/6 10/6 20/6 39/6 11/- 21/6 42/- 12/3 24/3 47/6 13/9 26/9 52/6 15/3 30/- 59/- 16/9 33/- 65/-
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.212 - vue 231/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 213
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ELECTRICAL WIRES ON REELS
  - MANGANIN WIRE.—Temperature co-efficient o-ooooi per degree Centigrade
  - Cat. No. Weight of Wire on Reel. Description. Standard Wire Gauge : and Price per Reel.
  - 14 16 18 20 22 24 26 28 30 32 34 36 38 40
  - 1500 | lb. Bare 2/4 2/4 2/5 2/7 2/8 2/10 3/- 3/3 3/4 3/8 4/- 4/3 5/- 6/5
  - 1501 i lb. >t • • • • 4/5 4/6 4/8 4/10 5/2 5/5 5/9 6/3 6/5 7/- 7/6 8/3 9/9 12/6
  - 1502 i lb. tj f > 8/6 8/9 8/10 9/4 10/- 10/6 11/- 12/- 12/6 13/6 14/6 16/- 19/- 24/6
  - 1503 1 lb. ,, 16/- 16/6 17/- 18/- 19/- 20/- 21/- 23/- 24/- 26/- 28/- 31/- 37/- 48/-
  - Double
  - 1504 1 lb. Silk Covered 3/4 3/6 3/7 3/9 4/- 4/4 4/8 5/3 5/6 6/6 7/3 8/7 11/3 12/9
  - 1505 i lb- tt 6/4 6/6 6/10 7/3 7/9 8/4 9/- 10/3 11/3 12/6 14/- 17/- 22/3 25/6
  - 1506 i lb. ft 12/6 13/- 13/3 14/- 15/- 16/3 17/6 19/9 22/- 24/6 27/6 33/- 43/6 50/6
  - 1507 1 lb. tt 24/- 25/- 25/6 27/- 29/- 31/6 34/- 39/- 43/- 48/- 54/- 65/- 87/- 100/-
  - PLATINOID WIRE.—Temperature co-efficient 0-00025 Per degree Centigrade.
  - Cat. No. Weight of Wire on Reel. Description. Standard Wire Gauge and Price per Reel.
  - 14 16 18 20 22 24 26 28 30 32 34 36 38 40
  - 1508 1509 1510 i lb. i lb. I lb. Bare SJ }} 1/1 2/1 3/6 1/2 2/2 3/9 1/3 2/3 4/- 1/4 2/6 4/3 1/6 2/9 4/9 1/7 2/11 5/3 1/9 3/3 6/- 2/- 3/8 6/6 2/2 3/10 7/3 2/4 4/5 8/- 2/8 5/1 9/3 3/- 5/8 10/6 3/5 6/8 12/6 4/3 8/3 15/6
  - 1511 1512 1513 i lb. i lb £ lb. Double Silk Covered tt tt 1/10 3/5 6/3 1/11 3/6 6/6 2/2 4/- 7/3 2/4 4/6 8/6 2/8 5/- 9/- 3/- 5/8 10/6 3/2 5/9 11/3 3/10 7/6 14/- 5/- 9/9 18/6 5/5 10/6 20/- 6/4 12/- 23/- 7/5 14/5 28/- 9/6 18/6 36/- 12/- 23/6 46/-
  - ELECTRIC BELL WIRES
  - 1514. — Silk-covered Flexible Bell Cord. Two-strand
  - medium. Conductors of fine H.C. copper wires, insulated cotton, silk lapped and twisted.
  - Per yard. Per 12 yards. Per 100 yards.
  - 5d. 4/- 31/-
  - 1515. —Copper Wire, tinned, insulated with single pure rubber. Double cotton covered and paraffined.
  - Per 12 yards. Per 100 yards.
  - 10d. 7/-
  - 1516.—Pure Refined Tin Fusible Wire, for Cut-outs.
  - Standard wire gauge .. .. .. .. .. 21
  - Approximate Fusing Current Amperes .. .. 9-4
  - l lb. reels ............................each 1/6
  - 23 24 25 • 26 28 3i 34 36
  - 6-io 5*35 4-64 4 3 2 1-44 1
  - 1/10 2/- 2/- 2/- 2/3 2/10 3/6 5/9
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to tho
  - complete furnishing of the largest laboratory.
- p.213 - vue 232/555
- - 214 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS..
  - ACCUMULATORS
  - I5I7/5°3 1517/523 I5I7/512
  - 1517.—Portable Ignition Batteries, fitted in strong Celluloid Boxes, with sealed lids, Vent Plugs, and Non-corrosive Terminals. Sizes 515-519, 523-529, are supplied in wood crates as shown in illustration No. 523, and for these Batteries the overall height is increased to 6f- in. Stock is kept of all Sizes ready for immediate delivery.
  - Size Number to be quoted when ordering. Ignition Capacity. Charge Rate. Approximate Overall Dimensions (inches). Approximate Weight with Acid. Price.
  - Ampere Hours. Amperes.
  - 2 Volt 500 501 502 503 504 505 506 507 508 509 0000000000 N CO O N 00 O M M H H H Il 2* 4 5 6 8 9 10 11 12 Length. ft 2ft 2| 3ft- 3f 4ft 4f 5ft 6 Width. 4^' 4ft 4ft 4ft 4ft 4ft 4ft 4ft 4ft 4ft Height. 6f 6f 6f 6| 6| 6f 6f 6f 6f 6f Lbs. 2i 3i 5 6f 8* 10 11 i I2f I4i I5f £ s. d. 0 12 10 0 16 1 0 19 3 12 8 1 5 11 19 6 1 12 10 1 15 11 1 19 0 2 3 8
  - 510 20 i* ift 4ft 6| 4* 12 9
  - 511 40 2ft 4ft 6| 7i 1 8 11
  - 512 60 4 4* 4 ft 6| ioi 1 15 11
  - 513 80 5 5ft 4ft 6| i3i 2 2 9
  - 4 Volt 514 100 6 6ft 4ft 6f 16* 2 10 2
  - 515 120 8 8* 4ft 6| i9i 3 2 2
  - 516 140 9 8f 4ft 6* 22| 3 9 5
  - 517 160 10 8f 5i 6| 25i 3 15 9
  - 518 180 11 8| 6ft 6* 28| 4 2 0
  - 519 200 12 8f 6| 6| 3ii 4 15 3
  - 520 20 2ft 4ft 6f 6f 1 13 0
  - 521 40 2* 4t 4ft 6 i iof 2 2 9
  - 522 60 4 6ft 4ft 6| i5i 2 13 3
  - 523 80 5 8| 4ft 6| 20J 3 6 3
  - 524 100 6 10 ft 4ft 6| - 25I 3 16 3
  - Volt 525 120 8 I2I 4ft 6| 29t 4 12 3
  - U V Ull 526 140 9 x3ft 4ft 6i 33f 5 3 0
  - 527 l60 10 I3ft 5t 6| 38 J 5 11 6
  - 528 l80 11 I3ft 6ft 6i 42f 6 19
  - 529 200 12 I3ft 6| 6| 47 £ 6 12 6
  - Acid is not included in the prices, and is not sent unless specially ordered.
  - The capacities are based on ignition rating, and for continuous discharge the capacities will be halved.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.214 - vue 233/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 215
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ACCUMULATORS
  - 1518.—“ M.E.L. ” TYPE PORTABLE BATTERIES for General Laboratory Work.
  - THESE PORTABLE BATTERIES ARE SPECIALLY MADE FOR USE IN HOT CLIMATES SUCH AS THAT OF INDIA, but are equally suitable for use elsewhere. They are of robust and strong construction throughout, and each cell has a sealed cover to prevent the electrolyte spilling.
  - The use of celluloid or ebonite for the cell containers is avoided, and this type of battery is strongly recommended as being the best for export purposes.
  - 1518/662 4-Volt Battery.
  - Size No. to be quoted when ordering. Number of Plates per cell. Capacity, Ampere Hours. Working Rate, Amperes. Approximate Overall Dimensions of Battery. Dilute Acid required. Approx. Weight
  - Voltage. Inter- mittent. Continu- ous. Normal Charge. Max. Dis- charge. Length. Width. Height. com- plete with Acid. PRICE.
  - • 650 3 20 10 Ii 4 Inches. 1 Inches. 5i Inches. 7l Pints. •23 Lb. 5i £ s- d. 110
  - 651 5 40 20 21 3 2M 5i 7\ •39 7 14 4
  - 652 7 60 30 4 4* 2 si 5i 7\ •56 9 17 4
  - 2 653 9 80 40 5 6 3x1 5* 7% 75 11 1 10 0
  - 654 11 100 50 6 7\ 4x\ 5i 7& •94 13 1 13 8
  - 655 i5 I40 70 9 io£ 5x1 5* 7\ . i-3o i6f 1 19 4
  - 656 21 200 100 12 i5 7xV 5* 7i 1-90 22| 2 9 4
  - 66b 3 20 10 i£ 3l 5i 71 •46 9l 1 13 0
  - 661 5 40 20 21 3 4i 5i 71 •78 13 1 18 8
  - 662 7 60 30 4 4i 5t 5l 7l I'I2 16I 2 4 8
  - 4 663 9 80 40 5 6 6* 5i 7i i*5o T9t 2 10 0
  - 664 11 100 50 6 1\ 7t 5l 7l i-88 23 2 16 4
  - 665 i5 I40 70 9 io* io£ 5l 7i 2-60 30 3 7 11
  - 666 21 200 100 12 15 10 & 7ffV 71 3'8o 4©1 4 4 10
  - 670 3 20 10 *1 4H 5i 7l •69 i4l 2 18
  - 671 5 40 20 2* 3 6bV 5l 7l i*i7 20 2 11 0
  - 6 672 7 60 30 4 4l 83 V 5l 7l i-68 25 3 0 10
  - 673 9 80 40 5 6 9xf 5* 71 2-25 3ol 3 10 4
  - 674 11 100 50 6 1\ iixf 5* 7i 2-82 36 3 19 8
  - 675 15 140 70 9 io£ *4xf 51 71 3-90 47 5 14
  - 676 21 200 100 12 i5 14I 7x1 71 570 62 6 8 4
  - 680 3 20 10 ii 8* 51 71 i-38 28^ 4 2 9
  - 681 5 40 20 2| 3 iif 51 7l 2-34 38 4 18 4
  - 682 7 60 30 4 4* I5i .51 7i 3-36 . 47 5 13 4
  - 12 683 9 80 40 5 6 i8f 5l 7i 4'5o 59 6 9 4
  - 684 11 100 50 6 7\ 22 51 71 5*64 69 8 10
  - 685 i5 140 70 9 io£ 28* 51 7ik 7-80 90 8 16 10
  - 686 21 200 100 12 i5 29tSt 7tfl 7& 11-40 120 11 3 4
  - 1518/682 12-Volt Battery.
  - Acid is not included in the prices and is not sent unless specially ordered.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.215 - vue 234/555
- - 216 F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ACCUMULATORS
  - “T.Y.L. ” TYPE PORTABLE ACCUMULATORS
  - These cells are specially made for portable purposes, and are suitable for Temporary Lighting Installations. They are also largely used for Wireless Telegraphy, Telephones, Telegraphs, Phonographs, Electric Signalling and general laboratory work. Suitable connections are provided for joining the cells together.
  - The discharge rate of these cells can, for short periods, be increased to two and a half times the 5-hour rate without injury to the plates.
  - Acid is not sent with these cells unless specially ordered.
  - The overall height of these cells is i6§ inches.
  - Cat. Number of Plates per Cell. Capacity, Ampere Hours. Charge Rate, Amperes. Discharge Rate, Amperes. External Dimensions of Cell. Dilute Acid per evil Weight of Complete
  - No. 10 Hour Rate. Normal. Maxi- mum. For 10 Hours. For 7 Hours. For 5 Hours. Length. Width. Vw'Cll, Part of Carboy. Cell, including Acid.
  - Inches. ! Inches. Lb. £ * d.
  - 1519 5 45 6 10 4-5 5 7 3w 7i •04 25 2 3 0
  - 1520 7 67 9 15 67 8 11 4i 7i •06 34 2 13 4
  - 1521 9 90 12 20 9-0 11 i5 5i 7& •07 45 3 4 4
  - 1522 11 112 15 25 II-2 14 18 6* 7i •09 51 3 19 9
  - 1523 13 135 18 30 13-5 17 22 7i 7} •10 60 4 2 1
  - 1524 i5 157 21 35 157 20 26 8* 7i •II 67 4 10 3
  - 1525 17 180 24 40 18-0 23 30 9i 7i •13 76 4 19 5
  - 1526 19 202 ! 27 45 ! 20*2 26 33 10 i 7\ •15 84 5 10 4
  - 1527 21 225 30 5o ; 22-5 29 37 7i •l6 92 6 0 9
  - 1528 23 247 33 55 ! 247 32 4i 12& 7l •l8 101 6 11 0
  - 1529.—Portable Batteries. Fitted in polished hardwood cases, with lids, leather handles and two brass terminals.
  - Their low internal resistance, constancy and absence of local action make them unrivalled for Medical and Laboratory purposes, especially for X-Ray work ; as now supplied to all the principal hospitals throughout the United Kingdom and the Colonies. Practical results in Wireless Telegraphy, Scientific Research, etc., have proved that they retain their efficiency for many months without re-charging.
  - The illustration represents the 6-cell 30 A.H. Battery fitted with terminals to each cell, so that 2, 4, 6, 8, 10, or 12 volts can be taken at will.
  - . No. of Cells. 14 A.H. 21 A.H. 30 A.H. 45 A.H. 60 A.H.
  - £ d. £ s. d. £ s. d. £ s- d. £ s. d.
  - I 1 9 9 1 I5 9 2 2 6 2 11 0 3 1 0
  - 2 2 4 3 2 15 3 3 9 9 4 5 9 5 4 9
  - 3 2 19 0 3 17 0 4 17 0 6 0 9 7 8 0
  - 4 3 13 9 4 14 3 6 4 0 7 15 9 9 11 3
  - Prices of
  - larger Batteries on application.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.216 - vue 235/555
- - F. E. BECKER & CO., N1VOC HOUSE, HATTON WALL, LONDON, E.C.1. 217
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - FULLER BLOCK TYPE ACCUMULATORS
  - Block Accumulators have the invaluable quality of holding their charge when not working. Shaking and rough usage do not injure them as with plate cells.
  - They are specially recommended for Lighting or Dual Ignition Systems, etc., where the current required is intermittent, but at the same time it is desirable to have a cell which will retain its charge for a long period.
  - The Block Cell will hold its charge for a much longer period than ordinary accumulators, and can be left for months without attention.
  - The Block Type Accumulator is manufactured from practically the same materials as the standard plate type cells, but its patent construction gives it many advantages over ordinary accumulators.
  - They are more robust and less liable to injury
  - THROUGH ROUGH HANDLING OR NEGLECT.
  - The chief advantage of the block cell, however,
  - IS ITS ABILITY TO RETAIN ITS CHARGE FOR A LONG PERIOD OF INTERMITTENT SERVICE.
  - The Block Cells have been known to keep active on their initial charge for over two years, and this feature makes them especially useful for laboratory work.
  - The elements comprising the Block Cell are solid in construction, and therefore practically proof against mechanical injury.
  - 1530. 4-Volt Unit. 1531- 6-Volt Unit.
  - Prices and Dimensions.
  - * Intermittent Capacity in Ampere Hours, Dimensions in in. Price.
  - Cat. No. Volts. Length. Width. Height.
  - 1530 4 24 3i 2t 5i £ s- 1 3 d. 6
  - 1531 6 24 5t 2i 5i 1 15 0
  - 1532 8 24 3& 4t 5i 2 7 0
  - 1533 4 3° 4i 2i H 1 6 6
  - 1534 6 30 61 2i H 2 0 0
  - 1535 8 30 4* 4i 2 13 0
  - 1536 4 45 4i 3f 1 11 0
  - 1537 6 45 7\ 3* 6£ 2 7 0
  - 1538 8 45 7\ 4* 6* 3 2 0
  - 1539 4 60 6i 3i 7\ 2 1 0
  - 1540 6 60 9i 3i 7\ 3 1 6
  - 1541 8 60 6* 6* 7i 4 2 0
  - 1542 4 120 8* 4i 7h 3 13 6
  - * The " Intermittent ” rating of these cells is twice the actual capacity, taken at a 20-hour rate.
  - CABLE TYPE ACCUMULATORS
  - Ideal Batteries for Laboratory Work.
  - In these batteries the cells are nested together in polished hardwood cases, with lids and leather straps, but the cases are so made that the terminals are protected by the lid—while accessible for use as required without opening the same. Each cell is separate and only connected by lead fuse or copper wire as may be required in series, parallel, or parallel-series.
  - Thus the 6 cell, 40 a.h., as illustrated open, gives 12 volts when connected in series, but by re-arranging the cells, two or three in parallel, it can be altered into a 6 volt 80 a.h. or a 4 volt 120 a.h. battery.
  - No. of Cells. 10 A.H. 20 A.H. 30 A.H. 45 a.h. 60 A.H.
  - £ s. d. £ s. d. £ s. d. £ s. d. £ S. d. ,
  - 2 2 5 3 3 4 0 3 11 0 4 8 6 5 15 3
  - 4iX3 X7l 4ix5$X7i 5iX4fx8| 5ix5ix8f 5?x6f x8|
  - 3 3 10 4 7 0 5 9 9 6 5 0 8 4 3
  - 4l X 4| X 7\ 4l x 7j x 7-|- 5ix6|x8| 5lx7£x8f 54X9|x8f
  - 4 3 17 3 5 12 9 7 10 8 16 10 12 6
  - 4ix5iX7l 4s x 9§ X 7~| 5jx8f x8| 5iX9fx8f 5ixi2|x8|
  - 5 4 13 6 6 16 0 8 12 9 9 9 9 13 0 3
  - 4i-x6fx7l 4fcxriiX7i 5ixiofx8f 5ixnix8f 5lxi5ix8|
  - 6 5 9 9 8 16 10 4 0 11 14 6
  - 4ix 7^x7! 4ixi3|X7i 5£xi2|x8f x 13! x8|
  - Approx. Weight lb. oz. lb. oz. lb. oz. b. oz. lb. oz.
  - pejr Cell with acid. 2 6 4 0 6 4 7 2 9 4
  - Discharge 1 hour. 4 Amps. 8 Amps. 10 Amps. 16 Amps. 24 Amps.
  - The 60 a.h. Battery can be discharged at 40 amps, for half-an-hour.
- p.217 - vue 236/555
- - 218 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - “EXIDE” BATTERIES
  - These Exide batteries are not designed for very heavy discharges. They are, however, entirely suitable for use when discharges at fairly slow rates are required, e.g., in connection with the filament heating of thermionic valves, etc.
  - EACH BATTERY CONSISTS OF THE REQUISITE NUMBER OF SEPARATE 2-VOLT CELLS CEMENTED TOGETHER AS REQUIRED. This design is infinitely superior to that commonly employed, in which the cells are compartments in a single box and are separated from each other only by a thin celluloid partition« Such partitions give endless trouble by way of breakage and leakage from one cell to another, due to their frailty and to the insecurity of the sealing of the partition to the sides of the box.
  - The boxes are made of best quality celluloid. The sealing of the lids to the boxes is of special design, ensuring acid-tight edges and corners.
  - The terminals consist of specially designed brass studs fitted with brass nuts heavily covered with ebonite.
  - Hard wood containers for the above batteries are supplied when required.
  - Cat. No. 1544. 1545. 1546. 1547. 1548. 1549.
  - Voltage 2 2 4 4 6 6
  - No. of cells .. I I 2 2 3 3
  - Normal charge current amps. 2 5 2 5 2 5
  - Capacity const, amp. hours . . 30 60 30 60 30 60
  - Weight in lb. 5 9i 10 19 16 33
  - Price 17/- £16 0 £1 14 0 £2 12 0 £2 11 0 £4 5 6
  - ACCUMULATOR HYDROMETERS, Etc.
  - 1550.—Syringe Hydrometer for testing the Acid in Accumulators. To take a reading squeeze the bulb and insert the rubber tube into the acid through the filter cap of the battery. On gradually releasing the bulb, sufficient acid will be drawn into the glass tube to float the hydrometer. Remove from the cell and the actual sp. gr. will be shown on the scale at the point of flotation.
  - The required density is usually stated on the battery, but for ordinary purposes it may be taken as 1,200.
  - Each........... ..............4/9
  - 1550A.—Hydrometers. These instru-
  - ments are used for measuring the specific gravity of electrolyte in cells. They have a very open scale, divided into unit degrees to enable the readings to be accurately taken.
  - Price............................3/3
  - 1551.—Pole-finding Paper, for determining the negative pole. Turns to a purple tint after being damped and brought into contact; In books containing 100 tests.
  - Per book ... .. .. .. .. 2/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.218 - vue 237/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 219
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LIGHTING TYPE CELLS
  - 1552/1566
  - ** IM.L. 99 Lighting Type Cells in Glass Boxes. This type of cell is suitable for electric lighting installations and general purposes. All cells are fitted with our patent non-corrosive terminals.
  - India rubber discs are supplied, instead of trays, for 5 to 13-plate cells, and in these five sizes the dimensions given represent the outside measurements of the glass boxes.
  - Cat. Number of Capacity, Ampere Hours. Normal Charge Discharge Rate, Amperes. External Dimensions of Tray. (See note above.) Dilute Acid per Cell, Part of Carboy. Weight of Complete Cell, including Acid. Price.
  - Number. Plates per Cell. 10 Hour Rate. Rate, Amperes. For 10 Hours. For 7 'Hours. For 5 Hours. Length. Width.
  - 1552 5 108 10 10-8 14 18 Inches. 4t Inches. Ilf •18 Lb. 77 £ s- d. 2 11 9
  - 1553 7 162 15 16*2 21 27 5f Ilf •24 101 3 6 6
  - 1554 9 2l6 20 21-6 28 36 6* Ilf •30 126 4 2 2
  - 1555 11 270 25 27-0 35 45 8* Hf •35 150 4 19 9
  - 1556 13 324 30 32-4 42 54 9t Hf •4i 173 5 17 7
  - 1557 15 378 35 37-8 49 63 ill I2l *47 202 6 15 3
  - 1558 17 432 40 43-2 56 72 I2i 12! •54 227 7 12 6
  - 1559 19 486 45 48-6 63 81 14 I2l •59 250 8 9 7
  - 1560 21 540 50 54-o 70 90 I5i I2| •65 279 9 6 10
  - 1561 23 594 55 59‘4 77 99 i6| I2l •70 301 10 3 10
  - 1562 25 648 60 64*8 84 108 i7t I2l 77 326 11 0 8
  - 1563 27 702 65 70-2 92 117 19 I2l •82 351 11 17 2
  - 1564 29 756 70 75'6 99 126 20I 12! •88 375 12 13 10
  - 1565 3i 8lO 75 81 *0 106 135 2l| 12! •94 402 13 10 11
  - 1566 33 864 80 86-4 113 144 22§ I2f •99 424 14 8 4
  - Acid is not sent with these cells unless specially ordered.
  - Glass boxes, patent non-corrosive terminals and all accessories are included in above prices.
  - Every requisite for Chemical! Physical! and Bacteriological work supplied! from a test tube to the
  - complete furnishing of the largest laboratory.
- p.219 - vue 238/555
- - 220 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ACCUMULATOR CHARGING SETS
  - FOR DIRECT CURRENT MP”
  - 1567.—Direct Current Accumulator Charging Sets (Patent).
  - These sets are universal, which means that they may be used on any Direct Current circuit from 25 to 250 volts. Instead of charging through lamps, they are provided with adjustable resistances with roller contact to maintain any charging rate desired, regardless of the number of accumulators being charged at one time.
  - Size A. Intended to charge at rates varying from about 1 to 2.\ amperes.
  - Size B. Intended to charge at rates varying from about 2 to 5 amperes.
  - 1567
  - The sets may be stood on the floor or a shelf, but should preferably be fixed to a wall. The resistance is protected on both sides with a sheet of Uralite, and enclosed in a perforated sheet metal cover. The front consists of an enamelled slate panel on which is mounted an instruction tablet, a pair of high grade double pole change-over switches with a central off position, fuse, main terminals, battery terminals and terminals for a wireless set, also an ammeter reading sufficiently high to enable it to be used for any number of valves.
  - With these sets, the accumulators need not be disconnected at any time. It is only necessary to pull down the switch to charge, and to push up the switch to use the wireless.
  - Size A. Price................................£5 10 0 Size B. Price................................£6 12 6
  - IMPORTANT.
  - These Sets will also charge a large number of accumulators in series without increasing the cost or time of charging.
  - 1568
  - PRICES.
  - A. Rectifier with Commutator only .. .. .. £7 15
  - B. Transformers only, 25 volts, 5 amps ... .. .. 118
  - C. 50 volts, 5 amps .. .. .. .. .. 2 9
  - Rectifier complete on switchboard, as illustrated.
  - D. Output 25 volts, 5 amperes .. .. .. .. 115
  - E. Output 50 volts, 5 amperes .. .. .. .. 1215
  - FOR ALTERNATING CURRENT
  - 1568.—Alternating Current Full Wave Rotary Rectifiers (Patent).
  - The Rectifier is a self-starting, synchronous motor of ample power, fitted with a heavily constructed, reliable full wave rectifying commutator, which does not require assistance from the accumulator to start or keep it running. It is therefore the most economical alternating current charging set on the market, having nearly 100 per cent, efficiency.
  - When used with the special switchboard illustrated, the charging of accumulators is reduced to the mere operation of a switch to charge either one or several accumulators as desired.
  - The switchboard is provided with a central zero indicator, marked “ charge ” and “ discharge,” an ammeter, battery terminals, switch and fuse. It is also provided with wire and plug, and a regulating resistance to enable charging to be done at any rate desired.
  - We can supply these outfits for any Voltage, BUT it is necessary, when ordering, to state the Voltage and Periodicity on which it is to be used. Larger sizes can be made to order.
  - Otir Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.220 - vue 239/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 221
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - “NIVOC” DRY CELLS
  - Special Features : Great recuperative powers. Do not freeze.
  - Do not corrode.
  - Do not deteriorate if stocked in a dry place.
  - Do not burst.
  - Made on scientific principles.
  - Dry Cells"jjj
  - Novel
  - Construction.
  - Pronounced perfect by experts.
  - Scientifically
  - made.
  - After a series of very exhaustive tests the “ Nivoc ” Dry Ceil has been found by the leading experts to be the best in the market.
  - These cells have been adopted by all the largest users, and have been found to be more efficient than any similar type of dry cell in the market.
  - For electric bells, telephones, small lamps, indicators, automatic machines, medical batteries, intermittent light, signalling, etc., etc.
  - “NIVOC” DRY CELLS.
  - 1569.—“ Round ” Pattern.
  - No. i. 6£ X 2§ in. i*5 volts 12-14 amps. each 2/6
  - No. 2. 6i x in. 1-5 ,, 14-16 ,, „ 3/-
  - No. 3. 6f x 2f in. 1-5 ,, 16-18 „ ,, 3/6
  - 1570.—“Square” Pattern.
  - No. 4. 3 x in. 1-5 volts 5 amps.
  - No. 5. 4I x i£ in. i*5 ,, 6 ,,
  - No. 6. 6| X 2i in. 1-5 „ 14 „
  - each 1 /6 » 2 /-„ 4/-
  - Special Quotations given for Large Quantities.
  - We do not think it necessary to publish the hundreds of testimonials which we have received from various users and sellers of “ Nivoc ” Dry Cells. They can, however, be seen at our offices when required, but we do think that the following letter will prove conclusively to those who have not yet handled our manufacture that we are making an article which is the best in the market:—
  - Copy of Letter received from probably THE LARGEST USERS OF DRY CELLS IN THE WORLD.
  - To the Manufacturers of the “ Nivoc ” Dry Cells.
  - Dear Sirs,—In reply to yours of the 13th inst., we do not think we can say anything more conclusive about your cells than just state that after testing every well-known (and many not well known) makes of dry cells, we have for over three YEARS USED NO OTHER THAN “ NlVOC ” CELLS.
  - We are repeatedly testing other cells against them, with the result that we go on buying “ Nivoc.” Should you desire any further particulars, we shall be most happy to furnish you with same.
  - (Signed) H. W. Tilley, Managing Director,
  - The British United Automatic Machine Co., Ltd.
  - Our stock of pure Chemicals and Acids is very considerable j hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.221 - vue 240/555
- - 222 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - Suitable for Wireless, and for all purposes where a higher voltage is required than that given by the " Nivoc” ordinary cells, on previous page. High Tension Batteries are not intended for heavy discharge, but for long life on a small discharge, The “ NIVOC ” HIGH TENSION BATTERIES are intended to give the highest possible efficiency for all purposes, They can be supplied of any voltage, but the following units are strongly recommended and multiples of such for higher voltages.
  - 1571. —10 VOLT, 7 CELL UNIT (6 x 2f x * in.).
  - A. Fixed voltage .. .. .. .. .. .. .. .. . . . . . . .. .. each 3/6
  - B. Variable voltage (3 volt steps) .. .. .. .. .. . . .. .. . . .. .. ,, 4/-
  - 1572. —15 VOLT, 11 CELL UNIT (9| x 2f x f in.).
  - A. Fixed voltage .. .. .. .. .. . . .. . . . . . . .. . . .. .. each 4/6
  - B. Variable voltage (3 volt steps) . . .. .. . . .... .. . . . . . . .. ,, 5/-
  - 1573. —25 VOLT, 18 CELL UNIT (7f x 2f x if in.).
  - A. Fixed voltage .. .. .. .. .. .. .. .. .. .. .. .. .. .. each 7/-
  - B. Variable voltage (3 volt steps) .. .. .. .. .. .. .. .. .. .. .. ,, 8/-
  - 1574. —36 VOLT, 25 CELL UNIT (6f x 2f x 2f in.).
  - A. Fixed voltage.. .. .. .. .. .. .. .. .. .. .. .. .. .. each 10/6
  - B. Variable voltage (3 volt steps) .. .. .. .. .. .. .. .. .. .. .. ,, 11/6
  - 1575. —50 VOLT, 36 CELL UNIT (8 x 2| x 3| in ).
  - A. Fixed voltage.. .. .. .. .. ............ .. .. .. .. .. .. each 13/6
  - B. Variable voltage (3 volt steps) .. ............. .. .. . . .. .. .. .. ,, 15/6
  - 1576. —60 VOLT, 44 CELL UNIT (9** x 2| x 3f in.).
  - A. Fixed voltage .. .. .. .. .. .. .. .. .. .. .. .. .. .. each 15/-
  - B. Variable voltage (3 volt steps) .. .. .. .. .. . . .. . . .. . . .. „ 17/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.222 - vue 241/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 223
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GALVANOMETERS
  - 1577.—F. E. Becker & Co.’s New d’Arsonval Galvanometer (as supplied to His Majesty's Government), the best instrument on the market for Dead Beat or Ballistic work. 3280 The permanent magnet is built up of thin steel stampings. The steel is specially prepared, and has a high degree of saturation. The method of coil suspension is shown in the illustration, the bottom part of the upright support exactly fitting a slot at the base of the galvanometer, it being then held rigid by means of a thumb-screw. The aperiodic coil is wound on a very light copper frame, and the suspension is of thin phosphor-bronze strip.
  - ADVANTAGES.
  - Interchangeability of the suspended coils—there being sufficient coil clearance to enable the coil to be withdrawn from its position in the magnetic field without removing the permanent magnet.
  - All parts are “ get-at-able.”
  - Every galvanometer is fitted with a special lever clip (see Fig. A), the engagement of which releases the strain from the suspensions.
  - Deflections are approximately proportional to the current.
  - Will withstand a great deal of wear and tear.
  - Aperiodic Coils.
  - Identification letter .. .. E F G H
  - Approximate resistance of coil ... 5 95 225 1,000 ohms.
  - Ballistic Coils.
  - Identification letter .. .. A B C D
  - Approximate resistance of coil ... 5 95 225 1,000 ohms.
  - Price of Galvanometer, complete with one coil, A, B, C, D, E, F, G, or H (when ordering, please state which).
  - £6 17 6
  - 1578.—Spare Coils, complete with mirror and suspension (everything shown in Fig. A), fitted in velvet-lined box.
  - When ordering, please state resistance required. eaC^ ^ ^ ^
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.223 - vue 242/555
- - 224 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - D’ARSONVAL GALVANOMETERS
  - 1579.—Students’ d’Arsonval Galvanometer, of solid construction. This instrument is fitted with an aperiodic coil of about 150 ohms—this being the most useful for general laboratory work— or with a ballistic coil if so specified when ordering. 3284
  - Price, complete as figured .. .. . . £3 17 6
  - 1580.—Hibbert’s Cheap d’Arsonval Galvano-
  - meter. 3282 This is a simple galvanometer which has been arranged by Mr. Hibbert for use with a magnetic balance. It will measure with fair approximation the value of transient currents, and it is useful for determining any ordinary magnetic flux, such as the number of magnetic lines existing between the poles of a bar-magnet. For this purpose the galvanometer is connected to a coil, which can be slipped on to the middle of a bar or horseshoe magnet. The galvanometer needle being at rest, the magnet is suddenly removed from the coil ; an induced current flows in the galvanometer, and the first swing of its needle is a measure of the number of magnetic lines cut by the coil as it is removed from the magnet. The magnets are specially prepared, and the instrument has lately been highly improved and submitted to Mr. Hibbert to test, and has proved very satisfactory. For convenience of transit a clamping screw for coil has been fixed. Approximate resistance of coil = 8 ohms.
  - Price, complete .. .. .. .. .. .. £2 15 0
  - (See Hibbert’s “ Magnetism.”)
  - 1581.—Students’ d’Arsonval Galvanometer. This is a simple moving coil galvanometer on the d’Arsonval principle. The coil has a resistance of about 150 ohms. The permanent magnet is solid and formed of steel, having a high degree of saturation.3283
  - Each
  - £3 0 0
  - 1582.—Mirrors for Reflecting Galvanometers.
  - These are guaranteed optically worked, and best quality made. 3329
  - A. 1 cm. diameter, plane .. .. .. .. .. .. each 2/6
  - B. 1 cm. ,, concave, 50 cm. radius .. .. . . ,, 3/6
  - C. 1 cm. ,, ,, 100 cm. ,, .. .. .. ,, 3/6
  - D. 1 cm. ,, ,, 200 cm. ,, .. .. .. ,, 3/6
  - E. | in. ,, ,, 18 in. „ ................ ,, 4/-
  - F. | in. ,, ,, 18 in. ,, ............... ,, 5/6
  - 1583.—Reels of Phosphor-Bronze Strip, for
  - the repairing of d’Arsonval galvanometers. 3328
  - When ordering please state whether an aperiodic or ballistic coil is required.
  - Each
  - 2/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.224 - vue 243/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.G.1. 225
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - REFLECTING GALVANOMETERS
  - 1584.—F. E. Becker & Co.’s Improved Reflecting Gal-
  - vanometer, with two coils in hinged frame, fitted with control magnet, levelling screws, etc. Mirror and magnets are suspended in a detachable brass frame. 3289
  - £5 7 6 (Higher resistances than 2,000 ohms charged extra.)
  - 1586.—Simple Reflecting Galvanometer
  - (Stewart & Gee’s), with two coils of Nos. 18 and 28 insulated wire, on polished circular base with three levelling screws. Complete, with Controlling Magnet. 3290
  - Each............................£2 5 0
  - FRONT. BACK.
  - 1585.—Simple Reflecting Galvanometer, after the style of No. 1586, but better make and finish, wound to about 600 ohms resistance, in polished mahogany case, mounted on brass tripod with three levelling screws. Complete, with Controlling Magnet. 3291
  - Price .. .. .. .. .. £3 17 .6
  - 1587.—Thomson’s Astatic Galvanometer (Cambridge pattern). 3286
  - The four coils are fixed to the two wooden leaves, as shown. The upright one is a fixture, the other moves on a hinge, thus allowing the construction and arrangement of the instrument to be inspected. There are four terminals on the base, two for the lower and two for the upper pair of coils. The mirror is suspended in centre of the upper pair of coils, and is connected by , aluminium rod with similar-magnets hanging in centre of the lower coil.
  - The instrument has a resistance of about 800 ohms, and has some 8,000 turns of wire. It is more sensitive if furnished with a quartz fibre suspension (price on application).
  - Price
  - 1588. —Ditto, ditto, for low resistance,
  - usually about 10 ohms. 3287 Price .. .. .. £8 10 0
  - 1589. —Ditto, ditto, for high and low resistances, an extra set of coils being supplied. 3288
  - Price .. .. . £14 10 0
  - £10 10
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from
  - complete furnishing of the largest laboratory.
  - a test tube to the
  - p
- p.225 - vue 244/555
- - 226 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GALVANOMETER
  - 1590. — Poynting’s Galvanometer Lamp and Scale. This apparatus was designed by Professor Poynting of the Birmingham University. It is also used in the Birmingham Municipal Technical School. It consists of a semitransparent glass scale, 50 cm. in length, mounted in a polished teak frame. The whole of the stand and lamp are made of brass (oxidized). The total height of stand when raised to its maximum is about 18 in. The lamp-holder, which takes ordinary Ediswan lamps, is fitted with a telescopic tube for focussing. 3308
  - Price .. .. .. .. .. £4 15 0
  - LAMPS AND SCALES
  - 1592. — “ Nivoc ” Pattern Galvanometer Lamp and
  - Scale. 3310 This apparatus, which was designed by us for use in our own test rooms, obviates the inconvenience of having a galvanometer lamp and scale on the test table, the scale alone being visible. The galvanometer and lamp are arranged beneath the table and closed in, this arrangement keeping them free from vibration and immune from accident. The beam of light is thrown on the scale, through a slot cut in the table, by means of mirrors and a transparent scale. The latter is so arranged that zero can always be maintained without disturbing the galvanometer. As the galvanometer and lamp are in total darkness a very brilliant spot is produced and the scale can be easily read in daylight. For more delicate readings an adjustable light protector is fixed over the scale, and by this means any portion can be screened off. This apparatus can be fixed to any table which has available space beneath of 4 ft. x 1 ft.
  - Note.—The lamp supplied is of 4 volts, and may be used with an accumulator. Already in use in many schools.
  - Price of the complete apparatus, consisting of Galvanometer Scale, Lamp on Stand, ____and two Mirrors on Stand_..___..____..___..___..____ £4 12 6
  - 1591.—George’s New Pattern Galvanometer Lamp and Scale. 3309 Registered design. This
  - apparatus is in use in the Manchester University and several works’ laboratories. It is about 4 ft. high, very compact, and fitted with an arrangement for fastening to wall. As will be seen by the illustration, the galvanometer can be placed quite out of reach, in which position it is free from vibration and immune from accident. The telescope is fitted to a cross-piece sliding on two nickel-plated brass rods. Both telescope and scale are adjustable. A table carrying an adjustable mirror is fitted on top of the tall mahogany stand, and the box at the base serves for holding accumulator or dry cells.
  - Price, not including galvanometer -.....................................................£7 10 0
- p.226 - vue 245/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1. 227
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GALVANOMETER LAMPS AND SCALES
  - FRONT VIEW. BACK VIEW.
  - 1593.—Galvanometer Scale, Lamp and Stand, complete, with scale about 8 in. in length ; paraffin lamp sliding on metal cross-piece, for illuminating galvanometer mirror ; focussing lens in sliding mount, and wooden board on foot with hinged flap, as figured.
  - Price £1 12 6
  - 1594.—Galvanometer Scale, Lamp and
  - Stand, improved pattern, mahogany scale stand, adjustable vertically, fitted with scale metre long, sliding horizontally; adjustable flap, paraffin lamp and condensing lens in sliding mount3312 . . . . £3 10 0
  - 1595 .—Ditto, superior make and finish, and also provided with double rack and pinion for vertical adjustment, as figured3313 .. .. ...........£3 19 6
  - BECKER. HATTON WALL. LONDON.
  - 1596.—Galvanometer Scale, on ground glass, accurately divided, \ metre
  - 1597 —Ditto, on plain paper, £ metre
  - 1598 —Ditto, on tracing paper, £ metre
  - 1599 —Galvanometer Scale, on celluloid, metre, graduated in millimetres and numbered 0-50
  - 1600 —Ditto, but mounted in brass, J metre
  - 1601 *—Galvanometer Scale, on celluloid, | metre, graduated in millimetres and numbered 25-0-25
  - 1602 —Ditto, but mounted in brass, ^ metre
  - each 12/6
  - 12/6
  - 21/-
  - 12/6
  - 21/-
  - 1603.—Galvanometer Scale, on tracing paper, mounted in polished wooden frame (glass both sides), fitted with hooks.at top for hanging on brackets 3324 .. .. .. each 14/6
  - 1604 —Ditto, but scale on ground glass 3325
  - each £110
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.227 - vue 246/555
- - 228 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TANGENT GALVANOMETERS
  - 1605.—Students * T angent Galvanometer, cheap make. Height over all, 8 in. ; diameter of brass ring, 5 in. Agate centre needle with aluminium point moving upon steel pivot. Two windings—one having a resistance of 0-02 ohm, and the other 0-2 ohm. Mounted on polished teak base, fitted with three levelling screws. 3339 Each...............................£15 0
  - 1607. — “ Nivoc ” Tangent Galvanometer. This
  - Instrument is strongly made and well finished, and represents splendid value for the money. Its height over all is 27 cm., and diameter 25 cm. The suspension is of the reel type, needle being suspended by means of unspun silk. The dial, which is I2| cm. in diameter, is clamped by means of special tight-fitting clips to the brass ring. The brass ring, which is well finished and nicely lacquered, is clamped to the polished base by a very neat arrangement, whereby ring is held absolutely rigid. The mean diameter of ring is 13^ cm. The length of needle is 16 mm. Period of swing = 6 seconds. This galvanometer is provided with anti-parallax mirror and two windings, viz., 2 and 20, or 10 and 500. The resistance of 10 turns is about 0-13 ohm. The resistance of 500 turns is 126 ohms. The base is made of teak, highly polished, and fitted with three good levelling screws.3340 .. Price £2 15 0
  - 1606.—“ Nivoc ” Improved Tangent Galvanometer, guaranteed highest quality and finish. Provided with brass compass box, agate-centred magnetic needle, aluminium pointer, ring and base of polished mahogany, anti-parallax mirror and one winding = 300 ohms. 3341
  - Price.....................£2 5 0
  - 1608.—“ Nivoc ” Improved Tangent Galvanometer, guaranteed highest quality and finish. Provided with brass compass box, magnetic needle (agate centre), aluminium pointer, highly finished ring and base, anti-parallax mirror and three windings, viz., 2, 50, and 500 turns. Note.—The reduction factor using two coils is practical unity, hence the tangent of the deflection is practically the value of the current in amperes. 3342 Price complete as figured .. .. £2 10 0
  - (This Instrument has been adopted by the London County Council for use in the L.C.C. Schools.)
- p.228 - vue 247/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 229
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TANGENT GALVANOMETERS
  - 1609.—Brass Compass Box, as supplied with galvanometers Nos. 1606 and 1608, best quality, 4% in. diameter, fitted with anti-parallax mirror and sensitive magnetic needle with jewelled centre No. 1195. A good magnetometer when used in conjunction with two ordinary metre rules. 3343
  - Each.........................................19/6
  - 1611.—Sine and Tangent Galvanometer,
  - “ University ” pattern, with latest improvements. Coil on brass frame, rotating on brass tripod foot, anti-parallax mirror, sensitive needle with pointer, circular spirit level, etc. 3346
  - Price .............................£7 10 0
  - 1610.—Tangent Galvanometer, new desigh, ' high and low resistance, brass bobbin and pillar, with brass turntable turning in brass bed. This instrument is of the very best workmanship, and has been specially introduced to meet the requirements of science schools. Numbers of turns known and resistance carefully measured. It is provided with anti-parallax mirror and circular spirit level 3344 . . . . £5 15 0
  - 1612.—Tangent Galvanometer, new design, high and low resistance, brass bobbin and pillar, with turntable turning in brass bed. Number of turns known and resistance carefully measured. Provided with sensitive needle, aluminium pointer, anti-parallax mirror, circular spirit level, set of shunts. The whole enclosed in glass shade, as figured 3346 .. £8 17 6
  - Our Balances and Weights have achieved World-wide Reputation: vide Opinions of the
  - Leading Scientific Press.
- p.229 - vue 248/555
- - 230 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TANGENT GALVANOMETERS
  - 1613.—Gaugain’s Tangent Galvanometer, having two separate rings fixed parallel to each other, accurately divided silvered dial, suspended needle, all parts guaranteed best workmanship and finish 3347
  - £10 10 0
  - 1614.—Tangent Galvanometer, Post
  - Office pattern, for testing by received currents. Wound with two coils of 160 ohms each, with a short-circuiting key, and fitted with shunts of multiplying powers io, 20, 40, 80, 160, and 320, and having an extra coil of 750 ohms. In an outside box 3350 .........£25 0 0
  - 1615.—Tangent Galvanometer, Stewart & Gee’s pattern, comprising deflection magnetometer, mahogany ring with two coils of copper wire—one having a resistance of about 0-02 ohms, and the other about o-2 ohms. Ring so made that number of turns can be counted. Compass box is made of polished mahogany and is provided with bar needle (agate-centred), anti-parallax mirror, graduated dial, and two movable arms, each having a graduated boxwood scale. 3352 Price, complete .. .. £4 10 0
  - 1616. — Tangent Galvanometer,
  - fitted with removable compass box for determining the variation of the magnetic field due to a steady current in a circular coil at the centre of the same : (a) when the number of coils varies, but the radius is constant ; (b) when the
  - number of coils is constant, but the radii vary. 33
  - Each .. .. £22 6
  - 1617.—Ayrton-Mather’s Universal Shunt. This shunt can be used with any galvanometer, irrespective of the resistance of the instrument. Our stock pattern is provided with four coils giving tuW t$tf» tV of the total resistance respectively. Total 2,000 ohms. 3332
  - Price.. .. £3 10 0
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.230 - vue 249/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 231
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ASTATIC GALVANOMETERS
  - 1618.—Astatic Galvanometer. This instru-
  - ment is fitted with an aluminium pointer, the coils being wound on a special brass frame which allows needle to work freely. The base is of polished teak and fitted with three levelling screws. 3353
  - The length of silk suspension is 120 mm.
  - The length of the needle 30 mm.
  - The low resistance coils are about o-2 ohm.
  - • • «
  - The high resistance coils are about 70 ohms.
  - 1619.—Astatic Galvano-
  - A. Low resistance. Price, complete .. £112 6
  - B. High „ „ 1 15 0
  - meter, as No. 1618, but provided with coils of high and low resistance, and three terminals on base, as figured. 3354
  - Price, complete .. £1 17 6
  - 1620.—Astatic Gal-
  - vanometer, as No.
  - 1618, but better make and finish, and fitted with movable coil frame. 3355
  - A. Low resistance. Price,
  - 1621.—Astatic Galvanometer, “ University” pattern, guaranteed best make and finish ; engine - divided silvered dial, reflecting mirror, etc. Wound with any resistance up to 1,000 ohms. 3356
  - purposes. This galvanometer is provided with a nicely balanced needle (with aluminium pointer bent at right angles) and moves in front of an open vertical scale, 18 cm. long. The coil, which is approximately 35 ohms resistance, consists of double silk-covered copper wire (No. 36) wound on a brass frame. The base is 8 in. in diameter, and fitted with terminals and levelling screws. 3358
  - Price .. ..£2 2 6
  - complete .. £2 7 6
  - £4 15 0
  - B.
  - High resistance. Price, complete .. £3 2 6
  - 1622. —Ditto, with two coils wound differentially. 3357
  - £5 0 0
  - 1624.—Reels Silk 3360 ..
  - of
  - Unspun
  - each 1/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.231 - vue 250/555
- - 232 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORQE (LONDON), Ltd., PROPRIETORS.
  - 1625. — Lecture Galvanometer, with high and low resistance coils, sliding on upright support; graduated arc and tangent division. This is a very delicate instrument, well finished, and always gives every satisfaction. 3361
  - £5 0 0
  - GALVANOMETERS
  - (VARIOUS)
  - 1626.—Small Lecture Galvanometer, sensitive enough to show induction as well as thermoelectric currents ; the scale is made of milk glass and can be removed ; both scale and needle can be seen at a distance. A small magnet serves for bringing needle to zero—the magnet being placed on lecture table and moved towards and away from the galvanometer until correct distance has been found. 3362
  - Price, including magnet.. £1 15 0
  - 1627.—Lecture Gal-
  - vanometer, on tall metal support, provided with high and low resistance coils; very sensitive, and suitable for demonstrating induction and thermo-electric currents ; scale and ^needle can be seen at a distance. Full instructions for use are sent out with each instrument. 3363 Each .. .. £3 17 6
  - 1628. — Small Galvanometer, "Midget" pattern. Diameter over all, if in. 3373
  - Each .. .. 2/3
  - 1629.—S i m p I e Galvanoscope, on
  - polished foot, with magnetic needle, coil of wire, and two terminals. 3371
  - Each ................................8/6
  - 1630.—Simple Galvanoscope, made to take to pieces for showing construction. Box is <\\ in. square, and is provided with two terminals, as figured. 3372
  - Price...................10/6
  - 1631. —Galvanoscope, vertical, for use with science lantern, transparent scale ; needle, 6 in. long. 3375
  - Price for best make, each .. £2 12 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.232 - vue 251/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 233
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GALVANOMETER DIALS
  - (COMPASS CARDS.)
  - Lithographed from Copper-Plate. Divided in Degrees. Illustrations are shown full size.
  - 1632.—Galvanometer Dials, 4 in. diameter; lithographed from copper-plate; divided in degrees as figured—
  - each 5d.
  - 1633. g_=_* • 1633.
  - 1633.—Galvanometer Dials, 4 in. diameter; lithographed from copper-plate; divided in degrees as figured—
  - each 5d.
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.233 - vue 252/555
- - 234 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GALVANOMETER DIALS
  - (COMPASS CARDS.)
  - Lithographed from Copper-Plate. Divided in Degrees. Illustrations are shown full size.
  - 1634.
  - 90—=-
  - -=—»<> 1634.
  - 80
  - 50
  - 40
  - 50
  - 60
  - 1634.—Galvanometer Dials (compass cards); 6 in. in diameter; lithographed from copper-plate; divided in degrees as figured. Illustration shown full size.
  - Each.........................................................................8d.
  - Per dozen .. ..........' .. ., .. .. .... .. .. .. ..........7/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.234 - vue 253/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 235
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GALVANOMETER DIALS
  - (COMPASS CARDS.)
  - Lithographed from Copper-Plate. Divided in Degrees. Illustrations are shown full size.
  - 1635.—Galvanometer Dials (compass cards); 6 in. in diameter; lithographed from copper-plate; divided in degrees as figured. Illustration shown full size.
  - Each .. .. .. ...................“ .....................................8d.
  - Per dozen.............. .. ..............................................7/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.235 - vue 254/555
- - 236 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - AMMETERS AND VOLTMETERS
  - (See page 240 for “ Watch ” form and “ Switchboard ” Type.)
  - 1636. — Demonstration Ammeter, 0 2 to 2 amperes, with shunt for reading to 10 amperes. Price for best make, including shunt. 3387
  - Each..........£5 12 6
  - 1638. —Demonstration Ammeter, as No.
  - 1636, but fitted in h i g h 1 y-fi n i s h e d glass case. 3389
  - £5 18 6
  - 1639. —Demon-s t r a t i o n Voltmeter, as
  - No. 1637, but fitted in highly-finished glass case. 3390
  - £5 18 6
  - 1637. — Demonstration Voltmeter, reading to 3 volts, with extra resistance for reading to 30 volts. Price for best make. 3388
  - Each.. .. £5 12 6
  - “ Nivoc ” Ammeters and Voltmeters
  - (" GRAVITY ” TYPE). — The points of this instrument should instantly recommend it to Science Masters. The case can be easily removed so that the whole interior working of the instrument may be observed.
  - The relative positions of the fixed and moving irons and their individual positions in the magnetic field are clearly observable, and, in addition, the instrument is always available for accurate current measurements. 3391-34oo
  - Gravity Type 1640-1649.
  - A m m ete rs. —Catalogue No. 1640
  - Range 0 to 1
  - Divided in.. o-oi
  - Price .. £2 12 6
  - Voltmeters—Catalogue No. .. 1645
  - Range 0 to 1
  - Divided in o-oi
  - Price .. £2 12 6
  - 1641 1642 1643 1644
  - 0 to 3 0 to 5 0 to 10 0 to 20 amps.
  - 0-05 0-05 o-i 0-2
  - £2 12 6 £2 12 6 £2 15 0 £2 15 0 each.
  - 1646 - 1647 1648 1649
  - 0 to 3 0 to 5 0 to 10 0 to 20 volts.
  - 0-05 0-05 o-i 0-2
  - £2 12 6 £2 12 6 £2 15 0 £2 15 0 each.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.236 - vue 255/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 237
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - AMMETERS AND VOLTMETERS
  - Moving Coil Type 1650-1659
  - “ Nivoc ” Ammeters and Voltmeters (MOVING COIL TYPE)—This series of Ammeters and Voltmeters is of the moving coil type. They are portable and accurate and consist of a permanent magnet, moving in the field of which and between its poles is a light coil wound on an aluminium frame.
  - The framework and the coil are extremely light. The space between poles and core, in which the coil turns, is very small. The field is therefore very strong and very constant in strength.
  - The small mass, strong field, and strength of control springs, which can be adjusted by a small lever, cause the instrument to be very quick in action.
  - Moreover, induced “ Eddy ” currents in the aluminium frame in which the coil is wound, flow in such a direction, having relation to the magnetic field, that they exercise a damping action on the coil. Hence, it is very dead beat.
  - We can furnish these instruments with permanent magnets of Tungsten steel at proportionally higher prices. 3401-3410
  - Resistance of the coil is -2 ohm.
  - ,, between terminals, i ohm.
  - ,, material, Copper.
  - Movement.—Dead-beat moving coil. Case.—Best polished walnut.
  - Dial.—Silvered and engraved.
  - Size.—7 in. X 7 in. X 3 in. over all.
  - Ammeters.—Catalogue No............. 1650
  - Range .. .. .. o to 1
  - Divided in.. .. .. *oi
  - Price ...............£3 18 6
  - Voltmeters.—Catalogue No........... 1655
  - Range .. .. .. o to 1
  - Divided in .. .. *oi
  - Price ..............£3 18 6
  - 1651 1652 1653 1654
  - 0 to 3 0 to 5 0 to ro 0 to 20 amps.
  - •05 •05 •1 '2 „
  - £3 18 6 £3 18 6 £4 0 0 £4 0 0 each.
  - 1656 1657 1658 1659
  - 0 to 3 0 to 5 0 to 10 0 to 20 volts.
  - •05 •05 •1 *2
  - £3 18 6 £3 18 6 £4 0 0 £4 0 0 each.
  - 1660.—“ Nivoc ” Combined Ammeter and Voltmeter (MOVING COIL PATTERN). Improved “Dead Beat” Ammeter and Voltmeter (Combined), reading up to 5 amperes in iVths, and o to 20 volts, guaranteed highest quality and finish. 3411
  - £5 15 0
  - N.B.—When using this instrument, see that plug is pushed well home to ensure a good contact being made.
  - Every requisite for Chemicai, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.237 - vue 256/555
- - 238 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - DEAD-BEAT MOVING-COIL INSTRUMENTS
  - “STANDARD” PATTERN.
  - Description.
  - Movement.—Dead-beat moving-coil.
  - Case.—-Cast metal, enamelled and nickelled on polished oak base. Dial.—Silvered, with engraved scale and inset mirror.
  - Size.—7! in. X in. X 2\ in. over all.
  - Accuracy.—Within 1 per cent.
  - (National Physical Laboratory Certificate can be supplied at an additional cost.)
  - AMMETERS. VOLTMETERS.
  - Cat. No. Range. Price. 1661—0 to 1 £4 18 6 Cat. No. Range. Price. 1669—0 to 1 . . £4 18 6
  - 1662—0 „ 5 5 7 6 1670—0 „ 3 5 7 6
  - 1663—0 „ 10 ' 5 17 6 1671—0 „ 5 5 17 6
  - 1664—0 „ 20 6 2 6 1672—0 „ 10 5 17 6
  - 1665—O ,,50 6 5 0 1673—0 ,,50 5 17 6
  - 1666.—0 ,, 100 6 10 0 1674—0 ,,150 6 2 6
  - 1667—0 ,,150 6 15 0 1675.—0 ,, 250 6 5 0
  - 1668—0 ,,300 7 0 0 1676.—0 ,, 600 7 0 0
  - A. Polished Travelling Case, with leather handle.......................................................£0 19 6
  - B. Leather Case, lined and fitted . . .. . . .. .. . . . . . . . . . . ..£186
  - 1677.—DEAD-BEAT MOVING-COIL POINTER GALVANOMETER.
  - This Galvanometer consists of one of our pivotted moving-coil movements, having specially wound coil and springs to give a very high degree of sensitiveness. It is dead-heat, portable, requires no levelling, and is unaffected by vibration. The standard winding consists of 250 turns, having a resistance of 150 ohms, this being found the most useful for general laboratory work. Any winding can be supplied to order. The scale is divided into 150 divisions, and reads approximately in micro-amperes, being the deflections proportional to the current. The scale can be supplied with the zero in the centre if so desired. A mirror is provided to prevent parallax errors in reading. The galvanometer is substantially made and well-finished. Having no delicate suspensions it is not easily damaged, and forms a most useful and necessary adjunct to any laboratory or test room. 3427
  - Movement.—Dead-beat moving-coil.
  - Case.—Last metal, enamelled and nickelled.
  - Dial.—Silvered and engraved, with mirror. Central or side zero. Size.—7 in. X 7 in. X 2| in. over all.
  - A. Price of Galvanometer .. .. .. . . ..£576
  - B. Polished Wood Case, with leather handle .. extra 0 19 6
  - C. Leather Case, with sling .. .. .. .. .. 186
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.238 - vue 257/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 239
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PORTABLE STANDARD INSTRUMENTS
  - AMMETERS, VOLTMETERS, MILLI-AMMETERS, AND MILLI-VOLTMETERS.
  - These instruments are supplied complete in polished oak carrying cases, with strap handles. Leather cases £1 extra. Note.—It is not advisable to place these instruments too close to Dynamos, and they should be used as far as possible in a position free from stray fields.
  - Centre zeros can be supplied free of charge.
  - An extra range of 0—1-5 can be supplied with any of the Voltmeters at an extra charge of £1.
  - 1677/A
  - MILLI-AMMETERS
  - 1679
  - —MILLI-VOLTMETERS.
  - Ranges in Number of Milli-amperes Price. Ranges in Number of Milli-volts per Price.
  - Milli-amperes. Divisions. per Division. Milli-volts. Divisions. Division.
  - 0— 20 . 100 •2 £9 10 0 0— 20 . . 100 •2 £9 10 0
  - 0— 50 • . 100 *5 9 10 0 0— 50 . . 100 •5 9 10 0
  - 0— 100 . 100 I 9 10 0 0— 100 . . 100 I 9 10 0
  - 0— 500 . . 100 5 9 10 0 0— 500 . . 100 5 9 10 0
  - 0—1000 . 100 10 9 10 0 0—1000 . . 100 10 9 10 0
  - 0— 50) . TOO '• 1} •• 11 10 0 0— 501 . . IOO •' •• •• 11 10 0
  - 0— 500) 0— 500 I
  - 0— 1001 . 100 •' /I •• 11 10 0 0— 100 I . . 100 .. .. 11 10 0
  - 0—1000 J 10 ) 0—1000 J 10 J
  - 1678. —AMMETERS. 1680.- VOLTMETERS.
  - Ranges in Number of Amperes per Price. Ranges in Number of Volts per Price.
  - Amperes. Divisions. Division. Volts. Divisions. Division.
  - 0— 2 . 100 •02 £10 15 0 5 . . 100 •05 £10 15 0
  - 0— 5 • . 100 •05 10 15 0 5o . . 100 *5 10 15 0
  - 0— TO . 100 •I 10 15 0 150 • • 150 1 10 15 0
  - 0— 25 . 100 •25 10 15 0
  - 0— 50 . 100 •5 10 15 0 300 • • 150 2 10 15 0
  - 0— 100 . 100 I 11 10 0 600 . . 120 5 •• 13 0 0
  - 12 15 1000 . . 100 10 15 10 0
  - 0— 200 . 100 2 0
  - 0— 300 . 150 2 13 0 0 0— 3) • • 150 •02) 13 0
  - 0— 400 . 80 5 •• 15 10 0 0— 150 J .. if 0
  - 0— 500 . 100 5 •• 16 0 0
  - 0— 800 . 80 10 19 0 0 0— 1501 . . 150 n .. .. 14 15 0
  - 0—1000 . 100 10 21 0 0 0— 300) 21
  - 0— 101 0— 100 V . . 100 :: I! 22 10 0 0— 3001 0— 600f • • 150 :: 16 5 0
  - 0— 500 J 5j
  - 0— loN .. -i\ 0— 15) •IN
  - 0— 1001 . 100 •• l\ •• 25 10 0 0— 150 [ . . 150 n - i •• * • 22 10 0
  - 0— 500 f 5 0— 300 2
  - 0—1000/ 10/ 0— 600/ ..4)
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.239 - vue 258/555
- - 240 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - AMMETERS AND
  - 1681. —Ammeters, electro-magnetic type, nickel-plated cases. Dial 2| in. Back flange 3 in. 3430
  - These instruments compare favourably in finish and reliability to those usually sold at much higher prices. To read .. . .0 to 6 10 15 25 35 amps.
  - Price .. .. 10/6 10/6 12/6 13/6 16/6 each.
  - 1682. —Voltmeters. 3431
  - To read .. .. o to 6 10 15 25 35 volts.
  - Price .. .. 10/6 10/6 12/6 13/6 16/6 each.
  - Pocket Watch Type Voltmeters and Ammeters,
  - nickel plated and with flexible lead.
  - 1685. —Voltmeters.
  - Each.
  - A. o- 6 volts 8/6
  - B. 0-12 ,, 8/6
  - C. 0-16 „ 8/6
  - 1686. — A m -meters.
  - Each.
  - A. 0-6 amps. 10/6
  - B. 0-30 „ 12/-
  - 1687.—Combined Volt and Ammeters,
  - watch type, nickel plated, with two flexible leads of
  - different colours.
  - A. 6 volts 15 amps...................each 10/6
  - B. 8 „ 30 ,, „ 10/6
  - C. 16 „ 30 „ .. .. .. „ 10/6
  - D. 25 „ 30 „ „ 10/6
  - VOLTMETERS
  - VOLTS
  - 1683.—Ammeters, electro-magnetic type, 3^-in. dial, with polished and lacquered brass cases. Back flange 4 in. 3432 These instruments compare favourably in finish and reliability to those usually sold at much higher prices.
  - To read . .. 0 to 6 10 15 25 50 amps.
  - Price .. 21/- 21/- 21/ 22/6 27/6 each.
  - 1684.- -Voltmeters, 3433
  - To read . .. 0 to 6 10 15 25 30 volts.
  - Price 21/- 21/- 21/ 22/6 27/6 each.
  - To read . .. 0 to 50 100 150 250 volts.
  - Price .. 27/6 27/6 31/6 33/- each.
  - 1688.—Ammeter, gravity type, glass front, silvered dial, graduated to 4 amperes in TVths— 3428
  - each £1 10 0
  - 1687/ E. —Strong leather purses to take above meters. Each .....................................1/9
  - 1689. —Voltmeter, gravity type, glass front, silvered dial, 4 volts in TVths 3429 .. .. each £1 10 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.240 - vue 259/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 241
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SERIES RESISTANCE BOXES, WHEATSTONE
  - BRIDGES, Etc.
  - SPECIMEN CERTIFICATES for 10 RESISTANCE BOXES manufactured by us and taken at random from
  - stock shelves.
  - CERTIFICATE-
  - ---OF-----
  - EXAMINATION
  - OF
  - Of Resistance Bridge No. 781, 6280,by F.E.Beoker 4 Co.
  - Series Coils.
  - Coil, Resistance,International Ohms at 15$5 C.
  - 4000 4000
  - 3000 8000
  - 2000 2000.1
  - 1000 999.9
  - 400 400.1
  - 300 300.0
  - 200 200.1
  - 100 100.02
  - 40 40.02
  - 30 30.0i
  - 20 20.0i
  - 10 10.0q
  - 4 4.0o
  - 3 3.0q
  - 2 2.0q
  - 1 i.o0
  - The above values are exclusive of Box Resistance.
  - Box Resistance - all plugs in = 0.002 ohm.
  - Left Hand
  - Right Hand
  - November
  - Rtftrntt E.T.D. 59.
  - Coil
  - 10
  - 100
  - 1000
  - 1000
  - 100
  - 10
  - 11th., 72.
  - Ratio Arm3.
  - Resistance,Internetional Ohms at 15?5 C.
  - >910
  - 10.00-
  - 100.04°
  - 1000.2
  - 1000.0
  - 100.03
  - io.oo6
  - a
  - Dirttlcr.
  - Left Rand Right Rand
  - CERTIFICATE •
  - ---OF----
  - EXAMINATION
  - or
  - Of Resistance Bridge No. 779, l€ 6279, by F.E.Becker & Co
  - Series Colls.
  - Coll. Resistance, International Ohms at 15?5 C.
  - 4000 4000
  - 3000 3000
  - 2000 2000.a
  - 1000 1000.2
  - 400 400.1
  - 300 300.0
  - 200 200.1
  - 100 100.00
  - 40 40.02
  - 30 30.Oi
  - 20 20.01
  - 10 10.Oi
  - 4 4.0q
  - 3 3.00
  - 2 2.00
  - 1 l.Oo
  - The above values are exclusive of Box Resistance. Box Resistance - all plugs In = 0.002 ohm.
  - Coil.
  - 10
  - 100
  - 1000
  - 1000
  - 100
  - 10
  - Ratio Arms.
  - Heal stance.International wnms at 15?5 C.
  - 10.00fi
  - 100.02
  - 1000.4
  - 1000.3
  - 100.03
  - 10.006
  - November 11th.,
  - Rt/trput E.T.D. 59. 67
  - >92 0-
  - Drruler.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
  - Q
- p.241 - vue 260/555
- - 242
  - F. E. BECKER & CO., NIVOC HOUSE,
  - W. & J. GEORGE (LONDON),
  - HATTON WALL, LONDON, E.C.1.
  - Ltd., PROPRIETORS.
  - eft Hand I Ught Hand
  - • CERTIFICATE
  - ----OF-----
  - EXAMINATION
  - zW QF
  - Of Resistance Bridge No. 782, 6281,by P.E.Becker & Co
  - Coil. Series Coils. Resistance.International '
  - 4000 4000
  - 3000 3000
  - 2000 1999.a
  - 1000 1000.x
  - 400 400.1
  - 300 300.0
  - 200 200.1
  - 100 100.02
  - 40 40. Ox
  - 30 30. Ox
  - 20 20.0Q
  - 10 10.00
  - 4 4.0q
  - 3 3.00
  - 2 2.00
  - 1 i.o0
  - The above values are exclusive of Box Resistance
  - Box Resistance
  - Coll.
  - 10
  - 100 1000 1000 100 10
  - all plugs in = 0.002 ohm.
  - Ratio Arms.
  - Resistance.International Ohms at 15°5 C,
  - 10.007
  - 100.04
  - 1000.2
  - 1000.3
  - 100.04
  - IO.OOq
  - November 11th., 19IO.
  - Rt/irtnci E.T.D. 59. 71.
  - A
  - Dtrtekr.
  - %
  - CERTIFICATE
  - ----OF----
  - EXAMINATION
  - OF
  - Resistance Bridge No. 774, K? 6274, By P. E. Becker & Co.
  - Series Coils.
  - Resistance. International Ohms at 15?6 C.
  - 4000 2999 2000.o 1000.?
  - 400.1 300.0
  - 200.1
  - 100.Oi
  - 40.01 30.0.
  - 20. Oq 10. Oq 4.00 3.00 2.0(5 1.00
  - The above values are exclusive of Box Resistanoe.
  - Box Resistance - All Plugs in = 0.002 ohm.
  - Ratio Arms.
  - Resistance International Ohms at 15?5 C.
  - CoU
  - 4000
  - 3000
  - 2000
  - 1000
  - 400
  - 300
  - 200
  - 100
  - 40
  - 30
  - 20
  - 10
  - 4
  - 3
  - 2
  - 1
  - Left Hand
  - Right Hand
  - Rtjtrtncc
  - Etd.59. 66
  - Coil.
  - 10
  - 100
  - 1000
  - 1000
  - 100
  - 10
  - November 11th.,1910.
  - 10.006
  - 100.03
  - 1000.3
  - 1000.3
  - 100.03
  - 10.006
  - a
  - Dtralcr
  - jeft Hand
  - tight Hand
  - • CERTIFICATE
  - ---OF----
  - EXAMINATION
  - OF
  - Of Resistance Bridge No.775, 6275,by P.E.Becker & Co,
  - Series Coils.
  - Coll. Resistance. International Ohms at 15?5 C.
  - 4000 4001
  - 3000 30OI
  - 2000 2000.6
  - 1000 1000.3
  - 400 400.1
  - 300 300.0
  - 200 200.1
  - 100 100.O2
  - 40 40.Ox
  - 30 30.Ox
  - 20 20.Ox
  - 10 10.Oo
  - 4 4.0o
  - 3 3.0Q
  - 2 2.00
  - 1 1.00
  - The above values are exclusive of Box Resistanoe Box Resistance - all plugs m = 0.002 ohm.
  - Ratio Arms,
  - foil.
  - 10
  - 100
  - 1000
  - 1000
  - 100
  - 10
  - Resistance. International Ohms at 15?5(
  - IO.OO7 100.05 1000.4 1000.4 100.04 10.008
  - November 11th.,
  - jiifiTiuti E.T.D. 59* 69
  - ^lnrrr\
  - 19^0 -
  - Director
  - Lfcft Hand
  - Right Hand
  - Coil.
  - 4000
  - 3000
  - 2000
  - 1000
  - 400
  - 300
  - 200
  - 100
  - 40
  - 30
  - 20
  - io
  - 4
  - 3
  - 2
  - 1
  - CERTIFICATE •
  - ---OF-----
  - EXAMINATION
  - OF
  - Of Resistanoe Bridge No. 776, 6272, by F.E.Beoker & Co.
  - Series Colls
  - Resistanoe. International Ohms at 1595 C.
  - 4000
  - 3000
  - 2000.5
  - IOOO.3
  - 400.1
  - 300.1
  - 200.1 100.Oi
  - 40. Ox 30. Ox 20. Ox 10.00 4.00 3. Oq
  - 2.C0
  - 1.00
  - The above values are exclusive of Box Resistance Bok Resistance - all plugs in = 0.002 ohm.
  - Coll
  - 10
  - 100
  - 1000
  - 1000
  - 100
  - 10
  - Ratio Arms.
  - Resistance.Irrternational Ohms at 157 5 C
  - November 11 th., Rtfttnet E.T.D. 59. 70.
  - SVf^
  - 190.0.
  - 10.00 100.05' 1000.4 1000.3 100.04
  - 8
  - 10.00
  - 8
  - Dirutor.
  - Our stock of pure Chemicals and Acids is very considerable ; hence ail orders are executed with the
  - utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.242 - vue 261/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 243
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - jeft Hand
  - light Hand
  - • CERTIFICATE •
  - ----OF-----
  - EXAMINATION
  - OP
  - Of Resistance Bridge No.780, N? 6279,by P.B.Booker & Co,
  - Series Coils.
  - Coll. Resist anc e. In t e mat ioi
  - 4000 4001
  - 3000 3000
  - 2000 2000.A
  - 1000 1000.o
  - 400 400.2
  - 300 300.2
  - 200 200.1
  - 100 100.02
  - 40 40.02
  - 30 30.0,
  - 20 20.07
  - 10 10. oi
  - 4 4.08
  - 3 3.00
  - 2 2.00
  - 1 1.00
  - The above values are exclusive of Box Resistance Box Resistance - all plugs in =* 0.002 ohm.
  - Coll.
  - 10
  - 100
  - 1000
  - 1000
  - 100
  - 10
  - Ratio Arms.
  - Resistance.International Ohms at 1S?5 C.
  - 10.00-
  - 100.03°
  - 1000.4
  - 1000.3
  - 100.03
  - 10.007
  - November 11th•, Reftrtncs E.T.D. 59. 68.
  - 1910.
  - O'
  - zZl>
  - DirteUr.
  - CERTIFICATE •
  - ---OF----
  - EXAMINATION
  - OF
  - Resistance Bridge No. 777, 6277, by F.E.Becker & Co
  - Series Colls.
  - Coil Resistance.International
  - 4000 4000
  - 3000 3001
  - 2000 2000.4_
  - 1000 1000.x
  - 400 400.2
  - 300 300.1
  - 200 200.1
  - 100 100.o4
  - 40 40. Ox
  - 30 30.02
  - 20 20.02
  - 10 10. Oi
  - 4 4. Oo
  - 3 3. Oo
  - 2 2 .Oo
  - 1 i.o0
  - The above values are exclusive of Box Resistance Box Resistance - all plugs in = 0.002 ohm.
  - Left Hand Right Hand
  - Coll.
  - 10
  - 100
  - 1000
  - 1000
  - 100
  - 10
  - Ratio Arms.
  - Resistance,International Ohms at 15?5 (1
  - Bovember 11th., Rtfcrtnci E.T.D. 59. 74,
  - I9&0,
  - 10.00c
  - 100.05*
  - 1000.2
  - 1000.2
  - 100.05
  - 10.00,
  - Duettor
  - • CERTIFICATE •
  - ---OF----
  - EXAMINATION
  - OF
  - Resistanco Bridge No. 783, *£ 6282,by F.E.Becker & Co
  - Series Coils.
  - Coil. Resistance.International
  - 4000 3999
  - 3000 3000
  - 2000 1999.9
  - 1000 IOOO.5
  - 400 400.2
  - 300 300.0
  - 200 200.1
  - 100 100.0,
  - 40 40.Ox
  - 30 30.Ox
  - 20 20.Ox
  - 10 10.00
  - 4 4.00
  - 3 3.00
  - 2 2.00
  - 1 1.00
  - ThtTibove values art •xdluslvt of Box Resistance. Box Roslstanoe • all plug* in 0.002 ohm.
  - Left Hand
  - Right Hand
  - SMI-
  - 10
  - 100
  - 1000
  - 1000
  - 100
  - 10
  - Ratio Arms.
  - Resistance.International Ohms at 1595C
  - 10.00a
  - 100.05
  - 1000.3
  - 1000.3
  - 100.05
  - 10.00a
  - Noveiriber 11th
  - Rtftunu E.T • D. 59. 73.
  - <940.
  - J*-Z&5
  - Dtrtttor.
  - 4000
  - 3000
  - 2000
  - 1000
  - 400
  - 300
  - 200
  - 100
  - 40
  - 30
  - 20
  - 10
  - 4
  - 3
  - 2
  - 1
  - CERTIFICATE
  - ------OF-------
  - EXAMINATION
  - OF
  - Of Resistance Bridge No. 770, 6283,by F.E.Becker & Co
  - ^ries Coils.
  - Rejjstance.International Ohms at 1595 C
  - 4000 3000 1999.9 1000.2 400.2 300.1 200.0 ICO.Ox
  - 1 40.Ox
  - 30.01 20. Ox 10. Oo 4.0o 3. Oq 2.00 1.00
  - The above values are exclusive of Box Resistance, Box Resistance - all plugs in = 0.002 ohm.
  - eft Hand
  - Coil.
  - 10
  - 100 1000 1000
  - ight Hand 100
  - 10
  - ^ November 11th.
  - Riftuiut E.T.D, 59 75.
  - SWrrv
  - Ratio Arms.
  - Resistance. International Ohms at 15?5 (
  - <910.
  - 10.006 100.03 1000.3 1000.3 100.03 10.00A
  - Dirtcto*
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.243 - vue 262/555
- - 244 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - POST OFFICE RESISTANCE BOXES
  - The Resistance Boxes can be fitted with the All-Metal Plug Contacts, see next page.
  - 1690
  - 1690.—Standard Pattern Post Office Resistance Box, guaranteed same quality and finish as supplied by us to His Majesty’s Government. This box is made in well-polished mahogany or teak, the dimensions of the case being gf in. X 6f in. X 6f in. 3483
  - The inside of the lid is lined with purple velvet. The ebonite top measures 8f X 5§ in. X \ in. thick. The brass blocks are lozenge-shaped and under-cut. The plugs, which are interchangeable, are fitted with rectangular fluted ebonite tops. Or the all-metal plugs (see next page) may be fitted if preferred. The resistance is from 1—4,000 ohms, with proportional arms of 10, 100, and 1,000, and totals to 13,330 ohms. The large terminal screws are provided with double milled heads. Coils are non-inductively wound in platinoid wire. Temperature co-efficient of all the coils does not exceed 0-03 per cent, per degree Centigrade. Correct to within -05 per cent. (See copies of National Physical Laboratory Certificates on previous pages.)
  - The Resistance is adjusted to correct B. T. ohms at 15-5° C.
  - Price ...................................................... ...................................£12 10 0
  - (N.P.L. Certificate extra.)
  - 1691.—Standard Post Office Box, “ Mica Frame ” type. The specification of this box is similar to No. 1690, except that it is wound in manganin wire, on mica frames. Special care and attention is bestowed on its construction, and if required it can be supplied with National Physical Laboratory Certificate. This forms a useful standard box for the laboratory, and the price is a moderate one. 3484
  - Price..............................................£17 10 0
  - (N.P.L. Certificate extra.)
  - 1692.—Post Office Box, “ Science School ” pattern. This is a similar box to our 1690, but constructed in a more economical fashion for use in schools. The outside case is in hard wood, polished.
  - The top is in thick ebonite, and the brass blocks are lozenge-shaped and undercut. The plugs are interchangeable and have fluted ebonite tops. The resistances are from 1—5,000 ohms, with proportional arms 10, 100, 1,000, and totals to 13,330 ohms. The large terminals have double milled heads and the coils are wound non-inductively from the centre in a wire having a negligible temperature co-efficient. Correct to -i per cent. 3485 Price .. £8100
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.244 - vue 263/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 245
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RESISTANCE BOXES
  - THE ALL-METAL PLUG CONTACT.
  - Any of our Resistance Boxes can be supplied at the same price, with the all-metal plugs as illustrated, if preferred instead of ebonite.
  - When ordering, please state clearly which is preferred.
  - The All-Metal Plug Contact.
  - 1693
  - Can be supplied with either Ebonite or the All-Metal Plug Contacts.
  - When ordering, please state clearly which is required.
  - 1693-1702.—Series Resistance Boxes and Bridges. Guaranteed highest quality and finish, and adjusted to the utmost degree of accuracy for laboratory measurements.
  - All the coils are adjusted on the Carey-Foster Bridge, and are treated to avoid risk of deterioration in hot or damp climates. Correct to within *05 per cent. 3491-3503
  - Resistance Boxes. Price.
  - 1693.— i, -2, -2, *5 ohm to a total of 1 ohm £6 10 0
  - 1694.-—1, 2, 2, 5 ohms to a total of 10 ohms 6 10 0
  - 1695.—o-i to 5 11 ,, 7 10 0
  - 1696.—1 „ 50 no ,, 7 10 0
  - 1697.—o-i ,, 50 in ,, 9 0 0
  - 1698.—1 ,, 500 1,no ,, 10 0 0
  - 1699.—-i ,, 5,000 ,, ,, , ,, n,no ,, 11 0 0
  - High Resistances. i
  - 1700.—10,000, 20,000, 20,000, 50,000 . 100,000 ohms 11 10 0
  - 1701.—5 Coils each 50,000 .. 250,000 19 10 0
  - 1702.—Megohm, 4 Coils each 250,000 1,000,000 ,, 35 0 0
  - Our stock of pure Chemicals and Acids is very considerable : hence ail orders are executed with the
  - utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.245 - vue 264/555
- - 246 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PORTABLE TESTING SET
  - 1705. —Com b i ned Testi ng Set for rapidly testing either resistance
  - or insulation, and has a range from -oi ohm to 20 megohms. The galvanometer is of our pivotted moving coil type of a high degree of sensitiveness, and as no levelling is required the apparatus can be set up ready for use in a very few minutes. The readings are practically unaffected by the proximity of motors, dynamos, or cables carrying heavy currents. A set of instructions is affixed to each instrument, which enables anyone to make a test, no previous knowledge of the apparatus being required 3504 A . . .. . . .. £21 0 0
  - 1706. —Portable Testing Set, to measure resistances from •01 ohm to 10,000 ohms, with galvanometer, in case as illustrated. 3504 B
  - £16 10 0
  - 1707. —Portable Testing Set, to measure insulation from 10,000 ohms to 20 megohms, with galvanometer, in case as illustrated. 3504 c
  - £11 15 0
  - 1706/1707
  - RESISTANCE BOXES
  - For Commercial Measurements.
  - Correct to 0-05 per'cent.
  - Wound in wire, having a negligible temperature co-efficient, and mounted in polished mahogany cases, with heavy ebonite tops. Plugs are interchangeable and provided with rectangular fluted ebonite tops.
  - Catalogue No. Coils. Total Resistance. Price.
  - 1708. .. o-i, o-2, 0-3, 0-4 1 ohm. .. £4 10 0
  - 1709. .. o-l, 0-2, 0-2, 0*5, 2, 2 . 5 ohms 4 15 0
  - 1710. .. O-I, 0-2, 0-2, 0-5 1 ohm. 4 15 0
  - 1711. 10, 20, 20, 50 100 ohms. 4 15 0
  - 1712. .. 100, 200, 200, 500 . 1,000 ohms. 4 15 0
  - RESISTANCE BOXES
  - Students’ Pattern.
  - Adjusted'to o-i per cent, accuracy.
  - 1713— 0 1 ohm to a total of j 1 ohm.
  - 1714— 1 „ 10 ohms
  - 1715— 0-1 „ . n „
  - 1716— 1 ,, no ,,
  - 1717— 0-1 ,, in ,,
  - 1718.— 1 ,, 1,no ,,
  - Price.
  - £3 15 0 315 0 4 10 0 4 10 0 6 0 0 6 0 0 8 0 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.246 - vue 265/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 247
  - W. St J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RESISTANCE BOXES
  - 1720.—Set of Resistance Coils, having a total resistance of 410 ohms (1, 2, 2, 5, 10, 20, 20, 50, 100 and 200 ohms). The brass blocks are lozenge-shaped and under-cut; plugs are interchangeable, with rectangular fluted ebonite tops. The top is made of best quality ebonite, and mounted on polished mahogany box having glass sides, as figured. Correct to one-tenth per cent. 3512 ...............£4 10 0
  - RESISTANCE BOARD
  - 1721.—Gee Resistance Board. This consists of a polished mahogany board on which are fixed two parallel rows of five coils, each of 1 ohm resistance. The coils are all covered, the cover in each case being marked with a letter. The board is arranged so that the student can easily work out for himself the various methods of using the coils. For example :—the Wheatstone Bridge can be demonstrated, using coils A—-G as the standard resistance, and G—H as one proportional arm, and I—J as the other. The method of connecting up in series and parallel can also be shown. 3563 Each .. . . £2 10 0
  - STANDARD RESISTANCE COILS
  - Standard Resistance Coils (“ Flat ” Type) for use with small currents only as master standards for reference. The wire is of manganin alloy, wound in the form of a flat double spiral, and enclosed in a thin, flat, water-tight box. The copper electrodes are encased in the central vertical tube, and the case is now made with one joint only. This form of coil rapidly takes the temperature of the water-bath, ensuring quick and accurate measurements. (See “ Electrician,” April 1, 1892, for description read before the Physical Society of London.)
  - Catalogue number 1722 1723 1724 1725
  - Resistance .... 1 10 100 1,000 ohms.
  - Price................£4 15 0 £5 5 0 £5 15 0 £6 5 0 each.
  - 1726. —Wooden Case, fitted for any of the above .. extra £0 10 0
  - 1727. —Special Thermometer, reading to fifths of a degree
  - extra 0 10 6
  - 1728. —National Physical Laboratory Certificate Extra
  - 1729. —Square Copper Tank, for immersing coil.. extra 0 12 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.247 - vue 266/555
- - 248 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - RESISTANCE COILS
  - SINGLE RESISTANCE COILS.
  - 1730.—Resistance Coils, cheap pattern, for students' use; correct to o-2 per cent. 3513
  - Catalogue Reference ABC DEF GHKLMN Resistance . . -i -2 *5 i 2 5 10 20 50 100 500 1,000 ohms.
  - Price .. ..4/- 4/- 4/- 4/6 4/6 4/6 5/- 5/- 5/- 5/- 5/6 5/6 each.
  - RESISTANCE COILS (enclosed pattern).
  - Each coil is wound non-inductively on a bobbin, enclosed in a brass case. Top is of ebonite, and has the resistance legibly stamped thereon.
  - Correct to o-i per cent.
  - Catalogue No. .. 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742
  - Resistance .. o-i 0-2 o-5 1 2 5 10 20 50 100 500 1,000 ohms.
  - Price .. . . 5/6 5/6 5/6 6/6 6/6 6/6 6/6 6/6 7/6 7/6 9/6 9/6 each.
  - RESISTANCE COILS FOR WORKSHOP USE.
  - Wound with wire of negligible temperature co-efficient. Ebonite tops mounted on imitation ivory boxes.
  - Brass terminals.
  - Correct to o-i per cent.
  - 1744 1745 1746
  - Catalogue No.
  - Resistance
  - Price
  - 1743
  - 1
  - 18/6
  - 2
  - 18/6
  - 3
  - 18/6
  - 5
  - 18/6
  - 1747
  - 10
  - 18/6
  - 1748
  - 20
  - 21/-
  - 1749
  - 50
  - 21/-
  - Catalogue No. .. 1751 1752 1753 1754 1755 1756
  - Resistance 200 500 1,000 2,000 4,000 10,000
  - Price .. . . 24/- 24/- 24/- 27/6 27/6 27/6
  - 1750
  - 100 ohms. 21/- each.
  - 1757
  - 00,000 ohms. 38/6 each.
  - STANDARD RESISTANCE COILS, superior make and finish for very accurate work.
  - These coils are mounted on best quality ebonite, and fitted in nicely finished brass boxes.
  - Corrected to 0-02 per cent.
  - pi 1 Catalogue No. . . 1758 1759 1760 1761 1762 1763, 1764
  - I i H Resistance 1 2 5 10 20 50 100 ohms.
  - 1| ti III Bap#' Price .. ... 45/- 45/- 45/- 48/- 48/- 48/- 54/- each.
  - Catalogue No. 1765 1766 1767 1768 1769 1770 1771
  - Resistance . 200 500 1,000 2,000 4,000 10,000 100,000 ohms.
  - Price 67/6 67/6 67/6 90/- 93/- 95/- 150/- each.
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.248 - vue 267/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 249
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DIAL RESISTANCE BOXES
  - The earlier pattern' Dial Resistance Boxes with outside contacts, which we have hitherto manufactured, have now been replaced by our new pattern instruments as illustrated. All
  - contacts are enclosed in the body of the instrument, and being dustproof, clean contacts are always assured.
  - 1772. —“ Nivoc ” Dial Resistance Box, College Pattern. Superior construction and finish, very accurately adjusted, for advanced laboratory work. With enclosed contacts, in polished teak case, with heavy ebonite top. Coils correct to o-i per cent.
  - A. With three dials—hundredths, tenths, and units ; total resistance 9-99 ohms . . . . . . each £6 0 0
  - B. Ditto, three dials—tenths, units, tens ; total resistance 99-9 ohms .. . . . . . . ,, £6 15 0
  - C. Ditto, three dials—units, tens, hundreds; total resistance 999 ohms -.. .. .. .. ,, £7 10 0
  - 1773. —“ Nivoc ” Dial Resistance Box, Students’ Pattern, of lighter construction than No. 1772, and not so highly adjusted. In polished wood box with ebonite top. Enclosed contacts. Coils correct to 1 per cent.
  - A. With three dials—hundredths, tenths, and units ; total resistance 9-99 ohms . . . . . . each £2 2 6
  - B. Ditto, tenths, units, tens; total resistance 99-9 ohms .. .. . . . . . . . . ,, £2 5 0
  - C. Ditto, units, tens, hundreds ; total resistance, 999 ohms . . .. . . . . . . . . ,, £2 15 0
  - CARBON MEGOHMS
  - 1774. —Carbon Megohm, consisting of a film of graphite enclosed between
  - two ebonite boards 3558 . . .. .. . . .. .. ..£276
  - 1775. —Set Of 5 Carbon Megohms, with separate terminals, for connection
  - in series or parallel 3559 ...........................................£6 17 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.249 - vue 268/555
- - 250 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. Sc J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - THE “WOODHOUSE ” LAMP RESISTANCE
  - (Manufactured by us to the design of Mr. G. F. Woodhouse, M.A., Senior Science Master, Sedbergh School, Yorks.)
  - 1776A
  - 1776.—The “ Woodhouse 99 Lamp Resistance consists of four, six OP eight electric lamps mounted upon an ebonite-topped cabinet, containing a special improved form of switch, this switch being the outstanding and unique feature of the instrument. A great variety of currents can be obtained by simply turning the switch-knob, thus connecting the lamps in series or parallel.
  - For example, with a four-lamp set the following seven combinations may be obtained, and the currents further varied by using different type lamps.
  - One Lamp in circuit
  - Two Lamps in series Three Lamps in series Four Lamps in series
  - Two Lamps in parallel Three Lamps in parallel Four Lamps in parallel
  - The currents will vary from about 'i ampere to 2 or 3 according to the type of lamp used. The instrument is used straight off the electric light main and no batteries, accumulators or expensive resistance boxes are reqU i red. It wilt be found exceedingly useful for such experiments where variable currents are required, as for example':—
  - 1. Hysteresis Curves by traction or magnetometer methods (small currents may be easily obtained, examples of
  - current strengths, *i, ‘15, ‘25, ‘64, V2, i*8, 2*35).
  - 2. Proof of Joule’s Law.
  - ECt X 10^
  - 3. Determination of Joule’s equivalent H =----j--- (current instantly adapted to available voltmeter).
  - 4. Force at centre of coil proportional to current strength.
  - 5. Electrolysis experiments.
  - 6. Use in potentiometer for main current.
  - 7. Electro magnetic experiments.
  - 8. Accumulator charging.
  - 9. Reduction factor of galvanometer (lamps in series).
  - A. Price of complete instrument as per illustration, without lamps
  - B. „ ,, ,, fitted for 6 lamps, without lamps
  - C. ,, „ ,, ,, „ 8 lamps, without lamps
  - D. Carbon filament lamps, extra
  - E. Metal filament lamps, extra
  - £4 17 6 5 19 6 7 10 0
  - each 1 9
  - ,,2 6
  - When ordering, please state voltage of lighting main and whether required with or without lamps.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.250 - vue 269/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 251
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RESISTANCES
  - 1777.—Lamp Resistance. In this
  - form of resistance the current can be . varied by fixing in a greater or less number of lamps, or by using incandescent lamps of varying voltage, according to requirements. The six lamp-holders (standard size) are screwed on to a polished base and joined in parallel to two terminals as figured. When ordering, please state voltage of lamps. 3628
  - A. Price, not including lamps .. 24/-
  - B. Lamps extra .. .. each 2/-
  - Please state voltage when ordering.
  - 1778.—Divided Megohm. These form very useful laboratory measuring instruments, where comparatively rough measurements are required. The total resistance is a megohm, and it is correct to i part in 5,000. The divisions are approximately 100,000 ohms each, but these are not standardized to the same degree of accuracy. The coils are wound in wire having a negligible temperature co-efficient, and the whole is finished in a polished mahogany case 12 in. long, furnished with a stout ebonite top. The terminals are all well insulated on, strong ebonite columns. 3561
  - Price £9 0 0
  - 1779.—Standard Low Resistance. This resistance is arranged in a very practical form for measuring 1/100 ohm. Maximum current 150 amperes. The material of which it is formed is very specially selected manganin strip annealed. The strips are brazed vertically into massive blocks of copper. The total length of instrument over all is 20 in. The strips are heavy, so that any heating effect can be neglected. It forms a most useful standard in the laboratory, and is so strongly and substantially made that it will bear hard, rough usage without injury. 3564
  - Price .. ..........................................................................£9 10 0
  - It can be used with Potentiometer, Voltmeter, and Galvanometer, to measure current or conductivity.
  - 1780 .—Ditto, resistance 0-05 ohm, carrying capacity 40 amperes .. .. .. .. .. .. £7 10 0
  - 1781 .—Ditto, ,, o-i ohm, ,, 20 ,, .. .. . . .. . • .. 5 17 6
  - 1782. —Ditto, ,, i-o ohm, ,, 2 ,, - . . . . .. . . .. 4 15 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 252 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WHEATSTONE BRIDGES
  - 1783.—Wheatstone Bridge, Standard pattern, for testing by Foster’s method. Highest quality and finish. The raised scale is i metre long, divided into millimetres, and numbered in both directions. Foster’s method of testing is employed to increase the sensibility of the bridge by the insertion of two extra resistances at A and B, which resistances become, according to Kempe, “ ungraduated prolongations of the slide wire.” 3569
  - Price, complete, with Spring Jockey, as figured .. .. . . . . .. . . .. .. .. £5 15 0
  - 1784. —Wheatstone Bridge, I metre long, fitted with additional terminals and blocks for testing by Foster’s
  - method. This bridge is fitted with a special spring jockey, accurate boxwood scale, copper mounts and brass terminals, the whole mounted on nicely polished mahogany base 3570 .. .. .. . . . . .. each £3 0 0
  - 1785. —Ditto, but i metre long 3571 . . . . . . .. .. .. .. . . .. . . ,, 3 1 7 6
  - 1786. —Wheatstone Bridge, cheap pattern, for students’ use, | metre long, with sliding jockey, accurate boxwood
  - scale, and hard wood base 3572 .. . . . . .. .. .. .. .. .. . . . . each 19/6
  - 1787. —Ditto, but r metre long 3573 .. .. .. .. .. .. .. ,, 27/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 253
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WHEATSTONE BRIDGES, Etc.
  - 1788.—Wheatstone Bridge, I metre long, every joint and binding screw soldered, carefully selected platinoid wire, mounted on polished mahogany board ; accurate boxwood scale divided in millimetres and numbered in both directions.
  - Price, including knife-edge jockey with terminal for wire 3574 . . . . each £12 6
  - 1789. —Ditto, but i metre long 3575 . . . . . . . . ,, 1 7 6
  - ENLARGED VIEW OF KNIFE-EDGE JOCKEY.
  - 1790. —Wheatstone Bridge, £ metre long, provided with accurate boxwood scale and Hoffert’s sliding spring jockey. This jockey consists of a heavy metal rod carrying a terminal and strip of celluloid, the latter being pressed down when it is desired to make contact with the wire. A thin line etched on the celluloid serves for taking the readings. 3576
  - Each £17 6
  - 1791. —Ditto, but i metre long 3577 . . . . . . ,, 1 12 6
  - 1792.—Wheatstone Bridge, for demonstration purposes. The manganin measuring wire is i metre long. Front part of the bridge is graduated in ^-decimetres, and top part in millimetres. 3578 Price, for best make and finish .. .. .. . . .. .. . . . . .. . . .. £3 17 6
  - 1793.—Carey-Foster Bridge. This type of bridge is indispensable where resistances have to be compared with the highest degree of accuracy attainable. The bridge with our latest modifications can be rapidly handled. The commutator is of the most solid construction. The slide wire is very carefully tested, and spare slide wires are provided to suit each standard coil. 3579
  - A. Carey-Foster Bridge, as figured, with one wire . . £17 10 0
  - ^,B. Ratio Coils, wound in pairs, on vulcanite bobbins, with copper legs, each pair of i, io, ioo, or i,ooo ohms .. £2 15 0
  - C. Extra Slide Wire, mounted on a vulcanite block, with copper legs......................................... £2 15 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 254
  - F. E. BECKER & CO.,
  - w. &
  - NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - POTENTIOMETERS
  - 1794.—Stewart and Gee’s Potentiometer, best quality, with sliding contact and boxwood scale on mahogany base, with terminals as figured.
  - Each ...............15/-
  - 1794
  - 1795
  - 1795.—Potentiometer, Schuster & Lee’s pattern ; designed specially for students’ use 3587 each 16/-
  - (See Schuster & Lees “Practical Physics.’’)
  - 1796
  - 1796.—Potentiometer and Wheatstone Bridge. This apparatus, which was designed by Dr. Sumpner, of the Birmingham Municipal Technical School, consists of an accurately graduated |-metre scale, divided into 1000 parts ; five lengths of manganin wire connected to copper mounts ; three additional terminals and four spring jockeys working on one slider, with pointer, as figured. 3588
  - Price, complete .. .. .. . . .. .. . . .. .. . . . . . . . . . . £115 0
  - 1797.—Laboratory Potentiometer ('Liverpool
  - University ” pattern). This apparatus consists of ten wires, each 1 metre long, stretched over a plate of opal glass. The raised scale is accurately divided into millimetres throughout its length. The spring jockey is triangular in shape and provided with three legs, two of which slide in a V-shaped groove. 3585
  - Guaranteed highest quality and finish £5 10 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
  - 1797.
  - 17 97
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 255
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - POTENTIOMETERS
  - 1798.—Potentiometer, Latimer-Clarke’s standard pattern, with improved sliding jockey, highest quality and finish .. .. . . .. . . . . . . . . . . . . .. . . ..£400
  - CONDENSERS
  - 1799
  - 1799.—Paper Condensers, cheap form, in mahogany case, with two terminals, mounted on strip of polished ebonite. 3589
  - A. 0*1 micro-farad .. .. .. each £1 17 6
  - B. 0-25 „ . . „ 2 0 0
  - C. 0-5 „ „ 2 7 6
  - D. i-o „ „ 2 12 6
  - E. 2-0 „ „ 2 17 6
  - F. 3-0 „ „ 4 10 0
  - 1800
  - 1800.—Paper Condensers, superior quality paraffined paper dielectric, with short-circuit plug on polished strip of ebonite, as figured. 3590
  - A. rV micro-farad
  - B. i
  - C. *
  - D. h
  - each £2 10 0
  - „ 3 0 0
  - „ 3 10 0
  - „ 4 0 0
  - „ 5 0 0
  - RHEOSTATS
  - 1801.—Carbon Rheostats. These are designed for use as regulators, and are largely used in the calibration of measuring instruments.
  - They are intended for continuous use, and in this case they will carry the current as stated. They can be used for currents up to four times that stated if they are left in contact for a short period only.
  - The plates are cut out from hard retort carbon, they are quite flat, and each side is well roughened. They are held in a strong iron-frame case ; pressure is brought to bear on the plates by means of a steel screw with a fine thread, the screw being worked by the brass wheel shown in sketch. 3634
  - Size. To take Current. Resistance.
  - A. .. 15 amperes .. . . . . o*i to 5 ohm
  - B. .. 25 „ ............0*05—3 ohm
  - 1801
  - If smaller currents are used, the resistance can be increased considerably by loosening the screw which clamps the plates.
  - Size of Plates. Total Weight. Price.
  - 48 of 3^ in. X 3! in. .. 20 lb...........£3 12 6
  - 22 of 6 in. X 7 in. . . 25 lb. .. .. 5 5 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 256 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - KOHLRAUSCH BRIDGES
  - 1802.—KOHLRAUSCH’S UNIVERSAL BRIDGE, for determining the resistance of solid conductors from o-i to 20,000 ohms, with sufficient accuracy for technical purposes.
  - It comprises five multiplying coils—o-i, i-o, 10, 100 and 1,000 ohms ; an accurately divided ohm scale ; induction coil; slider with pointer, etc., etc. The whole mounted on polished mahogany base.
  - PRICES.
  - 1802/a. —-Price, complete as figured. 3580
  - £16 10 0
  - 1803/b. —Ditto, but without induction coil. 3581
  - £10 10 0
  - 1804/c.—Telephone, made specially for use with Kohlrausch Bridges 3582 each £1 17 6
  - POTENTIOMETERS
  - 1805/d.—Hibbert's Potentiometer. The
  - wire is wound upon a revolving cylinder, thus giving a maximum length for the space occupied. A very neatly devised contact-maker travels from end to end of a scale indicating the number of turns while a fixed pointer gives readings on a fractional scale encircling the end of cylinder. The cylinder is rotated by milled heads at its extremities. This potentiometer obviously has many advantages over the board pattern. 3583
  - Price..................£3 10 0
  - 1806/e. — “ N i v o c ” Potentiometer, improved pattern. This apparatus consists of 10 boxwood scales, divided into 1,000 parts, each division being 1 cm. long. The platinoid wire is placed on the top, and the whole is mounted on polished teak, every joint being soldered. 3584
  - Price £1 18 6
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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  - W. & J. GEOROE (LONDON), Lid., PROPRIETORS.
  - RESISTANCE UNITS
  - 1802.—Vitreous Enamelled Resistance Units, consisting of a high grade alloy wire, having a temperature co-efficient at ‘000023 per degree C., embedded in a vitreous refractory mass, fired at high temperature to a smooth glossy finish in various colours. Units exceeding 2,000 ohms are wound with a special grade of nickel-chrome alloy, temperature co-efficient -00025 approx.
  - The ohmic values stated below are accurate within 10 per cent., but units can be made to any degree of accuracy with corresponding increase of price.
  - The current carrying capacities listed are for permanent loading, and correspond to a temperature rise of approximately 200° C., if the units are mounted in a well ventilated position.
  - For motor starters or intermittent work the current rating may be increased by the usual factor.
  - The units should preferably be mounted on loose fitting vertical rods, provided with a spring washer at one end, in order to allow for the unavoidable expansion and contraction when heating up and cooling down.
  - Unit 1802/1. Unit 1802/2. Unit 1802/3. Unit C* O CO Unit 1802/5. Unit 1802/6. Unit 1802/7.
  - 2 in. X | in. 3i in- X | in. 6* in. X | : in. 8£ in. x 1, in. 4 in. X i in. 4 in. X i| in. 6 in. X xl in.
  - Ohms Amps. , Price Ohms Amps. Price Ohms Amps. Price Ohms Amps. Price Ohms Amps. Price Ohms Amps. Price Ohms Amps. Price
  - approx. max. each. approx. max. each. approx . max. each. approx. max. each. approx. max. each. approx. max. each. approx. max. each.
  - i-8 4 3-6 4 5 4-5 10-5 4-2 500 0-28 5000 0-15 \ 10000 0-13 1
  - 2‘54 3-5 5 3-5 7 375 15-4 3-5 700 0-23 7/6 6000 0-15 f 15/- 15000 0-12 [19/6
  - 3-6 2-8 7 3 10-5 3 22 3 1010 0-2 7000 0-125 20000 1-0
  - 5 2-5 10-5 2‘5 I5‘4 2‘5 31-6 2-5 1490 0-16 8000 0-12 30000 0-05 J
  - 7 2 I5‘4 2 22-6 2 45 2 2000 0-14 1 9000 O-I /
  - 10-5 175 22 i-6 31-6 17 60 i-8 3000 o-x ) 10000 O-I )
  - 15-4 i-4 31-6 i-4 45 i-4 89 1-4 4000 0-075 9/- 15000 0-075 11/6
  - 22 31-6 1-22 I ,4/9 45 60 1 0-9 6/4 60 89 1-2 I-I 9/- 126 174 1-2 I 10/6 5000 0-05 ) 20000 0-05 )
  - 45 0-8 89 o-8 126 0-9 255 0-9
  - 60 °7 126 0 7 174 o-8 356 o-8
  - 89 o-6 174 o-6 255 0-65 500 0-65
  - 126 o-5 255 o-5 356 o-54 700 0-52
  - 174 0-4 356 0-4 500 o-45 1010 o-45
  - 255 o-35 500 o-35 ) 700 Q-375 1490 o-35
  - 356 0-28 700 o-3 XOIO o-3 1 2000 0-3
  - 40000 50000 0-05 0-05 | 22/6
  - 1802
  - RESISTANCE FRAMES
  - 1803.—Resistance Frame. —Enamelled slate mounts, fireproof, japanned iron frame ; best quality.
  - plain
  - Circuits—200 to 250 volts
  - Ohms 40 25 16 9 6-5 4-5 3-0 2-1
  - Max. amperes 5 7 9 15 20 30 45 65
  - Price 110/- 130/ - 160/- 195/- 215/- 235/- 260/- 300/-
  - Circuits—100 to no volts :—
  - Ohms 10 6-25 4 2-25 i-6
  - Max. amperes 10 14 18 30 40
  - Price 115/- 132/6 167/6 210/- 230/-
  - Circuits—400 to 500 volts :—
  - Ohms .. 64 36 26 18 12 8-4
  - Max. amperes 4-5 7-5 10 15 22 32
  - Price .. 160/- 195/- 215/- 235/- 265/- 300/-
  - When ordering, please state clearly the voltage available and the amperage required.
  - 1803
  - Oup stock of pure Chemicals and Acids is very considerable;! hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
  - R
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  - w. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ADJUSTABLE RESISTANCES
  - (SLATE TYPES).
  - This type of Resistance comprises a bar or slab of specially selected slate free from metallic veins, machined and turned with a spiral groove, in which is wound under tension a suitable resistance wire, so that the increased length when expanded by heat does not result in the convolutions working loose and leaving the spiral grooves.
  - The sliding contact with the wire is made by means of laminated spring brass brushes arranged in such a way as to conduct the current direct from the wire to the triangular sectioned guide bar entirely independent of the perfection of fit between the triangular hole and the guide bar.
  - GRADED WINDING. All resistances of our manufacture can be supplied with windings of increasing cross section, by means of which economy of space and cost can be effected in special cases, as the section of the resistance wire can be made to increase at approximately the same rate as the current, when the slider is moved to diminish the resistance in circuit.
  - Type “ A.”
  - Cat. No. 1804-1809. Arranged for switchboard mounting.
  - SINGLE
  - SLATE
  - PATTERNS.
  - Current values listed
  - are for intermittent
  - work only.
  - Permanent loading should not exceed 60% of the listed current.
  - Type “ B.’’
  - Cat. No. 1804-1809.
  - Arranged for bench and wall mounting.
  - Cat. No. 1804. —Size of Slate, 4§ X 14V X f- in. Weight of Type “A,” 8.oz. Weight of Type “B,” 11 oz.
  - Amps. . . 0-3 o-45 o-6 1*0 1-2 i-5 2-0 3*0 4-o 5-o 7-0 10-o 15-0
  - Ohms (approx.) 250 140 85 55 40 24 *4 8 6 2-8 17 0-85 0-4
  - Price, Type "A ” 17/3 17/3 17/3 17/3 17/3 17/3 17/3 17/3 17/3 18/3 18/3 18/3 18/3
  - Price, Type “ B ” 19/7 19/7 19/7 19/7 19/7 19/7 19/7 19/7 19/7 21/3 21/3 21/3 21/3
  - Extras, as follows, if required : for non-inductive winding, 4/-. For graded winding, 3/6 ; for lead screw motion (see page 263), 16/- ; for fixing scale of ohms, 4/- .
  - Cat. No. 1805.—Size of Slate, X ItV X t in. Weight of Type “ A,” 12-5 oz. Weight of Type " B,” 14-5 oz.
  - Amps. .. °;3 o-45 o-6 i-o 1-2 i*5 2-0 3*0 4-0 5-o 7-0 10-o 15-0
  - Ohms (approx.) 400 250 140 no 60 40 24o 16 10 4-5 3 i*5 o-8
  - Price, Type “A” 21/- 21/- 21/- 21/- 21/- 21/- 21/- 21/- 21/- 22/3 22/3 22/3 22/3
  - Price, Type “ B ” 23/9 23/9 23/9 23/9 23/9 23/9 23/9 23/9 23/9 25/- 25/- 25/- 25/-
  - Extras, as follows, if required : for non-inductive winding, 4/-. For graded winding, 3/6 ; for lead screw motion (see page 263), 16/-; for fixing scale of ohms, 4 /-;
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS. “
  - ADJUSTABLE RESISTANCES
  - (SLATE TYPES).
  - See previous page for illustrations.
  - SINGLE SLATE PATTERN—{continued).
  - Cat. No. 1806.—Size of Slate Bars, 7! x 2 x -fir in • Weight of Type “A,” if lb. Weight of Type “ B,” 2flb.
  - Amps. . . o-3 o-45 0-6 I'O 1-2 i-5 2*0 3-o 4’° 5-o 7-0 io-o 15*0 20-0
  - Ohms (approx.) 650 420 230 150 IOO 65 35 24 16 8 5 2-5 i'0 0*5
  - Price, Type “A” 26/4 •26/4 26/4 26/4 26/4 26/4 26/4 26/4 26/4 29/- 29/- 29/- 29/- 29/-
  - Price, Type “ B ” .. 34/9 34/9 34/9 34/9 34/9 34/9 34/9 34/9 34/9 37/2 37/2 37/2 37/2 37/2
  - Extras, as follows, if required : . non-inductive winding, 5 /6. For graded winding, 4 /- ; lead screw motion {see page 263), 19/- - ; for fixing scale of ohms, 4 /9 ; for
  - Cat. No. 1807.—Size of Slate Bars, IlfV x 2 x I in. Weight of Type “A,” 3 lb. Weight of Type “ B,” 4 lb.
  - Amps. o-3 o-45 o-6 i’0 1*2 i-5 2-0 3-o 4-0 5-o 7-0 io-o 15-0 20-0
  - Ohms (approx.) . . 1200 800 450 300 220 120 70 45 28 15 8 4 2 I
  - Price, Type “A” 33/ 33/- 33/- 33/- 33/ 33/ - 33/ 33/ 33/- 36/6 36/6 36/6 36/6 36/6
  - Price, Type “ B ” 42/10 42/10 42/10 42/10 42/10 42/10 42/10 42/10 42/10 47/- 47/- 47/- 47/- 47/-
  - Extras, as follows, if required : non-inductive winding, 5 /6 For graded winding, 4 /- •; lead screw motion {see page 263), 19/- - ; for fixing scale of ohms, 4 /9 ; for
  - Cat. No. 1808.—Size of Slate Bars, i5f x 2 x 1 in. Weight of Type "A,” if lb. Weight of Type " B,” if lb.
  - Amps. o*3 0-45 o-6 i-o 1*2 1-5 2-0 3-0 4-0 5-0 7-0 io-o 15*0 20-0
  - Ohms (approx.) .. 1700 1150 700 440 285 170 105 65 44 22 13 6 3 i-6
  - Price, Type “A” 53/4 53/4 53/4 53/4 53/4 53/4 53/4 53/4 53/4 56/- 56/- 56/- 56/- 56/-
  - Price, Type " B ” 56/9 56/9 56/9 56/9 56/9 56/9 56/9 56/9 56/9 58/9 58/9 58/9 58/9 58/9
  - Extras, as follows, if required : For graded winding, 6/9 ; lead screw motion {see page 263), 24/6 ; for fixing scale of ohms, 6 /-; for non-inductive winding, 7/6.
  - Cat. No. 1809.—Size of Slate Bars, 17! x 2§ X if in. Weight of Type " A,” if lb. Weight of Type " B,” if lb.
  - Amps. o*3 0-45 o-6 i*o i*2 . 1-5 2*0 3-0 4-0 5-0 7-0 io-o 15-0 20-0
  - Ohms (approx.) .. 2400 1550 950 550 450 250 130 90 60 30 16 8-5 4 2-5
  - Price, Type “ A ” 61/6 61/6 61/6 61/6 61/6 61/6 61/6 61/6 61/6 64/2 64/2 64/2(64/2 64/2
  - Price, Type “ B ” 64/10 64/10 64/10 64/10 64/10 64/10 64/10 64/10 64/10 66/2 66/2 66/2 66/2 66/2
  - Extras, as follows, if required : For graded winding, 6/9; lead screw motion {seepage 263), 24/6; for fixing scale of ohms, 6/-; for non-inductive winding, 7/6.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the ,,
  - Leading Scientific Press.
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- - 260 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - . W. & d. GEOROE (LONDON), Ltd., PROPRIETORS.
  - ADJUSTABLE RESISTANCES
  - (SLATE TYPES).
  - Current values listed are for intermittent work only.
  - Cat. No. 1810. —Dimensions of Slates, 7I x 2 x if in. Net weight, about 4 lb.
  - ; Amps. o-3 o-45 o-6 I‘0 1*2 i-5 2‘0 3-o 4-o 5-o 7-o I0‘0 15-0 20‘0
  - Ohms (approx.) .. 1300 840 450 300 220 130 70 48 32 i5 10 5 2 1-2
  - Price 56/9 56/9 56/9 56/9 56/9 56/9 56/9 56/9 56/9 55/4 55/4 55/4 55/4 55/4
  - Extras, as follows, if required : For graded winding, 4/9 per slate ; lead screw motion {see page. 263), 16/-; for fixing scale of ohms, 4 /9 ; for non-inductive winding, 6 /9 per slate.
  - Cat. No. 1811.—Dimensions of Slates, u-\% X 2 x 1 in. Net weight, about 6J lb.
  - Amps. 0‘3 0-45 o-6 1-0 1-2 i-5 2-0 3-o 4-o 5-o 7-o 10-o 15-0 20‘0
  - Ohms (approx.) .. 2400 1600 900 600 450 220 140 92 60 30 16 8 4 2‘5
  - Price 70/3 70/3 70/3 70/3 70/3 70/3 70/3 70/3 70/3 68/2 68/2 68/2 68/2 68/2
  - Extras, as follows, if required : For graded winding, 4 /9 per slate ; lead screw motion {see page 263), 16/-; forfixing scale of ohms, 4/9; for non-inductive winding, 6/9 per slate.
  - Cat. No. 1812 .—Dimensions of Slates, 15! x 2 x 1 in. Net weight, about 8f lb.
  - Amps. o-3 o-45 o-6 I‘0 1-2 i'5 2‘0 3-0 4-o 5-o 7-o 10-0 I5-0 20‘0
  - Ohms (approx.) .. 3400 2300 1400 800 600 340 210 130 80 44 25 12 6 3-5
  - Price 85/9 85/9 85/9 85/9 85/9 85/9 85/9 85/9 85/9 82/4 82/4 82/4 82/4 82/4
  - Extras, as follows, if required : For graded winding, 7 /6 per slate ; lead screw motion {see page 263), 19/-; for non-inductive winding, 6 /9 per slate. for fixing scale of ohms, 4/9 ;
  - Cat. No. 1813 .—Dimensions of Slates, 17I x 2f x if in. Net weight, about 13! lb.
  - Amps. o*3 0-45 o*6 i-o i-2 1-5 2-o 3-0 4-0 5-0 7-0 io-o 15-0 20-0
  - Ohms (approx.) .. 4800 3300 1900 1100 900 500 260 180 120 60 32 18 8 5-5
  - Price 93/10 93/10 9310 93/10 93/10 93/10 93/10 93/10 93/10 90/6 90/6 90/6 90/6 90/6
  - Extras, as follows, if required : For graded winding, 7/6 per slate ; lead screw motion {see page 263), 19/-; for fixing scale of ohms, 4 /9 ; for non-inductive winding, 6 /9 per slate.
  - ‘Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
  - DOUBLE SLATE PATTERN.
  - Fitted with five terminals for Series and Potentiometer use.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 261
  - W. Jt J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ADJUSTABLE RESISTANCES
  - (SLATE TYPES).
  - COMBINATION SLATE PATTERN.
  - Fitted with two independent sliders and six terminals for universal use.
  - Current values listed are for intermittent work only.
  - Cat. No. 1814.—Dimensions of Slates, 7f x 2 x I-& in. Weight, approx., 4 lb. Cat' N°' l8l4_l8l7‘
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.261 - vue 280/555
- - 262 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ADJUSTABLE RESISTANCES
  - (TUBULAR TYPES)
  - Type “ B.”
  - Cat. No. 1818-1820.
  - ‘Fitted with three terminals for series and potentiometer Fitted with three terminals for series and potentiometer r use, and arranged for switchboard mounting. use, and arranged for bench or wall mounting.
  - SINGLE TUBE ADJUSTABLE RESISTANCES
  - The Current Values of Tubular Type are for PERMANENT LOADING.
  - •Cat. No. 1818.—Length of Tube, 6 in. Diam. of Tube, i£in. WeightofType “A,” i2oz. Weight of Type “B,”i4oz.
  - Amps. 0-3 0-45 o-6 i-o i-2 i*5 2-0 2*8 3-3 5-0 6-5 8-5 12 14
  - Ohms (approx.) . . 700 380 220 150 80 45 25 15 10 5 3 2 I 0*6
  - Price, Type “A” 19/4 19/4 19/4 19/4 19/4 19/4 19/4 19/4 19/4 22/- 22/- 22/- 22/- 22/-
  - Price, Type “ B” 22/- 22/- 22/- 22/- 22/- 22/- 22/- 22/- 22/- 24/4 24/4 24/4 24/4 24/4
  - Extras, as follows, if required : For graded wiring, 3/8; lead screw motion (seepage 263), 17/-; perforated covers (see page 263) on Type “ B " only, 9/6; fixing scale of ohms, 4/9.
  - Cat. No. 1819.—Length of Tube, 12 in. Diam. of Tube, 2§ in. Weight of Type “ A," 35 oz. Weight of Type “ B,” 42 oz.
  - Amps. 0*3 0’45 0‘6 1-0 1-2 1-5 2-0 2-8 3-3 5-0 6‘5 8-5 12-0 14-0 l6*0 20*0 25-0
  - Ohms (approx.) 3000 1500 925 620 380 210 120 70 50 25 15-5 7*6 4*2 2*8 I‘9 I 07
  - Price, Type “ A " 44/6 44/6 44/6 44/6 44/6 44/6 44/6 44/6 44/6 46/3 46/3 46/3 46/3 46/3 46/3 46/3 46/3
  - Price, Type “ B " 47/10 47/10 47/10 47/10 47/10 47/10 47/10 47/10 47/10 49/- 49/- 49/- 49/- 49/- 49/-49/- 49/-
  - Extras, as follows, if required : For graded wiring, 4/9 ; lead screw motion (see page 263), 19/6 ; perforated covers (see page 263) on Type “ B ” only, 11 /6 ; fixing scale of ohms, 4/9.
  - Cat. No. 1820.—Length of Tube, 20 in. Diam. of Tube, 2f in. Weight of Type “ A,” 5| lb. Weight of Type “ B,” 5f lb.
  - Amps. . . 0-3 0-45 o-6 i-o 1-2 1*5 2-0 2*8 3-3 5-0 6-5 8*5 12-0 14-0 i6-o 20-0 25-0
  - Ohms (approx.) 5500 2750 1700 1130 700 390 220 120 90 45 28 14-4 7*8 5*2 3-6 i-o i*3
  - Price, Type “A” 60/- 60/- 60/- 60/- 60/- 60/- 60/- 60/- 60/- 62/- 62/- 62/- 62/- 62/- 62/- 62/- 62/-
  - Price, Type “ B " 63/3 63/3 63/3 63/3 63/3 63/3 63/3 63/3 63/3 64/- 64/- 64/- 64/- 64/- 64/- 64/- 64/-
  - Extras, as follows, if required: For graded winding, 5/- per tube ; lead screw motion, 22/3 ; perforated cover (see page 263) for Type “ B ” only 12/10; for fixing scale of ohms, 4/9.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.262 - vue 281/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1. 263
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ADJUSTABLE RESISTANCES
  - (TUBULAR TYPES).
  - Type “C.”
  - Cat. No. 1821.
  - Fitted with two independent sliders and six terminals for universal use.
  - Type " D.”
  - Cat. No. 1821.
  - Fitted with five terminals, for series and potentiometer use, and arranged for bench and wall mounting.
  - DOUBLE TUBULAR AND COMBINATION TYPES.
  - Cat. No. 1821.—Length of Tube, 20 in. Diam. of Tube, 2§ in. Weight of Type “ C,” 8£ lb. Weight of Type “ D,” 7J lb.
  - Amps— 0-3 0*45 o-6 i-o 1-2 1*5 2*o 2-8 3’3 5-o 6-5 8-5 12-0 14-0 16-0 20-0 25-0
  - Ohms (approx.)— 11000 5500 3400 2260 1400 780 440 240 180 90 56 28-8 15-6 10-4 7-2 3-8 2-6
  - Price, Type “ C ”— 105/- 105/- 105/- 105/- 105/- 105/- 105/- 105/- 105/- 108/- 108/- 108/- 108/- 108/- 108/-108/-108/-
  - Price, Type “ D ”— 112/- 112/- 112/- 112/- 112/- 112/- 112/- 112/- 112/-115/6 115/6 115/6 115/6115/6 115/6 115/6 115/6
  - Extras, as follows, if required : For graded winding, 5 /- ; lead sere w motion (see below), 22 /3 ; for fixing scale of ohms, 4/9.
  - 1822.—Illustration shows a resistance fitted with lead screw motion ; this can be fitted to all the resistances listed at an extra charge. 1823.—Perforated Covers for Type “ B ” resistances ; all terminals are under cover, and the lead in wires are protected from injury. Supplied with Type “ B ” resistances extra.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.263 - vue 282/555
- - 264 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. St J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ADJUSTABLE RESISTANCES
  - VENTILATED PATTERNS
  - For heavy currents,. May be used horizontally or vertically. Special care has been given to the contact surfaces in order to minimise resistance between wire and contact-brush and contact-brush and guide-rod, which is of triangular section, ensuring absolute rigidity. The wire being partly free, its ventilation is very good. The maximum currents given below may be applied continuously with this type of rheostat.
  - SINGLE TYPE “A” VENTILATED
  - RESISTANCE
  - 1824.—Length of slate, 10 f X 3$ in.
  - Max. current Approx. 5 7 10 15 20 amps.
  - resistance 20 11 6 3 2 ohms.
  - Price 72/6 72/6 72/6 75/- 75/-
  - 1825.—Single Type Ventilated Resist-
  - ance as “ Ventilated ” Pattern No. 1824, but
  - both windings in parallel.
  - Max. current Approx. 10 14 20 30 40 amps. 0-5 ohms.
  - resistance 5 275 i-5 075
  - Price 75/- 80/- ! 80/- 85/- 87/6
  - 1826. —Single Type “ A ” as No. 1824, but slates 14! X 31-in.
  - 1827. —Single Type “ A ” as No. 1824, but slates 18 x 3i in.
  - Max. current Approx, resistance.. Price
  - Max. current Approx, resistance. . Price
  - 40 amps. 1 ohms.
  - 10 15 20 10 14 20 30
  - 10 6 4 9-5 5-5 2-5 1-5
  - 112/6 112/6 120/-122/6122/6 120/- 120/- 125/-130/- 130/-
  - 5 7 10 15 20 10 14 20 30 40 amps.
  - 27 16 8 4-6 3 675 4 2 1-15 075 ohms.
  - 87/6 92/6 95/- 97/6 97/6 90/- 90/- 95/- 100/-100/-
  - POUBLE TYPE “ B ” VENTI-LATED RESISTANCE
  - 1828.—Length of slates, iof X 3| in.
  - Max. current 7 10 15 amps.
  - Approx, resistance 22 12 6 ohms.
  - Price 146/- 150/- 150/-
  - Max. current 20 30 40 amps.
  - Approx, resistance 4 i-5 1 ohms.
  - Price 150/- 162/6 162/6
  - 1829. Double Type (t B,n as No. 1828, but slates 14I x 3i in.
  - Max. current .. . . 5 7 10 15 amps.
  - Approx, resistance 54 32 16 9 ohms.
  - Price................ 170/- 170/- 170/- 187/-
  - Max. current .. 20 30 40 amps.
  - Approx, resistance .. 6 2*3 1-5 ohms.
  - Price .................. 187/- 200/- 200/-
  - 1830.—Double Type “ B,’ f as No.. 1828, but slates 18 X 3! in.
  - Max. current .. .. 5 7 10 15 amps.
  - Approx, resistance .. 76 44 20 12 ohms.
  - Price.............. 225/- 225/- 225/- 237/6
  - Max. current .. 20 30 40 amps.
  - Approx, resistance 8 3 2 ohms.
  - Price .................. 237/6 250/- 250/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.264 - vue 283/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 265
  - W, & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ELECTRIC LAMPS AND FITTINGS
  - 1831.—Incandescent Lamps, fitted with small bayonet caps, any voltage from i-| to 12 volts . . each 1 /-
  - 1832 —Ditto,'"any voltage from 13 to 30 volts............... .. .. .. .. each 1/3
  - 1833. —Incandescent
  - Lamps, with bottom loops, guaranteed best make. Any voltage from i|- to 12 volts. Carbon filament—
  - each 1 /3
  - 1834 .—Ditto, any voltage from 13 to 30 volts .. each 1 /6
  - METAL
  - FILAMENT
  - and
  - CARBON FILAMENT LAMPS, Standard and “Half Watt” types supplied at current prices.
  - 1835.—Spiral Spring Holders, for lamps with bottom loops, complete on stand with terminals as figured, but without lamp.
  - Each ............2/3
  - 1836
  - 1836.—English Standard Lamp-Holders, for "Capped” lamps. Thread, f in. For circuits up to 250 volts—
  - each, 10d. ; per dozen 9/6
  - 1837 —Ditto, but with shade carrier .. each, 1/3; per dozen 13/6
  - 1838. —English Standard Lamp-Holders, for circuits up to 250 volts, fitted with back-plate. Thread, | in.—
  - each, 1/1 ; per dozen 12/-
  - 1839. —Ditto, but with shade carrier .. each, 1/3; per dozen 13/6
  - 1840. —Miniature Lamp Holders, to take small lamps,
  - No. 1831......................................each 1/3
  - 1841 —Ditto, but with shade carrier .. .. . . .. ,, 1/5
  - 1842.—Miniature Lamp Holders, with back plate to take small lamps, No. 1831................ ............ each 1/5
  - 1843 .—Ditto, but with shade carrier .. .. .. .. ,, 1/6
  - 1844.—Connector for Flexible Wire, particularly useful for providing a temporary connection between an existing wall socket and a standard lamp, fan, or any apparatus of a similar portable nature, hardwood.
  - 1845.—Plug Adaptor, for tapping current off any ordinary bayonet-catch lampholder; made of polished hardwood.
  - Each, 10d.; per dozen 9/-
  - Each ............................... .3/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.265 - vue 284/555
- - 266 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.G.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ARC LAMPS
  - 1846. —Electric Arc Lamp,
  - simple form, comprising pair of carbons with sliding motion and terminals, etc., mounted on polished stand, as figured—
  - £15 0
  - 1847. —E I e c t r i c Arc
  - Lamp, new pattern with horizontal positive carbon and vertical negative carbon. Each carbon can be fed separately or simultaneously. This lamp is well made in gun-metal and cast-iron, and adjustments are provided for horizontal and vertical centring. • A steel shield is also fitted to cut off any extraneous light.
  - Price . . £3 17 6
  - 1848.—Electric Arc Lamp for bayonet-holder of house supply, comprisingScissors type Arc lamp, with both arms adjustable. The carbons are fed by means of a screw having a wood-fibre milled head. The jaws open sufficiently wide to take io mm. carbons. The lamp is carried on a mechanically-controlled tray, as figured, and can be used on any ordinary light main from ioo to 250 volts, either alternating or direct current. The resistance enables fine adjustments to be made and ensures a steady burning and non-hissing arc.
  - A. Complete outfit as illustrated with Arc lamp, Wire Adaptor, Resistance and supply of Carbons.
  - 5 mm. solid and 6 mm. cored for direct current, or 6 mm. cored for alternating current .. .. £3 15 0
  - B. Ditto on mechanical tray . . . . . . . . .. . . .. .. . . . . .. .. 4 17 6
  - C. Spare carbons, per 25 .. .. .. .. .. • • • • • • .. • • • • • 0 3 0
  - D. Resistance only .. .. .. .. .. •• •• ............. •• •• 250
  - E. Arc lamp only .. .. .. .. .. .. .. .. .. .. •• •• •• 150
  - 1849.—Electric Arc Lamp, “Scissors” type, suitable for currents up to 20 amperes, made in gun-metal, and highly finished. The base, which is made of cast-iron and enamelled, is 4§ in. wide. As will be seen by the illustration, this lamp is fitted with all movements for centring the arc.
  - Price .. . . . . £3 17 6
  - 1850 .—Ditto, plain model without arrangement for centring horizontally and vertically.
  - Price £2 15 0
  - FOR ARC LAMP RESISTANCES SEE PAGE 257.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the ..largest laboratory.
- p.266 - vue 285/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 267
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ARC LAMPS
  - 1851.—Electric Arc Lamp, " University ” pattern. This lamp is provided with all the latest improvements and adjustments; it is substantially built and beautifully finished. The tray is of iron, enamelled, and is of standard width, 4H in. ; the remainder of the lamp is mainly constructed of best quality gun-metal and steel. All the pinions are of steel cut from the solid, the racks are also machine-cut from solid drawn brass. Carbon holders are massive, and insulated from the body with mica ; the leads to the terminals are asbestos covered. It is capable of carrying up to 50 amperes. The width between carbon holders at full extension is 8| in., and when closed up 1 \ in., which provides for a lengthy lecture without recarboning. The centre of the lamp is adjustable from 4f in. to 6 in., and even greater range can be obtained by using the angle adjustment.
  - Commencing from the top of illustration, the first fibre knob allows of the adjustment of the crater of the positive carbon ; the second knob is for striking the arc ; the third knob is for adjusting the angle of the carbons—-this is operated by a steel-cut worm working into a worm-wheel segment, which is cut on the main body casting. The third knob gives vertical movement, and the fourth knob horizontal movement. The weight of the complete lamp, as illustrated, is 8 lb. Price £8 10 0
  - ARC LAMP CARBONS
  - 1852. —Arc Lamp Carbons, specially developed for projection work, and are unequalled for light and steadiness. The arc burns absolutely without noise, and is easier to control than with any other carbons; the arc settles down immediately on striking or re-striking.
  - The Carbon, No. 3077B, is the smallest diameter Negative Carbon
  - ever put on the market. The diameters advised carry the current without stripping, tapering or overheating. The small diameter of the negative carbon ensures entire absence of screen shadow, and therefore encourages economy in current consumption. The success of these carbons induced foreign carbon manufacturers to copy them.
  - PRICES (STANDARD SIZES) PER 25 PIECES.
  - FOR DIRECT CURRENT.
  - A. Positive Carbons.
  - Diameter. 8 in. 12 in.
  - 16 mm. 6/2 12/4
  - 18 „ | 8/6 17/-
  - 20 ,, 10/8 21/6
  - 22 ,, 13/2 26/4
  - 25 17/6 35/-
  - B. Small Dia. Negative.
  - Diameter. 6 in. long.
  - 8 mm. 4/11
  - 10 5/6
  - ii V-
  - 12 „ 7/9
  - 14 » 9/6
  - C. FOR ALTERNATING CURRENT.
  - Diameter. Length 6 in. Length 12 in.
  - 16 mm. 9/2 18/4
  - 18 ,, 12/7 25/2
  - 20 ,, 14/6 29/-
  - 22 ,, 16/- 32/-
  - 25 „ 19/7 39/2
  - Correct combinations of carbons for use with direct current :— For currents under—
  - 20 amps. 16 mm. cored positive and 8 mm. small dia. negative.
  - 20 to 40 „ 18 „ „ io „ From 40 to 50 amperes .. 16 mm,
  - 4° » 6o ,, 20 ,, II „• „ 50 „ 60 .. 18 „
  - 6o „ 85 „ 22 „ ,, 12 ,, „ 60 „ 70 • • 20 „
  - 85 „ 100 ,, 25 „ » i4 „ Over 70 ,, .. 22 „
  - Correct combinations | of carbons for use with alternating current
  - Both carbons.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.267 - vue 286/555
- - 268 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. A J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SMALL ELECTRIC MOTORS
  - 1853
  - 1853.—Set of Motor Parts (for easy construction). The Motor Parts illustrated are extremely simple to construct, no drilling or tapping of parts is required. The bobbin is supplied ready wound ; the parts go well together, and make up splendid working models. Each set packed in box with complete instructions. Complete parts for constructing the motor illustrated, a screwdriver being the only tool required.
  - Price for the complete set . . . . . . .. . . .. 3/3
  - 1854
  - 1854.—'‘Self-Start i ng” Motor, with tripolar armature. The brushes are so arranged as to be capable of fine adjustment. This is a well-finished and strongly constructed motor, nicely lacquered and mounted on a polished walnut base .. 11/-
  - 1856
  - 1856.—“Three-Pole” Arma-
  - ture Motor. Self-starting; very powerful; can be run with a No. 2 “ Nivoc ” dry cell .. .. 9/-
  - 1857
  - 1857.—Electric Motor, central station type, semi enclosed, tri-polar armature, copper gauze brushes with former wound field coils.
  - A. 4 volts each 13/-
  - B. 6 „ „ 16/6
  - C. 8 „ „ 19/6
  - 1855
  - 1855.—The “ Excel ” Self-Starting Motor,
  - a strongly made and powerful motor.
  - Each.......................................11/6
  - Smaller model .. .. .. .. .. 8/6
  - 1858
  - 1858.—Motor, with Colour Discs, and fitted with a self-starting tri-polar armature and a wound field magnet.. .. .. .. .. .. .. 8/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.268 - vue 287/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 269
  - W. A J. QEORQE (LONDON), Ltd., PROPRIETORS.
  - ELECTRIC MOTORS AND REGULATORS
  - %
  - These motors are of robust construction and are recommended for electrical and mechanical laboratories. The armature is truly balanced, giving freedom from vibration whilst running. The commutator, which is composed of hard drawn copper segments, has a large brush surface and the brushes are of carbon, giving the maximum efficiency with the minimum of wear.
  - Alternating Current Motor. DIRECT CURRENT IVIOTORS. Direct Current Motor.
  - SERIES WOUND.
  - Cat. No. H.P. ! Revs, per Min. Cons, in Watts. Net Weight ! Prices. Starting: Regulators. Prices.
  - in lb. 65-130 volts. 150-220 volts.
  - 1859 I /ioo 2,000 20 i 4 £2 12 6 £2 18 6
  - 1860 x /6o 2,000 30 t 6 2 14 0 3 0 0 18/-
  - 1861 1/30 2,000 60 i 12 3 10 6 3 18 0 18/-
  - 1862 1/16 2,000 95 20 4 12 6 4 17 6 18/-
  - 1863 j 1/8 2,000 154 21 4 15 0 5 5 0
  - 1864 1/8 1,500 154 17 4 19 6 5 12 6 18/-
  - 1865 | 1/6 2,000 220 17 4 19 6 5 12 6
  - 1866 .1/6 1,500 220 28 7 10 0 7 17 6 19/6
  - SHUNT WOUND.
  - 1867 1/30 2,000 60 12 £4 10 0 £5 5 0 21/-
  - 1868 1 /16 2,000 ! 95 20 5 5 0 5 12 6 21/-
  - 1869 1/8 2,000 j 154 21 6 0 0 7 2 6
  - 1870 1/8 i,5°o ; 154 17 5 17 6 6 10 0 21/-
  - 1871 1/6 2,000 220 17 6 0 0 6 10 0
  - 1872 1/6 I>5°° 220 28 8 12 6 8 18 6 21/-
  - ALTERNATING CURRENT IVIOTORS.
  - INDUCTION TYPE : Single Phase.
  - 1873 1/30 1 1,400 IOO 15 £6 6 0 £6 10 6 These motors are
  - 1874 1 /16 ' 1,400 105 24 7 2 6 7 5 0 self starting but
  - 1875 1/8 ' 1,400 180 35 8 12 6 9 0 0 cannot be regu-
  - 1876 1/6 1,400 j 200 35 9 1 0 0 9 6 0 lated.
  - Special pulleys for single phase motors for starting against full load . . .. . . . . . . .. each 187-
  - Higher periodicities up to ioo .. .. . . . . .. . . . . .. . . .. . . . . extra 57-
  - SERIES REPULSION : Single Phase.
  - 1877 1 /ioo 2,000 25 4 £2 12 6 £2 12 6
  - 1878 I /60 2,000 45 6 2 16 0 3 0 0 30/-
  - 1879 1/30 2,000 70 12 3 15 0 3 18 0 30/-
  - 1880 I /i6 2,000 no 17 4 17 6 5 5 0 30/-
  - 1881 1/8 2,000 180 26 6 0 0 6 10 0 30/-
  - 1882 1/6 2,000 200 39 8 8 0 8 12 6 30/-
  - 1883 i/4 2,000 350 44 10 10 0 10 15 0 Fitted with adjustable brush gear for speed regulation.
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.269 - vue 288/555
- - 270 F. E. BECKER & CO.,
  - W. i
  - NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 1884
  - 1884.—The “ E.S.” Magneto Dynamo. Requires exceptionally small power. Finished in enamel, and all metal parts bright. Guaranteed output is plainly engraved on a brass metal plate fixed to the machine. Gives 4! volts, but will light up a 6-volt lamp at 3,000 revolutions.
  - Price . . . . . . .. . . .. . . 7/6
  - 1885
  - 1885.—The Demonstration Dynamo, complete with powerful dynamo lamp bracket, lamp, and large hand gear drive, all mounted on polished wood base.
  - Each .........................£3 12 6
  - 1886
  - 1886.—The “ N ” Model Dynamo. This
  - machine will light a metal filament lamp brilliantly, and, owing to small power required, it will be found particularly useful for driving from model steam engines, etc. As there are no brushes or commutators the machine cannot get out of order.
  - Price, complete, with metal filament lamp .. 16/-
  - 1887
  - 1887.—The “ N ” Model Dynamo, as No. 1886,
  - but fitted with driving gear as figured.
  - Price, complete, with metal filament lamp .. 35/-
  - 1888
  - 1888.—The “W.M.” Dynamo, large size, fitted with a rocking brush-gear. 8 volts, 3 amps., 3,000 r.p.m. Windings are of the single field type with “ H ” armature.
  - £1 15 0
  - 1889.—Hand-Driving Gear,
  - comprising: cast-iron wheel 9 in. diameter, with multiplying arrangement for getting a high speed.
  - Price, complete, as figured .. 17/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.270 - vue 289/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 271
  - W. & J. GEORGE ^ (LONDON), Ltd., PROPRIETORS.
  - ELECTRIC GENERATORS
  - These machines are of very massive construction and can be well recommended for use in electrical laboratories.
  - Catalogue Watts Speed Price with Extra for
  - No. Approx. Enclosed Vent. Slide Rails.
  - 1890 200 1300,
  - 1890A 400 1600 ) £17 15 0 £2 2 0
  - 1891 400 I300|^
  - 1892 750 1600 j 19 15 0 2 2 0
  - 1893 750 1300)
  - 1894 1450 1600 j 24 0 0 2 12 6
  - 1895 1500 13001
  - 1896 i860 1500} 33 0 0 2 12 6
  - 1897 2000 IIOO 1
  - 1898 3000 1400 j 39 10 0 3 5 0
  - 1899 3000 IIOO |
  - 1900 3700 1250} 49 15 0 3 5 0
  - 1890-1900
  - These machines are supplied as Direct Current Generators (Dynamos), prices remaining the same, output as above. On 1890 to 1900 15/- extra for higher voltages than 250 volts.
  - CHARGING DYNAMO FOR CHARGING ACCUMULATORS, OR FOR HOUSE LIGHTING, ETC.
  - OUTPUT:
  - 16 volts 6 amps.
  - 1901
  - 1901.-—Charging Dynamo. Since the above photograph was taken this machine has been greatly improved. The brush holders are now of the box pattern, spring loaded and adjustable, large plain bearings are
  - fitted with screw down lubricators, and a large carrying ring is provided A. Output 6 volts 3 amps. £1 10 0
  - on the top. The armature is of the 8 pole type 2 X 4! in. and a solid 8 B. ,, 10 ,, 5 >> 2 17 6
  - section copper commutator is fitted. C. „ 30 „ 5 » 10 10 0
  - Each .. £7 10 0 D. „ 30 „ 15 „ 17 10 0
  - 1902
  - 1902.—Dynamos, of solid construction, heavy castings, semi-enclosed, laminated armature, copper gauze brushes, adjustable brush rockers, shunt wound.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.271 - vue 290/555
- - 272 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON. E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DEMONSTRATION MODELS
  - 1903
  - 1903.—H a m m e r I’s Apparatus for producing currents in
  - Gramme’s ring by taking a continuous alternating or a turning current. This apparatus consists principally of a fixed and a movable glass plate. On the latter there can be fixed for the various experiments corresponding paste plates with a drawing of a Gramme’s ring. Turns and collectors are transparent, so that when using a suitable black paste plate, cut into lines, and which is used for covering the fixed glass plate, there will appear luminous points, when lit from the back, which are displaced when turning the movable plate, and in this manner the course of the current is rendered visible.
  - Price .. £8 15 0
  - 1907
  - 1904
  - 1904.—Large Model of a Drum Armature.
  - 1907. — Model of a Gramme’s Ring. Collector and axle made of wood.
  - Complete, as figured..
  - £2 15 0
  - Price, complete with windings, as figured .. £2 2 0
  - 1905
  - 1905.—Model of Siemens’ Armature. Col-
  - lector and axle made of wood .. each £2 2 0
  - 1908.—Model of Gramme’s Ring Armature, 20 in. in diameter .. each £1 16 0
  - 1906
  - 1906.—Model of a Gramme’s Ring ; ring,
  - collector and axle made of wood .. each £1 15 0
  - Our stock of pure Chemicals and Acids is very considerable j hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 273
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ELECTRIC BELLS, Etc.
  - 1909
  - 1909.—C heap Electric
  - Bell, stamped iron base and cover, black enamelled, two bobbins wound with silk-covered wire to 21 ohms, and fitted with nickel-plated steel gong 2| in. in diameter ; absolutely damp-proof.
  - Each.......................2/6
  - 1910.—Electric Bell,
  - in polished hardwood case, with real walnut front, nickel-plated gong, two large bobbins wound with enamelled wire to 5 ohms, tempered blue steel spring with riveted platinum contact. Well finished and fitted with special double adjustment device.
  - A. With gong 2\ in. dia.—
  - each 4/3
  - B. With gong 3 in. dia.—
  - each 5/6
  - 1912
  - 1912.—Electric Bell, best quality case of selected polished wood, frame of cast iron black enamelled. Fine nickel-plated bell gong, clear tone. Bobbins wound with best quality H.C. wires well insulated. Bushed eyelets for fixing to wall.
  - A. 2f in. diameter gong .. .. each 6/6
  - B. 3 „ „ „ •• •• „ 8/6
  - C. 4 „ „ „ ...... „ 12/6
  - 1911
  - 1911.—Electric Bell Set,
  - on board,' complete with dry battery, push wire and staples.
  - Price complete .. .. 11/6
  - BUZZER
  - 1913.—Electric Buzzer, best quality, with electric bell movement, and a wide armature, emitting a buzzing noise when actuated.
  - Price, complete in polished teak case and
  - box .. .. . . . . .. 8/-
  - 1913
  - RELAY
  - For Automatically Closing Local Circuits.
  - 1914.—Cheap Quality Relay,
  - 5 ohms resistance, for use on short lines, or with indicators.
  - Price, complete as figured .. 15/6
  - 1914
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
  - s
- p.273 - vue 292/555
- - 274 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Lid., PROPRIETORS.
  - 1915.—W o o d Bell
  - Pushes, 2\ in. diameter, polished wood .. each 1/3
  - 1916 —Ditto; better quality-each 2/3
  - BELL PUSHES
  - 1917.—Cast Brass Bell Pushes, diameter 2-| in. Each.............2/-
  - 1918. —Pear Bell
  - Push, polished wood .. each 1/4
  - 1919. —Ditto, better quality .. each 1 /6
  - ELECTRO PLATING APPARATUS
  - 1920.—Plating Outfit for Amateurs. This outfit contains
  - everything necessary for plating in an experimental way, and consists of:—i bunsen battery {complete), r jar rich gold solution, i jar rich silver solution, i jar rich copper solution, i jar A battery powder, i jar B battery powder, i plate brush, 1 hand scratch brush, i box rouge, i bag sawdust, i enamelled iron vessel, copper wire for connecting and hanging, i spirit stove, i copper anode.
  - Complete in box
  - £2 17 6
  - 1920
  - 1921.—Complete Gilding and Plating. This
  - outfit, complete in itself, has met a long-felt want for a thoroughly practical combination at a low price. Several additions have been made to improve the outfit originally submitted—2 bunsen batteries (complete), 1 jar A battery powder, 1 jar B battery powder, 1 jar rich gold solution (| pint), 1 jar rich silver solution (1 pint), 1 jar rich copper solution (1 pint), 2 enamelled vessels for solutions, etc., 1 tripod stand, 1 bunsen burner and tubing, 1 copper anode, 1 tin pure cyanide potassium, copper wire for connecting and hanging, 1 hand scratch brush, 1 plate brush, 1 washing out brush, 1 tin cleaning compound, 1 enamelled vessel for cleaning solution, bag of boxwood sawdust, 1 polishing cloth, 1 box of rouge.
  - Price, complete, in handsome fitted box, with book of instructions .. .. .. .. .. £450
  - 1921
  - Oup Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.274 - vue 293/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 275
  - W. & J. OEOROE (LONDON). Ltd., PROPRIETORS.
  - TELEPHONES
  - 1922
  - 1922.—C o m p I e t e Wall Telephone,
  - black and nickel finish, with oblong walnut wall box, 3-in. circular bell and ringing key. To ring both ways.3971
  - Price .. .. £2 7 6
  - Diagrams of connections on application.
  - 1923.—The “ Elite ”
  - Wall Telephone,
  - without bell, but with terminals provided for same.3975 Price .. .. 32/6
  - These instruments are suitable for private telephone systems for distances up to 200 yards.
  - 1923
  - 1924.—Wa I I Telephone, with bell, etc. 3979
  - Price .. each £2 5 0
  - This instrument is suitable for distances up to 200 yards.
  - 1925.—Large Pat-tern Battery Wall Telephone,
  - comprising revolving granular carbon transmitter, induction coil, double-pole “ Watch ” receiver, call bell, automatic switch-hook and ringing key; metal parts nickel-plated; woodwork solid walnut. 3990
  - Price .. each £2 12 6
  - 1926.—S u p e r i o r Quality Battery Wall Telephone,
  - comprising "Hunning-scone ” granular carbon transmitter, with sanitary glass mouthpiece, induction coil, best quality doublepole “ Watch ” receiver, “ Caledonian" call bell, automatic switch-hook and ringing key; metal parts nickel-plated; woodwork solid walnut. 3991
  - Price .. each £3 10 0
  - 1926
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.275 - vue 294/555
- - 276 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TELEPHONES
  - TELEPHONE PARTS
  - TO SHOW CONSTRUCTION
  - 1927
  - 1927.—Table Telephone, with hand-combination, buzzer inside the box, flexible connecting cord and wall rosette. 3978
  - Price ...............................each £3 7 6
  - (Suitable for distances up to 200 yards.)
  - 1928.—Standard Pattern D o u b I e-p o I e “ Watch ” Receiver,
  - 40 ohms resistance, in nickel-plated metal case with electrose ear-piece, and including flexible connecting cord with metal tag-ends. 4021
  - Price .................13/6
  - 1929
  - 1929.—Standard Pattern D o u b I e-p o I e “ Ring ” Receiver,
  - 150 ohms resistance, with nickel-plated case and ebonite ear-piece, and including flexible connecting cord with metal tag-ends. 4023
  - Price .................17/6
  - 1931
  - 1931.—Bell’s Telephone. In Bell’s telephone a thin plate of iron is fixed in a frame immediately in front of a bar-magnet, the end of which is surrounded by a coil of fine wire. Any motion of this thin plate modifies the magnetisation of the bar, and causes a variation of the magnetic flux through the coil. The resulting induced currents pass into the coil of a second apparatus identical with the first, and cause corresponding changes in the magnetisation of the second magnet, and motions in the iron plate which are identical with those of the first, except as regards strength.
  - The system is perfectly symmetrical, and therefore reversible. The two apparatus—the transmitter and the receiver—are in reality two identical alternating current machines, the former acting as generator and the latter as motor ; the period continually varies from one moment to another, but at each instant is identical for the two. Experiments made by Lord Rayleigh on a telephone of this type show that a current of 4-4 x 10-8 amperes, alternating with a frequency of 640 times per second, was quite able to produce an audible sound when passed through it. For lower frequencies than this the requisite current is greater. Pair of Bell’s Telephones, made to take to pieces to show .construction. 4017 Per pair .. .. .. .. .. ..£176
  - (See “ Elementary Treatise on Electricity and Magnetism,” by G. Carey Foster, F.R.S., and Alfred W. Porter, B.Sc.)
  - 1930
  - 1930.—Pair of String
  - Telephones, for
  - demonstration purposes.
  - Per pair
  - 15/-
  - 1932.—Telephone Bar Magnets,
  - with adjusting screw. 4034
  - A. Length, 4 in. .. .. each 2/6
  - B. „ 5 in. .. .. „ 2/9
  - 1932
  - 1933.—Double-pole “Bell”
  - Receiver in nickel-plated metal case, with ebonite cover and ear-piece. Including flexible connecting cord with metal tag ends. 4026
  - Price
  - 16/~
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 277
  - w. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - COMMUTATORS, SWITCHES, PLUG KEYS
  - 1934.—One-way Plug Switch, best quality, mounted on ebonite base 4064 each 12/6 Ditto, on teak base 4062
  - each 6/6
  - 1934
  - For Lever Switches, etc., see page 282.
  - 1935.—Two-way Plug
  - Switch, best quality, mounted on ebonite base.4071
  - 1935
  - Each
  - £15 0
  - 1936
  - 1936.—Four-way Plug Key Commutator,
  - on ebonite base. 4075 Each............17/6
  - 1937.—P lug Key Battery Switches,
  - medium quality, ebonite bases. 4076
  - 1937
  - A. Two-way each 10/6
  - B. Three-way „ 14/-
  - C. Four-way „ 19/6
  - D. Six-way „ 27/6
  - 1938
  - 1938.—Plug Key Battery Switches, ebonite
  - bases, heavy make. 4077
  - A. Two-way .. . . . . . . . . each
  - B. Three-way . . . . . . . . . . „
  - C. Four-way . . .. . . . . .. ,,
  - D. Six-way .. .. .. .. .. ,,
  - 13/6
  - 22/6
  - 27/6
  - 37/6
  - 1939
  - 1939
  - 1939.—Cheap Commutator, for use without mercury. Designed by W. E. Cross, M.A., Headmaster of the King's School, Peterborough 4074 .. each 4/6
  - 1940. —Pohl’s Commutator, cheap make, for students’ use 4082 each 4/6
  - 1941. —Ditto, better
  - quality, com p»r i s i n g rocker with vulcanite handle, mercury caps,
  - 6 terminals, and connecting wires4083 each 6/6
  - 1942. —-Ditto, but on thick ebonite base, and nicely
  - finished 4084 . . . . . . each 17/6
  - 1943.
  - P o h I’s Commutator, “University " pattern, extra strongly made, and provided with raised sides to prevent loss of mercury. As made by us and supplied
  - to Prof. Poynting, of the Birmingham University. 4085 Price...........................................37/6
  - 1943
  - 1944.—R u h m ko rff’s Commutator,
  - mounted on ebonite base. 4086
  - Each........28/6
  - 1944
  - 1945.—Ruhm-korff’s Com-mutator,
  - “Unive rsity ” pattern for large currents of finest construction and workmanship. As made by us for Sir Oliver Lodge 4087
  - 1945
  - each 39/6
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 278 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - COMMUTATORS, MORSE KEYS, Etc.
  - 1946
  - 1946.—Bertin’s Commutator, best quality, on
  - ebonite base. 4088
  - Each ...............................£2 10 0
  - 1947.—Four-way Commutator, of substantial build and construction for physiological work. 4091
  - Each ............32/6
  - 1948
  - 1947
  - 1950.—Du Bois Raymond Key.
  - Stout ebonite base, 5 in. x 3 in. thick, all working parts in massive brass, with ebonite handle. The clamp below is also in brass. 4090
  - Price................each 30/-
  - 1950
  - 1951.—Single Contact or Press Key,
  - cheap make, on teak base 4062 .. .. each 4/6
  - medium quality, on ebonite base
  - 1953.—Ditto, superior make and finish, with heavy platinum contacts 40 6 4—
  - each 12/6
  - 1952
  - 1954.—Double Con-
  - tact or Press Key,
  - medium quality, on ebonite
  - base. 4065 Each . 25/- 1
  - 1954
  - 1955.—Double Con-
  - tact or Press Key,
  - superior make and finish, with platinum contacts. 4066
  - Each .. .. . . 37/6
  - (Price varies.)
  - 1955
  - 1948.—Professor Poynting’s Combined Tapping and Plug Key, as made and supplied by us to the Birmingham University. 4075 Each .. .. . . .. .. .. 14/6
  - 1949
  - 1949.—Morse Key, single current, G.P.O. pattern, polished brass fittings, with platinum contacts. 4106 Each ..................... ..£2 7 6
  - 1956/1958
  - 1956.—Morse Key, cheap make 4103 .. each 3/6
  - 1957 .—Ditto, better quality and larger size 4104—
  - each 7/-
  - 1958 .—Ditto, heavy make for wireless telegraphy 4105—
  - each 16/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.278 - vue 297/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 279
  - W. St J. GEORGE {LONDON), Ltd., PROPRIETORS.
  - TELEGRAPH INSTRUMENTS
  - FRONT. BACK.
  - 1959. —Model of Single Needle Telegraph,
  - with 6 in. needle, for demonstration purposes 4096—
  - each 27/-
  - 1960. —Telegraph Alphabet Cards 4097—
  - each 1 /6
  - 1961
  - 1961.—Pair of Morse Telegraphs, mounted
  - on wooden supports, showing the connection of one station with another. A splendid set for the lecture table.
  - Price, for best make . . .. per pair £15 0 0
  - FOR OTHER TELEGRAPHY INSTRUMENTS,
  - SEE “WIRELESS ” SECTION, PAGES 283 TO 299.
  - 1962.—M o r s e Writing A pparatus. This is a good working model, with clockwork action, stop-key, ink wheel, paper drum, etc., and will be found useful in connection with cheap wireless telegraph apparatus for recording messages.
  - Each .. £3 7 6
  - 1963
  - 1963. —Kemp’s Discharge Key, superior quality, with heavy platinum contacts. 4095
  - Each.................................£5 17 6
  - 1964. — Morse Sounder, with
  - low resistance coils, mounted on mahogany base.
  - Price, for best make .. 24/-
  - 1965. — Ditto, not so highly finished—
  - 21/-
  - 1966
  - 1966.—Morse Sounder, G.P.O. pattern, special shunt coil in base, combined resistance of coil and shunt = 20 ohms.
  - Price, for best make .. ... .. each £2 12 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 280 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - INDUCTION COILS
  - (See also next Page.)
  - 1967.—Ruhmkorff’s Induction Coils. Cheap
  - make, wound with silk-covered copper wire, with paraffin-wax insulation ; mounted on polished mahogany bases. 4155
  - Size
  - Length of Spark
  - A. Price, with ordinary Commutator
  - B. ,, ,, Ruhmkorff’s ,,
  - 1967
  - 12/6
  - B C D E F G H
  - i fV -nr :) 10 1 .•? 1 nr i£ in.
  - 15/- 19/6 28/6 42/- 55/- 80/- —
  - — • — 32/6 48/- 62/6 87/6 95/-
  - 1968
  - 1968.—Du Bois Raymond Coil. In this instrument the primary coil is fixed at one end of the polished mahogany base. In the primary, a coil of soft iron wire is surrounded with a coil of stout copper wire. The secondary coil is arranged to slide in the groove in the base, and can pass up to the end and surround the primary. The base board is hinged as shown, and unfolds to 1 metre in length. A metre scale passes over its full length. 4153
  - Good Substantial
  - 1969
  - 1969.—Ruhmkorff’s Coil,
  - make for general laboratory work, covered with ebonite, and fitted with platinum break, Ruhmkorff’s commutator, etc., as figured. 4154 Size.. ..A B C D E
  - Length of Spark 40 50 60 75 100 mm.
  - Price .. 110/- 135/- 157/6 190/- 230/-each.
  - Price ..
  - £6 5 0
  - 1970.—F. E. Becker & Co.’s Induction Coil, “ C. & S.” pattern, extra strongly made for colleges and schools. This coil has been specially designed by us for school use ; it will be found useful for several experiments, such as sparking eudiometer
  - tubes, vacuum tube experiments, etc., etc. It is of the highest quality and finish, having a spark length of 25 to 30 mm. It is furnished with condenser, special commutator, platinum break, and insulated spark collectors,
  - which may be removed when not
  - required. 4148
  - Price.......................£7 19 6
  - 1970
- p.280 - vue 299/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 281
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - INDUCTION COILS
  - 1971.—Induction Coils, guaranteed best make and well adapted for all general laboratory and X-Ray work, fitted with hammer type platinum contact breaker, commutator, discharging pillars and points, condenser, etc. Battery terminals are provided and also terminals for connecting a separate interrupter. Complete on highly finished polished mahogany base with polished ebonite standards, cheeks and cover for coil. All brass fittings lacquered. These coils can be worked off accumulators of voltages from io to 16 volts.
  - Cat. No. Spark length of coil, inches. 3 4 6 8 10 12 14 16
  - 1971. Induction Coils, as per specification and illustration above £17 10 £19 £24 £28 £35 £42 £50 £58
  - 1972. Induction Coils, as above, but fitted with variable primary windings £27 10 £31 £39 £44 £53 £62
  - 1973. Hammer Type Contact Breakers only, as fitted to the above coils, complete with platinum points £7 10 £7 10 £7 10 £7 10 £11 10 £11 10 £11 10 £11 10
  - 1974. Platinum Points only, as fitted to above Contact Breakers .. £2 15 £2 15 £4 £4 £7 5 £7 5 £7 5 £7 5
  - 1975.—Standard Pattern Induction Coils, for
  - use with both mercury and electrolytic interrupters (see page 306), and on voltages from 50 to 250. Secondary potential equivalent to a sparking discharge in air of :—
  - A. 12 inches...................................£32 10 0
  - B. 16 inches................................... 50 10 0
  - *C. 36 inches...................................101 10 0
  - * Note.—The H.T. pillars are not placed at a greater distance apart than 24 in. in order to reduce size of coil and unnecessary insulation.
  - 1976.—Condenser, in separate polished wood case, suitable for use with:—
  - A. 12-inch coil .. .. ........... .. .. ............
  - B. 16-inch coil ........... ..
  - C. 36-inch coil .................................................
  - £3 3 0 3 12 6 7 10 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.281 - vue 300/555
- - 282 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MICROPHONES
  - 1967/A. —Simple IVliCPOphone. A pointed rod of carbon, A, is in contact with two pieces of carbon, C and C1, fixed to an upright piece of wood. The carbon forms part of a circuit made up of the battery V, the line wire, and the telephone receiver. With a permanent current the telephone does not speak, but any movement of the carbon changes the resistance of the circuit, and, modifying the strength of the current, entails a displacement of the plate of the telephone. Experiment shows that, when a person speaks before the instrument, the vibrations communicated to it are transmitted to the plate of the telephone so as to reproduce the spoken words with greater or less distinctness.
  - Price, complete as figured
  - (See “ Elementary Treatise on Electricity and Magnetism,” by G. Carey Foster, F.R.S., and Alfred W. Porter, B.Sc.)
  - 8/6
  - 5
  - 5
  - 1967/A
  - 1968/B
  - 1968/B. — IVI icro-phone, skeleton type. Each .. . . 19/6
  - Resistance of—
  - Primary = 1 ohm Secondary=25 ohms
  - Each
  - 5/-
  - 1970/D.—Steel Staples, coppered, for indoor wiring.
  - Size f l | | 1 1 i ij 2 in.
  - Price 1/6 1/6 1/6 1/2 1/2 1/2 1/2 1/2 per lb.
  - LEVER SWITCHES
  - 1971/E.—Lever Switch, on solid walnut base,
  - one-way* . . each 1 /4
  - 1972/F.—Ditto, two-way „ 1/6
  - 1973/G.—Ditto, three-way .. „ 1/9
  - 1974/H.— Ditto, five-way „ 2/2
  - 1975/J.—Ditto, seven-way . . „ 2/6
  - 1976/k.—Lever Switch,
  - square, base, polished walnut, nickelled fittings, one-way.
  - Each ..................1/4
  - 1977/l.—Double Pole Change-over
  - Switch, mounted on walnut base.
  - Each .............................25/-
  - 1978/IVI.—Lever Switch, ebonite base, nickelled
  - fittings, one-way .. .. .. .. each 3/3
  - 1979/n .—Ditto, two-way .. .. .. ,, 3/9
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - F. E. BECKER &. CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 283
  - W. & J. GEORGE (LONDON). Ltd.. PROPRIETORS.
  - APPARATUS FOR THE RECEPTION OF
  - WIRELESS TELEGRAPHY AND TELEPHONY
  - The Marconi Unit System consists firstly of those parts which are essential to every Wireless Receiver, and secondly of a number of parts which may be added to the basic portions so that a highly sensitive and yet simple Receiver may be gradually evolved.
  - The neatly finished cases containing the various Units are uniformly made to stand side by side, the terminals being joined by short copper bars. There can be no mistake in joining up as the various pairs of terminals to be connected are immediately adjacent and opposite to one another. One Low-Tension Battery and one High-Tension Battery serve to feed all the Units.
  - Every portion of the Unit System is constructed with the same accuracy and care and all parts are interchangeable.
  - The various units are as follows :—
  - Unit i.—-Variable Condenser, capacity -ooi mfd. ,, 2.—Retroactive TUNER, 300-25,000 metres. „ 3.—HIGH-FREQUENCY AMPLIFIER.
  - „ 4.—AMPLIFYING DETECTOR.
  - ,, 5.—NOTE MAGNIFIER.
  - ,, 6.—-Telephone Transformer.
  - Special Unit.—High Frequency Unit, with reaction on Tuned Anode Circuit.
  - Unit 1, condenser ) Unit 2, Tuner ; and Unit 4, Detector, form the nucleus of the set and represent a very efficient single-valve combination.
  - When it is desired to increase the range and sensitivity of this combination, a Unit 3 high-frequency Amplifier
  - is connected between Unit 2 and Unit 4 in the straightforward fashion illustrated. This results in a very considerable increase in signal strength and the amplification factor per stage is higher and better sustained than with any other high-frequency device of an aperiodic nature.
  - Further Units of this type may be linked into circuit, the amplification being geometrically progressive.
  - In additionjo thus amplifying the signals or speech before passing the energy to Unit 4 it may be magnified after leaving the Detector by means of one or more Unit 5 Note Magnifiers. These give “ body ” to the signals or speech, and deliver a constant magnification factor—one that is not affected by the wave-length of the signals received.
  - It will be obvious that many different arrangements are possible.
  - Any number of high-frequency Units up to six may be used, while one, two, or three Note Magnifiers may also be employed. It will be seen that the high-frequency stages are more economical than the low-frequency stages, but it will be found that the installation of one Unit 5 following upon, say, two Units 3 will result in a greater amplification from the standpoint of audibility.
  - The terminal connections on all the instruments are so arranged that any of the Units may be connected into circuit by direct strapping with the copper pins provided (see illustration). The scheme of connection is quite clearly and simply indicated, and Units may be introduced into, or removed from, the circuit within a few seconds.
  - (Continued on next page.)
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 284 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & il. GEORGE {LONDON), Ltd., PROPRIETORS.
  - MARCONI UNIT SYSTEM APPARATUS
  - (continued)
  - THE MARCONI UNIT SYSTEM
  - Unit 1. 1980
  - Variable Condenser.
  - •ooi mfd. £4 0 0
  - Unit 4. 1983
  - Amplifying Detector
  - £4 5 0
  - With valve .. 5 0 0
  - Unit 2. 1981
  - Tuner.
  - 300-25,000 metres .. .. £13 15 0
  - Special Unit. 1984
  - For High-Frequency Amplification, fitted with full reaction and non-radiating .. £7 0 0 With valve .. .. .. 8 4 0
  - Unit 6. 1986
  - Telephone Transformer.
  - For 120 ohm ’phones .. .. £110 0
  - Unit 3. 1982
  - High Frequency Amplifier.
  - Fitted with 10 stud switch—
  - £5 0 0
  - With valve .. 6 4 0
  - Unit 5. 1985
  - NOTE.—We would draw the attention of customers in the United Kingdom to the fact that the above Unit System Apparatus can only be used under an Experimental Licence.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.284 - vue 303/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 285
  - w. & J. GEOROE (LONDON), Ltd., PROPRIETORS. '
  - MARCONI UNIT SYSTEM APPARATUS
  - (continued)
  - ADDITIONAL UNITS
  - The Units illustrated hereunder represent various combinations of the standard instruments dealt with in the previous pages. Whilst retaining the same efficiency factor it has been possible to manufacture them in a more compact manner. The terminal connections are arranged on the same lines as those of the individual units, to which they may be attached if desired.
  - Units 7 and 8. 1987
  - 1987. —Unit 7.—Comprises one High-Frequency Amplifier (Unit 3)> one Detector (Unit 4) and one Note Magnifier (Unit 5). This combination will be found particularly suitable for the reception of Wireless Telephony. Low transmission power is usually used in this branch of Wireless and consequently it is essential that the receiver should possess sensitivity of a very high order. This is only obtained by the introduction of high frequency amplification.
  - 1988. —Unit 8.—Is a combination of one Detector (Unit 4) and two Note Magnifiers (Unit 5).
  - While giving good all-round results this is more especially suitable for Telegraph reception. Since the signal currents are amplified after rectification the magnification factor is constant over all wave-lengths this is not the case when radio-frequency amplification is used.
  - Amplifier.
  - 1987. —No. 7 .. £14 10 0
  - 1988. —No. 8 15 10 0
  - “ R ” Type valves extra (see page 290).
  - Units 9 and 10.
  - Units 9 and 10.—Represent two and three cascaded Units 5 respectively. From the standpoint of compactness and ease of operation Units 9 and 10 present advantages.
  - 1990
  - Note Magnifier. Valves extra.
  - 1989.—No. 10, three valves .. £16 0 0 1990 .—No. 9, two valves .. 11 0 0
  - Apart from the Aerial System the only other accessories required for the Unit System are a 6-volt Accumulator and a dry-cell battery of ioo-volts, made up in two 50-volt sections. (For which see pages 214 to 218 and page 222 respectively.) The Accumulator is attached to the Tuner at the terminals marked. Make sure the positive ( + ) terminal of each battery is connected to the instrument terminal correspondingly marked. Leads should be taken from the terminals of the dry-cell battery to each of the Units, but care must be taken that these leads are not connected to the lo\V-tension terminals, or the valves will be irretrievably damaged.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - 286 F. E. BECKER & CO., IN I VO C HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WIRELESS RECEIVING SETS
  - FOR EXPERIMENTAL LICENCE HOLDERS ONLY
  - 1991
  - *1991.—4-Valve Experimental Receiving Set. This is an extremely sensitive and powerful Receiving Set. It contains four valves, one a high frequency amplifier, one a detector, and two note magnifiers. Each valve has a separate switch and its own control resistance, permitting the use of any desired combination of valves. The panels are ebonite of ample thickness. The stage of H.F. amplification magnifies the signals before they reach the second valve, enabling the latter to rectify weak signals which would otherwise remain undetected. This having once been achieved, the two last valves magnify the result so that it becomes strong enough in the Telephones or Loud-Speaker. The Tuner is contained in a separate unit provided with external coil holders for plugging in honeycomb coils. The cabinet contains a variable Tuning Condenser on the aerial circuit, a Vernier Attachment for fine tuning, and a Variable Reaction Condenser.
  - The results given by this set are remarkable. The various radio concerts can be received anywhere in the United Kingdom ; and within about 50 miles of any high-power Broadcasting Station music on a Loud-Speaker can be heard at a distance of several hundred yards from the instrument.
  - A. Tuner Cabinet £9 10 0
  - B. Amplifier 35 0 0 EXTRAS.
  - C. Set of 9 Tuning Coils, wave range 700 to 21,000 metres 4 10 0 Valves, High and Low Tension Batteries, etc. See Index.
  - D. Set of 4 Special Concert Coils, 160-900 metres 1 0 0
  - 1992
  - 1992.—Inductively Coupled Crystal Rece i V i n g Set, for Radio Speech and damped wave reception of very superior construction and highly efficient design. The ends of the Primary winding are matt finished ebonite, and the Secondary is finished in the same way with a stud switch operated by a laminated phosphor bronze arm. Two Condensers are provided of the continuously variable air dielectric type, with rotary aluminium vanes and ebonite top and bottom plates for the close tuning of the Primary and Secondary circuits, as well as a small mica and foil 'phone condenser. The latest type enclosed detector with a supersensitive Crystal Rectifier, together with a pair of 2,000 ohms telephones, make this an exceedingly fine set.
  - A. Price, complete..........£8 8 0
  - B. ,, but without variable condensers—
  - £6 6 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 2S7
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WIRELESS TELEGRAPHY AND TELEPHONY
  - In this and the following pages are illustrated and described Receiving Sets suitable for use in Educational Institutions, the higher priced ones naturally being most sensitive and having the longest range of reception. If desired, the usual head telephones may be dispensed with, and a Magna vox or other loud speaker employed to reproduce the sound, so that all may hear in comfort. This is rendered possible, even on the lowest power receiving set, by the use of a Magnavox Power Amplifier (see page 297), which magnifies the small current received until it becomes capable of vibrating even the stiff diaphragm of the loud speaker.
  - 1993
  - 1993.—Crystal Receiving Set (passed by the Postmaster-General, No. 130) may be used under a Broadcast Licence in Great Britain. One of the most efficient crystal receiving sets ever put on the market, having a range of about 25 miles for telephony reception, and a very extensive range for the reception of telegraphy.
  - The Aerial Tuning Device consists of an inductance, variable by means of tappings taken to Stud Switches, one each for coarse and fine adjustment of wave lengths. The Crystal Detector is furnished with the most sensitive of specially selected crystal, and allows of easy adjustment and contact to any part of the crystal surface.
  - An extra coil of the honeycomb type is provided with standard plug and socket for the reception of the Paris (Eiffel Tower) time signals. Coils giving other wave lengths may be inserted at will. (Prices on application.)
  - The equipment includes one pair of Double Head Telephones wound to a resistance of 2,000 ohms the pair.
  - The apparatus is mounted on an ebonite panel, and enclosed in a polished walnut case.
  - Price of complete instrument, including one pair Double Head Telephones and Paris time signal coil .. £6 17 6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 288 F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WIRELESS RECEIVING SETS
  - (FOR USE UNDER BROADCAST LICENCE IN GREAT BRITAIN)
  - 1994
  - Combined Crystal and Valve Receiving Sets.
  - This Receiving Set is an instrument with unique features ; it not only marks a distinct advance on all self-contained Single Valve Sets, but has a longer range than any two-valve set on the market. Range variable, from approximately 280 to 2,800 metres. The Radio Frequency Signals are impressed on the valve acting as a Radio Frequency Amplifier ; they are rectified by a Crystal Detector of unique design ; finally they are re-amplified by the same Valve acting as an Audio Frequency Amplifier. The result is a range of reception unachieved by any ordinary two-valve receiving set. The average reception range for British Broadcast, using standard P.M.G. aerial, is approximately 150 miles.
  - The Vertical Cabinet has folding doors, hinged top for access to valve, and detachable panel below for battery compartment. The instrument panel is mounted with a foolproof and dustproof special Crystal Detector having a novel adjustment, which is effected by means of a vertical milled wheel. Two Variometers of special design are mounted for tuning purposes, operating on 3 different ranges of wave length, which are controlled by a Drum Switch. Other items include a Filament Resistance with “ off ” position ; sockets for 2 pairs of Head Telephones ; and a valve-inspection window. The low temperature Valve to be used on this set is very economical and highly efficient, enablings. Low Tension Dry Battery to be used, which, with the High Tension Battery, is contained in the case. A panel at the back is provided with sockets for connecting to “ earth,” aerial and separate Low Tension Battery (if desired). All woodwork is walnut matt finished with oxidised fittings.
  - 1994. —Crystal and Valve Receiving Set, fitted in vertical cabinet, with folding doors, as described above, complete with a pair of Head Telephones (2,000 ohms), High and Low Tension Batteries, and all necessary Plugs and Cords.
  - Price ..........................................................................................£20 15 0
  - 1995. —Crystal and Valve Receiving Set, but fitted in sloping cabinet, with removable back panel for access
  - to valve and batteries, and without folding doors, complete with a pair of Head Telephones (2,000 ohms), High and Low Tension Batteries, and all necessary Plugs and Cords. Price .. . . . . .. . . . . £20 0 0
  - 1996. —1 Dull Emitter Valve for above .. .. . . . . . . . . . . £17 6
  - A Low Tension 2 Volt Accumulator, in teak case, may be used, if desired, instead of L.T. Dry Battery.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 289
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WIRELESS RECEIVING SETS
  - (FOR USE UNDER BROADCAST LICENCE IN GREAT BRITAIN)
  - 1997.—Two Valve Receiving Set, range 280 to 2,800 metres. This Two-Valve Receiving Set embodies all the most recent improvements and is the result of many years of experience. Its handsome appearance, superb finish, high-class workmanship and efficiency render it an ideal instrument for the reception of radio telephony signals.
  - The average reception range for British Broadcast, using standard P.M.G. aerial, is approximately 80 miles.
  - Specification.—Sloping Cabinet with removable back panel for access to valves and H.T. Battery. The instrument panel is mounted with a Variometer of special design for tuning purposes, operating on 3 different ranges of wave length, which are controlled by a Drum Switch shown on the left of the panel; on the right is mounted a Filament Rheostat with “ off ” position. Other items include sockets for 2 pairs of Head Telephones, and 2 valve-inspection windows. A panel at the back is provided with sockets for connecting to “ earth,” aerial and Low Tension Battery. All woodwork is walnut matt finished, with oxydized fittings.
  - 1997.—-Two-Valve Receiving Set, fitted in Sloping Cabinet, as described, complete with a pair of Head Telephones (2,000 ohms), High Tension Battery, and all necessary Plugs and Cords.
  - Price, without valves .. .. .. .. .. . . £20 5 0
  - 1997
  - 1998. —R. Valves (2 required)
  - each 15/-
  - 1999. —Low Tension Accumulator, in teak case—6 Volts, 30 amp. hrs. (actual) £2 12 6
  - 2000. —Alternatively, 6 volts, 44
  - amp. hrs. (actual) .. £3 7 9
  - 2001.—Two Valve Receiving Set, as No. 1997, but
  - with Vertical Cabinet with folding doors, hinged top for access to valves and detachable panel below for H.T. Battery compartment.
  - Price, without valves .. .. .. .. £21 0 0
  - 2001
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
  - T
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- - 290 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2002
  - R ” Type Valve.
  - THERMIONIC VALVES
  - MARCONI VALVES FOR RECEPTION
  - 2002. —“ R ” Type. For all-round purposes. Fil 3-8 volts, anode 50-100 volts
  - each 15/-
  - 2003. —“ V.24 ” Type. H.F. Amplifier or Cumulative Rectifier. Fil 5-2
  - volts, anode 30-50 volts.......................... .. each £1 6 6
  - 2004. —“ Q.X.” Type. H.F. Amplifier or Cumulative Rectifier. Fil 5-2 volts, anode 100-150 volts. Pure rectification with anode 30 volts .. each £1 12 0
  - 2005. —“ Q ” Type. For use after a number of H.F. Amplifications, pure
  - rectification being obtained on the lower bend of the characteristic curve. Fil
  - 5*2 volts. As. H.F. amplifier anode 150-200 volts .. .. each £1 15 0
  - 2003 2006.—“ F.E.1.” Special 4 electrode Valve for reflex working—
  - “V 24 "Type. each 2 0 0
  - SPECIAL LOW TEMPERATURE VALVES FOR RECEPTION
  - 2007. —Type L.T.1. Fil i-8 volts, -4 amp. anode 36-50 volts..............................each £3 0 0
  - 2008. —Type L.T.2. „ 35 „ n „ „ 36-50 „ ........................ „ 1 17 6
  - (Prices of valves for transmitting on application.)
  - TELEPHONES
  - 2009.—Double Head Telephone Receiver. A well constructed instrument, designed to give clear reproduction of Radio Telephonic speech and music. Each receiver is fitted with a double pole permanent magnet, adjusted to give concentrated action on a stalloy diaphragm.
  - The cases are of aluminium with swivel and trunnion movement, which, together with the smooth and well finished ear caps, ensures a perfectly comfortable fit to the ears, Adjustable coslettized steel headbands are supplied, which will not corrode or lose their shape. Each instrument is complete with 6 ft. of flexible cord and pin terminals. Weight 10 oz.
  - A. 120 ohms the pair (in series) . . . .• . . . . . . ..£126
  - B. 2000 ,, ,, ,, .... 14 0
  - C. 4000 ,, ,, ,, . . . . . . • . . . .. .. 15 0
  - 2009
  - 2010.—Marconi Standard Double Head Telephone Receiver. A
  - high grade instrument specially designed for wireless telephony and wireless telegraphy and pre-eminently suited to the former. The multiple permanent magnets are of a special shape and of the maximum length possible in the space available. The ends of the magnets are so disposed that the field is concentrated at the point required. Each pole piece is made from Stalloy laminations riveted together to form a solid mass. The case is of aluminium, with swivel and trunnion movement, affording a comfortable fit to the ear of the user. The headbands are of Duralumin and are adjustable. Each instrument is complete with 6 ft. of best-quality flexible cord. Weight 9^ oz.
  - (Manufactured under Brown’s Patent, 134353/18.)
  - No. 2010 (Double). No. 2011 (Single).
  - Resistance. Price. Resistance. Price.
  - A. 120 ohms the pair (in series) £1 17 6 A. 1000 ohms £1 1 9
  - B. 2000 2 0 0 B. 2000 ,, . . .. .. 12 9
  - C. 4000 ,, ,, ,, 2 2 0 C. 4000 15 6
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 291
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - FILAMENT RESISTANCES
  - 2012.—Rotary Filament Resistance,
  - designed for mounting on the panels of wireless receiving sets and amplifiers, and suitable for the control of one or two valves. The current is auto-2012 matically cut off
  - when the knob is turned to the extreme left, so that an additional switch for this purpose is not required. The spring contact finger will make contact-on each turn of the resistance coil, varying the resistance turn by turn over the entire range.
  - Each ....................................5/-
  - 2013.
  - Improved Form Filam e n t Rheostat,
  - patent "worm” pattern. This patent variable resistance is of
  - unique design and furnishes a remarkably smooth and even adjustment. The slate former is pivoted and by means of a spring is brought into firm contact with the copper worm. The resistance may be mounted in a vertical or horizontal plane, the brass frame being drilled to allow of either. Resistance 2-5 ohms, to carry 4 amps.
  - Each ................ .............15/-
  - 2013
  - TRANSFORMERS
  - 2014.—Intervalve Transformer, specially designed to meet the demand for an efficient intervalve transformer having the 2014 characteristics
  - essential for the avoidance of distortion and other undesirable effects in radio speech and music. Insulation between the windings and also between windings and frame, tested at 500 volt pressure.
  - Its production is based on long experience in the manufacture of kindred apparatus, and only the highest quality of workmanship and material is employed.
  - A. Intervalve transformer mounted on ebonite
  - base .. • • • • • • • • each £110 0
  - B. Ditto, but unmounted .. .. 15 0
  - 2015.—Telephone Transformer, suitable for use with low resistance telephones. Wound on ebonite former, with high 20x5 conductivity cop-
  - per wire of ample cross-section. Ratio between primary and secondary 13 : 1. Insulation between windings and between coil and frame tested to withstand 1,000 volts. The transformer is mounted on an ebonite base, having two strips on the underside for clearing connections, etc. Four terminals, two each for primary and secondary, are fitted. All brass parts polished and gold lacquered. Over all dimensions 4! in. x 2f in. x in. high.
  - A. Telephone transformer mounted on ebonite
  - base .. .. .. .. .. each £1 15 0
  - B. Ditto, unmounted .. .. .. ,, 17 6
  - 2016.—H i g h Frequency Trans-former. Range 150-24,000 metres, in nine stages with dead-end switch. Mounted on ebonite panel. 5 in. X 4 in. X £ in.
  - Price
  - £2 17 6
  - 2016
  - 2017.—High Frequency Transformer Bobbin. H.F.
  - transformers interchangeable to fit standard" R ” valve socket. Wound with 40 S.W.G. D.S.C. wire. Turned matt finished ebonite, fitted with 2017
  - four split pin contacts to take the standard valve socket. Most useful for making your own H.F. transformers. Diameter 2J in., £ in. slot, f in. deep.
  - Price
  - 37-
  - Primary and secondary wound in same groove, insulated from each other.
  - No. 0 Range 150 metres 6/-
  - „ 1 ,, 300 6/6
  - ,, 2 „ 600 6/9
  - „ 3 „ 1,200 7/6
  - » 4 „ 1,800 8/-
  - „ 5 „ 2,500 8/9
  - „ 6 6,000 10/6
  - .. 7 ,, 8,000 „ 12/6
  - „ 8 ,, 24,000 ,, 15/6
  - Intermediate wave lengths can be obtained by placing •0003 condenser across primary.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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- - 292 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WIRELESS ACCESSORIES—CONDENSERS
  - 2018A.
  - 2018.—Variable Condensers, can
  - be supplied “ A ” in celluloid boxes, “ B ” in polished wood cabinets, or “ C ” unmounted, as desired.
  - Capacity Mfd. A. PRICES. B c.
  - •0015 42/6 35/- 27/-
  - •OOI 38/6 27/6 24/-
  - •00075 32/- 22/6 21/-
  - •0005 26/- 18/6 19/6
  - •0003 23/- 17/6 17/6
  - •0002 21/- 16/- 15/-
  - •OOOI 18/6 15/6 12/-
  - •OOOO5 17/- 15/- 10/-
  - 2018B.
  - VARIABLE CONDENSERS. Best quality for precision work.
  - 2019. —Capacity -ooi mfd. With air dielectric. Ready for panel mounting.. .. .. .. .. £1 10 0
  - 2020. —Capacity -0005 mfd. With air dielectric. Ready for panel mounting .. .. .. .. 18 6
  - 2021. —Capacity -00025 mfd. Recommended for transformers and anode circuits arranged for H.F. amplification. Ready for panel mounting.. .. .. .. •. .. . • • • • • • • ..£170
  - 2022. —Capacity •0001 mfd. With air dielectric. Ready for panel mounting .. .. .. .. 15 0
  - Any of the above mounted in teak cases 10/- extra.
  - DOUBLE TYPE VARIABLE CONDENSER.
  - Best quality for precision work. -00025 mfd.
  - Double Condensers, specially recommended for Anode and Transformer circuits arranged for High Frequency Amplification. These condensers can tune two anode circuits simultaneously, thus obviating the tedious operation of “ searching ” over a wide range of wave lengths, but particular attention should be paid to the ease with which the two halves of the condensers can be connected either in series or in parallel, thus offering several different combinations of capacity.
  - The combinations obtainable are as follows :—
  - Series -000125. Single -00025. Parallel -0005.
  - cities: -ooi, -0015, -002, -003, -oooi, -00015, -0002, •00025, -0003, -0004, -0005 .. .. each 2/6
  - 2026.—Condenser Panels (3 Clip). Any
  - above values .. .. .. .. .. .. 10/6
  - 2023. —Price, complete .. .. .. £117 6
  - 2024. —Mounted in teak case, with three terminals.
  - Price ..£2100
  - For ACCUMULATORS, see pages 214 to 218.
  - „ HIGH TENSION BATTERIES, see page 222.
  - „ TERMINALS, etc., see pages 206 to 209.
  - „ WIRES, BARE AND INSULATED, see pages 210 to 213.
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 293
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WIRELESS ACCESSORIES—CONDENSERS
  - Dubilier Fixed Condensers (Type
  - 600). Designed primarily for use in receiving apparatus, to have minimum losses and therefore the highest possible efficiency. They are constructed with mica, the best dielectric known, and embody all the best features of condenser design.
  - In addition to small screw terminals of the usual type, these condensers are provided with metal tags, to which soldered connections can be made when they are installed as a permanent part of a receiving equipment or other instrument.
  - If the condenser is required for use in the grid circuit of a detecting valve, it is fitted with spring clips to carry a grid leak (see illustration), thus dispensing with the need for any separate holder for the grid leak. The use of the condenser is not, however, limited to valve grid circuits, as it may be employed in any part of the receiving circuit where a condenser is required. The condenser itself is enclosed in a moulded insulating case tested to 1,000 volts.
  - Dubilier Type 600 condensers can be supplied in any capacity between o-oooi and 0-005 microfarads, the capacities being accurate within 15 per cent.
  - PRICES.
  - 2027. —Capacities between o-oooi and o-ooi mfd. .. . . . . . . . . . . . . . . .. each 2/6
  - 2028. — ,, from o-ooi to 0-005 mfd... .. .. .. .. . .. .. .. ,, 3/-
  - 2029 —Condensers fitted with Grid Leaks . . . . . . .. . . .. . . . . . . . . ,, 5/-
  - 2030/2031
  - Dubilier Fixed Condensers (Type 600A). The terminals of the condenser are in the form of metal lugs, which are moulded with the insulating case, so that the external connecting wires can be soldered to them. Since there are no projections on the sides of these condensers any desired number of them can be mounted close up against each other without occupying much space on the instrument panel.
  - Can be supplied in any capacity up to 0-005 microfarad, the capacities being accurate within 15 per cent.
  - 2034
  - 2034.—The Dubilier Universal Condenser,
  - Type 577, for audio and radio frequency circuits, receiving equipment, self-rectifying circuits, direct current transmitters and other valve transmitters up to 100 watts ;
  - PRICES.
  - for grid condensers ; plate “ by-pass ” condensers ;
  - 2030. Capacities below o-ooi microfarad.. each 2/6
  - 2031. from o-ooi to 0-005 microfarad-
  - each 3/-
  - antenna series condensers, etc. Suitable for use in any circuit in which the D.C. voltage on their terminals does not exceed 2,000 volts D.C., or in which the low-fre-
  - 2032.—Grid Leaks, best quality for experi-
  - — ; ~1 mental work, etc.
  - A. 2-0 megohms .. each 2/6
  - B. i-5 „ „ 2/6
  - C. i-o ,, „ 2/6
  - D. -5 „ „ 2/6
  - 2033.—Anode Resistances, for wireless recep-
  - tion, best quality, 80,000 ohms.
  - Each .............................................2/6
  - quency alternating voltage does not exceed 1,000 volts A.C. The larger capacities in this type will carry radiofrequency currents up to 1 ampere, but should not be subjected to a greater radio-frequency voltage than 500 volts H.F. Capacities from o-oooi microfarad to o-oi microfarad and accurate to plus or minus 10 per cent.
  - Price (any capacity) .. .. .. .. each 7/6
  - Our stock of pure Chemicals and Acids is very considerable ,* hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 294 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WIRELESS ACCESSORIES
  - .......•?
  - 2036
  - 2035.—Adjustable Inductance or Tuning Coil. Wound with enamelled copper wire on insulated former with ebonite ends.
  - A. Single Slide, 9^ x 4 X 4 in. each 25/6
  - B. Double ,, 9I x 4 X 4 in. ,, 30/-
  - C. Single „ io| X 5* X 5i in. „ 30/-
  - D. Double „ io| X 5^ X 5^ in. „ 35/-
  - in illustration. The primary is variable sliders. Size 12 long, 4 in. diam.
  - 2036. — Double Purpose Sliding Inductance. Enabling direct Tesla or Oudin selection. The interior secondary is divided into sections, which are selected by means of the switch shown by use of the two ..£3 7 6
  - 2037.
  - Inductively CoupledTun-i n g Inductance. This Tuner has a wave length of approximately 400-1,200 metres. The entire insulated parts, with ,the exception of the base, which is mahogany, are of best matt finished ebonite, making it suitable for both crystal and valve use. Primary fitted with new type slider, and secondary tapped off in seven sections with rotary switch. Size of base, 14 in. X 5 in. Height, 7 in. Weight, 3^ lb. Price £2 15 0
  - 2037
  - 2039
  - 2039.—Honeycomb Type Inductance Coils.
  - No. of Turns. True Inductance Micro-Henries. Distri- buted Capa- city. Micro Farads. Wave lengths in Metres when shunted by CONDENSERS. Price each moun- ted.
  - F. •0005 mfd. G. •001 mfd.
  - 25 30-2 26 60-230 60-330 5/-
  - 35 60-3 34 85-340 85-470 5/-
  - 50 134 47 150-500 150-700 5/2
  - 75 297 38 200-750 200-1,050 5/6
  - 100 517 43 280-1,000 280-1,350 7/-
  - 150 1,151 3i 360-1,450 360-2,050 7/10
  - 200 2,150 28 470-2,000 470-2,800 8/8
  - 250 3,480 22 530-2,500 530-3,500 9/-
  - 3°° 4,980 27 700-3,000 700-4,200 9/5
  - 400 8,980 26 900-4,000 900-5,700 10/3
  - 500 14,510 25 1,150-5,200 1,150-7,250 10/6
  - 600 20,110 25 1,350-6,100 1,350-8,500 11/-
  - 750 32,300 22 1,600-7,700 1,600-10,800 11/10
  - 1,000 59,740 22 2,200-10,400 2,200-14,700 12/8
  - 1,250 91,830 22 2,700-13,000 2,700-18,200 14/-
  - 1,500 136,400 21 3,200-15,900 3,200-22,200 15/-
  - Note.—The above figures are based on exhaustive tests made by the National Physical Laboratories, and are therefore authoritative. By experience it has been found that with an average aerial the Aerial Tuning Inductance (A.T.I.) should be chosen from Column F. or G., and the-Reaction Coil should have from 2} to 3 times the number pf turns of the A.T.I. Coil.
  - 2038
  - 2038. — Universal Tuner. Can be used with equal efficiency as an inductively coupled tuner, a variometer or regenerative tuner.
  - It is an instrument for the most critical tuning, and will be found to give really first-class results. The utmost care has been taken with the insulation and all ebonite parts have been matt-finished to avoid surface leakage. Made in two ranges, 390 metres to 2,500 metres and 1,400 to 9,200 metres. Size, 6| in. X 6| in. x 7 in. Weight, 2 lb...................... ......................... Price £4 19 6
  - N.B.—To reach 2,500 metres a condenser of -0003 M.F. is required, and 9,200 metres a condenser of *00045 M.F.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.294 - vue 313/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 295
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WIRELESS ACCESSORIES
  - 2040
  - 2040.—Basket Inductances. These coils will be found highly efficient in service. Compactness is a feature of this style of coil. Efficiency is high, there being no losses owing to dead end effects.
  - WAVE LENGTH. Price each.
  - Aerial Circuit. Closed Circuit. ^ Reactance.
  - Min. Max. Min. Max.
  - A 350- 1,000 1/9
  - B 700- 2,400 — 35°~5>000 2/-
  - C 2,000— 5,000 1,400— 4,000 — 2/3
  - D 4,000— 9,000 — -— 2/6
  - E 8,000-18,000 — 4,000-22,000 3/-
  - F 12,000-25,000 10,000-22,000 — 3/6
  - G 23,000-30,000 500- 1,700 — 4/-
  - H 3,500-10,200 4/6
  - 2041. — Slab Pattern I n ductance Coils. These inductances will tune to the wave length given be-
  - 2042 low when used
  - with a variable condenser with a maximum capacity
  - of -ooi mfd.
  - No. 1 700-1,500 No. 5 3,800- 6,600
  - ,, 2 .. 1,200-2,200 „ 6 6,500-11,000
  - .. 3 .. 1,800-3,400 » 7 .. 10,000-14,500
  - » 4 .. 3,000-4,500 „ 8 • • 13,500-20,000
  - 2042. —Set of 8 coils 300 to 30,000 metres, .per set 23/6
  - 2043. „ 7 ,, 300 to 25,000 metres, .per set 21/-
  - 2051
  - 2051. Potentiometer, Patent "Worm” pattern, giving smooth and even ad-j ust m e n t. Resistance 200 ohms. Each .. 15/-
  - 2044.—T uning Inductance Holder. This instrument is designed for use with Basket Holder Tuning Inductances, and will be found exceedingly quick and easy to manipulate. The finish is of best matt-finished ebonite and polished mahogany. The best value in this
  - 2044
  - class of instrument on the market Price 25/6 Coils extra.
  - 2045.—Tuning I n ductance Holder. An*
  - except ionally well made and cleverly designed stand for Basket or Slab coils. A special feature is the method of making contact between the stand and the holder, which ensures maximum efficiency and facility in changing the coils. Matt finished ebonite throughout, with extended handles.
  - Price, wthout coils .. .. .. .. .. 25/6
  - 2045
  - 2046. —Valve Holders
  - for "R” Type Valves, ordinary circular pattern.
  - Each ..............1 /-
  - 2047. —Valve Holders*
  - for "R” Type Valves, as illustrated .. each 1 /6
  - 2048. —Valve Holders
  - for “V 24” Type Valves .. .. .. Each 2/-
  - 2049. —Horizontal Adapters for "V24” Type
  - Valves, enabling them to be fitted into “ R ” Type Holders ............... .. .. each 3/6
  - 2050. —Vertical Adapters for fitting "V 24 ” Type Valves into " R ” Type Holders each 4/-
  - For VALVES see page 290
  - If ACCUMULATORS see pages 214 to 218
  - 19 HIGH TENSION BATTERIES see page 222
  - If TERMINALS, Etc see pages 206 to 209
  - If WIRES, BARE AND INSULATED see pages 210 to 213
  - FOR POTENTIOMETERS, RHEOSTATS, ETC., FOR WIRELESS WORK, SEE PAGES 257 to 264.
- p.295 - vue 314/555
- - 296 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LOUD SPEAKING RECEIVERS
  - 2052.—“ Amplion ” Loud Speaker, a remarkably efficient electro-magnetic and acoustic combination. Weight, 2 lb.
  - A. 120 ohms .. .. £2 10 0
  - B. 500 ohms .. 2 10 0
  - C. 2,000 ohms . . 2 12 6
  - D. 4,000 ohms .. 2 15 0
  - 2055
  - 2055.—The “Sterling ” Loud Speaker
  - giving sufficient volume for all ordinary purposes, enabling a number of people to listen-in without the use of head telephones. It is particularly effective in regard to articulation and purity of reproduction. “ Sterling ” Loud Speaker, as illustrated, complete with 14-inch horn.
  - A. Resistance 120 ohms—
  - £6 0 0
  - B. Resistance 2,000 ohms—•
  - £6 2 6
  - 2053
  - 2053.—“Amplion” Loud
  - Speaker, improved design. Weight, 41 lb., diameter of trumpet 14 inches.
  - A. 120 ohms .. £5 2 6
  - B. 500 ohms 5 2 6
  - C. 2,000 ohms 5 5 0
  - D. 4,000 ohms 5 7 6
  - 2054
  - 2054.—“ Amplion ” Loud Speaker, with “Music Master” style horn and fine adjustment. Weight 41 lb., diameter 14 inches.
  - A. 120 ohms . . £6 0 0
  - B. 500 ohms . . 6 0 0
  - C. 2,000 ohms . . 6 2 6
  - D. 4,000 ohms . . 6 5 0
  - 2056.—The “ Magna vox ” Junior, a “ loud
  - speaking ” device which will reproduce concerts, lectures, speeches, etc., loudly enough to enable a large number to hear without the necessity of each member of the audience wearing a pair of head telephone s Magna vox Junior Loud Speaker is pre-eminent in ilu foregoing requirements and is acknowledged to be foremost in design, operation and efficiency.
  - The apparatus can be connected to a wireless set of any design and construction with good results; but to obtain that extra volume of sound for which the Magna-vox stands supreme, the use of a 2-stage power amplifier as described on next page is recommended.
  - A. Price complete, with step down transformer and 14-inch diameter spun copper horn, black enamel finish ...............................£8 0 0
  - B. Ditto, with 18-inch horn
  - £9 0 0
  - 2056
  - 2057.—The “ Magnavox ” Senior. A large, powerful Loud Speaker, the instrument for Extreme Volume, designed for large audiences, open-air reception, etc..
  - £15 10 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.296 - vue 315/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 297
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - POWER AMPLIFIERS
  - For use with the Loud Speakers on opposite page.
  - 2058. 2 valves. 2059. 3 valves.
  - 11 Magnavox n Power Amplifiers, designed for the amplification of wireless signals, giving speech and music free from distortion.
  - A feature of these amplifiers is that the output is entirely controlled by switches on the panels, thus avoiding the use of complicated connections to one, two or three valves. The switches operate the filaments and complete the output circuit to the Loud Speaker. A separate rheostat is provided for each valve, and the instruments are well finished in polished mahogany with polished bakelite panel and nickelled fittings.
  - 2058. —li Magnavox ” Two-valve Power Amplifier, as above, price (without valves) £16 16 0
  - 2059. —Three-valve Power Amplifier, as above (without valves) ...................22 0 0
  - 2060. — LS2 ” Valves extra ...................................................... . . each 1 15 0
  - Note.—A six volt accumulator should be used for filament lighting and the high tension battery (for plate) must be
  - from 100 to 300 volts.
  - When using a Magnavox Power Amplifier it is necessary to connect a Low Frequency Input Intervalve Transformer between the output of the receiving set and the input of the Power Amplifier.
  - LOW FREQUENCY AMPLIFIER UNITS
  - Low Frequency Amplifiers, these may be connected either to a crystal set with the necessary batteries, or to a valve receiver. One, two or three stages may be used, as desired, coupled together with the special connectors supplied. Ideal for the purpose of amplifying for loud speaker reproduction, or for increasing the audibility of a crystal set.
  - 2061 2062 2063
  - with 1 valve with 2 valves with 3 valves
  - £4 10 0 £8 2 0 £12 5 0
  - 2064.— R " Valves for above, extra .. each 15/-2065 «—Connectors for coupling . . . ,, 7/6
  - 2061 2062
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.297 - vue 316/555
- - 298 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WIRELESS ACCESSORIES
  - 2066
  - A
  - 2066.—Crystal Detector.
  - simple yet efficient detector fitted with crystal and fine wire contact. Mounted on ebonite base if in. x i| in. X j in.
  - Price ......................3/6
  - 2067
  - 2067.—Crystal Detector.
  - This is a simple yet effective type of detector for wire to crystal combinations and quite suitable for small stations. Mounted on polished mahogany base, complete with crystal. Size of base, 3! in. x 2f in. Price ....................7/6
  - 2068
  - 2068. —Carborundum Detector. A particularly efficient instrument of the Army type, mounted on ebonite and polished mahogany, complete with crystal. Size of base 4^ in. X 2f in. x \ in. Price 8/6
  - 2069. —Ditto, Twin Crystal
  - Type with switch for cutting out one crystal and bringing in the other. A very handy arrangement should one crystal fail during reception. Size of base, 5 in. X f in. x \ in. Price 17/6
  - 2070
  - 2070.—Morse Key, single current, as used by G.P.O. ; polished brass fittings, with platinum contacts.
  - £2 7 6
  - 2071/2073
  - 2071. —Morse Key, cheap make .. each 3/6
  - 2072. —Ditto, better quality and larger size ,, 7/-
  - 2073. —Ditto, heavier pattern .. .. ,, 16/6
  - 2074.—M o r s e Sounder, with low resistance coils, mounted on mahogany base. Price, for best make .. 24/-
  - 2075.—Selected Crystals for Detectors.
  - Bornite .. 1/- Iron Pyrites 2/-
  - Carborundum .. 1/- Manganese V-
  - Copper Pyrites .. 1/- Molybdenite 1 /-
  - Fused Silicon .. 1/- Zincite 2/-
  - Galena .. 1/- Woods Alloy for fixing 1/6
  - Hertzite 1/6
  - 2076.—Lever Switch,
  - mounted on ebonite base, one-way .. each 3/3
  - 2077 .—Ditto, two-way—•
  - each 3/9
  - 2078.—Lever Switch, on
  - solid walnut base, one-way— each 1 /4
  - 2079 —Ditto, two-way—
  - each 1 /6
  - 2080 .—Ditto, three-way—
  - each 1 /9
  - 2081 —Ditto, five-way—
  - each 2/2
  - 2082 •—Ditto, seven-way—
  - each 2/6
  - 2083.—D o u b I e Pole Double Throw Switch,
  - mounted on heavy ebonite base, 3$x 2§ X | in .. 12/-
  - 2084a.— Single Pole Double Th row Kn if e
  - 2083
  - Switch, mounted on ebonite. Suitable for earthing Aerial when not in use. Protects apparatus from lightning. Size, 3| X i| X f in. ..............................8/6
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.298 - vue 317/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 299
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WIRELESS ACCESSORIES
  - 2084.—Aerial Wire, 7/22 gauge hard drawn copper strand.
  - A. Per 100 ft. coil....................3/-
  - B. „ 140 „ ......................3/9
  - 2085.—L i g h t n i n g Arrester. Brass fittings on ebonite base. Fitted in aerial-earth circuit to protect apparatus.
  - Each...................12/6
  - REEL
  - PILLAR
  - SHELL
  - Aerial Insulators,
  - 2086 .—Reel Type, 2 in. dia. 2087.—Egg ,, i| X 1 in.
  - 2088A.—Spreader Type 1 x 1 in.
  - 2088b.
  - 2089.—Pillar 2090a.—Shell 2090b. 2090c. Galvanised
  - ,, i| X i-| in.
  - „ 2| X ij in.
  - ,, i| x ii- in.
  - „ 2|X2fin.
  - „ 3f X 4 in.
  - Iron Pulley Blocks
  - porcelain.
  - each 3d.
  - „ 3d.
  - „ 3d.
  - „ 4|d.
  - „ 6d.
  - „ 4|d.
  - „ 1/3
  - „ 2/8 .. V-
  - 2091.—Earth Clips.
  - For making rapid and efficient connection to water pipes, etc.
  - Each ...............2/8
  - Ditto, cheaper quality—
  - each 10d.
  - “WIRELESS TELEGRAPHY” LANTERN SLIDES
  - 2092 .—These slides are published by the kind permission of Sir W. H. Preece and Sir Oliver J. Lodge ; and those of the Marconi system and installations have been photographed with the kind assistance of the Wireless Telegraph and Signal Company.
  - Notes on this subject were published in the School World for November, 1901.
  - 1 Prof. H. Hertz. Portrait with Autograph.
  - 2 Standard Hertz Resonator.
  - 3 Prof. Oliver J. Lodge, D.Sc., F.R.S., etc. Portrait.
  - 4 Syntonic Leyden Jar Experiment.
  - 5 Spiral Wire Coherer.
  - 6 Diagram of Lodge’s Experiments with Receiver enclosed in
  - Metal.
  - 7 External view of Lodge’s proposed Syntonic Signalling Stations.
  - 8 Lodge’s Single-point Coherer and Diagrams of Coherer Circuits.
  - 9 Lodge’s and Muirhead’s improvements in Syntonic Telegraphy,
  - showing all connections for a complete station.
  - 10 Sir W. H. Preece, C.B., F.R.S., etc. Portrait.
  - 11 Diagram of apparatus for magnetic induction showing principle
  - of Preece’s system as adopted by the Post Office.
  - 12 Lodge’s Magnifying Telephone Devices showing details of magnet
  - and microphonic relay.
  - 13 Complete arrangement of Lodge’s Magnifying Telephones in
  - series.
  - 14 Signor Marconi. Portrait.
  - 15 Marconi’s Short-distance Apparatus.
  - 16 Marconi’s Receiver and Transmitter.
  - 17 Receiving Apparatus with cover removed.
  - 18 Wireless Telegraph Station at the South Foreland Lighthouse.
  - All Lantern Slides as above
  - 19 The Marconi Transmitter in the Lighthouse connected for tele-
  - graphing to Wimereux.
  - 20 The Receiving Apparatus at the Lighthouse connected up.
  - 21 The mast carrying the vertical wire at the South Foreland.
  - 22 Receiving a message at the South Foreland.
  - 23 The mast at the Wimereux station.
  - 24 Receiving a message from Dover at Wimereux station.
  - 25 Facsimile and transcription of Dot and Dash Message sent by
  - H.M. the Queen from Dover to Wimereux to the Mayor of Boulogne.
  - 26 Morse Printer.
  - 27 Morse Alphabet.
  - 28 Diagram showing Steady Flow of Energy.
  - 29 Portrait of Signor Marconi, taken at Poldhu.
  - 30 ,, ,, ,, on edge of cliff at Poldhu.
  - 31 Signor Marconi at work.
  - 32 „ ,, on one of the Towers at Poldhu.
  - 33 Wireless Telegraphy station at Poldhu.
  - 34 The Wireless Guidance of Torpedoes by Electric Waves (The
  - Orling-Armstrong Torpedo). <
  - 35 Wireless Telegraphy at Sea. The Italian Ship “ Carlo Alberto.”
  - 36 The Marconi Transmitter at Work.
  - 37 A Cruiser communicating with Squadron by Wireless Telegraphy.
  - I
  - ............................................each 2/-
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.299 - vue 318/555
- - 300 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - HERTZ ELECTRIC WAVES
  - 2093.—Set of Apparatus for Demonstration of Hertz Waves : —
  - (a) Sending station, consisting of a parabolic cylindrical mirror, small spark box with micrometer adjustment with oil
  - trough, as illustrated .. .. .. .. .. .. .. .. .. .. .. £10 0 0
  - (b) Receiving station, consisting of a parabolic cylindrical mirror with large coherer, as illustrated .. 6 5 0
  - (c) Frame, with parallel wires to be mounted in front of the sending mirror in three positions ; wires horizontal, wires
  - vertical, and wires under 450 to the focal plane of the mirrors .. .. .. .. .. 1150
  - (d) Metal plate to show reflection of electric waves .. .. .. .. .. .. .. .. 090
  - (e) Vertical galvanometer to demonstrate action of waves .. .. .. .. .. .. .. 7176
  - (/) Polarised relay, to make a second circuit, instead of the demonstration galvanometer, for connection of an incandescent lamp or an electric bell .. .. .. .. .. .. .. .. .. .. 550
  - (g) Reed pipe, adjusted to receiving station, to show the acoustic waves. By using the pipe the same effect can be got as by using the electric waves .. .. .. .. .. .. .. .. .. .. 110
  - Full instructions for use sent out with each complete set of apparatus.
  - TESLA’S HIGH FREQUENCY APPARATUS
  - 2094
  - 2094.—Tesla’s High Frequency Apparatus,
  - small size. The main apparatus consists of the transformer, the secondary and variable primary coil, Leyden jar, variable spark box of ebonite, and variable self-induction mounted on polished walnut base. The accessory apparatus are the same as stated for high frequency apparatus, No. 2095, but simpler and smaller, and without the items (/), (g), (h). Price of the complete set of apparatus as illustrated, with the accessory apparatus in cardboard box.. £14 15 0
  - 2095.—Tesla’s High Frequency Apparatus, “ Science School ” type. This apparatus consists of a transformer, with adjustable secondary and variable primary coil, spark box, and variable self-induction on oak base, and two large Leyden jars in oak case.
  - Price of complete apparatus as figured £21 10 0
  - For complete accessories for use with the above apparatus, see next page.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.300 - vue 319/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 301
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TESLA’S HIGH
  - FREQUENCY APPARATUS
  - Accessory Apparatus, for use with Nos. 2094 and 2095 on previous page.
  - (a) Two insulating stands to carry certain items, and
  - to be put on the table .. .. .. 39/6
  - (b) Two right angular wires to get brush dis-
  - charges .. .. .. .. .. 13/6
  - (c) Two conical rings for the same experiment.. 30/-
  - (d) Two high frequency fields .. .. .. 42/6
  - (e) One vacuum tube, 70 cm. long .. .. 8/6
  - (/) One vacuum tube, 30 cm. long .. .. 5/-
  - (g) One vacuum tube, bulb shaped .. .. 8/6
  - (h) One Tesla lamp, with chalk cone.. .. 21/6
  - (k) One wire ring, with two incandescent lamps to
  - obtain inductivity .. .. .. 27/6
  - (£) One incandescent lamp, with handle and wire, to show impedance .. .. .. .. 39/6
  - * If required, we can supply a really high-class induction coil, made specially for use with this apparatus. It is provided with a special quick-acting Deprez break, Ruhmkorff commutator, coil covered with ebonite, high terminals, and mounted on an elegantly finished mahogany base which carries the condenser. The self-induction and capacity of this coil are such that it will give sparks of great intensity, and it can charge big capacities. The length of spark varies from 140 to 170 mm. in length. This coil will also be found useful for showing Hertz waves, X-rays, and wireless telegraphy.
  - 2096.—Tesla’s High Frequency Apparatus, large size,
  - “ University ” type. This apparatus gives discharges astonishing both in their violence and force, and consists of a large battery of nine Leyden jars, spark box (adjustable) in glass cylinder, variable self-induction, arranged in transportable oak table, as figured. All connections are ready for use, so that only the inductor and the accessory apparatus or earth circuit have to be connected. On the table are placed the secondary coil and primary coil, and the latter
  - • can be placed in two different positions (a) in the centre of the secondary coil, for the use of the accessory apparatus, and
  - (b) at the foot of the 2096
  - secondary coil, in order to obtain especially strong discharges at the top end of the secondary coil.
  - Price of the complete apparatus, as figured. £60 0 0
  - Accessory Apparatus, of extra large size, suitable for use with the above “ University ” set:—
  - (a) Two insulating stands to carry certain items, and
  - standing on the level.
  - (b) Two right angular wires for brush discharges.
  - (c) Two conical rings for the same experiment.
  - (d) Two high frequency fields.
  - (e, f, g) Three vacuum tubes to obtain Tesla light.
  - (h) One Tesla lamp.
  - (k) One wire ring, with two incandescent lamps to obtain inductivity.
  - (/) One incandescent lamp, with handle and large wire to show impedance.
  - Price of complete set of accessories .. £19 10 0
  - Price........................................£26 10 0
  - 2097.—Apparatus for making Electric Waves visible (to be worked by the small set of Tesla’s apparatus, No. 2094). This set of apparatus comprises one resonance bobbin, 1 metre long ; one small helium tube ; one vacuum tube, 1 metre long ; also earth plate and handle for finding loops and nodes along the bobbin.
  - Price, complete.. .. .. .. .. £10 0 0
  - 2098.—Apparatus for making Electric Waves Visible (to be worked by the “ University ” and “ Science School ” sets of Tesla’s high frequency apparatus)—
  - (a) Large resonance bobbin (to be used as Seibt
  - bobbin), 2 metres long, constructed to take two parallel wires or a vacuum tube 2 metres long, which shows nodes and loops.
  - Price of bobbin without the tube .. £10 0 0
  - (b) Large vacuum tube, about 80 in. long £3 0 0
  - (c) Helium tube, for finding loops and nodes along the
  - bobbin .....................£2 10 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.301 - vue 320/555
- - 302 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - THERMO-ELECTRICITY
  - 2IOO
  - 2100.—Thermopiles of Bismuth and Antimony, with brass mount, ball and socket joint, support with rising adjustment and silver cone, guaranteed best make and finish. These piles are very carefully constructed from bars of antimony and bismuth connected up in series. The current proceeds from the bismuth to the antimony across the heated junction, the bismuth forming the positive. The insulation is very carefully attended to, and in use very great caution is required, the junctions being, from their nature, very brittle, and a fracture of any one of them renders the pile useless. The pile should be used with a very sensitive low resistance galvanometer, our No. 2102 being specially adapted for the 'purpose. 4195
  - Cat. Reference A B C D
  - No. of Pairs 12 20 24 40
  - Price 70/- 90/- 100/- 120/-
  - Cat. Reference E F G
  - No. of Pairs . • 54 60 90
  - Price.. 140/- 155/- 190/-
  - Note.—Our Thermopiles are guaranteed to be the most sensitive instruments procurable. The warmth from the hand placed within a few inches of the junctions will cause a deflection of from 5 to 10 degrees on one of our cheap low resistance galvanometers. Cheaper and unreliable Thermopiles cannot be recommended.
  - 2102.—Astatic Galvanometers, specially made for use with thermopiles 4196 .. .. each £1 12 6
  - 2103.—T h e r mo-
  - pi I e , simple form. If a number of copper and iron wires are joined together as figured, the free ends, A B, being connected to a galvanometer, a comparatively strong current will pass through the latter when one set of junctions is heated as shown. If the wires are thick, and the electrical resistance of the galvanometer is high, for a given difference of temperature between the hot and cold junctions, the deflection of the galvanometer will be proportional to the number of couples employed. 4197 Price ...................................3/3
  - 2104.—Bismuth and Antimony Bars, V-shaped, for showing thermo-electric current.
  - Mounted on nicely-finished brass support. 4199
  - Price .. .. ... .. 10/6
  - 2104
  - 2106.—Chain of Alternate Links of Platinum and Silver, for showing heating effect of
  - (See Edser’s “ Heat for Advanced Students.”)
  - 2105. — Bismuth and Antimony
  - Bars, V-shaped, for showing thermoelectric current. 4198
  - Per pair .. 7/-
  - current on different metals. Total length 36 in., with 3 in. links. 4203
  - Price .. .. 10/6
  - Price varies according to the market price of platinum.
  - 2107 .—Ditto, but 12 in. long, and with shorter links. 4204 (Price varies.) eac^ ®/“
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.302 - vue 321/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E;C.1. 303
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - THERMO-ELECTRICITY, VOLTAMETERS, Etc.
  - 2108
  - 2108.—Prof. Langley’s Bolo-
  - meter.—This instrument is designed to measure, the heat produced by the absorption of light (or, more generally speaking, radiation) corresponding to various parts of the spectrum. The instrument itself consists of a couple of gratings, punched from very thin platinum foil, and covered with a layer of platinum black. The thickness of the foil used only amounted to mm. These gratings form two arms of a Wheatstone's bridge, and the resistances in the remaining arms are so adjusted that, when both gratings are shielded from radiation, the galvanometer needle is undeflected. When radiation is allowed to fall on one of the gratings, its resistance instantly increases and a consequent deflection of the galvanometer occurs. A difference of temperature amounting to C. will produce a
  - readable deflection. Using this instrument, Prof. Langley was able to investigate the heat which reaches us from the moon. Price of the complete instrument mounted on brass upright with sliding rod. 4205 .. .. £4 10 0
  - (See Edser’s “ Heat for Advanced Students.’’)
  - 2109. —Joule’s Calori-
  - meter, simple form, consists of silvered copper calorimeter, with ebonite top, which carries German silver wire and stirrer ; the top has hole in centre for thermometer. Price, without thermometer 4209.. .. 9/-
  - 2110. —Ditto, larger size and better quality, with outer vessel of silvered copper insulated from inner vessel. Price, including finely divided and very accurate thermometer. 4210
  - £12 6
  - 2109/2110
  - 2111. —P e 11 i e r’s Apparatus, for the demonstration of heat and cold by means of the galvanic current, consisting of a differential thermometer, bulb of which contains a bismuth and antimony element, with divisions on milk glass, on polished wooden foot. Price, complete as figured 4211 .. £2 5 0
  - 2112.—C opper Volta-
  - meter, simple form, consisting of a circular glass trough carrying two hard teak cross-pieces, each fitted with a copper plate and terminal as figured. Size of trough about 6 in. high and 4 in. diameter. 4235
  - Price
  - 8/-
  - 2113.—Vo I tarn ete r for Mixed Gases,
  - Schuster & Lees’ pattern. The graduated tube is easily filled by slightly tilting apparatus on one side ; any excess liquid overflows into the side reservoir. Pressure always remains constant. We are sole makers of this apparatus.
  - Price
  - 2113
  - 18/6
  - 2114.—C opper Voltameter. In
  - this apparatus the two outer plates of copper form the anode, and the central plate is the cathode, which is much smaller than the anode plate. The plates hang from copper wires, C, which are supported by the two vulcanite rods, V and V'. The solution used is a 15 per cent, solution of copper sulphate, to each litre of which 5 c.c. of concentrated sulphuric acid have been added. The cathode is sufficiently large to allow 50 sq. cm. of surface for each ampere of current. 4233
  - Price complete, as figured .. .. • • 15/-
  - See H. E. Hadley’s “ Magnetism and Electricity for Students.”
  - 2114
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.303 - vue 322/555
- - 304 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - VOLTAMETERS
  - 2115
  - 2115.—Becker’s Improved
  - Apparatus for Decomposing Water into One Part of Oxygen and Two of Hydrogen,
  - with two stopcocks, bulb reservoir and platinum electrodes. We specially recommend this form of apparatus, as the platinum electrodes are fitted through india-rubber corks. This arrangement is a great improvement on the earlier patterns which have the platinum wires fused through the glass, and consequently are a continual source of trouble owing to the platinum loops breaking off.
  - A. Price, with plain limbs .. 19/6
  - B. Ditto, with the limbs gradu-
  - ated in ccms. .. .. 22/6
  - C. Special stand for above, with
  - adjustable clamp and support and with two terminals on base .. .. . . 10/6
  - 2116
  - 2116. —Apparatus for
  - the Decomposition of Water, “ Lecture Table ” pattern, consisting of a funnel-shaped glass basin having two platinum electrodes, each ending in a barrel-shaped terminal for connecting to wires of battery; two glass limbs suspended from hooks of sliding carrier ; mounted on nicely-finished metal stand with hooks and adjustable ring. Price, complete as figured .. .. 30/-
  - 2117. —Ditto, but limbs
  - graduated .. . . 35/-
  - 2118. —Dr. Classen’s
  - Apparatus for the elec-trolytical estimation of copper, consisting of platinum cone and spiral, and stand with adjustable clamp with binding screws.
  - (Price varies according to
  - the market price of platinum. Lowest price on application).
  - 2119. —Silver Volta-
  - meter, consisting of silver cone and spiral, and stand with adjustable clamp with binding screws.
  - The silver is deposited on a platinum cup from a solution of pure nitrate of silver in water. Greater accuracy is obtained than with the copper voltameter.
  - Price complete, as figured .. .. .. £118 6
  - 2120.—Voltameter for Mixed
  - Gases, “ Nivoc ” pattern, consisting of an accurately graduated tube open one end, and well ground-in stopcock at the other. Price, including insmolten platinum electrodes .. .. .. .. each 9/6
  - 2121.—Science Lantern Voltameter,
  - small size, with platinum electrodes and two brass terminals fixed to ebonite cover. The trough is made of finest white crystal glass.
  - 2121 Price, complete .. 15/-
  - 2122
  - 2120
  - 2122.—C opper V o I tarn eter, simple form, consisting of a sliding copper disc, copper basin mounted on polished mahogany base with upright and two terminals. Price complete, as figured .. .. .. 15/-
  - 2123.—Silver Voltameter, comprising adjustable silver anode clamped to a double terminal of special design which can be raised or lowered and clamped at desired height ; strong brass ring with terminal at side; with brass upright mounted on nicely finished slate base. This apparatus will take a platinum vessel measuring about 30 mm. high X 35 mm. diameter, and weighing approximately fths of an ounce. This voltameter is fully described in Watson’s “ Text-Book of Practical Physics.”
  - Price complete, as figured
  - 2123
  - .. £1 15 0
  - 2124.—Platinum Vessel for use with above, Price varies according to the market price of platinum.
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.304 - vue 323/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 305
  - W. & J. QEORQE (LONDON), Ltd., PROPRIETORS.
  - X-RAY APPARATUS
  - For Induction Coils for X-Ray work, see page 282.
  - 2125.—Wall Type Baseboard Mounting, as illustrated
  - and arranged to take high tension fittings as desired, complete with
  - fixing screws.
  - A. To take 12 in. coil .. . . .. .. ..£550
  - B. „ 16 „ „ .................. 6 2 6
  - 2125
  - 2126.—Adjustable Spark Gap, as
  - illustrated, calibrated in inches or centimetres, with control to work from distance.
  - 2127
  - 2127.—Series Spark Gap, for cutting out inverse current. Each .. .. .. .. . • • • • ..£250
  - £3 15 0
  - 2128
  - 2129. —Valve Tube Holder,
  - improved pattern . * £112 6
  - 2130. —Valve Tube Holder,
  - improved pattern, but arranged to I take two valve tubes on the one upright support .. £2 12 6
  - 2131. —Cover for cutting off light
  - from valve tube .. .. 4/-
  - 2129
  - 2128.— Adjustable Spark Gap, as 2132.—Discharging Pillars and Points, mounted on
  - illustrated, with dial indicator and handle wooden b t0 attach to coil base.£3 7 6
  - control ........ £4 15 0
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.305 - vue 324/555
- - 306 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - X-RAY APPARATUS
  - 2133/2134
  - 2133. —Electrolytic Interrupter, consisting of positive pole complete with 12 swg. platinum point, porcelain sleeve and holder with adjustment for amount of platinum exposed, negative lead electrode and glass container.
  - A. Single Pole .. .. .. .. . . .. ..£900
  - B. Double . .. .. .. .. 16 0 0
  - C. Triple ......................................... 23 0 0
  - (The prices of Electrolytic Interrupters are subject to alteration with the market value of platinum.)
  - 2134. —Silencing Cabinet, as shown, lined throughout with felt.
  - A. To take single or double pole interrupter .. .. £2 2 0
  - B. To take triple pole interrupter .. .. .. .. 2 5 0
  - 2135
  - 2135.—Auto-Magnetic Jet, fitted
  - with an auto-magnetic drive. The break is designed to work off any voltage of direct current supply, and is specially suitable for portable work. Interrupter requires 4 lb. of mercury.
  - Auto-magnetic jet type interrupter
  - as described .. .. .. £12 12 0
  - Control Switchboards,
  - for use with mercury or electrolytic interrupters.
  - Specification.
  - Double Pole Chopper Type Switch for Main.
  - Ammeter 6 inch Gravity Type, reading o to 50 amps.
  - Coil Control Switch, Patent No. 22547/11.
  - 9-Stud Resistance for regulating Primary Current.
  - Automatic Change-over Switch-gear from Mercury to Electrolytic Break (1 or 2 Pole) automatically adjusting the inductance of the Primary windings to suit the break in use.
  - Switch and Speed Regulator for Motor of Mercury Break.
  - Pilot Light and Switch.
  - Above fittings mounted on Polished Enamelled Slate Base with Terminals for connection to Coil, Mercury Break, Motor, Two-pole Electrolytic Interrupter, Mains and Foot Switch.
  - 2136.—Switchboard as detailed, for attaching to wall, for voltages up to no D.C. .. .. .. .. .. £42 Q 0
  - 2137.—Switchboard, as detailed, for attaching to wall, for voltages from no to 240 D.C. .. .. .. .. 45 0 0
  - The illustration shows the above switchboard without motor circuit for mercury
  - interrupter.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.306 - vue 325/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 307
  - W. & J. GEORGE (LONDON), Lid., PROPRIETORS.
  - X-RAY TUBES
  - 2138.
  - Becker
  - X-Ray Focus Tubes,
  - suitable for use with static machines and coils having spring or mercury breaks.
  - Length of spark .. .. .. 3-8 8-10 10-15 15-20 cm.
  - Diameter of bulb .. .. .. 65 80 100 no mm.
  - Price............................ 27/6 27/6 37/6 45/- each.
  - 2139.—X-Ray Tubes, furnished with standard regulating device. The regulator will be found to control efficiently the vacuum during the life of the tube. These tubes are suitable for all kinds of light work.
  - In order to obtain a sharper definition the anticathode is provided with a rim and the clean division of the fluorescence is very noticeable.
  - A. Diameter of bulb, 5^ in. .. each £3 5 0
  - B. ,, ,, 6 in. .. 3 10 0
  - C. ,, ,, 6J in. .. 3 15 0
  - D. „ „ 7 in 3 18 6
  - 2139
  - 2140.—X-Ray Tubes. These instruments are admirably adapted for use with installations where only a limited number of tubes are kept; they are moderate in price and suitable for all classes of work where medium currents are employed. Standard regulators are fitted to these tubes.
  - A. Diameter of bulb, 6 in.
  - B. „ „ 7 in.
  - C. ,, ,, 8 in.
  - £5 10 0
  - 5 15 0
  - 6 5 0
  - 2140
  - Oup Balances and Weights have achieved World-wide Reputation i vide Opinions of the
  - Leading Scientific Press.
- p.307 - vue 326/555
- - 308 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - X-RAY TUBES
  - 2141
  - 2141.—X-Ray Tubes. These tubes are one of the best designed and best constructed X-Ray Tubes on the market, and users can rely upon satisfaction in every way.
  - They are fitted with very heavy copper anti-cathodes of great heat-conducting capacity, which ensures the rapid absorption of heat and its radiation through the apertures in the upper part of the tube.
  - The target of tungsten or platinum-faced plate has unusual capabilities of resistance, thus the tubes are well suited for the heavy currents needed for instantaneous work, as for time exposures and screen work. It is desirable when ordering these tubes to state for which particular class of work it is required, so that a tube may be selected which will exactly meet the worker’s need.
  - These tubes are fitted with a standard regulator which may be operated without disconnecting the wires from the tube terminals.
  - With Platinum With Tungsten Target. Target.
  - Bulb 6 in. diameter .. £8 10 0 .. £9 5 0
  - ,, 7 in. diameter 8 15 0 .. 9 12 6
  - ,, 8 in. diameter .. 9 12 6 .. 10 7 6
  - When ordering, please state whether required with Platinum or Tungsten Target.
  - 2143
  - 2143.—Oscilloscope Tube, one to indicate the presence and amount of reverse current .. 17/6
  - Valve Tubes. For use with electrolytic breaks, cutting out the secondary
  - discharge and prolonging the life of the X-ray tube.
  - 2144. —Single Valve Tube ..................................£3 7 6
  - 2144A,—Double Valve Tube ................................... 6 0 0
  - 2145. —Triple, as illustration, for very heavy currents .. . . 8 15 0
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.308 - vue 327/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 309
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - X-RAY APPARATUS
  - Adjustable Tube Stand, for Radiography and Radio-Therapy. This tube stand has been specially designed to ensure ease of manipulation combined with rigidity. The tube box is supported on a rod which can be extended and rotated, both movements being locked by one clamp. This double movement is situated on the end of an arm on which moves a collar attached to another arm, the opposite ends of both arms being attached to a long collar moving on the upright of the stand. The upright is fitted on a heavy metal base, mounted on castors. When the tube box is placed in any desired position, it is automatically supported in that position, but clamps are provided to prevent any accidental movement being made.
  - 2146. —Tube Stand, complete with extension
  - tube, as illustrated .. .. .. .. £26 0 0
  - Treatment fittings as follows :—
  - 2147. —Pastille holder with lead backing .. .. 12/6
  - 2148. —Set of 4 aluminium discs, £, i, 2 and 3 mm. thick 6/3
  - 2149. —Fitting for attachment to tube shield for pastille holder to
  - slide in . . . . . . . . . . .. . . . . 8/3
  - 2150. —Adaptor to take treatment fittings .. .. £110
  - 2151. —Set of 5 glass stops, £, 1, i£, and 3^ in. diam. £2 15 0
  - 2152. —Set of 4 aluminium filters, 1, 2 and 3 mm. thick 16/6
  - 2153. —3-peg diaphragm for ringworm treatment .. £14 9
  - 2154. —Complete set of treatment fittings as above . . £7 4 3
  - 2155
  - 2155.—Tube Rack, complete with iron supporting end brackets, felt lined slots for tubes and finished in ebonised wood. To take 6 tubes.. .. .. .. £1 15 0
  - 2156 .—Ditto, to take 4 tubes .. .. 17 6
  - 2161.
  - 2162.
  - 2163.
  - 2164.
  - 2165.
  - 2166.
  - glass
  - 2167.
  - head
  - ili/iiillnHiiillllllSillllililllllliilijlyiih
  - 2157.—Protective Lead Rubber Apron,
  - large size, as illustrated . . . . .. £4 12 6
  - 2158 —Ditto, small size .. . . .. 3 0 0
  - 2159.—Protective Lead Rubber Gloves,
  - lined fabric, short pattern, medium size.
  - Per pair ..£1180
  - 2160 —Ditto, long pattern, with gauntlet to elbow. Per pair ........................£2 2 0
  - Protective Material.
  - —Lead rubber sheet, 4-7 density, canvas one side.. .. per lb. 4/-—Ditto, with canvas both sides .. .. .. . . ,, 4/3
  - Supplied in 1-5 mm. and 2-5 mm. thickness.
  - Lead Glass.
  - Density 3-8. Thickness approximately 4 mm.
  - —Price .. .. .. .. .. per square foot £15 0
  - —Specially selected.. .. .. .. .. .. .. 200
  - Lead Sheet in any thickness.
  - Price .. .. .. .. .. .. .. .. per lb. 8d.
  - Protective Lead Glass Spectacles.
  - —Protective lead glass spectacles, fitted with metal frames and large lead eyepieces .. .. .. .. .. .. per pair £110
  - Protective Face Mask.
  - —Protective face mask, fitted with lead glass eyepieces, and adjustable strap...........................................each £2 17 6
  - 2157
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.309 - vue 328/555
- - 310 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - X-RAY APPARATUS
  - 2168
  - Fluorescent Screens, extra thickly coated, for direct observation. The screens are the best quality obtainable, and the prices include a cardboard case for the protection of the screens. Prices are subject to the fluctuations of the market.
  - 2168. —White Salt Type.
  - Size. Screen only.
  - A. 7 x 5 in. .. .. £1 15 0
  - B. 10 x 7 in............ 3 5 0
  - C. 12 x 9 in............ 5 0 0
  - D. 16 X 12 in............ 9 10 0
  - 2169. —Barium Platino Cyanide Type.
  - Screen with Lead Glass Cover.
  - £2 9 6 4 5 0 6 10 0 12 5 0
  - A. 7 x 5 in. £3 5 0 . . £3 19 6
  - B. 10 X 7 in. 6 10 0 . 7 14 6
  - C. 12 x 9 in. 10 0 0 . 11 11 0
  - D. 16 x 12 in. 19 0 0 . . 21 17 6
  - 2170.—Intensifying Screens, for reducing exposures. These are made of materials which, on being placed under the influence of the X-rays, fluoresce blue, and assist in producing a photograph rapidly. They are a great improvement on any yet produced. They are flexible, and the grain is as fine as that of the photographic plate, and the best yet produced.
  - N.B.—The glossy side of the screen is placed next to the film on the plate, and must be kept in close contact.
  - 4t X 6| in. . . each £0 18 0
  - 6| X 8i in. 1 8 0
  - 8 x 10 in. . . 1 15 0
  - 10 X 12 in. , . „ 2 10 0
  - 12 X 15 in. „ 3 15 0
  - 2171
  - 2171 __Metal Handles for screwing on to the
  - fluorescent screens to protect the hands of the operator.
  - Per pair £110
  - 2172 .—Ditto, detachable pattern „ £1 10 0
  - 2173. —Fluoro-
  - SCOpe, made of thin wood, covered with leather, fitted with flexible eye apertures to exclude light.
  - To take screens 7x5
  - in. .. £1 18 6
  - To take screens 12
  - in. .. £2 19
  - 2161
  - 2174.—Cassettes, for use with intensifying screen and plate or two screens and duplitized films.
  - N.B.—The only satisfactory cassette for use with duplitized
  - films.
  - A. 10 in. X 8 in. .. £2 10 0
  - B. 12 in. X 10 in. 2 18 0
  - C. 15 in. X 12 in. 3 12 0
  - 2175.—Photographic Dry Plates, special quality for X-ray work, of the following makes : Ilford,
  - Imperial, Wellington, Barnet, or Paget, all makes same
  - price. Ordinary Double
  - Packing. Envelopes.
  - A. 4I x 31 in. .. 2/9 .. .. 3/3
  - B. 5 x 4 in. 4/6 5/3
  - C. 6i X 4f in. .. .. 6/- .. 6/9
  - D. 7x5m... 7/6 8/9
  - E. 8| X 6| in. .. 11/6 .. 13/-
  - F. 10 X 8 in. .. 19/- .. .. 21/3
  - G. 12 X 10 in. .. 28/- .. .. 31/3
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.310 - vue 329/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 311
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - VACUUM TUBES
  - Geissler’s Vacuum Tubes. These are made of various combinations of white, uranium, and other glasses, and when used in conjunction with our Induction Coils or Wimshurst Machines give most interesting and spectacular effects. Especially so is this the case with those tubes which contain phosphorescent substances, liquids, and artistic designs.
  - 2180. —Set of Geissler Tubes, each 8 in. long, assorted
  - shapes and colours, fitted in case, with hinged glass cover
  - and commutator .. .. ,. .. each £3 15 0
  - 2181. —Ditto, containing 6 tubes, each io in. long.
  - Each ..................................................£4 5 0
  - 2182. —Ditto, containing 6 tubes, each 12 in. long.
  - Each ..................................................£4 10 0
  - 2180
  - Geissler’s Tubes of
  - white and uranium glass, any design as illustrated.
  - Each.
  - 2183. -8 cm. long 1/2
  - 2184. —io „ ., 1/4
  - A B
  - Geissler’s Tubes, any design as illustrated, in white and uranium glass, giving excellent effects. 2185.—12 cm. long .. .. each 1/9 2187.—16 cm. long *
  - 2186—14 „ .................................... 1/10 2188.-18 ...............................
  - (For Supports and, Rotating Apparatus, see page 319.)
  - each 2/-
  - „ 2/2
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.311 - vue 330/555
- - 312 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GEISSLER’S VACUUM TUBES
  - (See page 319 for Supports and Rotating Apparatus for these tubes.)
  - Geissler’s Tubes, made of white and uranium glass in any design, as illustrated.
  - 2189. —20 cm. long .. _ each 2/6
  - 2190. -25 „ „ „ 3/6
  - 2191. —30 „ „ „ 4/-
  - 2192. —40 „ „ „ 7/6
  - 2193. —50 „ „ „ 14/-
  - A B C D E
  - 2194.—Geissler Tubes, cylindrical, with designs blown inside, five different shapes.
  - Length
  - about 8 10 12 14 16 18 20 30 cm.
  - Each .. 1/9 2/- 2/2 2/4 2/6 3/- 3/9 7/6
  - 2195.—Set of Four Cheap Geissler Tubes,
  - each 4 in. long, complete in cardboard box.
  - Per set .. .. .. .. .. 5/6
  - IMPROVED FORM GEISSLER’S TUBES
  - A new departure in Vacuum Tubes. They are composed of different-coloured glass tubing and give very effective and beautiful lights ; particularly the ruby, which produces the greatest effect, surpassing all other light rays.
  - 2196
  - 2197
  - 2196. —Geissler Tubes, of five different kinds of glass, green, violet, ruby, yellow and blue. The effect produced by this composition is splendid, in three shapes.
  - Length about .. ..............10 12 16 20 25 30 40 cm.
  - Each................................. 2/2 2/10 3/10 5/9 7/- 10/6 15/-
  - 2197. —Geissler Tubes, as above, cylindrical form, figures blown into tubes, in three shapes.
  - Length about . . ..................... .. ..12 16 20 30 cm.
  - Each...................................................... 3/6 4/6 7/- 13/6
  - 2198. —Geissler Tubes, as above, but filled with blue or green fluorescent liquids, brilliant effect.
  - Length about.. ***'ti"r .... .. .. .. 12 16 20 30 cm.
  - Each......................................................5/6 6/- 8/6 15/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.312 - vue 331/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 313
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SPECIAL SETS OF GEISSLER TUBES
  - FOR DEMONSTRATION PURPOSES.
  - 2201.—Demonstration Set of Geissler’s Vacuum Tubes, containing four tubes, about 15 cm. long, in cardboard case, the set consisting of:—
  - 1 tube containing fluorescent liquid. 1 tube of white and uranium glass.
  - 1 ,, ,, phosphorescent substance. 1 ,, with uranium glass cup.
  - Price, per set complete .. .. .. .. . . .. .. .. .. .. 11/6
  - 2202 .—As above, but tubes 20 cm. long .. .. .. . . .. per set 19/6
  - 2201 / 2202
  - 2203.—Demonstration Set of Geissler’s Vacuum Tubes, containing six tubes, about 25 cm. long, in cardboard case, consisting of:—
  - 1 tube containing fluorescent liquid.
  - 1 ,, ,, phosphorescent substance.
  - xi ,, of white glass with uranium glass ornaments.
  - 1 ,, containing two gases
  - 1 ,, ,, mercury, rendered luminous by shaking.
  - 1 ,, ,, mercury salts, changing their colour by heating.
  - Per set, complete .. .. .. .. .. .. .. .. .. .. .. .. .. ..£1150
  - 2204.—Demonstration Set of Geissler’s Vacuum Tubes,
  - containing seven tubes, about 20 cm. long, in cardboard case, consisting of :— tube containing fluorescent liquid (green or blue radiation).
  - ,, ,, phosphorescent substance (post radiating orange or green).
  - ,, made of five different kinds of tubing (ruby, blue, green, yellow and violet).
  - ,, containing two gases.
  - ,, ,, mercury, rendered luminous by shaking.
  - ,, ,, mercury salts, changing their colour by heating.
  - 1 ,, showing stratified light.
  - Price, per set complete .. .. .. .. . . .. ..£1196
  - 2204
  - 2205
  - 2205.—Demonstration Set of Geissler’s Vacuum Tubes,
  - containing seven tubes, about 35 cm. long, in cardboard case, the set consisting of :—
  - 1 tube containing two fluorescent liquids.
  - 1 ,, ,, two phosphorescent substances.
  - 1 „ of white glass with uranium glass ornaments.
  - 1 ,, containing two gases.
  - 1 ,, ,, mercury, rendered luminous by shaking.
  - 1 ,, ,, mercury salts, changing their colour by heating.
  - 1 ,, showing stratified light.
  - Price, per set complete.. .. .. .. .. .. .. £2 19 6
  - Tube 3 in five different kinds of coloured glass instead of in white and uranium glass,
  - 1/9 per set extra.
  - 2206.—Vacuum Tubes, filled with different fluorescent liquids
  - Length about 8 10 12 14 15 16 18 20 25 cm.
  - Each.. .. 1/9 2/- 2/2 2/9 3/- 3/3 3/6 3/10 4/9
  - With one liquid.
  - 2207 •—Ditto, with two liquids.
  - Length about .. .. 20 35 cm.
  - Each ....................6/6 8/6
  - 2208 —Ditto, with three liquids, about 55 cm. long.
  - Each ........................................25/-
  - 2206
  - 2208
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.313 - vue 332/555
- - 314 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GEISSLER TUBES
  - SPECIAL PATTERNS, GIVING MOST BEAUTIFUL EFFECTS.
  - 2209 2210
  - 2216
  - 2217
  - 2211 2212 2213 2214 2209.—Geissler Tube, "Gridiron” pattern, 8 in. high 22x5 .. each 7/6
  - 2210.— » " Vase ” „ • • .j 7/6
  - 2211.— i) " Harp ” ,, ,, „ 7/6
  - 2212.— jj “ Rosette ” ,, ,, CD
  - 2213.— jj " Star ” ,, ,, • • „ 7/6
  - 2214.— jj " Four-Spiral ” „ ,, • • „ 7/6
  - 2215.— jj " Heart ” „ „ CD
  - 2216.— “ Loop & Spiral”,, ,, •• „ 7/6
  - 2217.— jj “ Eye ” „ ,, .. „ 7/6
  - ABODE
  - 2218.—Geissler Tubes, oval bulbs, with designs blown inside, in five different shapes, on polished wooden stands.
  - Height about .. 18 25 30 cm.
  - Each ..............7/- 14/- 18/6
  - 2219 .—As above, but extra large and strong, about 50 cm. high, on polished wooden stand.
  - Each ..........................£3 10 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.314 - vue 333/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 315
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2220
  - VACUUM
  - 2221
  - 2222
  - TUBES
  - Extra Large Vacuum Tubes, on stands, very effective, made of white and uranium glass, in three different shapes, as illustrated, on polished wooden stands.
  - 2220. —Shape of a lyre, about 30 cm. high, on
  - polished wooden stand .. .. .. each 27/6
  - 2221. —Shape of a grill, about 35 cm. high, on
  - polished wooden stand.. .. .. each 27/6
  - 2222 .—With four spirals and two loops, about 35 cm. high, on polished wooden stand., each 27/6
  - VACUUM
  - 2223
  - 2224
  - TUBES CONTAINING LIQUIDS
  - 2225 2227
  - FLUORESCENT
  - 2228 2230
  - Each.
  - 2223. —Geissler Tube, containing one fluorescent liquid and two loops of uranium glass, about 35 cm. long 14/-
  - 2224. — ,, ,, containing one fluorescent liquid and two uranium glass spirals, about 35 cm. long 14/-
  - 2225. — ,, ,, containing one fluorescent liquid and spiral, on polished wooden stand, 20 cm. long 10/6
  - 2226. — ,, ,, containing one fluorescent liquid and spiral, on polished wooden stand, 30 cm. long 12/-
  - 2227. —Geissler Tube, U-Shaped, containing two fluorescent liquids, on polished wooden stand.
  - Height about .. .. .. .....................12 15 25 40 cm.
  - Each ......................................................6/9 If- 10/- 25/6
  - 2228. —Geissler Tube, U-shaped, containing two fluorescent liquids and two spirals, about 30 cm. high, on polished
  - wooden stand .. .. .. .. .. .. .. .. .. • • • • • • • • • • each 27/6
  - 2229. —Geissler Tube. As above, but with cups in the bulbs instead of the spirals .. .. ,, 27/6
  - 2230. —Geissler Tube, containing two fluorescent liquids, one bulb with spiral and two bulbs with uranium glass
  - figures, about 55 cm. high, on polished wooden stand........................................... each £2 10 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.315 - vue 334/555
- - 316 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GEISSLER TUBES FILLED WITH FLUORESCENT
  - LIQUIDS
  - SPECIAL PATTERNS, GIVING VERY PRETTY AND BRILLIANT EFFECTS.
  - 2231. —Geissler Tubes, U-shape, containing four liquids, on polished wooden stand.
  - Height about.................15 20 25 30 cm.
  - Each.........................10/6 16/- 19/- 25/-
  - 2232 .—Ditto, but extra large and strong, about 50 cm. high, on polished wooden stand .. .. .. .. .. • • each £3 7 6
  - 2233.—Geissler Tubes, with four limbs, two tubes containing fluorescent liquids and coloured ornaments, the other two tubes with
  - figures of coloured glass, 15 cm. high .. .. .. .. 14/-
  - 2234. —Ditto, 20 cm. high .. .. .. .. .. each 27/6
  - 2233/2234
  - 2235.—Geissler Tube, containing two fluorescent liquids, 8 in. high .. .. .. .. each 9/6
  - 2236 .—Ditto, containing four fluorescent liquids.
  - Each.......................................15/-
  - 2237 .—Ditto, containing one fluorescent liquid.
  - Each.......................................10/6
  - 2238 .—Ditto, containing one fluorescent liquid.
  - Each .. .. .. .. .. .. .. 10/6
  - 2239. —Geissler Tube, containing three fluorescent liquids each 15/-
  - 2240. —Ditto, containing two fluorescent liquids .. .. each 10/6
  - 2241. —Ditto, containing two fluorescent liquids .. .. each 9/-
  - 2242. —Ditto, containing two fluorescent liquids .. .. each 11/-
  - 2243. —Ditto, containing one fluorescent liquid .. .. each 11/-
  - 2239 2240
  - *2241 2242 2243
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.316 - vue 335/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 317
  - w. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PHOSPHORESCENT VACUUM TUBES
  - 2249
  - 2244 2245 2246
  - 2244.—Tube containing phosphorescent rose-twig, bulb 6-5 cm. diameter .. .. .. each 14/_
  - 2245 .—Ditto, containing phosphorescent parrot, bulb
  - 6-5 cm. diameter .. . . . . .. each 10/6
  - 2246 .—Ditto, containing phosphorescent butterfly,
  - bulb 6-5 cm. diameter . . .. .. each 10/6
  - 2247. —Tube containing phosphorescent beetle, bulb
  - 6-5 cm. diameter .. .. .. .. each 10/6
  - 2248. —Ditto, containing phosphorescent bee and
  - flower, bulb 6-5 cm. diameter . . .. each 15/-
  - 2249 .—Ditto, containing phosphorescent bouquet.
  - A. Small size .. .. .. .. each 22/6
  - B. Large size .. .. .. .. ,, 38/6
  - LARGE VACUUM TUBES WITH LUMINOUS MINERALS, Etc.
  - 2250
  - 2251
  - 2250. —Tube containing coral; showing most beautiful colours, bulb 12 cm. diameter .. .. each 23/6
  - 2251 .—Ditto, containing five different phosphorescent minerals, bulb 12 cm. diameter .. .. each 30/-
  - 2254
  - 2252
  - 2253
  - 2252.—Tube, containing five different phosphorescent minerals, bulb 17 cm. diameter .. .. each 70/-
  - 2253 —Ditto, containing phosphorescent flowers and radiometer, bulb 13-5 cm. diameter, very effective.
  - Each ...........................................60/-
  - 2254.—Tube, containing phosphorescent shells, calcspar, etc. .. .. .. .. .. .. each 19/6
  - 2255 2258/2259 2256
  - 2255.—Vacuum Tube, 6 in. long, containing one 2258.—Vacuum Tube, 8 in. long, containing two
  - phosphorescent substance .. .. .. each 4/6 phosphorescent substances .. .. .. each 7/6
  - 2256 .—Ditto, 10 in. long, containing one phosphor-.2259.—Ditto, 14 in. long, containing two phosphorescent substance ...................................each 7/6 escent substances..........each 11/-
  - 2257.—Vacuum Tube, 20 in. long, containing four phosphorescent substances ..............each 24/-
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.317 - vue 336/555
- - 318 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PHOSPHORESCENT VACUUM TUBES
  - SHOWING MOST BEAUTIFUL NATURAL COLOURS.
  - A B C
  - 2260.—Small Vacuum Tubes, containing
  - phosphorescent flowers, stones, corals, butterflies, birds, beetles, etc. Height about 15 cm.
  - Each . • • • •• • • • • • • • • 7/6
  - 2261
  - 2262
  - 2263
  - 2264
  - 2261. —TU be, containing artificial ruby 37/6
  - 2262. — ,, ,, phosphorescent butterfly 30/-
  - 2263. — „ ,, mineral 7/6
  - 2264. — „ ,, ,, flower .. 7/6
  - RADIOMETERS
  - 2265
  - 2266
  - 2267
  - 2268
  - 2265.—Radiometer, Crooke’s single, with
  - blackened mica wings, on polished wooden stand—
  - ’ each 8/6
  - 2266 .—Ditto, double pattern, with vanes rotating in
  - opposite directions; mounted on wooden support, height about 23 cm................each 21 /-
  - 2267 .—Ditto, double cylindrical pattern each 21/-
  - 2268.—Electric Radiometer, with two side
  - electrodes and radiating cross of wings, for weak current, on polished wooden stand .. .. each 13/6
  - 2269
  - 2274
  - 227172272
  - 2269.—Electric Radiometer, with rotating mica cylinder, on polished wooden stand.. £2 7 6
  - 2270 .—Ditto, with two semi-cylindrical wings, on
  - polished wooden stand .. .. .. 15 0
  - 2271 .—Ditto, with four phosphorescent wings, beautiful radiation, on polished wooden stand .. £18 6
  - 2272 .—As above, but smaller size .. 11/6
  - 2273 .—Ditto, extra large, diameter of bulb 17 cm.
  - £2 17 6
  - 2274 .—Ditto, with fixed aluminium cross and movable
  - disc, on polished wooden stand .. .. £112 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.318 - vue 337/555
- - F. E. BECKER & CO., NIVOC HOUSE, HflTTOIM WALL, LONDON, E.C.1. 319
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SUPPORTS AND ROTATING APPARATUS FOR
  - VACUUM TUBES
  - 2275. —Geissler Tube, with two liquids and uranium glass bulb in centre, about 50 cm. long—
  - each 17/6
  - 2276. —Geissler Tube, with two liquids and spiral in the uranium glass bulb, about 50 cm. long—
  - each 23/6
  - 2277. —Geissler Tube, with two liquids, three uranium glass bulbs and spirals, about 75 cm. long—
  - each 37/6
  - 2278. —Rotation Apparatus, for hand-driving,
  - with three tubes filled with fluorescent liquids as figured. Price complete .. .. £8 15 0
  - 2275 2276 2277
  - 2278
  - 2279/2280
  - 2279. —IVlotor, fitted with vacuum
  - tube rotator. This combination is very useful for lecturers, students, or for drawing-room entertainments. The rotator has adjustable holders for tubes up to 5 in. .. .. .. .. each 17/6
  - 2280. Ditto, for tubes up to 9 in.—
  - each 30/-
  - ADJUSTABLE SUPPORTS FOR VACUUM TUBES.
  - These Supports will take Vacuum Tubes of any length up to 12 inches.
  - 2281.—Adjustable Support, on tripod foot, for one vacuum tube—
  - each 18/6
  - 2282 —Ditto, ditto, for 2 vacuum tubes . .. „ 22/6
  - 2283— „ 3 „ 25/-
  - 2284— „ 4 „ 30/-
  - 2285— „ 6 „ 39/6
  - 2286.—Apparatus for
  - ' vacuum tubes.
  - Price, including stand No. 1341 and holder No. 1342 .. 9/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.319 - vue 338/555
- - 320 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - VACUUM TUBE SUPPORTS
  - 2291. —T wo Stands, insulated with glass rods, about 50 cm. high, can be used for
  - the smallest as well as for the largest tubes. Price, complete (but without tube) per pair 37/6
  - 2287.—Stand, for sets of demonstration vacuum tubes (see page 313), arranged for four tubes, about 20 cm. long .. each 27/6
  - 2288 —Ditto, for six tubes, about 25 cm. long .. ,, 40/-
  - 2289 —Ditto, for seven tubes, about 20 cm. long .. ,, 40/-
  - 2290 —Ditto, for seven tubes, about 35 cm. long .. ,, 48/-
  - (The above prices do not include the tubes.)
  - FLUORESCENT LIQUIDS, Etc.
  - 2292.—Sets of Phosphorescent Substances, very high intensity, in sealed glass tubes, each 10 cm. long, phosphorescing different colours after exposure to daylight.
  - A. Set of 3 tubes, complete in velvet
  - lined case 13/6
  - B. „ 5 „ „ 19/6
  - C. „ 7 „ „ 30/-
  - These post-radiating substances are produced from the purest raw material, and they are extremely difficult to make. They should not be confused with somewhat cheaper substances on the market which give only a very weak radiance. The name of the substance is burnt in on each tube.
  - 2293.—Dark Chamber
  - for examining phosphorescent tubes, complete with set of seven tubes containing phosphorescent substances.
  - 2293
  - The substances are first exposed to daylight for about one minute. The lid is then closed, the tubes then being in a dark-room and the post radiation can be easily observed.
  - Price, complete .. .. . . .. .. .. .. £2150
  - 2294.—Sets of Fluorescent Liquids, in sealed glass tubes, each 10 cm. long, fluorescing different colours, mounted in polished wooden case with two hinged sides.
  - Complete in case.
  - A. Set of 6 tubes .. 19/6
  - B. „ 8 „ .. 29/6
  - C. „ 10 „ .. 32/6
  - D. „ 12 „ .. 37/6
  - 2295.—Blue Radiating Powder (Balmain’s luminous paint).
  - Per 10 grammes .. .. . . .. .. .. .. .. 3/-
  - Per 100 „ ................................ .. 15/-
  - 2296.—Phosphorescent Substances, loose, same as contained in tubes No. 2292 .................per gramme 3/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.320 - vue 339/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1. 321
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - VARIOUS VACUUM TUBES
  - TUBES CONTAINING MERCURY.
  - 2297
  - 2297. —Vacuum Tube, 8 in. long, containing mercury, and which is illuminated by shaking each 8/6
  - 2298. —Ditto, 10 in. long ,, 9/6
  - 2298a.- Ditto, 14 in. long .. . . ,, 10/6
  - FRICTION TUBES.
  - ..."
  - 2299
  - 2300
  - 2299. —Vacuum Tube, 20 in. long ; illuminated by
  - rubbing with silk, 1 spiral .. .. each 13/6
  - 2300. —Ditto, ditto, 2 spirals ,, 16/6
  - TUBES SHOWING STRATIFICATION.
  - 2301
  - 2301. —Vacuum Tube, 8 in. long; showing
  - stratification .. .. .. .. .. each 5/6
  - 2302. —Ditto, 14 in. long ; showing stratification—
  - each 9/6
  - 2303 .—Ditto, 20 in. long ; showing stratification—
  - each 12/6
  - 2303a .—Ditto, 40 in. long ; showing stratification—
  - each 19/6
  - 2304
  - 2304. —Vacuum Tube, 8 in. long, showing stratification more strongly and more distinctly—
  - each 8/-
  - 2304a. —Ditto, 20 in. long. .. .. ,, 22/6
  - 2305. —Ditto, 40 in. long.............. ,, 45/-
  - 2306
  - 2306. —Vacuum Tube, 24 in. long, with bulb of uranium glass, showing stratification each 18/6
  - 2308
  - 2308.—Vacuum Tube, 40 in. long; showing stratification, special quality, with bulbs and spiral of uranium glass .. .. .. .. each 32/6
  - 2309 .—Ditto, extra large, 60 in. long .. ,, 63/-
  - TUBES CONTAINING GASES.
  - 2312
  - 2310.—Tube, 8 in. long, containing two gases, each gas showing a different colour .. .. each 7/6
  - 2311 —Ditto, 12 in. long, containing two gases—
  - each 10/6
  - 2312 —Ditto, 30 in. long, containing three gases—
  - each 30/-
  - 2312 a .—Ditto, 40 in. long, containing three gases—
  - each 39/6
  - TUBES CONTAINING GASES AND WHICH REMAIN PHOSPHORESCENT FOR A SHORT TIME AFTER ELECTRIC DISCHARGE HAS BEEN STOPPED.
  - 2313
  - 2313.—Tube, filled with post-radiating gases, " wave ” shaped, about 60 cm. long .. .. each 28/6
  - 2314.—-Tube, “ Single Wreath ” pattern, mounted on wooden support .. .. .. .. each 28/6
  - 2315 .—Ditto, “ Double Wreath " pattern ,, 55/-
  - 2307 .—Ditto, 40 in. long, with bulbs of uranium glass, showing stratification ..................... „ 27/6
  - Every requisite for Chemical, Physical, and Bacteriological^ work supplied, from a test tube to the complete furnishing of the largest laboratory.
  - x
- p.321 - vue 340/555
- - 322 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DE LA RIVE’S APPARATUS
  - De La Rive’s Apparatus to show the action of a magnet on the electric discharge in rarefied gases.
  - If the tube is placed on an electro-magnet the thread of light thus produced rotates in the same direction as the current which runs through the coil.
  - 2316. —Tube only, of white glass
  - 2317. — „ ,, uranium glass
  - 2318. —Electro-mag net, as illustrated
  - 2319.—
  - on base with switch
  - each 16/6 „ 19/6
  - „ 14/6
  - „ 33/
  - 2316, 2317 and 2319
  - 2316, 2317 and 2318
  - CROOKES’ TUBES
  - 2320
  - 2320.—Set of Three Tubes, made of uranium, German and English glass, each on polished wooden stand .. • • • • • • per set of three 19/6
  - 2321
  - 2321.—Five Phosphorescent Tubes, made
  - of glass, each phosphorescing a different colour, viz. green, yellow, blue-white, blue and red per set 55/-
  - 2322
  - 2322.—Vacuum Tube to demonstrate the Crookes’ dark space, on wooden stand .. .. each 16/6
  - 2323 .—Ditto, smaller size .. .. ,, 10/6
  - 2324 .—Ditto, extra large, about 7 cm. diameter—
  - each 35/-
  - 2325.—Tube, to prove that radiant matter extend in a straight line .. .. . • • • each 16/6
  - 2326 2327
  - 2326. —Low Vacuum Tube, for showing phos-
  - phorescence and rectilinear spreading of the cathode rays. Mounted on foot .. .. .. each 17/6
  - 2327. —High Vacuum Tube ) the discharge takes the form of a continuous spark. Mounted on foot—
  - each 19/6
  - Oup Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.322 - vue 341/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 323
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CROOKES' TUBES
  - 1 2328.—Tube, with semi-cylin-
  - drical negative pole, causing the rays to come to a focus and then diverge .. .. .. 17/6
  - 2328
  - 2330
  - 2330.—“ Dark Space ” Tube, for illustrating the mean free path of the molecules.
  - Price, not including stand .. .. .. ..17/6
  - 2332.—Shadow and Stencil Tube, with
  - aluminium cross showing shadow caused by placing a solid body in the molecular stream, also for showing that radiant matter alters in some way the surface of the glass where it strikes. Large size.
  - Each..............................25/-
  - 2333.—R a i I w a y
  - Tube, for demonstrating the strong mechanical action of radiant matter. Suitable for projection on the screen by means of a lantern .. 38/6
  - 2333
  - 2329.—V acuum Tube,
  - showing the intensity of the heat in the focus of concave negative pole ; using a very moderate current, the strip of platinum placed in the focus of the concave cup is readily brought to a white heat.
  - £18 0
  - 2331’
  - 2331.—Vacuum Tube, containing assorted brilliantly phosphorescing minerals such as calcium sulphide, various kinds of shells, foraminiferous marble coral, Iceland spar, etc.
  - Price, not including stand .. .. .. .. 19/-
  - 2334. —Shadow and Stencil Tube, Crookes'
  - Fleming’s, without magnet .. .. each 29/6
  - 2335. —Ditto, specially large .. .. ,, 55/-
  - 2336. —Electro Magnet, spool shaped to fit
  - tube No. 2334 .. .. .. .. each 30/-
  - 2337 .—Ditto, to fit tube No. 2335 .. ,, 35/-
  - Note.—The shadow can be turned right or left by turning the magnet coil, according to the direction in which the current runs through the coil.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.323 - vue 342/555
- - 324 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CROOKES’ TUBES
  - 2338
  - 2338.— Mica Wheel Tube, for illustrating the deflection of radiant matter by the magnet. When the rays are deflected, the wheel may be made to rotate to the right or to the left; suitable for projection on the screen by means of a lantern.
  - Price, not including magnet . . .. .. £118 6
  - 2339.—Vacuum Tube, with
  - concave mirror, for illustrating the heating effect of the cathode rays concentrated in the focus of the mirror. The lecturer may prove this by using a magnet to deflect the focus so as to fall on the side of the tube, thus causing the coating of wax previously applied to melt.
  - Price, including wooden support—
  - 15/-
  - 2339
  - 2340
  - 2341
  - 2340.—Potash High Vacuum Tube,
  - for illustrating the dependence of the phosphorescence of the glass on the degree of exhaustion. We do not guarantee these tubes to act satisfactorily after the first time. Price, including support.. .. .. 27/6
  - 2341.—Vacuum Tube, with semi-cylindrical cathode.
  - Price, including wooden support .. 14/6
  - 2342
  - 2342.—Low Vacuum Tube, for illustrating the deflection of radiant matter by an electro-magnet. Price, not including electro-magnet .. .. .. 9/-
  - 2343.—Vacuum Tube, for illustrating that radiant matter in high vacua is entirely deflected by an electromagnet. With this tube the lecturer may (by means of the caustic potash) vary the vacuum and thus show the influence of different degrees of exhaustion on the deflection.
  - Price, not including electro-magnet .. .. 27/6
  - 2344
  - 2344.—Vacuum Tube, to demonstrate that two bunches of equal cathode rays repel each other, with polished wooden stand .. .. .. 32/6
  - 2345
  - 2345.—Vacuum Tube, for illustrating the deflection of radiant matter by an electro-magnet. The negative terminal has a disc cathode in front of which is a mica screen with a small hole in the middle. When the current is passed, a molecular discharge takes place and is made visible by means of a longitudinal phosphorescent screen. By bringing an electro-magnet under the tube, the line of discharge can be drawn down and can be made to wave about as the electro-magnet is moved to various positions.
  - Price, including support ..........................25/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.324 - vue 343/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 325
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PULUJ’S TUBES
  - 2346
  - 2347
  - 2348
  - 2349
  - 2350
  - 2346. —Puluj’s Shadow Tube, with light and
  - dark cross. Price, including wooden support .. 27/6
  - 2347. —Puluj’s Tube, for demonstrating the conduction of heat in mica and its corresponding phosphorescence. Price, including wooden support 27/6
  - 2348 .—Ditto, for demonstrating the phosphorescence in electrical shadows. Price, including wooden sup-port .. .. .. .. .. .. . . 27/6
  - 2349.—Puluj’s Electrical Radiometer, with
  - rotating mica cylinder. Price, including wooden support .. .. .. .. . . 47/6
  - 2350 —Ditto, with phosphorescent vanes. Price, includ-ing wooden support . 28/6
  - 2351
  - 2352
  - 2354
  - 2355
  - 2351. —Puluj’s Electrical Radiometer, with semi-circular vanes. Price on polished wood support
  - 22/6
  - 2352. —Ditto, with phosphorescent rotating disc and fixed vanes. Price, including wooden support 32/6
  - 2353. —Ditto, with two sets of phosphorescent vanes
  - (each phosphorescing different colours and rotating in opposite directions) and one fixed disc. Price, including wooden support .. .. .. .. .. 55/-
  - 2354.—Puluj’s Phosphorescent Lamp,
  - mounted on wooden support . . .. .. 25/6
  - 2355 •—Ditto, extra large, bulb shape .. each 57/6
  - The luminous substance in these tubes is so bright that one can easily read by its light.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.325 - vue 344/555
- - 326 F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PULUU’S TUBES
  - 2356
  - 2356.—Puluj’s Tube, for demonstrating that the
  - cathode rays, at high vacuum, can only pass through the tube in one direction, as they are influenced by the static charge of the glass walls.
  - Price, including wooden support .. .. .. 25/6
  - 2357
  - 2357.—Puluj’s Valve Tube each 17/6
  - The discharge can only run in one direction as it will be influenced by the static discharge on the glass walls.
  - HERTZ’
  - 2358
  - 2358.—Hertz’ Tube, made of uranium glass, with electrodes, for demonstrating Herzian waves.
  - Each ..........................................7/6
  - VACUUM TUBE
  - EXHAUSTED TO THE HIGHEST DEGREE.
  - /rflTlTiT! ITIVI i'i Wii’lYl'M'll'nTntrnrlTiTITli'i i'i-i'b* '-n hrirHitrirriTM+riTlTminfftv
  - c\>— " - -
  - 2360
  - 2360.—Vacuum Tube, exhausted to the highest degree to prove that a discharge cannot take place under these conditions, length 14 in. .. each 30/-
  - TUBES
  - 2359
  - 2359.—Hertz’ Tube, with brass loops for measurements.. .. .. .. .. each 8/6
  - 2361.—Hittorf’s Tube,
  - on large polished wooden stand.
  - Each ................38/6
  - In these tubes the current runs over the longer distances, the static electricity prevents a discharge at the points of the electrodes.
  - 2361a .—Ditto, but small, without stand each 10/-
  - EBERT’S TUBES FOR HIGH FREQUENCY ALTERNATING CURRENT
  - 2362.—E b e rt ’ s Cylindrical Discharge Tube, straight.
  - Price
  - .. 9/-
  - 2364.—Ebert’s Cylindrical Discharge Tube, with fixed and movable electrode, mercury pack-
  - B*
  - 2363.—Ebert’s Wide Tube, with
  - bulbs at ends.
  - Price.....................14/6
  - mg. Price .
  - 19/6
  - 2365.—Ebert’s Twin Tube,with
  - parallel connection.
  - Price.......................17/6
  - 2366.—Ebert’s Four-w a y Tube, with central pump tube. Price.. .. .. 17/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.326 - vue 345/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 327
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2367. —Tesla Vacuum Tube, without electrodes;
  - bulb about 12 cm. Price, mounted on foot .. 8/6
  - 2368. —Ditto, with one electrode. Price, mounted on
  - foot .. .. .. .. .. .. each 10/6
  - 2369 .—Ditto, with one electrode and phosphorescing cross .. .. .. . • •. . • each 14/-
  - 2370. —Tesla Vacuum Tube, with phosphorescing mineral. Price, mounted on foot each 18/6
  - 2371. —Ebert’s Phosphorescent Lamp, with
  - two electrodes. Price, mounted on foot each 24/6
  - 2372
  - 2372.—Tesla Rectangular Tube, mounted on foot .. .. .. .. .. .. each 8/6
  - 2373
  - 2373.—-Tesla Tube, “ Snake ” pattern, about 10 in. long..................................each 4/6
  - 2373a. —Ditto, “Snake” pattern, about 20 in. long-
  - each 7/6
  - 2373b. —Ditto, “ Snake ” pattern, about 40 in. long—
  - each 10/6
  - 23 77
  - 2377.—Tesla Rectangular Tube, “Loops and Spiral ” pattern ; mounted on foot. .. each 13/6
  - 237S
  - 2378.—Tesla Tube, without electrodes, showing white or red light, length 16 in. .. .. each 6/6
  - 2379
  - 2379.—Tesla Tube, without electrodes and furnished with tinfoil rings, length of tube 16 in. each 7/6
  - 2374
  - 2374.—-Tesla Tube, without electrodes, showing white or red light, length 20 in. .. .. .. .. .. .. each 6/6
  - 2375 .—Ditto, without electrodes, showing white or red light, length
  - 30 in..............................................each 8/~
  - 2376 •—Ditto, without electrodes, showing white or red light, length
  - 40 in. .. .. .. .. .. .. .. .. each 9/6
  - 2380
  - 2380.—-Tesla Lamp, with fine carbon thread and layer of tinfoil each 13/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.327 - vue 346/555
- - 328 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS. _____________
  - CROSS’S VACUUM SCALE
  - 2385
  - For demonstrating the phenomena of radiation in different vacuo, consisting of six numbered tubes as follows :
  - I. 40 mm. pressure radiating thread.
  - 2. 10 ,, disappearance c
  - thread.
  - 3- 6 ,, ,, Geissler’s rays.
  - 4- 3 >> ,, Stratification.
  - 5- 0-14 ,,. Tesla’s rays.
  - 6. 0-03 Cathode rays.
  - 2382.— One Set of Tubes, as described above, about 20 cm. long—
  - the set 19/6
  - 2383 —Ditto, as above, but mounted on simple stand as figured.. ,, 28/6
  - 2384.—One Set of Tubes, about 40 cm. long .. .. ,, 35/6
  - 2385 —Ditto, as above, but mounted on polished wooden stand with switch—
  - the set 120/-
  - McFARLAN MOORE’S APPARATUS
  - 2386
  - 2386. —McFarlan Moore’s Vacuum Con-
  - tact-Breaker. Price, complete as illustrated, but without vacuum tube .. .. .. £6 5 0
  - 2387. —Vacuum Vibrator only ..£350
  - 2389.—McFarlan Moore’s Tube, with wire
  - spiral and positive ring electrode ; mounted on wooden support. .. .. .. .. .. each 21 /-
  - 2390 2391 2392 2393
  - 2390.—McFarlan Moore’s Tube, with straight
  - wire .. .. .. .. .. .. each 8/-
  - 2391. —Ditto, with wire spiral .. . . ,, 10/6
  - 2392. —Ditto, with spiral and three positive electrodes—
  - each 12/6
  - 2393. —McFarlan Moore’s Tube, with enclosed
  - vacuum tube .. .. .. .. each 16/6
  - 2394.—McFarlan Moore’s Tube, with metal rings and clamps, 50 cm. long .. .. each 13/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.328 - vue 347/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 329
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GOLDSTEIN’S TUBES
  - 2395 2396
  - 2399
  - 2397
  - 2395. —Deflection Tubes, with two parallel aluminium terminals as cathode
  - 2396. Ditto, with coin, which will become depicted on the walls of the tube
  - 2397. Ditto, with star-shaped wire, diameter of bulb about 12 cm.
  - 2398. Ditto, with star-shaped concave mirror-cathode, diameter of bulb about 12 cm.
  - each
  - 19/6
  - 19/6
  - 22/6
  - 22/6
  - 2399. —Tube, filled with potassium chloride, potassium iodide or sodium chloride, which under the influence of the
  - cathode rays change their colours, after some time they assume their original condition .. .. each 14/-
  - 2400. —Goldstein’s Canal Ray Tube, with slit grill-like cathode, through which the pink canal rays pass out.
  - each 32/6
  - CANAL RAY TUBES
  - 2403
  - 2401.—Goldstein’s Canal Ray Tube, new
  - shape as illustrated, height about 40 cm. each 32/6
  - 2402 —Ditto, as above, but specially large; diameter about 7 cm., height about 55 cm. each 62/6
  - 2403. —Canal Ray Tube, to demonstrate that canal rays are emitted from each cathode and have nothing to do with the anode .. each 45/-
  - In this tube the sieve-like disc serves as a shadow object for the cathode rays produced at the cathode. The cathode rays are drawn up by a magnet when they become visible behind the disc with the shadow.
  - 2404. —Canal Ray Tube, to demonstrate that the direction of the canal rays is dependent on the cathode rays, without magnet .. each 45/-
  - In the magnetic deviation of cathode rays beneath the cathode the canal ray band is also changed.
  - 2404 2407
  - 2405.—Canal Ray Tube, Wien’s, to demonstrate the positive and negative charges of cathode and canal rays each 30/-
  - 2406 —Ditto, specially large, diameter about 6 cm., height about 55 cm. .. .. .. .. .. ,, 85/-
  - 2407 .—Ditto, Wien’s, for electrostatic deviation, improved shape .. .. . . .. •. . • ,, 105/-
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.329 - vue 348/555
- - 330 F. E. BECKER & CO., INI I VO C HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CANAL RAY TUBES
  - THE CANAL RAYS APPEAR IN BEAUTIFUL PINK BANDS AS SHOWN
  - IN THE ILLUSTRATIONS.
  - 2408
  - 2408. —Canal Ray Tube,
  - with congruent cathode discs, being fixed opposite each other on the same axle.
  - In the even numbered corners the canal rays are emitted from the corners, and in the uneven ones from the middle of the edges. The illustrations show the rays in a five-cornered and in a six-cornered cathode. The canal rays form pink bands and are clearly visible.
  - Each........................................30/-
  - When ordering kindly mention if five or six cornered cathodes are required.
  - 2410
  - 2410.—Canal Ray Tube, with two round wires.
  - Price .. .. .. .. .. .. .. 48/6
  - 2412.—Canal Ray Tube, with three round wires, forming a square prism.
  - Price
  - 52/6
  - 2409
  - 2409.—Canal Ray Tube, with one oblong narrow piece of metal in a horizontal position.
  - Price...............................30/-
  - 2411.—Canal Ray Tube, with two oblong narrow pieces of metal in a horizontal position.
  - Price .. .. .. ...............48/6
  - 2413
  - 2413.—Canal Ray Tube, with three round wires forming an oblong prism.
  - Price.................. ..............52/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.330 - vue 349/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 331
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CANAL RAY TUBES
  - 2414
  - 2414.—Canal Ray Tube, with four round wires.
  - Price .. .. .. .. .. .. .. 60/-
  - 2416
  - 2416.—Canal Ray Tube, with one triangularshaped cathode.
  - Price.................................38/6
  - 2419
  - 2419.—Canal Ray Tube, with two triangularshaped cathodes, which are fixed in a position facing each other evenly.
  - Price.................................57/6
  - 24r5
  - 2415.—Canal Ray Tube, with one squareshaped cathode.
  - Price .. .. .. .. .. .. .. 38/6
  - 2417
  - 2417. —Canal Ray Tube, with two squareshaped cathodes, which are fixed in a position facing each other evenly.
  - Price..............................................57/6
  - 2418. —Canal Ray Tube, as above, but the square cathodes facing each other unevenly.
  - Price ................. ...........................57/6
  - 2420
  - 2420.—Canal Ray Tube, with the triangularshaped cathodes facing each other unevenly.
  - Price...............................57/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.331 - vue 350/555
- - 332 F. E. BECKER & CO., N1VOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BRAUN’S CATHODE RAY TUBES
  - 2421 2423
  - 2421.—Braun’s Tube to demonstrate the temporary course of variable currents, principally for alternating current, with screen about 9 cm. diameter, fitted with co-ordinates .. .. .. • • each £3 5 0
  - 2421a. —Ditto, improved form, with glass screen .. ,, £4 5 0
  - 2424
  - 2422. —Ditto, extra large, diameter of disc about 13 cm., length of tube
  - about 100 cm. .. .. .. .... .. each £9 10 0
  - 2423. —Braun-Wehnelt’s Vacuum Tube, for electrostatic deviation, with one diaphragm and pair of terminals .. each £4 5 0
  - 2423a. —Ditto, improved form, with glass screen .. ,, £5 15 0
  - 2424. —Vacuum Tube, Thompson’s, to demonstrate, that cathode
  - rays can be deviated by static electricity and by magnets, with two diaphragms and pair of terminals .. .. • • • • each £5 15 0
  - 2425. —Ditto, improved form, with glass screen .. ,, £6 10 0
  - 2426. —Wooden Stand, for the above Braun’s tubes .. £1 2 6
  - 2427. —Magnet Spools for above Braun’s tubes, ring bearing two spools On stand, for direct and single phase alternating currents £4 12 6
  - 2428. —Magnetizing Ring for Double Phase Alternating Current, without
  - tube .........................£4 12 6
  - 2429 .—Ditto, as above, but for revolving current
  - £5 2 0
  - 2430
  - 2430. —Thompson’s Luminous Bulb,
  - to demonstrate the luminous zones within the circle of discharge.
  - Each...........7/6
  - 2431.—T hompson’s Vacuurn Bulb, for the
  - so-called circular current ; extra large size, for demonstrating the course of induced electrical fields (so-called electrodeless circular currents in gases). Diameter of bulb about 40 cm.
  - Price..........£1 18 6
  - 2432
  - 2432.—Braun’s Cathode Ray Tube, for the study and timing of variable currents. Length about 75 cm. ; the screen is 8 cm. diameter, and provided with millimetre square divisions to enable easy graphic fixation of the travelling speck of light.
  - Price ...................................................£1 10 0
  - ...............£2 0 0
  - ...............£2 10 0
  - 2433 •—Ditto, latest improved pattern, with glass screen and diaphragm
  - 2434 •—Ditto, but with arrangement for varying the degree of hardness
  - Our stock of pure Chemicals and Acids is very considerable j hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.332 - vue 351/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 333
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CATHODE RAY TUBES
  - 2435.—Vacuum Tube, for secondary cathode rays (after S. P. Thompson). This tube is for the study of fascinating discharge phenomenon in highly-evacuated tubes.
  - Price..............................................£2 12 6
  - (See Proceedings of the Royal Society of London, LXI., August, 1897.)
  - LENARD’S TUBES FOR EXPERIMENTS ON CATHODE RAYS.
  - 2436.—Lenard’sTube, original form, with window of aluminium foil, ready for joining with pump, with material and tools, and full instructions for renewing aluminium window (Wiedemann’s “ Annalen der Physik und Chemie, 1894 ”).
  - Price .. .. .. .. •. £2 5 0
  - 2437.—Lenard’s Tube, with ground-on vacuum chamber and branch tube, with three best quality glass taps. This separate chamber is for experiments on cathode rays in partly evacuated air or gases.
  - Price, with material and tools for renewing window (Platinum extra) .. .. .. .. .. £7100
  - These Lenard’s cathode ray tubes cannot be sent out evacuated ready for use, as it is impossible to produce a permanent vacuum in them, owing to the microscopically fine perforations of the aluminium foil, which always permit the entrance of traces of air. It is therefore necessary to join the tube to the mercury pump in order to retain a constant vacuum. Tubes are sent out complete with aluminium window fixed and ready for connecting up to the pump. Instructions for further treatment and renewing of aluminium window are also supplied.
  - 2438.—Lenard’s Experimental Tube, with
  - ground-on cap, side electrodes provided with small hooks for suspending various objects in front of disc cathode, slanting side tube closed with quartz disc. Mineral-experimental tubes are usually supplied in two modifications for studying the phosphorescence of any substance.
  - Price ...............................£4 17 6
  - 2439
  - 2439.—Lenard’s Egg-shaped Mineral
  - Research Tube, large size, with filling-cap, tap, and ground plug. The tube leading to pump is between the electrodes for suspension ; diameter of
  - fill-opening about 35 mm. Price
  - 2440.—Lenard’s Co Shaped Tube, for
  - research, open at lower ground-on bottom.
  - Price
  - £1 18 6
  - n i c a I -
  - mineral end, with
  - £2 5 0
  - °€S:
  - 244x
  - 2441.—Lenard’s Vacuum Tube, long cylindrical shape, for fixing over mercury drum pump (Gaede, Pfeiffer, etc.) with glass stopcock and mercury packed plug.
  - Price.................................19/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.333 - vue 352/555
- - 334 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ANODE RAY TUBES
  - (GEHRKE AND REICHENHEIM’S.)
  - 2442.—Tube, with striction anode and cathode rays.
  - Price.............................................£450
  - The rays are only visible if the tubes are worked with a fairly large Wimshurst machine (about 30 cm. disc). In the bulb where the terminal serves as cathode a bunch of yellow anode rays is produced at the end of the fused-in tube, whereas in the other bulb a green fluorescent spot appears on the glass wall opposite the fused-in tube.
  - 2443.—Anode Rays Tube, with salt anodes, on polished wooden stand.
  - Price .. ...................................£2 17 6
  - These tubes show the anode rays very clearly as the anodes have been made from prepared salt sticks. Lithium gives red rays, barium blue, sodium yellow and the anode rays can also be examined by the spectroscope.
  - 2444.—Vacuum Tube, to demonstrate the blue, red and also the yellow rays.
  - Price .. .. .. .. .. .. ..£520
  - The above two tubes can be worked with induction current or with a Wimshurst machine. With these tubes the salt anode is first switched on for a few seconds as cathode, which causes vapours of iodide to be set free whereby the rays appear more sharply defined, than if the tube is switched on properly. After use the vapours will be absorbed again which regenerates the vacuum automatically.
  - 2444
  - HOLTZ’ VACUUM TUBES
  - 2445
  - 2448
  - 2445.—Holtz’ Tubes, simple, about 50 cm. long, with four funnels the ends of which run in one direction .. each 10/6
  - 2446 .—Ditto, double, U-shape, each limb with a funnel ,, 14/6
  - 2447 .—Ditto, double, with two funnels, about 20 cm. long ,, 10/6
  - 2448 .—Ditto, double, with eight funnels, about 60 cm. long ,, 19/6
  - 2449 .—Ditto, as above, specially large, about 100 cm. long, with
  - spirals, with pointed ends .. .. .. .. each 47/6
  - Note. For experiments with Holtz’ Tubes a low current should be used.
  - ARON’S TUBE
  - 2450.—Aron’s Tube, 6£ ft. long, for demonstrating electrical vibrations on wires .. .. each £6 0 0
  - 2451 —Ditto, without metal fittings and wires .. .. .. .. .. .. .. .. ,, 450
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.334 - vue 353/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 335
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WEHNELT’S VACUUM TUBES FOR EXPLAINING THE THEORY OF ELECTRIC CONDUCTION IN
  - GASES
  - The extraordinary efficiency of the modern theory of electric conduction in gases, which is explained by the existence of “ ions,” often produces a desire for demonstrating the more important properties of these ions. The number of ions produced in gases by the aid of mediums known up to the present (Rontgen rays, Becquerel rays, ultra-violet rays or radiant wires), is so small that observations are rendered possible only by the aid of very sensitive instruments. A very large number of negative ions, however, are emitted by metal oxides, and to an especially large degree by electrodes consisting of the alkalic elements (Ca, Ba, Sr) under high temperatures. By the aid of these radiant oxides, the more important properties of ions may be clearly demonstrated with the apparatus used in most colleges and schools. In addition to the vacuum tubes, the following are necessary :— two or three small accumulators capable of supplying from 3 to 4 amperes ; a source of continuous current of no to 220 volts ; a voltmeter suitable for these potentials ; and a reflecting galvanometer of moderate sensitiveness.
  - 2452.—Cylindrical Tube (Valve Tube), for ascertaining the number of electrones emitted by radiant calcium oxide, after the method of saturation currents. Price, mounted on stand .. .. .. £3100
  - 2454.—L a r g e Bulb Tube, with
  - cylindrical side projections (valve tube), for the production of stratified discharge.
  - Price, mounted on stand
  - £3 5 0
  - 2453.—Cathode Ray Tube, for
  - ascertaining velocity of an electrone, and the proportion of its charge to its bulk.
  - Price, mounted on stand .. £6 10 0
  - 2455.—Braun’s C a t h o d e Ray Tube,
  - large size, for deflection experiments with oxide - cathode (modified after W e h n e 1 t ).
  - Price, mounted on stand £6 10 0
  - 2456.—High Vacuum
  - Tube, with oxide-cathode, and phosphorescent mineral.
  - Price, mounted on stand-—
  - £5 10 0
  - 2457.—Large Valve
  - Tube, capable of carrying a load of 0-5 ampere for several hours at a time.
  - Price, mounted on stand—
  - £4 17 6
  - 2458.—Liquid Shunt Resistance.
  - 2457
  - Price ...............................6/-
  - If one of the above discharge tubes containing one incandescent and any number of cold metal electrodes is connected to an alternating current circuit of any periodicity, the tube acts as a valve, i.e., if the radiant electrode is cathode, the potential of the discharge is 18 to 20 volts only, whilst the potential rises (according to size and degree of the evacuation of the tube) to many thousand volts if the cold electrodes are connected as cathodes. By the aid of these tubes alternating or three-phase currents of any periodicity are converted into pulsating continuous currents, and after known methods of shunting both phases of the alternating current may be utilized.
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.335 - vue 354/555
- - 336 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - VACUUM TUBES FOR SPECTRUM ANALYSIS
  - The gases have been carefully generated according to the latest scientific data. The mercury vapours which get into the tubes while being exhausted with the mercury vacuum pump have been removed, foreign lines do not therefore interfere with the spectrum, as is the case with cheaper and less carefully manufactured tubes.
  - 2459.—Vacuum Tubes, for Spectrum Analysis, guaranteed best quality, any of the following each 7/6
  - A. Hydrogen. L. Chlorine.
  - B. Oxygen. M. Bromine.
  - C. Nitrogen. N. Methane.
  - D. Carbon Dioxide. P. Sulphur Dioxide.
  - E. Carbon Monoxide. Q- Sulphur Trioxide.
  - F. Nitric Oxide. R. Sulphuretted Hydrogen.
  - G. Nitrogen Peroxide. S. Ethene (Ethylene).
  - H. Ammonia. T. Ethine (Acetylene).
  - J. Water. U. Carbonic Acid.
  - K. Hydrochloric Acid. V. Stannic Chloride.
  - Also solids as follows : Mercury, Mercuric Iodide, Sulphur, Selenium, Iodine, Phosphorus, Sodium.
  - 2460.—Spectrum Analysis Tubes, as above, but containing rare gases as follows :
  - Argon £1 7 6
  - Helium 1 7 6
  - Neon 3 15 0
  - Krypton . . .. . . . . . . .. .. 7 10 0
  - Xenon .. 11 10 0
  - 2461.—Vacuum Tubes, for Spectrum
  - Analysis, Bulb pattern. Prices, etc., as No. 2459, plus 20 per cent.
  - 2462.—Spectrum Analysis Tube, for filling
  - with various gases.
  - Price, complete, with two well-ground-in stopcocks, as figured ................ .. .. each 10/6
  - 2463.—Vacuum Tubes, for Spectrum
  - Analysis, “ End-on quality, containing—
  - A. Oxygen
  - B. Hydrogen
  - C. Nitrogen
  - D. Chlorine
  - E. Carbonic Acid
  - F. Iodine
  - G. Bromine
  - H. Hydrochloric Acid
  - K. Argon
  - L. Helium
  - M. Neon
  - N. Krypton
  - O. Xenon
  - P. Mercury
  - Q. Cadmium
  - pattern,
  - guaranteed best Each.
  - .11/6 .. 11/6 .. 11/6 .11/6 .. 11/6 .. 11/6 .11/6 ..11/6 £1 17 6 1 17 6 3 15 0 7 10 0 11 10 0 12 6 12 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.336 - vue 355/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 337
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - VACUUM TUBES FOR SPECTRUM ANALYSIS
  - 2464
  - 2464.—Goetze ’s Vacuum Tubes for Spectrum Analysis. This
  - tube gives a spectrum of remarkable definition, and was awarded the Gold Medal at the St. Louis Exhibition. A well-known professor
  - detected a minute quantity of argon in one of these tubes filled with helium, and also, when using a Michelson’s Echelon Spectroscope, obtained the double helium line. {Further details will be sent free post on application.)
  - A. Price, filled with Hydrogen or other common Each.
  - gases £1 2 6
  - B. „ „ Argon 2 15 0
  - C. ,, ,, Helium 2 15 0
  - D. ,, ,, Neon 4 5 0
  - E. ,, ,, Krypton . . 4 5 0
  - F. ,, ,, Xenon 12 15 0
  - G. ,, ,, mixture of Helium and Argon in equal parts .. £2 15 0
  - 2465.—Goetze’s Vacuum Tubes for Spectrum Analysis, with windows made from Uviol glass. A. Price, filled with Hydrogen or other common Each.
  - gases .. .. £110 0
  - B.
  - C.
  - D.
  - E.
  - F.
  - Argon
  - Helium
  - Neon
  - Krypton
  - Xenon
  - 3 0
  - 3 0
  - 4 15 4 15
  - 13 5
  - 2466.—Goetze’s Vacuum Tubes for Spectrum Analysis, with windows made from quartz.
  - A. Price, filled with Hydrogen or other common Each.
  - gases . £3 15 0
  - B. ,, Argon 3 15 0
  - C. ,, Helium 3 15 0
  - D. ,, Neon 5 10 0
  - E. ,, Krypton . . 5 10 0
  - F. ,, Xenon 13 10 0
  - 2469.— Spectrum Analysis Tubes, containing
  - 2467.—Brass Spectroscope Stand, mounted on heavy iron foot, fitted with spring clips for making electrical contact with spectrum tubes, and rotating holders for platinum wires.
  - A. Price, complete, as figured
  - £17 6
  - B. Platinum wires fused into
  - glass tubes, extra—
  - each 2/-
  - 2467
  - 2468.—Insulated Stand to take six Spectrum Analysis Tubes, with contacts as figured.
  - Price, without tubes—
  - £1 19 6
  - Until quite recently it has been exceedingly difficult to make metal vapour spectra such as the alkali metals, mercury, cadmium, zinc, etc., as the tubes had to be heated to a very high degree and in consequence had a very short life. In the presence of helium however the metal spectra appear at low temperatures and the helium lines disappear. Mercury appears at room temperature and need not be heated.
  - Spectrum Analysis Tubes containing metal vapours as follows :—
  - A. Potassium and 3 mm. Helium .. .. .. .. . . .. .. . . .. .. each
  - B. Sodium and 3 mm. Helium
  - C. Rhubidium and 3 mm. Helium
  - D. Caesium and 3 mm. Helium.. .. .. .. .. .. .. ....
  - E. Mercury and 3 mm. Helium .. .. .. .. .. .. .. .. .. .. ,,
  - £3 7 6 3 7 6 5 5 0 5 5 0 3 5 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
  - Y
- p.337 - vue 356/555
- - 338
  - SECTION 10.
  - SOUND
  - 2480.—Wave Trough, with glass front, size 48 in. x 6 in. x 6 in. 4700 .. .each £2 8 6
  - 2481. —Round Zinc Trough, 18 in. diameter x 18 in. deep 4701 ...................each £0 19 6
  - 2482. —Ditto, 24 in. diameter x 18 in. deep 4702 .. .. .. .. .. .. .. .. each 17 6
  - 2483.—Apparatus for Demonstrating Transverse Waves. Can be used with Science Lantern. 4703 Price .. .. .. .. .. .. .. .. .. .. .. ..£4176
  - 2484 •—Ditto, but for demonstrating Longitudinal Waves 4703 .. .. .. .. .. ... price 4 17 6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 339
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WAVE DEMONSTRATION APPARATUS
  - 2485.— S ilvanus Thompson’s Wave Machine, extra large size, length about 8 ft.
  - This apparatus is for demonstrating how the waves—excited . by, , the prime conductor or radiator—progress gradually to the resonator, and having reached same produce synchronous vibrations, and then become stationary. 4706
  - Price, complete £13 15 0
  - 2486
  - 2486. —M ach’s Wave Machine, extra large size, for demonstrating progressive and ‘ stationary, transverse and longitudinal vibrations. This apparatus is 51 ft. long 4707 .. £1117 6
  - 2487.—Weinhold’s Longitudinal Wave
  - , Machine, best quality, consisting of a copper wire spiral about 70 in. long, from each spiral of which a double cord passes to the wooden bars, supported on iron feet, forming a V-shaped trough. This apparatus is in rather large demand, in that real wave motions, both progressive and stationary, can be produced. 4708
  - Price, complete as figured .. .. .. £4 15 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
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- - 340 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WAVE DEMONSTRATION APPARATUS
  - 2489.—Length of Indiarubber Tubing, 4 yards long, filled with sand, for demonstrating wave motions. 4718 Price * .. .. .. .. .. .. .. .. .. .; .. .. .. .. .. 6/-
  - 2490.
  - Powell’s Wave Machine, for
  - demon strating plane, circular, and elliptical vibration, motion of sound waves, giving two entire waves. 4710
  - Each £4 17 6
  - 2491.—Eisenlohr’s Wave Machine,
  - best quality, for illustrating undulating and oscillating waves. 4711
  - Each..........................£5 10 0
  - 2490
  - 2492
  - 2492.—Dorman’s Wave Slide, for demonstrating the motions of particles in a sound wave. Four lines of motion are shown travelling outwards at right angles to each other as from a bell. 4719
  - 2493
  - 2493.—Collision Ball Lantern Slide. 4720
  - Price .. ..£150
  - Each ....................................... 17/6
  - 2494.—Wright’s Wave Slide, for showing the motion of light and sound waves, and retardation of wave vibrations. 4721
  - 2495
  - 2495.—Woodward’s Interference
  - Wave Slide, showing two wave surfaces upon the screen ; when in the same phase they reinforce, and when in opposite phase they destroy one another. 4722
  - Price
  - £1 15 0
  - Price
  - £2 2 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.340 - vue 359/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 341
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WAVE DEMONSTRATION APPARATUS
  - 2496. —Melde’s Apparatus for demonstrating stationary waves by means of a length of catgut vibrating under the influence of a tuning fork. 4714
  - Price, complete as figured .. .. . • • • • • • • • • • • £4 0 0
  - 2497. —Ditto, but fitted with a platinum wire which can be made incandescent by means of the electric current, and thus made the experiment visible at a distance. 4715
  - Price, complete .. .. .. .. .. .. .. .. .. .. £5100
  - 2498 —Ditto, “ University ” pattern, fitted with a very powerful tuning fork intoned by an electro-magnetic apparatus for constantly maintaining the vibrations. 4716
  - Price, complete.............................................................£12 15 0
  - A
  - 2499.—Two Cardboard Cylinders,
  - with glass bell, for showing stationary waves in closed tubes 4740 .. .. per set 9/6
  - 2500 —Ditto, for showing stationary waves in open tubes 4740a .. .. .. per set 9/6
  - 2501.—Air Concussion Apparatus,
  - for showing difference between the propagation of air and sound in air, best quality. 4732 Price .. '..................£112 6
  - 2502 —Ditto, second quality, consisting of a square wooden box having a hole on one of its sides and a canvas sheet on the other, sometimes called a “ vortex-ring ” box. 4733 Price...............................19/6
  - 2503. —Cheshire’s Wave Motion Apparatus, for
  - showing the motion of the particles in stationary waves, comprising a glass disc, 8 in. in diameter, revolving in a metal frame having an adjustable slit. Designed for science lantern work. 4723 Price, complete .. .. .. • • • • • • £117 6
  - (For full details, see “ Nature,” xlv., page 347, February 11, 1892.)
  - 2504. —Crova’s Disc, to fit above 4724 each 14/6
  - 2505. —Cheshire’s Disc, with slit, printed on card-
  - bbard 4725 each 2/-
  - 2506. —Crova’s Disc, with slit, printed on cardboard 4726 each 2/-
  - 2507.—Tyndall’s Apparatus, consisting of metal tube 3 metres long, with supports, etc., for showing the propagation of sound in long tubes. 4737
  - Each ...............................£1 15 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 342 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SOUND EXPERIMENTS fT
  - 2508
  - 2508.—Bell Experiment,
  - “ University ” pattern. To be rung by electricity. This apparatus consists of a strong glass receiver, carrying two terminals for connecting up to battery. The electric bell is well made, and a piece of felt is fastened to its underside to prevent vibrations acting on plate of air pump. 4736
  - Price, complete .. £3 0 0
  - (For Air Pumps, see Sections 5 to 7, pages 161 to 163.)
  - MONOCHORDS
  - 2509
  - 2509.—Tyndall’s Apparatus,
  - “ University ” pattern, to show the propagation of sound in fluids and solid bodies. This apparatus comprises a sounding box with a brass fitting into which screw the following parts : 1 metal rod, 1 wooden rod, 1 glass rod and 1 tube with funnel for holding the water. 4739 Price, complete with tuning fork £2 15 0
  - 25x0
  - 2510.—Watson’s Spring Balance Monochord.
  - Each ............................. ..............I7/6
  - (See “ Watson’s Physics.”)
  - 2511
  - 2511.—Monochord, ordinary pattern, with two sets of brass and steel wires and two bridges, fitted with boxwood scale. 4743 Each ......................................25/-
  - 2513. —M onochord)
  - wall pattern, comprising polished board with accurately graduated boxwood scale, two bridges, one of which slides on a vertical guiding rod, two sets of brass and steel wires. Complete, with key for tightening up. 4746
  - Price, without weights—
  - £1 12 6
  - 2512.—Fry’s Spring Balance Mono-
  - chord, as used in the physical laboratories of the Bristol University. 4742
  - This apparatus consists of a stout base board upon which are stretched two thin steel wires. Each wire is 75 cm. long, and is attached at one end to a spring balance and at the other to a special “ Machine Head,” by means of which a fine adjustment of the tension is obtainable. The spring balances measure to tensions of 5,000 grammes by steps of 100 grammes. The wires are nearly parallel to the board, and it is thus possible to alter the effective length of either by movable bridges without the usual inconvenience of thereby altering the tension.
  - The wires are of different diameters, the mass of each in grammes per centimetre length being marked upon the base. With this instrument it is possible—
  - A. To study the effect upon its frequency of chang-
  - ing the length, tension, or mass of a stretched string. _
  - B. To compare the frequencies of two or more
  - notes.
  - C. To measure the absolute frequency of a note.
  - Price complete, as figured .. .. £17 6
  - 2513
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.342 - vue 361/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 343
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MONOCHORDS AND WEIGHTS
  - 2514
  - 2514.—Monochord, larger size, fitted with two brass and steel wires, two bridges, and two graduated scales. 4744 Price, including key for tightening up wires .. .. .. .. .. .. .. .. .. ..£300
  - 2515.—Set of Mono-chord Slotted
  - Weights, with hanger, consisting of
  - seven iron weights, £,
  - 1, 2, 5, 10 kilos, as illustrated. Price, complete .. £2 5 0
  - 2515a.—Set of Four Iron Slotted
  - Weights, with hanger, consisting of
  - three 10-lb. weights, and one 20-lb. weight. Price, complete ^. £2 7 6
  - 2515b.—Set of Slotted Weights, with
  - 25x5 hanger, consisting of
  - four iron weights, each weighing 1 kilo,
  - three of which are slotted to fit on rod of the fourth weight, which acts as the hanger. Price, complete .. .. .. 10/-
  - 2516
  - 2516.—ivionochord, “ University ” pattern, superior quality, and extra strongly made, edges of bridges are made of brass. 4745 Price .....................................£4 5 0
  - 2517. —Set of Slotted Weights, consisting of
  - one hanger weighing 500 grammes, and the following loose weights : one of 500 grammes, two of 200 grammes, and one of 100 grammes. Price, complete .. .. 10/-
  - 2518. —Slotted Weights, 1,000 grammes, to fit
  - hanger No. 2517. .............Price, each 2/-
  - 2519. —Set of Slotted Weights, consisting of
  - one hanger weighing 1 lb., and the following loose weights : 1 lb., 0-5 lb., 0-5 lb., 0-2 lb., 0-2 lb., o-i lb., 0-05 lb., o-02lb., 0-02 lb., o*oi lb. Price for complete set .. .. 18/6
  - 2520. —Slotted Weights, to fit hanger No. 2519.
  - A. 2 lb..................................each 2/-
  - B. 4 lb...................... .. .. „ 3/6
  - 2521.—Kilo Weights in Sets.
  - 200 grammes down to 50 grammes,
  - 2/- per set.
  - 500 grammes down to 50 grammes,
  - 3/3 per set.
  - 5 kilos down to 50 grammes, 14/6 per set.
  - 1 kilo down to 50 grammes, 2 kilos down to 50 grammes,
  - 5/- per set. 8/- per set.
  - 10 kilos down to 50 grammes, 20 kilos down to 50 grammes,
  - 27/6 per set. 35/- per set.
  - 2522.—Single Kilo Weights, shape as No. 2521.
  - 50 100 200 500 grammes. Size .. .. 1 2 5
  - Size
  - Price
  - 7d. 8d. 10d. 1/3 each.
  - Price ..
  - 2/- 3/- 6/-
  - 10
  - 10/6
  - 20 kilos. 19/- each.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 344 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TUNING FORKS
  - 2523
  - 2523. —Set of Large Size Certified Standard Tuning Forks, “University” pattern, all guaranteed accurate and of the highest quality and finish. This set consists of the following forks, each mounted on an elegantly-finished resonance box. 4756
  - Co C, A, C2 C3 C4
  - 128 256 435 512 1,024 2,048 vibrations.
  - Price, complete, including certificate of accuracy . . . . . . .. . . . . . . .. .. £13 15 0
  - 2524. —Large Size Standard Tuning Forks, “ University ” pattern, as used in set No. 2523. Sets may be had separately. 4757 Prices as follows :—
  - Co Ci A, C2 C3 C4
  - 128 256 435 512 1,024 2,048 vibrations.
  - £3 0 0 £2 8 6 £2 5 0 £2 5 0 £2 5 0 £2 5 0 each.
  - 2525
  - 2525.—Becker’s Special Set of “ Medium-Size ” Tuning Forks, of the following frequencies:—256, 320, 384 and 512, mounted on elegantly-polished resonance boxes. 4759 Price, complete, with hammer .. .. .. .. £3 10 0
  - 2526.—Set of Four Large Size Tuning Forks, giving a chord. Mounted on elegantly-finished resonance boxes. 4758
  - Price, complete .. .. .. £7 15 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 345
  - W. & <1. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TUNING FORKS
  - 2527.—Cheap Tuning Forks, with plain shanks C, A, and G 4765
  - Per doz. .. .. .. .. .. 13/6
  - 2528 —Ditto, larger, and nickel-plated, C, A, G, and C. 4766
  - Each ...............................2/9
  - 2530
  - 2531
  - A. Small size
  - B. Medium size
  - C. Large size
  - 2532
  - 2529.—Tuning Forks, high quality, with thread for screwing into resonance boxes.
  - Small. Medium. Large.
  - C (256) .. 2/9 .. 6/- .. 19/6
  - D .. 2/9 6/- 19/6
  - E .. 2/9 6/- 19/6
  - F .. 2/9 6/- 19/6
  - G .. 2/6 6/- 18/-
  - A .. 2/6 6/- 18/-
  - B .. 2/6 6/- 18/-
  - C (512) .. 2/6 6/- 18/-
  - 2530.—Set of Four
  - Tuning Forks, nickel-plated, giving a chord. Mounted on well-finished resonance box. 4761 Price, including hammer
  - £1 12 6
  - 2531.—Set of Three Tuning Forks, two
  - in unison (256 V’s) and one an octave higher (512 V’s), each mounted on a resonance box. 4762
  - Per set.
  - .............. £0 19 6
  - ........... 1 12 6
  - ............... 3 17 6
  - 2533
  - 2533.—Apparatus for Comparing the Frequency of Two Tuning Forks.
  - This apparatus consists of a strong wooden stand on which is clamped an upright with an arrangement on one side, in which a glass plate can be held. The upright has a small movement in a lateral direction, and can be clamped in any given position by a screw at the back.
  - On the bevelled block shown in the face of the diagram the two tuning forks to be tested can be clamped firmly by means of the bar and screws. They should be clamped so that there is a space of about an inch between the forks. A short lath to which a thread is attached supports the plate in position in the groove. As soon as the lath is pulled away, the plate drops.
  - In order to make an experiment, first smoke one side of the glass plate, then put it in position in the groove supported by the lath. Fix on the inside of the inner prong of each fork a short bristle or piece of aluminium foil, the same length on each fork. . Then loosen screw of slider and bring glass up to just touch the bristles. Let one observer hold cotton while the other bows the tops of the two forks with a cello bow till both forks are sounding loudly (the two different notes will indicate this). Then let the plate drop, remove the slide from contact with bristles, and take the plate carefully out. On the plate you will have two wave lines traced side by side. With a set square and a rule, cut off two equal portions of each tracing and count the oscillations. 4772
  - Price .. .. .. .. .. .. .. .. .. .. • • • • • • • • • • • • 13/6
  - (See Watson’s “ Practical Physics.”)
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
  - 2532.—Set of Two
  - “ Medium Size ” Tuning Forks (in
  - unison, A = 435), nickel-plated and mounted on well-finished resonance boxes. 4760 Price, including sliding weight and hammer—
  - £3 15 0
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- - 346 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TUNING FORKS
  - 2534
  - 2534.—Tuning Forks for the Measurement of Small Intervals of Time. 4770
  - The idea of measuring small time intervals by the tuning fork and a recording drum was suggested, in the first instance, early in the 19th century by Thomas Young. The idea was seized on by French scientists, and developed by Prof. Marey, of the College of France ; its development rendered possible great advances in scientific research.
  - The surface of the drum before using is covered with smoked paper : the action of the slightest rubbing clears the soot and leaves a white mark. The drum is caused to revolve, and against it presses a lever in connection with a seconds pendulum with a mercury electrical contact. Consequently, at each second there will be a break in the continuity of the line, the distance from break to break being the space the dram revolves during one second. If below this another lever or pointer is attached to a tuning fork calibrated to say 100 D.V. (double vibrations) per second, the lower pointer will trace a wave line on the smoked surface of the dram, each wave corresponding to x-^th part of a second.
  - We have given great care and attention to the production of tuning forks for these time measurements. All our forks are stamped with the consecutive number of the fork and its vibration number. The illustration above shows a fork, 50 D.V., and a tracing of its work for two seconds.
  - PRICES.
  - A. 10 D.V. ..
  - B. 50 D.V. ..
  - C. 100 D.V. ..
  - D. 200 D.V. ..
  - each £5 10 0 „ 2 17 6
  - 2 10 0 „ 2 5 0
  - 2536.—Large Tuning Fork, ^=256
  - vibrations, electrically maintained, mounted on resonance box. Complete, with electromagnet as figured. 4779 Price .. £5 15 0
  - 2537 •—Ditto, Ai=435 vibrations. 4780 Price.........................£5 10 0
  - 2538.—Sliding Weights,
  - for prongs of tuning forks.
  - 2535 --' •
  - 2535.—Heavy Stand for Tuning Forks, complete with
  - Each...............1 /-
  - 2539.—Hog’s Bristles
  - Per bundle .. .. 9d.
  - 2538
  - A.
  - B.
  - electro-magnet, mercury-cup, contact breaker, all adjustable. This stand has been made specially to take the accurately-adjusted tuning forks listed above (No. 2534).
  - Price, without tuning fork .. .. .. .. .. £4100
  - with ,, „ .. .. .. .. .. 6 12 6
  - 2540.—Small Mirrors,
  - for attaching to tuning forks. Each .. .. .. 2/6
  - 2541.—Chronographic Tuning Fork
  - (128 vibrations), mounted in handle, and fitted with writing point. 4774
  - Each .........................£1 19 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1. 347
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TUNING FORKS, Etc.
  - 2542
  - 2542.—Helmholtz1 Vi-bration Microscope,
  - highest quality and finish, consisting of a large tuning fork, which carries at the end of one prong the objective of a microscope with fixed eye-piece. The fork is electrically maintained and carries a small rider for adjusting the pitch to a slight extent. The string, of which the vibration is to be investigated, is fixed vertically in the field of view of the microscope, with a starch grain on it to serve as a luminous point. If the fork alone moves, the point is lengthened out into a bright vertical line, but when the string also moves, the point traces out a curve. 4783
  - Price, complete as figured—
  - £15 15 0
  - (See Poynting & Thomson’s “ Text-Book of Physics—Sound.”)
  - 2543
  - 2543.—Tuning Fork of
  - 4000 S.V. to demonstrate Doppler’s principle. 4777
  - £2 10 0
  - 2544. —H e I m-
  - holtz’ Synthesis of Sound Apparatus, “University ” pattern, large size, guaranteed highest quality and finish, and furnished with all latest improvements. This apparatus, which is fully described in Ganot’s “ Physics,” and other standard works, is fitted with eight tuning forks, resonators, clappers, electro-magnets, etc., for producing and explaining the vocal sounds of the human voice.4784 Price, complete .. £120 0 0
  - 2545. —Ditto, larger
  - size, with ten tuning forks, etc. 4785
  - £135 0 0
  - 2546.—Bezold’sTuning Fork (15 to 24 vibrations to the second) for experiments on the limit of deep sounds.4775
  - Each................................................................................£9 5 0
  - 2547.—Ditto, giving 12 to 18 vibrations 4776 .................. ....................£12 15 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 348 F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SOUND APPARATUS
  - 2548
  - 2548.—Apparatus for the Graphic Method of Determining Frequency, consisting of a recording drum, large electrically-maintained tuning fork with a style affixed to one of its prongs for writing vibrations on smoked paper, mounted on a polished stand. 4788
  - Price, complete as figured,
  - £21 0 0
  - 2553.—Pfaundler’s Appa-
  - ratus for showing Lissajou’s figures, simple form. 4793
  - Price .....................£2 15 0
  - 2549.— M elde’s Universal Kaleido-phone, with arrangement for clamping to table. 4796
  - Price.. .. £2 2 0
  - (See Tyndall’s “ Sound.”)
  - 2550.—Set of 4 Wooden Bars, giving
  - a chord when thrown on the floor. 4803
  - Price, complete .. .. .. .. 9/6
  - 2551.—set of 8 ditto, giving an octave. 4804 Price, complete .. .. .. .. 18/6
  - 2554
  - 2554. —Airy’s Double Pendulum, best
  - quality. 4798
  - 2552
  - Price, complete,
  - £2 10 0
  - 2555
  - 2555.—Set of 4 Wooden Rods,
  - giving a chord. 4800
  - Price, mounted as figured .. £110
  - 2552.—Set of 8 Steel Rods, giving
  - an octave. Mounted on nicely finished resonance box 4802 .. .. £3 5 0
  - 2556.—Set of 8 Wooden Rods,
  - giving an octave. 4801 Price, mounted .. .. £118 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.348 - vue 367/555
- - F. E BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 349
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RESONANCE APPARATUS
  - 2557.—Hammers for striking tuning forks. 4816 Each .......................1/9
  - 2558.—Violin Bows 4813
  - .. each 6/-
  - 2559.—Cello Bows 4814
  - 2560.—Bass Bows 4815
  - each 11/6
  - .. each 17/6
  - 2561.—Resonance Glass Jars,
  - made of finest white crystal glass. 4817
  - Height 10 12 12 12
  - Diam. 2 2i 3
  - Price .. V- 1/2 1/3 2/-
  - Height 16 17 18
  - Diam. 2 3i 2 5
  - Price 1/8 3/3 2/3 7/-
  - 14 m. 2
  - 2562
  - 2563
  - 2561
  - 2564
  - 2562.—Resonance Apparatus,
  - comprising a tall glass jar made of finest white crystal glass to which is accurately fitted a square brass plate having a slot, which can be varied by means of a brass slider, and measured with a metal scale as figured. 4818
  - 2563. —R esonance Apparatus, comprising glass jar, on foot, and glass tube 14 in. high, open at both ends, with clamp and metal stand. 4819
  - Price, complete
  - .. 12/6
  - Price
  - 10/6
  - 2564.—Resonance Apparatus,
  - comprising two brass tubes, telescoping into each other so that the column of air within the tube may be altered. Outer tube fits into a wooden base from which it can be removed when desired. 4820
  - Price, complete .. .. .. 8/6
  - (See Schuster and Lees’ “ Intermediate Course of Practical Physics.”)
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.349 - vue 368/555
- - 350 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RESONANCE
  - 2565.—Resonance Apparatus, tall pattern, consisting of a long glass tube ioo cm. long and 3 cm. in diameter, connected by means of a length of rubber tubing to a globular water reservoir, which can be fixed at different heights for varying the length of the column of air. An accurately graduated boxwood scale, divided into millimetres, is fixed on the tall upright by the side of the tube. The tuning fork is set vibrating and held over the open encf of the tube. The length of the column of air is now adjusted by raising or lowering the reservoir (thus altering the level of the water in the tube), until the maximum resonance is obtained, when the column of air will take up the vibration of the fork and resound to it.
  - Price, complete, mounted on heavy polished mahogany foot with levelling screws, etc. .. .. .. £4 10 0
  - 2567. —Resonance Apparatus, consisting of one long glass tube about 24 in. long and i£ in. outside diameter and one shorter tube of the same diameter, connected to the former by a length of rubber tubing for varying the length of the column of air.
  - Price, mounted on tall stand having two graduated scales, pulley, etc., as figured .. .. .. £110 0
  - 2568. — Tyndall's Apparatus, “ University ” pattern, for demonstrat-ing that the vibrating s e g-ments and nodes of a bell are similar to those of a disc.
  - Price, c o m p 1 e te, mounted on heavy metal base as figured—
  - £2 18 6
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E, BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 351
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RESONATORS
  - 2569/2570
  - 2569. —Set of Eleven Cylindrical Cardboard Resonators 4829 ............price £3 2 6
  - 2570. —Set of Eleven Cylindrical Zinc Resonators 4830 ................. 5 5 0
  - 2571.—Set of Fourteen Koenig’s Graduated Universal Resonators,
  - for tones from gi to e3. Guaranteed highest quality and finish. 4932
  - Price, per set .. £38 0 0
  - 2571
  - M's.
  - 2572.—Helmholtz’ Spherical
  - Resonators, made of thin brass and highly polished.
  - *
  - jjjf A. Set of 5 (g cx e g c2)
  - Per set .................. £7 15 0
  - ^§13# B. Set of 19, as figured.
  - w«^a»ji\si.w|Tesw|uo.u L^5b|s\^ov5| | h«j wqa\ vi's.^u^a I ho.t Per set .. .. .. £17 10 0
  - 2572
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.351 - vue 370/555
- - 352 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2573
  - 2573.—O r g a n
  - Pipes, open, made of polished wood, best make and finish. 4837
  - Each .. £12 6
  - ORGAN PIPES
  - 2574
  - . .. ___ of 4
  - en, giving a chord, od. 4838
  - -Set
  - Organ Pipes,
  - Made of polished
  - , per set .. .. ..£21
  - 5.—Set of 8 Organ Pi
  - sn, giving an octave. 4839 , per set
  - 19 6
  - pes,
  - 2576
  - 2576. — Open Organ Pipe,
  - with five openings for flageolet notes. 4844
  - Each £1 17 6
  - 2577
  - 2577. —O rgan Pipe, with graduated sliding rod giving chromatic scale. 4845
  - Each .. £2 2 0
  - * 2578
  - 2578.—O pen Organ Pipe,
  - with ' centre stop which closes it at the node. 4841
  - 2579. — Open Organ Pipe,
  - with adjustable mouth. 4842
  - 2580
  - 2580.—O pen Organ Pipe,
  - with three openings and stops. 4843
  - 2581
  - 2581.—Set of 2 Open Organ Pipes, one of which is provided with a slider for showing interference. 4840
  - Price .. £1 19 6
  - Price .. £1 12 6
  - Each .. £1 15 0
  - Price, per set
  - £2 12 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.352 - vue 371/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 353
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ORGAN PIPES
  - 2582
  - 2582. —O r g a n P i pe with Slider, having openings of different diameters for raising or lowering the pitch. 4850 Each .. £118 6
  - 2583
  - 2583. - Kundt’s Stopped Pipe, with 3 water manometers and valves, for experiments on pressure-change and motion in organ pipes. 4851
  - Each . . .. £5 5 0
  - (See Poynting & Thomson’s “ Text-Book of Physics-Sound.”)
  - 2584.—L a r g e Organ Pipe, fitted
  - with strong glass cylinder, into which slides an adjustable rod carrying a membrane" for showing nodes. 4853
  - Price .. £2 5 0
  - 2585.—L a r g e Organ Pipe, with
  - glass front, and membrane for showing nodes. If some lycopodium is placed on the membrane, the motion and quiescence of the sand, as the ring is lowered through the tube, indicates the position of the nodes and ventral segments. 4855
  - Price .. £2 2 0
  - 2585
  - 2586.— Pyramid
  - Price, per set
  - 2586
  - Set of 2 Pipes.4846 £3 7 6
  - 2587
  - 2587.—Set of 4 Closed Cubical Pipes,
  - giving a chord. 4847
  - Price, per set . . .. .. ..£450
  - 2588. —O r g a n Pipe, with Free Reed. To illustrate the construction and the method of tuning an organ pipe. The pipe is arranged to fix on the bellows. There is a metallic reed at the top which is set in vibration, the movements of which can be observed through the glass window. The funnel-shaped trumpet at the top reinforces the sound-? A wire, pressing on the reed, alters the period of its vibration. 4848
  - Price .. £2 12 6
  - ' 2589
  - 2589. —Organ
  - Pipe, with striking reed and cardboard horn. 4849
  - Each £3 0 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
  - z
- p.353 - vue 372/555
- - 354 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2590
  - ORGAN PIPES, Etc.
  - 2590.—Koenig’s Organ Pipe.
  - This pipe is fitted with three mano-metric capsules and gas jets, and with a gas chamber and supply pipe leading to the gas. The gas issues in three jets for lighting. The pipe is caused to give its primary note, and, being an open pipe, has a node at its centre, consequently the rapid movements of the membrane at this point extinguish the jet. If force of air is increased, the octave of the primary note is obtained. The centre point becomes a ventral segment, and the other two jets correspond with nodes, and are consequently extinguished. 4852
  - Price ..
  - £3 15 0
  - 2592. —Acoustic
  - Bellows with wind chest having nine
  - valves and keys. 4835
  - Price, without pipes—
  - £15 0 0
  - 2593. —Ditto, cheaper
  - make and finish, with wind chest, valves and keys, mounted on
  - wooden slab instead of a table. 4836 Price, without pipes—
  - £8 10 0
  - 2592
  - 2591.—Mach’s Organ Pipe, for experiments on pressure change and motion in organ pipes. Professors Poynting and Thomson in their “ Text-book on Physics—Sound,” state :—“ An organ pipe was fixed horizontally, and along the top wall on the inside ran a platinum wire previously wetted with sulphuric acid. When the wire was heated by an electric current, a fine line of vapour descended from each drop. The pipe was closed by a membrane at the centre to prevent any through draught of air, and when it was blown, the lines of vapour were carried to and fro ; one of the side walls was of glass, so that the lines of vapour could be seen, and their extent of excursion measured by a stroboscopic method. The excursion at the end of an open pipe 125 cm. long was 0-4 cm.” 4857
  - Price
  - £5 12 6
  - 2594
  - 2594.—Koenig’s Manometric Apparatus,
  - for comparing two organ pipe notes by the manometric flame method. The apparatus consists of five large pipes, Ci, cx, Ci, gx, c2, a well-made wind chest, with valves for two pipes, two manometric gas jets, and rotating mirror. 4856
  - Price, complete as figured
  - £21 10 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.354 - vue 373/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 355
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - ANALYSIS OF SOUND
  - 2595. —Analysis of Sound Apparatus, comprising 8 spherical Helmholtz resonators, 8 manometric flames, large revolving mirror, etc. ; guaranteed highest quality and finish.
  - Price, complete as figured .. £35 0 0
  - 2596. —Analysis of Sound Apparatus, as above, but fitted with 14 “ Universal ” resonators and 14 manometric flames.
  - The apparatus is built into a massive frame and is provided with hand-driven rotating mirror the mechanism of which is so arranged as to run absolutely silently. The fourteen Universal Resonators can be regulated in such manner that the highest tone of the larger always reaches the deepest tone of the smaller. They can therefore be set for any fundamental tone. The deepest arbitrary fundamental tone is g — 2 = 48 compound vibrations (sol — 1 = 96 v.s.). The resonators are connected with manometric flames. The latter are protected from air currents by mica strips, which entirely obviate any breaking or spurting of the flame.
  - Price, complete, with large revolving mirror, heavy stand, etc. .. .. £61 10 0
  - 2597.—Quincke’s Lecture Apparatus, for
  - determining the velocity of sound ; comprising a glass tube with movable piston rod and outlet tube, to which is joined a length of rubber tubing ending in a small glass tube for placing to the ear. An accurately divided scale graduated in millimetres is fitted on one side of the tube, and a coloured scale graduated in centimetres on the other. 4861
  - Price, with full instructions for use—
  - £2 19 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.355 - vue 374/555
- - 356 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. QEORGE (LONDON), Ltd., PROPRIETORS.
  - KUNDT’S TUBES
  - m m
  - 2598
  - 2598.—Kundt’s Dust Tube Apparatus, for showing the mode of vibration in a tube closed at both ends, and of determining the velocity of air waves in such a tube. This apparatus consists of a strong glass tube about 60 in. long and 11 in. in diameter, with a tight piston at one end, and a loose piston at the end of a glass rod at the other. 4858
  - Price, complete .... . . . . .. .. .. . . .. .. .. .. . . . . .. 15/-
  - 2599
  - 2599.—Kundt’s Dust Tube Apparatus, for showing the mode of vibration in a tube closed at both ends, and of determining the velocity of air waves in such a tube. This apparatus consists of a strong glass tube about 60 in. long by 1^ in. in diameter, with a tight piston at one end and a loose piston at the end of a glass rod at the other, with • rests for the tube, and screw-clamp for holding rod. Mounted on polished base, as figured. 4859
  - Price ........................................ ................................30/-
  - 2600
  - 2600.—Kundt’s Apparatus, for determining the velocity of sound in different gases. 4860
  - Price, complete with piston rods, brass taps and fittings, as illustrated .. .. .. .. .. £2 7 6
  - jrm
  - If BECKER & |jp^,**4.Cicicf LL.S«:»I— JlJH jTjHb
  - I lycopodium
  - ffesijSil {J*k
  - miiiiiiii^'Tiiinij!!!^^ 2602 2603 _
  - 2601 2602.—Iron Clamp, with 2603.—Iron Vice, with hori-
  - 2601.—Lycopodium Powder, groove for supporting the free end of zontal clamp, for holding glass tubes,
  - for dusting Kundt’s tubes. 4864 Kundt’s tubes. 4863 etc. 4862
  - Per bottle .. 1/6 Each .. .. .. .. 9/6 Each 10/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.356 - vue 375/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.357
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CHEMICAL HARMONICONS
  - 2604
  - 2604.—Simple Chemical Harmonicon, comprising a long glass tube with hinged metal cap on top, sensitive burner with stopcock and adjustable metal support for holding tube at various heights, inlet for coal-gas or hydrogen. 4®8®
  - Price, complete, with strong metal frame and heavy foot—
  - £2 12 6
  - 2605
  - 2605.—Double Chemical Harmonicon, comprising two glass tubes, each with hinged metal cover on top, two sensitive burners with stopcocks and adjustable metal supports for holding tubes at various heights. 4870 Price, complete, with strong metal frame and heavy foot, as figured .. .. £3 17 6
  - 2607.—Chem-i c a I Harmonicon,
  - “U niversity ” pattern. This apparatus consists of four glass tubes, each fitted with a hinged metal cap having a small hole in the centre, the sound occurring when the cap is open, but when closed the flame burns steadily in tube w i t h out sounding. Four sensitive burners are provided with adjustable metal supports for holding above tubes at various heights. The apparatus may be used for either coal gas or hydrogen. 4874
  - Price, complete, with strong metal frame and heavy foot, as figured.
  - £4 17 6
  - 2606. — Bresina’s Chemical Harmonicon, consisting of a gas-tight wooden box mounted on a wooden board; two sensitive burners, two glass tubes with hinged metal caps, two metal uprights with clamps for holding tubes at various heights, and three burners on metal stand for observing the vibrations of the flames in rotating mirror. 4874
  - Price, complete, with full instructions for use—
  - £7 10 0
  - 2607
  - 2608 .—Ditto, cheaper make, and smaller size, mounted on a polished mahogany frame. In this pattern the tubes are not fitted with hinged joints. 4872
  - Price, complete .. .. .. £3 3 0
  - 2609.—Chemical Harmonicon,
  - large size, about 80 in. in. height for demonstrating over-tones. Price, complete, with sensitive burner and half-a-dozen conical zinc resonators for producing overtones sol2> rez, solz, si3, reA and /a4-4873 Price .. .. £5 15 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.357 - vue 376/555
- - 358 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J GEORGE (LONDON), Ltd., PROPRIETORS.
  - SI55SSS?
  - SINGING FLAME APPARATUS
  - 2610.—Rijke’s Sound-in g T u b e. A very remarkable effect, discovered by Rijke, may be obtained with this apparatus, which consists of a long glass tube with a piece of gauze inserted about a third of its length. The tube is held vertical, and the gauze heated red-hot by a long gas flame. When the flame is withdrawn, the tube sounds its fundamental note very loudly while the gauze cools, so long as the tube is vertical, but the note ceases at once if the tube is turned into the horizontal position. 4868
  - Price, complete .. 12/6
  - (For further details, see Poynt-ing and Thomson’s “ Textbook of Physics—Sound,” and other well-known text-books.)
  - 2615.—H ydro-gen Singing Flame Apparatus, simple form, consisting of a flask, rubber cork, glass jet and tube.4865
  - Each .. .. 3/~
  - 2615
  - 2611.-S i ng-i n g Flame A p paratus,
  - consisting of a sensitive burner on metal foot, with clamp for holding tubes. Suitable for use with either coal-gas or hydrogen.
  - Price, c o m p le t e with three glass tubes of different sizes 4867 30/-
  - 2611
  - 2616.—Hydrogen Singing Flame Apparatus, simple form, consisting of Woulffe’s bottle, thistle funnel, and jet made of hardest Jena glass. 4866 Each .. .. 4/6
  - 2616
  - 2612.—P i n-hole Gas Burners,
  - for producing singing flames4875 Each.. ... 3/-
  - 2613 .—Ditto, but with stopcock4876 Each.. .. 4/-
  - 2614
  - 2614.—Sensitive Gas
  - Burner, best quality, with adjustable gauze and stopcock, as figured.
  - Each ................13/6
  - 2618.—IVI anometric Flame Apparatus, “University” pattern, with capsule, flame jet and stopcock, sliding on heavy brass upright. Complete with trumpet, as figured. 4881 Price ......................£3 5 0
  - 2617
  - 2617.—Koenig’s Sensitive Flame Burner, with disc of gauze, both adjustable. This burner is ordered largely, in that it works well at ordinary gas pressures. 4878
  - Price ................£2 5 0
  - 2618
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.358 - vue 377/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 359
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MANOMETRIC FLAME MIRRORS, Etc.
  - 2620
  - 2620. —IVl anometric Flame Mirror, simple
  - pattern, rotating in iron foot, as figured. 4884
  - Price.........£2 5 0
  - 2621
  - 2621.—S a v a r t Js Toothed Wheels, for determining the number of vibrations which affect the ear in a second. The set of wheels illustrated is arranged for use with any of our whirling tables. 4900
  - Price ........................18/6
  - 2622. —Humming Top Siren, furnished with tooth edged plate, having two rows of holes. 4901
  - Each .. .. 8/6
  - 2624.—Savart’s Toothed Wheels. This apparatus consists of three toothed wheels (fine, medium and coarse) mounted on a polished mahogany stand, with driving wheel. It is so arranged that when worked, each tooth of the wheel strikes a card, producing a distinct vibration. A musical note- is thus arrived at, rising or falling in pitch according to speed 4898 .. price £4 7 6
  - 2625 .—Ditto, with speed indicator 48984 .. ,, 4 17 6
  - 2623
  - 2623.—Sondhauss’ Lens, for experiments on the refraction of sound. Comprising a thin balloon for filling with carbonic acid gas ; mounted on a nicely-finished support, as figured. 4886 Price, for highest quality and finish £3 15 0
  - 2626
  - 2626.—Whirling Table Siren Disc,
  - best quality, provided with four rows of holes, giving a chord. 4902 Price, with blowing tube .. . • 13/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.359 - vue 378/555
- - 360 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2627.
  - Cagniard de la Tour’s Simple Siren, made of brass, and mounted on foot, as figured' 4891 Each £1 15 0
  - 2627
  - 2628
  - 2628.—Cagniard de la Tour’s Siren, large size, “ University ” pattern, solidly built, counting gear being visible and covered with glass window 4893 each £7 5 0
  - 2629.—Foot Bellows, on
  - feet, including supply of india-rubber tubing, for use with sirens .. each £3 5 0
  - SIRENS
  - 2630
  - 2630.—Cagniard de la Tour’s Siren, medium size, with indicator giving number of revolutions. 4892
  - Each .. .. £4 17 6
  - 2631
  - 2631. —Dove’s Siren,
  - large size, with double indicator, and four rows of holes, which can be opened and closed as desired. 4894
  - Price, for best quality—
  - £14 15 0
  - 2632
  - 2632.—H elmholtz’ Double
  - Siren, large size, “University” pattern. This instrument is provided with two chambers. There is a perforated plate for each chamber, provided with stops, on one axis, so that both can be rotated at same speed. The number of holes in each plate is so arranged that one box can be made to give double the number of vibrations of the other. The sound then produced being the octave of the other, by suitably regulating the stops one can arrive at any musical interval, say a fifth, and so on through the scale. The phenomena of interference and beats can also be shown. This is one of the most interesting and useful instruments for practically demonstrating the nature and composition of a "note. 4895
  - Price, for best quality .. £35 0 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.360 - vue 379/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 361
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - APPARATUS FOR CHLADNI’S FIGURES
  - 2633.—Square Chladni Plate, of polished
  - brass, 12 in. square, mounted on heavy iron foot as figured. 4909
  - Price .. .. .. .. .. ..£150
  - 2634.—Circular Chladni Plate, of polished brass, 12 in. in dia., mounted on heavy iron foot. 4910 Price ............... . . ..£150
  - base and supported by a steel rod, on which the mirror is clamped by means of a universal movement. The size of the mirror is 14 in. x 14 in., and it is of the greatest service on the lecture table in exhibiting to a class experiments taking place on a vertical plane. 4911 Price .....................£2 15 0
  - 2636. —S quare Chladni Plates, 8 in. square, for use with clamp No. 2639. 4912 A. Made of wood .. each 37-
  - glass
  - brass
  - 4/-
  - 8/-
  - 2637. —R ound Chladni Plates, 8 in. in diameter, for use. with clamp No. 2639. 4913
  - Made of wood glass brass
  - each 3/-
  - 2638
  - 2638.—Triangular Chladni Plates, 8 in. sides, for use with clamp No. 2639. 4914 A. Made of wood .. each 3/-
  - „ 4/- B. „ „ , glass • • „ 4/-
  - „ 8/6 c. „ „ , brass •• „ 8/-
  - 2641 EtC .—Violin Bows 4813 .. each 6/-
  - 2642. —Cello Bows 4814 ♦ .. each 11/6
  - — I'
  - 2639
  - 2639. — D o u b I e Clamp for holding Chladni plates. 4916 Each.................12/6
  - 2640
  - 2640. — Lycopod i u m Powder, for dusting over Chladni plates.4917 Per bottle .. .. 1/6
  - 2643.—Bass Bows
  - .. each 17/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.361 - vue 380/555
- - 362 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CHLADNI’S FIGURES, Etc.
  - 2644.—Set of Apparatus for Chladni Figures, comprising i glass plate, i wooden plate, 4 metal plates of different shapes, 1 clamp, 1 violin bow, resin, sand and lycopodium, the whole packed in a strong box. 4908 Price, complete, as figured .........................................................................£3 0 0
  - 2645.—Quincke’s Tube for
  - demonstrating the interference of sound waves. Rectangular pattern, with short rubber connections. 4924
  - Price .. .. .. .. 9/6
  - 2646.
  - Trevelyan’s Rocking Bar with Lead Block, for showing that musical 2646
  - vibrations are maintained by the communication of heat. Price .. .. • • .. .. .. .. 14/6
  - 2647.— Drenteln’s Apparatus for demonstrating the interference of sound waves, consisting of two globular glass resonators (each having three openings), three india-rubber tubes, two being 14 in. and the third about 30 in. in length. Price complete ..
  - 2648
  - 2648.—Q u i n c k e’s
  - Tube for demonstrating the interference of sound waves. 4922
  - Price .. .. .. 5/-
  - 2649.—Hopkins’ Forked Tube,
  - , for demonstrating the interference of sound waves. 4926 Each .. .. 17/6
  - 2649
  - 2650
  - 2650.—Kundt’s Tube, for
  - demonstrating the interference of sound waves, having one limb 36 in. long and the short one 18 in. 4925
  - Price, for best make .. £3 12 6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue
- p.362 - vue 381/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 363
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - REFLECTORS
  - 2651/2652
  - 2651.—Concave Reflectors, 38 cm. in diameter, made of copper, polished and silver-plated. Price per pair, including stands 4918 .. .. .. £3 5 0
  - 2652 .—Ditto, 45 cm. in diameter. Per pair, including stands 4919 ..............................£5 15 0
  - 2653.—Parabolic IVI irrors, superior quality, “ University ” pattern, made of German silver, highly polished and mounted on adjustable stands, for showing reflection of sound. 4921
  - Diameter of mirror .... 12 20 in.
  - Price per pair, including
  - special supports .. £1015 0 £1510 0
  - 2654/2655
  - 2654.—Parabolic Reflectors, made of nickel silver, highly polished. These reflectors are 35! cm. in diameter, cm. from back to front, and have a focus of 7 cm. 4920
  - Price per pair, including stands, as figured £2 10 0 2655 .—Ditto, diameter 23 cm. .. .. £2 5 0
  - GALTON’S WHISTLES, Etc.
  - 2656
  - 2656.—G a I t o n ’ s
  - Whistle, small size, with scale reading to 10 mm. in TVth mm. 4928
  - Price .............18/-
  - 2658
  - 2657.
  - Galto n’s Wh is tie,
  - medium size, with graduated scale and blowing ball. Price £1 17 6
  - 2659.—Acoustic Radiometer, consisting of four glass resonators with crosspiece rotating upon a pivot, for showing the mechanical action of sound. 4931
  - 2658.—Gal ton’s Whistle, “University” pattern. Guaranteed highest quality and finish. 4930
  - Price, complete, with blowing ball and nicely finished case—
  - £6 5 0
  - Price, complete, on stand, with steel point as figured .. 16/-
  - 2659
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.363 - vue 382/555
- - 364 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. CEORGE (LONDON), Ltd., PROPRIETORS.
  - VARIOUS APPARATUS FOR SOUND EXPERIMENTS
  - 2660
  - 2660. — P a p e r
  - Wheel, mounted on brass upright, with steel point, as figured. 4933 Price .. .. 10/6
  - 2661
  - 2661. — Stethe-
  - SCOpe, simple
  - 2662. —model Speaking Trumpets. 4934
  - 2665. —model o f Ear, five times natural size. 4938 Specification :—
  - A. The external ear consists of an expanded portion named pinna or auricle, the ext. auditory meatus,
  - (a) a cartilaginous portion of the auditory canal,
  - (b) an osseous portion of the auditory canal.
  - B. The middle ear, meatus and med. : (a) membrana tympani, (b) hammer or malleus, (c) incus or anvil, (d) stapes or stirrup closing the fenestra ovalis, (e) Eustachian tube.
  - C. Internal ear or labyrinth : (a) vestibule—(1) fenestra ovalis, (2) fenestra rotunda ; (b) semicircular canals, (c) cochlea, (d) acoustic nerve.
  - This model does not take to pieces .. .. price £12 6
  - 2666. —model of Ear, five times natural size. This model is divisible into three parts : the external, the middle ear or tympanum, and the inner ear or labyrinth. The external ear consists of an expanded portion or auricle (prima), the external auditory canal and the tympanic membrane. The middle ear is composed of the cavity of the tympanum, mastoid C2lls and the Eustachian tube. The internal ear consists of the osseous and the membranous labyrinth. 4939
  - Price, complete........................................£1 19 6
  - 2667. —model of Ear, large size, and entirely dissectible.4940
  - Price ............................ .. ... .. £4 15 0
  - form. 4935 Each
  - 2663
  - .. 5/6
  - Each
  - 6/6
  - 2663.—Binaural Stethe-
  - SCOpe, improved pattern. 4936 Each................11/6
  - 2664.—Ear Trumpets 4937.. each 12/6
  - FOR TELEPHONES AND
  - TELEPHONE PARTS
  - See pages 275 and 276.
  - 2668. — model of Larynx, natural size, with muscles. Divisible into two parts. 4941
  - Price .. .. 13/6
  - 2669. —model of
  - Larynx, with muscles, arteries, nerves, and glands. Can be taken to
  - pieces. 4942
  - Price .. .. 19/6
  - 2670.—model of Larynx, made specially for demonstrating the production of different sounds. This model can be taken to pieces ; also the vocal chords can be removed. 4943 ‘ Price .......... ...............£1 17 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.364 - vue 383/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 365
  - . W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GRAMOPHONES
  - Laboratory Gramophone, hornless cabinet type for use in Schools, Colleges, etc. It is not generally realized what a useful instrument a Gramophone is in the Laboratory, not only assisting to a great extent in the teaching of sound, acoustics, phonetics, etc., but for general use. Under the latter category we might mention the teaching of the Morse Code (suitable records for which are now being made by the leading manufacturers of gramophone records). Many other uses will readily present themselves.
  - Specification.
  - 2671.-—Gramophone, hornless type in well seasoned solid oak cabinet measuring 19 x 17 X 14 in. over all. Best quality double spring motor of exceptionally quiet running ; complete with speed regulator and indicator. Starting and stopping device. Sound box of improved construction giving very clear reproduction. All fittings highly nickel-plated.
  - Price, complete as per illustration .. .. £5 5 0
  - 2671
  - 2672. If desired we can supply the above Gramophone with an attachment to enable a large external horn to be used instead of the internal horn.
  - Price.................................... .....................................................£7 7 0
  - DISC RECORDS FOR GRAMOPHONES
  - 2673.—Zonophone Disc Records —
  - A. 10 in. double sided .. each 3/-
  - B. 10 in. Celebrity *. „ 4/-
  - C. 12 in. double sided • • „ 5/-
  - {Detailed list sent on application.)
  - Records of all other makes can be supplied at current prices.
  - NOTE TO CUSTOMERS ABROAD.
  - If desired, we shall be pleased to select an assortment of records suitable for school or college use.
  - A LARGE AND COMPREHENSIVE LIST OF
  - LANTERN SLIDES
  - COMPRISING SOUND, LIGHT, HEAT, MAGNETISM, ELECTRICITY, WIRELESS, MINING, NATURE STUDY, Etc., will be found at the end of this Catalogue.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.365 - vue 384/555
- - 366
  - SECTION 11.
  - LIGHT
  - 2674
  - 2674.—Rumford’s Photometer, consisting of
  - a ground glass screen, in front of which is fixed an opaque rod. Best quality and finish. 6001
  - Price .................................9/6
  - 2676
  - 2676.—Bunsen’s Grease Spot Photometer,
  - fitted with removable grease spot disc and plate-glass reflectors. As will be seen by the illustration this apparatus is fitted with a hinged top, and can be adjusted at various heights. 5005
  - Price, complete, with heavy iron foot .. £117 6
  - 2675
  - 2675.—Apparatus for showing the Rectilinear Propagation of Light, consisting of triple candle-holder and two screens. 5003
  - Price, complete.. .. .. .. .. .. 16/-
  - 2677
  - 2677.—Wire Pyramid, for demonstrating that the intensity of illumination on a given surface is inversely as the square of its distance from the source of light. 5000
  - Price .. .. .. .. .. .. .. 2/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.366 - vue 385/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 367
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2678
  - PHOTOMETERS
  - 2678. —Bunsen’s Grease Spot
  - Photometer, mounted on tripod foot 5007 ..........each 15/6
  - 2679. —Ditto, mounted on polished
  - mahogany base, with index mark, Fig A, page 374. 5007A .. .. each 17/6
  - 2680
  - 2680.—Jolly’s Paraffin Wax Photometer. 5009
  - Each...........4/6
  - 2682. Lees’ P h ©torn e t e r,
  - consisting of an oblong metal tube, open at both ends, and having two blocks 2682 of ground
  - glass fixed in the interior and an observation tube on top. The glasses are separated by a sheet of thin
  - tinfoil. 5010 Price, complete..
  - 13/6
  - 2681.—Prism Photometer, latest construction, consisting of two total reflecting prisms mounted on a marble base, as figured. 5012 Price .....................£3 18 6
  - 2683. —Lummer - Brodhun Photometer,
  - latest construction. Best make and finish. 5015
  - £15 10 0
  - (Full details will be sent post free on application.)
  - 2684. — Student’s Optical
  - Bench. This bench consists of three parts : (a) a metal candle-holder (“Box” pattern) which has a circular window in front covered with fine brass gauze, behind which a candle is held in a spring clip. The front of the candle-holder is made to fix easily on the end of a metre rule;
  - (b) a sliding lens-holder; and (c) a sliding screen on which the image can be focussed. The centre of the screen is marked by a black dot.
  - When using the apparatus for measuring the focal length of the convex lens directly, the lens-holder and screen are placed on a metre rule, which is held pointing towards the sun or any distant object, such as a tree or chimney, standing clearly out against the sky. The screen is moved along until a clear image of the object is seen near its centre ; the difference between the readings of the rule at the lens-holder and screen gives the focal length of the lens.
  - When using the apparatus as an optical bench, the end of the rule is placed in the hood of the candle-
  - holder, and the lens-holder and screen placed in position. The lens is held in position by means of two rubber bands and can be easily centred by moving it in the holder, adjusting its position until the light upon the screen is symmetrical. Finally, the screen is moved along until a clear image of the gauze can be seen, after which the reading can be taken. ...
  - All experiments on focal lengths of lenses and combinations of lenses can be easily performed, extra lens-holders being used when required.
  - The holders are made of a suitable size for spectacle lenses, but can be provided with larger apertures if lenses of a very large size are to be used. 5019
  - PRICES.
  - A. Student’s Optical Bench, consisting of metre rule, candle-holder, lens-holder, and screen .. .. per set 10/6
  - B. Ditto, without metre rule .. ........ .. .. .. .. .................... „ 7/6
  - C. Extra Lens-Holders .. .. .. .. .. .. .. .. .. .. .. .. ” 2/3
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.367 - vue 386/555
- - 368 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - OPTICAL BENCHES
  - 2685.—Student’s Optical Bench, i metre in length, consisting of a board having an accurately graduated boxwood scale on one side and the following sliders :—4 lens-holders, 1 zinc screen, fitted with a card having two holes, one of which has cross-wires, 1 wooden receiving screen, 1 needle on wooden foot, and 1 mirror glass on foot. 5020
  - Price, complete ’ .. .. .. .. . . . . . . .. .. .. .. .. . . ..£150
  - (See. Clay's “ Practical Exercises in Light.”)
  - 2686.—Optical Bench, 1 metre in length, accurately graduated in millimetres on one side and furnished with the following accessories, all of which are mounted on heavy sliders :—4 lenses in holders, metal screen with slit in centre, metal screen with iris diaphragm in centre, prism table, prism in holder, candle-holder, and paper screen. 5021
  - Price, including the ten heavy sliders, as figured .. .. .. .. . . . . .. .. ..£650
  - 2687 —Ditto, but bench 2 metres in length 5022 .. .. .. .. .. .. .. .. .. 7100
  - Oup stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.368 - vue 387/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 369
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - OPTICAL BENCH
  - 2688.—Optical Bench, superior quality, i metre in length and made entirely of metal. This bench is accurately graduated in centimetres on one side 5023 .. .. .. .. .. .. .. .. £2 7 6
  - 2689 •—Ditto, but 2 metres in length 5024 .. .. .. .. .. .. .. . .. .. 3 17 6
  - ACCESSORIES.
  - A. “ Nivoc ” Lens-Holder, for taking lenses up to 3 in. diameter each £0 11 6
  - B. Ditto, including slider 0 17 0
  - C. Concave Mirrors, 3 in. diameter, optically true, to fit above Lens-Holder .. yy 0 4 6
  - D. Convex Mirrors, ditto yy 0 4 6
  - E. Ground Glass Screen, in metal frame yy 0 7 0
  - F. Ditto, including slider yy 0 12 6
  - G. Metal Screen, with iris diaphragm in centre yy 0 11 6
  - H. Ditto, including slider yy 0 17 0
  - I. Metal Screen, with fine wire gauze in centre yy 0 8 0
  - J- Ditto, including slider yy 0 13 6
  - K. Metal Screen, with adjustable slit in centre .. .. .. yy 1 7 6
  - L. Ditto, including slider yy 1 13 0
  - M. 2 Transparent Screens, for intercepting actual or real pictures 0 15 6
  - N. Ditto, including slider .. * 1 1 0
  - 0. Bunsen’s “ Grease Spot ” Disc, mounted on metal rod each 0 12 6
  - P. Ditto, including slider >> 0 18 0
  - Q- Table for holding glass vessels, prisms, etc. ,, 0 5 0
  - R. Ditto, including slider yy 0 10 6
  - S. Prism, mounted on metal rod .. .. .. . .. „ 0 11 6
  - T. Ditto, including slider yy 0 17 0
  - U. Metal Holder, for 1 candle yy 0 5 0
  - V. Ditto, including slider yy 0 10 6
  - w. Metal Holder, for 4 candles „ 0 9 6
  - X. Y. Ditto, including slider .. .. .. . . .. Comparison Burner, for gas or petroleum. When ordering please state which ; if not stated, we shall in all 0 15 0
  - cases send a burner for gas .. .. each 0 10 6
  - Z. Ditto, including slider yy 0 16 0
  - Zi. Standard Candles {Other accessories to order.) 0 1 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
  - AA
- p.369 - vue 388/555
- - 370 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - OPTICAL BENCH
  - H.
  - I.
  - J.
  - K.
  - L.
  - M.
  - N.
  - O.
  - P.
  - Q*
  - R.
  - S.
  - T.
  - U.
  - V.
  - w.
  - X.
  - Y.
  - Z.
  - Zi.
  - 2690.—“ IMivoc ” Optical Bench, entirely new and improved pattern, the bed of which consists of truly turned heavy steel rods (nickel-plated) with engine-divided steel rule. The bench is constructed so that a full metre length can be measured. The sliders are heavy machined iron planes, provided with groove and a flat; by this method of construction they always slide truly and keep in the same plane. These sliders are fitted with heavy brass tube pillars l in. in diameter inside. 5025
  - Optical Bench, to measure i metre, with 5 sliders
  - fitted with pillars .....................each £8 10 0
  - 2690
  - Ditto, ditto, 2 metres
  - ACCESSORIES.
  - A. " NivocV’ Lens-Holder, will take lenses up to 3 in.
  - diameter .. .. • • • • .. each
  - B. Ditto, including slider
  - C. Concave Mirrors, 3 in. diameter, optically true, to
  - fit above lens-holder .. .. .. each
  - D. Convex Mirrors, ditto ..................
  - E. Ground Glass Screen, in metal frame
  - F. Ditto, including slider .................
  - G. Metal Screen,r furnished with an iris diaphragm „
  - 11 0 0
  - Ditto, including slider .. .. .. 1
  - Metal Screen, with fine wire gauze in centre Ditto, including slider Metal Screen, with adjustable slit Ditto, including slider
  - 2 Transparent Screens, for intercepting actual or real pictures Ditto, including slider
  - Bunsen’s “ Grease Spot ” Disc, mounted on metal rod Ditto, including slider
  - Table for holding glass vessels, prisms, etc.
  - Ditto, including slider Prism, mounted on metal rod Ditto, including slider Metal Holder for 1 candle ..
  - Ditto, including slider Metal Holder for 4 candles ..
  - Ditto, including slider
  - Comparison Burner, for gas or petroleum. When ordering please state which ; if not stated, we shall in all cases send a burner for gas Ditto, including slider Standard Candles ......................
  - (Other accessories to order.)
  - each
  - each
  - £0 11 0 17
  - 0 4 0 4 0 7 0 12 0 11 £0 17 0 8 0 13 1 7 1 13 0 15 1 1 0 12 0 18 0 5 0 10 0 11 0 17 0 5 0 10 0 9 0 15
  - 6
  - 0
  - 6
  - 6
  - 0
  - 6
  - 6
  - 0
  - 0
  - 6
  - 6
  - 0
  - 6
  - 0
  - 6
  - 6
  - 0
  - 0
  - 6
  - 0
  - 0
  - 6
  - 6
  - 0
  - 0 10 6 0 16 6 0 10
  - Oup Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.370 - vue 389/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 371
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - OPTICAL BENCH
  - 2691.—Experimental Optical Bench, “ University” Pattern, guaranteed highest quality and finish and of solid construction. This bench consists of a strong cast-iron bed 170 cm. long, A and plane in section, supported by four levelling screws. A German silver millimetre scale runs the entire length, and is read by vernier to -i mm. The scale is screwed and soldered to a stout brass bar affixed to the bed. Three pillars are fitted to the bed. Each pillar is mounted on a stout gun-metal slide, provided with clamp and vernier, and consists of a strong brass tube, truly cylindrical, sliding in a metal socket; and is actuated by rack and pinion vertically, and is provided with a clamp for the sliding tube. A steel stud of standard size is secured to the upper end-of the tube. One of the pillars has a transverse motion on a dovetail slide, and is moved by a fine screw ; a £ mm. scale is divided on the slide and read by an index. The micrometer eye-piece consists of a Ramsden eye-piece carried by a dovetail slide in a vertical frame, and is actuated by a | mm. screw furnished with an adjustable drum divided into fifty equal parts ; cross-wires are placed in the focus of the eye-piece and move with it. Two sets of jaws for clamping various pieces are supplied. Each set consists of three jaws sliding in grooves on a vertical plate, and capable of being clamped in any position ; the plate rotates on a hori-
  - zontal axis, and has coarse and fine adjustment. Price, complete as illustrated 6030 .. .. .. £42 15 0
  - A. Extra Pillars, with slide, rack and pinion, clamp and vernier, similar to those described above each 3 15 0
  - B. Pillars of simpler construction, on slide, with clamp, but without vernier or rack motion .. ,, 110 0
  - C. Pillar, with collimating lens, with arrangements for setting the lens in any position .. .. 110 0
  - D. Cylindrical Lens, mounted to fit the pillar of the collimating lens .. .. .. .. .. ,, 156
  - E. Stand for lamp to fit bench .. .. .. .. .. .. .. .. .. .. „ 0 8 3
  - F. Ditto, with adjustments .. .. .. .. .. .. .. .. .. .. .. „ 119
  - G. Sliding Rule, in German Silver, reading to -i mm., extending from 16 cm. to 30 cm., for measuring
  - the distance between two objects, in case .. .. .. .. .. .. .. .. ,, 250
  - H. Two Tables for supporting sources of light .. .. .. .. .. .. .. .. ,, 0113
  - J. Paper-Screen Holder .. .. .. .. .. .. .. .. .. .. .. .. „ 0 113
  - K. Screen, metal, provided with a revolving diaphragm to regulate the quantity of light, to fit pillar B „ 10 3
  - L. Two Glass Mirrors, hard-silvered, 5 cm. by 3-5 cm. .. .. .. .. .. .. .. ,, 015 0
  - M. Black Mirror, 5 cm. by 3-5 cm. .. .. .. .. .. .. .. .. .. .. ,, 0 7 3
  - N. Holder for the above mirrors .. .. .. .. .. .. .. .. .. .. ,, 0 12 0
  - O. Divided Horizontal Circle, reading to degrees, with mount for L. and M. ; arranged to show the
  - angle of incidence and reflection, and that the angle the image moves through is twice that
  - through which the mirror moves .. .. .. .. .. .. .. .. .. ,, 5 5 0
  - P. Two Frames, with stout cross-wires, for use in showing that the image is the same distance
  - behind the mirror as the object is in front of it .. .. .. .. .. .. „ 0 15 0
  - Q. Screen, with small hole to be illuminated and used as object .. .. .. .. .. ,, 053
  - R. Concave Mirror, mounted .. .. .. .. .. .. .. .. .. . . .. ,, 12 6
  - S. Convex Mirror, mounted .. .. .. .. .. ............. .. .. .. ,, 12 6
  - T. Black Metal Screen .. .. .. .. .. .. .. .. .. .. .. .. ,, 0 5 3
  - U. Ground Glass Screen.................................................................................. „ 083
  - V. Prism, crown or flint glass, angle 6o°, 3 cm. square faces, mounted to fit circle O .. .. ,, 17 0
  - W. Piece of Thick Worked Glass, mounted to fit circle 0 .. .. .. .. .. .. ,, 1100
  - (iContinued on next page.)
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.371 - vue 390/555
- - 372 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - OPTICAL BENCH
  - 2691.—Experimental Optical Bench.—Continued from previous page.
  - X. Set of Six Lenses, with cell, mounted to fit circle O..
  - Y. Observing Eye-piece, with cross-wires .. .. .. .. ....
  - Z. Observing Telescope, 7 in. long, with cross-wires, mounted to fit pillars
  - Zi. Two Small Scales, divided on glass, with observing eye-piece to each Z2. Three Different Coloured Glasses, with holder to fit pillars ..
  - Z3. Cover with Two Parallel Slits, to fit over cell X, for use with concave lenses .. Z4. Set of 8 Diffraction Screens, in case Z5. Slit, 1 mm. wide Z6. Adjustable Slit
  - Z7. Micrometer Slit, reading to -oi mm.
  - Z8. Fresnel’s Double Mirror, with adjustments Zg. Fresnel’s Biprism
  - Zio. Billet’s Split Lens, with micrometer adjustment Zn. Fizeau’s Biplates, with complete adjustments, and lens Z12. Lloyd’s Mirror Z13. Newton’s Rings Apparatus..
  - Z14. Copy of Rowland’s Grating, 14,500 lines to the inch Z15. Glass Gratings. Prices according to number of lines.
  - each £2 12 6 13 3 „ 2 12 6
  - 3 0 0 17 0 0 3 9 1 17 6 0 6 0
  - 1 17 6
  - 4 6 3 4 14 6 10 3
  - -,; 5 5 0
  - 7 10 0
  - 2 5 9
  - 3 15 0 12 6
  - Z16. Apparatus for Polarization by Reflection, consists of revolving diaphragm, collimating lens, 1 hard silvered mirror, 1 black mirror as polarizer and 1 ditto as analyser, and screen—all mounted to fit on pillars .. .. .. .. .. .. .... .. .. .. .. .. each 676
  - Z17. Apparatus for Polarization by Ordinary Refraction, consists of a bundle of thin glass plates, mounted to revolve on an axis parallel to the bench, to be used in place of the black mirrors of No. Z16
  - each
  - Apparatus for Polarization by Double Refraction :—
  - Z18. Divided Vertical Circle, with two opposite verniers and fine adjustment, reading to 1 minute „ Z19. Plate of Tourmaline, mounted to fit the circle Z18 .. .. .. .. .. .. .. ,,
  - Z20. Double-Image Prism, to fit circle Z18 .. .. .. .. .. .. .. .. .. ,,
  - Z21. Diaphragm with circular or diamond-shaped aperture .. .. .. .. .. .. ,,
  - Z22. Nicol Prism, to fit circle Z18 .. .. .. .. .. .. .. .. .. .. „
  - Z23. Senarmont’s double-image prism, to fit circle Z18 .. .. .. .. .. .. .. from
  - Z24. Rochon’s ditto .. .. .. .. .. .. .. .. .. .. .. .. ,,
  - Z25. Wollaston’s ditto .. .. .. .. .. .. .. .. .. .. .. .. ,,
  - Z26. Foucault’s ditto .. .. .. .. .. .. .. .. .. .. .. .. ,,
  - Z27. Gian’s ditto .. ....................................... .. .. .. .. .. „
  - Z28. Circular Plate, fitted to receive the polarizing prisms, etc. .. .. .. .. .. .. each
  - Z29. Red and Blue Glasses, to fit the plate Z28 .. .. .. .. .. .. .. .. ,,
  - Z30. Stage for crystals, etc., divided to degrees, to fit pillars..............................
  - Z31. Press for glass plates .. ................................ .. .. .. . • „
  - Z32. 2 Biconvex Lenses in separate mounts for convergent light.. .. .. .. .. .. „
  - 17 9
  - 4 10 0 10 3 2 5 0 0 4 6 1 10 0
  - 1 17 6
  - 1 10 0 17 0 17 0 12 6 0 18 9 0 11 3
  - 2 5 0 0 18 9 12 6
  - Apparatus for the Rotating Power and the Principle of the Saccharimeter and Polarimeter :•— Z33. Soleil’s Quartz Wedges and compensation plate mounted on slides actuated by rack and pinion, with scale
  - and vernier .. .. .. .. .. .. .. .. .. .. .. .. each 7 10 0
  - Z34. Small Telescope to fit circle Z18 .. .. .. .. .. .. .. .. .. .. ,, 12 6
  - Z35. Solution Tubes, 10, 20 and 30 cm. .. .. .. .. .. .. .. .. .. ,, 0 113
  - Z36. Support for solution tubes, adjustable .. .. .. .. .. .. .. .. .. ,, 0136
  - Z37. Collimating Lens, to fit plate Z28 .. .. .. .. .. .. .. .. .. ,, 0 5 3
  - Z38. Biquartz, to fit plate Z28 .. .. .. .. .. .. .... .. .... „ 133
  - Z39. Laurent’s Plate, to fit plate Z28 .. .. .. .. .. .. .. .. .. .. ,, 13 3
  - Z40. Poynting’s Plate, to fit plate Z28 .. .. .. .... .. .. .. .. ,, 133
  - Z41. Calcspar Plates, etc., to show the principle of Wild’s Polaristrobometer, to fit plate Z28 .. ,, 3 15 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.372 - vue 391/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 373
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - APPARATUS FOR OPTICAL BENCH EXPERIMENTS
  - 2692.—Ground Glass Screen, mounted on cheap metal stand, as figured. 5031 Price .. .. .. .. 6/6
  - 2696.—Candle Holder, complete, with
  - sliding pillar, adjusting screw and tripod foot.5036 Each...........................11/-
  - 2697 —Ditto, but mounted on polished
  - mahogany base with index mark, as Fig. A, page 374. 5037
  - Each...............................13/-
  - 2692
  - 2696
  - 2693.—Concave IVlirror,
  - with strip of silver scraped off. Diameter 6 in. 5032
  - Price, mounted on cheap metal stand, as figured .. .. 8/-
  - 2698.—Four-Way Candle Holder,
  - complete, with sliding pillar, adjusting screw and tripod foot. 5038 Each......................13/6
  - 2699 —Ditto, but mounted on polished mahogany base, as Fig. A, page 374. 5039 Each......................................................................................15/6
  - 2693
  - 2694.—Convex IVlirror,
  - with strip of silver scraped off. Diameter 6 in. 5033
  - Price, mounted on cheap metal stand, as figured .. .. 8/-
  - 2694
  - 2700.—Electric Incandescent
  - Lamp, complete, with sliding pillar, adjusting screw and tripod foot. 5040
  - Each .........................11/6
  - 2701 .—Ditto, but mounted on polished mahogany base with index mark, as Fig. A, page 374. 5041
  - Each ........................113/6
  - 2698
  - a
  - 2700
  - 2695
  - 2695.—Adjustable Slit.
  - Price, complete, with adjusting screw and cheap metal stand, as figured 5034 ....... 21 /-
  - 2703
  - 2702
  - 2702.—Kn i tti ng Needles, mounted on metal foot, as figured. 5035
  - Each .. .. 6d.
  - 2703.—Gas Incandescent Lamp,
  - complete, with sliding pillar, adjusting screw and tripod foot 5042 .. .. each 13/-
  - 2704 .—Ditto, but mounted on polished mahogany base, with index mark, as Fig. A, page 374 6043 .. .. .. each 15/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.373 - vue 392/555
- - 374 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - APPARATUS FOR OPTICAL BENCH EXPERIMENTS
  - Fig. A.
  - 2705.—“ Nivoc ” Lens-Holder, for holding
  - lenses up to 3 in. in diameter. Price complete with sliding pillar, adjusting screw, etc., mounted on polished mahogany base having an index mark 5044 .. 17/-
  - 2706 —Ditto, but mounted on tripod foot as illustration. No. 2715................................each 16/6
  - 2707.—Wire Gauze Screen, complete with sliding pillar, adjusting screw and tripod foot 5046 .. each 11/6
  - 2708 •—Ditto, but mounted on polished mahogany base having index mark as Fig. A, on this page 5047 .. each 13/6
  - 2707
  - 2709.—Comparison Gas Burner,
  - complete with sliding pillar, adjusting screw and tripod foot 6048 .. .. each 11/6
  - 2710 —Ditto, but mounted on polished mahogany base having index mark, as Fig. A, on this page 5049 .. each 13/6
  - 2709
  - 2713. —Ground Glass Screen, com-
  - plete with sliding pillar, adjusting screw and tripod foot 5052 .. .. .. each HZ-
  - 2714. —Ditto, but mounted on polished
  - mahogany base having index mark as Fig. A, on this page 5053 .. each 13/-
  - 2713
  - 2715. —“ Nivoc ” Lens-Holder,
  - for lenses up to 3 in. in diameter. Complete, with sliding pillar, adjusting screw and tripod foot 5054 each 16/6
  - 2716. —Ditto, but mounted on polished mahogany base having index mark, as Fig. A, on this page 5055 .. each 17/-
  - 2715
  - 2717. —Prism Table, complete with
  - sliding pillar, adjusting screw and tripod foot 5056 .. .. .. each 8/6
  - 2718. —Ditto, but mounted on polished mahogany base having index mark, as Fig. A, on this page 5057 .. each 10/6
  - 2717
  - 2719. —Bunsen’s Grease Spot Disc, complete with sliding pillar, adjusting screw and tripod foot. 5058
  - Each........................15/6
  - 2720. —Ditto, but mounted on polished mahogany base having index mark, as Fig. A, on this page 6059 .. each 17/6
  - 2719
  - 2711
  - 2711.—Metal Screen and Iris Diaphragm, for making apertures of different diameters. Complete, with sliding pillar, adjusting screw and tripod foot 5050 .. .. .. each 16/-
  - 2712 .—Ditto, but mounted on polished mahogany base having index mark as Fig. A, on this page 6051 .. each 18/-
  - 2721.—Adjustable Slit, complete
  - with sliding pillar, adjusting screw and tripod foot 6060 .........each £112 6
  - 2722 •—Ditto, but mounted on polished mahogany base having index mark, as Fig. A, on this page .. each £1 14 6
  - 2721
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.374 - vue 393/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 375
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2723.—C one
  - optically true,
  - jments, etc. Reference Diameter Focus Each
  - ave Mirrors. Best quality, unmounted, for optical bench experi-
  - A
  - 50
  - 150
  - B
  - 50
  - 100
  - C
  - 50
  - 200
  - D
  - 76
  - 76
  - MIRRORS
  - (See also page 376.)
  - 2727.—Set of 2 Cylindrical IVI irrors, consisting of semicircular glass rings, about 6 in. in diameter, one silvered on the inside and the other on the outside surface. 5072 Per pair .. 3/9
  - (See Clay’s “ Practical
  - E
  - 76
  - 102
  - F
  - 76
  - 150
  - Reference.. .. G H J K L 2728.—Cylindrical Mirror, superior quality,
  - Diameter .. .. 76 150 150 150 150 made of metal, for showing a caustic curve by reflec-
  - Focus • • 305 76 102 150 305 tion. 5073
  - Each .. 4/6 13/6 13/6 13/6 13/6 Each .. .. .. .. .. .. 2/6
  - 227224.—U O n V e X Mirrors. Best quality, optically true, unmounted, for optical bench experiments, etc.
  - Reference .. .. M N O P Q R
  - Diameter .. . . 50 50 50 76 76 76
  - Focus .. . . . . 150 100 200 76 102 150
  - Each............... 1/8 2/10 2/10 4/6 4/6 4/6
  - Reference. . .. S T U V W
  - Diameter .. .. .. 76 150 150 150 150
  - Focus .. . . .. 305 76 102 150 305
  - Each .................4/6 13/6 13/6 13/6 13/6
  - Special attention is drawn to the very low price of our optically true Concave or Convex Mirrors, 50 mm. diameter, focus 150 mm. The low price is only possible because of the heavy demand for this particular size.
  - 2725.—Concave Mirrors.
  - lengths not guaranteed.
  - A
  - Cheap quality, focal
  - Diameter Focus (approx.)
  - Each..............
  - Dozen
  - F
  - Diameter 3
  - Focus (approx.) 6 Each .. 1/4
  - Dozen
  - 4
  - V-
  - B
  - 2
  - 6
  - V-
  - c
  - 2
  - 8
  - 1/-
  - D
  - 2
  - 12
  - V-
  - E
  - 3 in.
  - 4 in.
  - 1/4
  - 10/6 10/6 10/6 10/6 14/-
  - G
  - 3
  - 8
  - 1/4
  - H
  - 3
  - 12
  - 1/4
  - J
  - 4
  - 4
  - 1/9
  - K
  - 4
  - 6
  - 1/9 1/9
  - L M
  - 4 4
  - 8 12
  - 1/9
  - 14/- 14/- 14/- 18/6 18/6 18/6 18/6
  - (Other focal lengths to order.)
  - 2726.—Convex Mirrors. Cheap quality, focal lengths not guaranteed.
  - N P Q R S T
  - Diameter 2 2 2 2 3 3
  - Focus (approx.) 4 6 8 12 4 6
  - Each V- 1/- 1/- V- 1/4 1/4
  - Dozen .. 10/6 10/6 10/6 10/6 14/- 14/-
  - \ u V w X Y Z
  - Diameter 3 3 4 4 4 4
  - Focus (approx.) 8 12 4 6 8 12
  - Each 1/4 1/4 1/9 1/9 1/9 1/9
  - Dozen 14/- 14/- 18/6 18/6 18/6 18/6
  - (Other focal lengths to order.)
  - 2727
  - 2729. —Concave Mir-rors, 6 in. in diameter, mounted in brass, with boss and thumbscrew for fixing on rods of mirror and retort stands. 5080
  - A. Price without stand
  - B. ,, with stand
  - 2730. —C oncave rors, as above, but
  - M
  - Each
  - . . 6/6 .. 9/6 Mir-
  - 9 m.
  - in diameter. 5081 Each
  - A. Price without stand 11/6
  - B. ,, with stand .. 14/6
  - 2729/2730
  - 2731. —Convex Mirrors,
  - 6 in. in diameter, mounted in brass, with boss and thumbscrew for fixing on rods of mirror and retort stands. 5082
  - Each.
  - A. Price without stand . . 6/6
  - B. ,, with stand .. 9/6
  - 2732. —Convex Mirrors,
  - as above, but 9 in. in diameter. 5083 Each
  - A. Price without stand 11/6
  - B. „ with stand .. 14/6
  - 2733.—Concave Mirrors, 3 in. in
  - diameter, optically true, mounted in brass, with boss and screw for fixing on upright rod of small retort stands, etc. 5078
  - Focus .. 76 102 150 305 mm.
  - Each .. 7/- 7/- 7/- 7/-
  - 2733 ^ 2734
  - 2734.—Convex Mirrors, 3in. in diameter, optically true, mounted in brass, with boss and screw for fixing on upright rod of small retort stands, etc. 5079 Focus .. . . 76 102 150 305 mm.
  - Each .. 7/- 7/- 7/- 7/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.375 - vue 394/555
- - 376 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MIRRORS, Etc.
  - 2735
  - (jFor Concave and Convex Mirrors, see previous page.)
  - 2735.—Plane Glass Mirrors, quality patent plate, unmounted. 5062 best
  - A. 3 in. X 1 in. .. .. per doz. 2/-
  - B. 6 „ X 1 „ 3/6
  - C. 4 „ X 3 » 5/-
  - D. 6 „ X 4 » 10/-
  - E. 5 „ x 5 „ 11/-
  - 2739
  - 2739.—Strip of IVlirror Glass, with brass spring clip, for pin experiments, as used at Harrow School. 5063
  - Each...................8d.
  - Per dozen .. .. .. 7/-
  - 2736
  - 2736.—St r i p of IVlirror Glass,
  - mounted on wooden foot. 5064
  - Each .. • • 8d.
  - Per dozen.. .. 7/6
  - 2737.—P lane Glass IVlirror, 10 in. X 8 in., in polished wooden frame, as figured. 5065
  - Each ..................12/6
  - 2738
  - 2738. —Plane Glass IVI i r r or,
  - arranged on a heavy-base and supported by a steel rod, on which the mirror is clamped by means of a universal movement. The size of the mirror is 14 in. X 14 in., and it is of the greatest service on the lecture table in exhibiting to a class experiments taking place on a vertical ,1 plane. 5066
  - Price .. £2 18 6
  - 2740.—A ngular Mirrors, mounted
  - on graduated base.
  - Each...........13/6
  - 2740
  - 2741.—A ngular M i r rors, superior make and finish, on graduated metal base. All parts extra strongly made. 5069
  - Each ..
  - £15 0
  - 2741
  - 2742.—Para I lei
  - Mirrors, best quality, in polished mahogany frame. 5070 Each .. £2 7 6
  - 2742
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.376 - vue 395/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 377
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MIRRORS, Etc.
  - 2743 *
  - 2743.—Pair of IVIirrors and Large Lens, etc., as described in the Laboratory Note-Books of Professor Wilberforce and Rev. T. C. Fitzpatrick (Cambridge University Press). This set consists of one large concave mirror 6 in. in diameter (C), one large convex mirror 6 in. in diameter (/l), and one large double convex lens 3! in. in diameter (D),
  - all mounted in strong wooden frames having special metal boss-heads. 5086 Price, for the complete set, including steel upright 20 cm. high, mounted on heavy iron foot 10 cm. square .. £2 0 0
  - The above may be had separately as follows :—
  - Concave Mirror, mounted in strong wooden frame with special boss-head (see Fig. C).. .. .. each 13/6
  - Convex Mirror, mounted in strong wooden frame with special boss-head (see Fig. A) .. .. .. ,, 13/6
  - Large Double Convex Lens, 3|- in. diameter, mounted in strong wooden frame with special boss-head (see
  - Fig. D)........................................................................ ................ „ 12/6
  - Steel Upright, on heavy iron base (as Fig. B).. .. .. .. .. .. .. .. .. ,, 3/6
  - 2745
  - 2744
  - 2744, —Small Mirror on brass stand, with adjusting screw, for directing a beam of light into water trough. 5087
  - Each .. ..................... .. 12/6
  - 2745.—Reflection and Refraction Troughs,
  - made of finest white crystal glass, and polished on all sides. Stock sizes are as follows 5088 :—
  - Height in cm. . • 25I 21 19 i6| 16
  - Length ,, 21 20 12 14 O H 10
  - Width „ • I2| 10 9 7i 4 4
  - Price . 17/6 15/- 14/- 13/- 12/- 10/6
  - (<Other sizes made to order at proportionate prices.)
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.377 - vue 396/555
- - 378 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - REFLECTION AND REFRACTION
  - 2746
  - 2748
  - 2748.—Muller’s Reflection Apparatus,
  - superior make and finish, consisting of graduated trough, revolving mirror, and indicator 5091 each £17 6
  - 2749 .—Ditto, cheaper make and smaller size.
  - Each......................................19/6
  - 2746.—Apparatus to show the Refractive Index of Water by the critical angle. This apparatus consists of a small glass tank, glass air-cell and a wooden stool about 6 in. in length as described in Clay’s “ Practical Exercises in Light.” 5089
  - Price, complete.. .. .. .. £ .. .. 10/6
  - 2747
  - 2747.—-Reflection and Refraction Trough,
  - for illustrating the laws of refraction, as described in “ Light ” by Mr. Lewis Wright 5090 .. £15 0
  - Consists of a rectangular trough 16 x 11 X 2 in.; one end glass, the rest tin. One face has a circle 5 in. radius cut out of the tin, its centre being 10 in. from the bottom ; in its place glass is substituted. A movable strip of tin 18 x 2 in., in which are cut two slits if x f in. at distance of 1 and 9 in. from one end. Tank and strip are blackened. On the circle are painted the vertical and horizontal diameters. Each quadrant is divided into nine equal parts.
  - Directions for Use.—Reflect a beam from the mirror M, so that it passes through the slit in the strip of tin and enters the water at the centre of the circle. The path of the rays in air is made visible by a little smoke, and in the water by adding a few drops of milk. For large angles, place the strip along the glass end. Fill the trough with water to the horizontal diameter. Use sunlight or a parallel beam from the lantern.
  - (The above details are taken from Mr. Mark R. Wright’s book on “ Sound, Light, and Heat.”)
  - 2750
  - 2750.—Muller’s Trough for the Refraction of Liquids, large size, best quality and finish. 5093 Each ...........................£15 0
  - 2751.—Reflection and Refraction Trough,
  - mounted on polished wooden base.-5095
  - Price, including small adjustable mirror sliding on upright support .. £3 10 0
  - 2751
  - 2752.—Reflection and
  - Refraction Apparatus,
  - comprising semicircular glass trough, metal circle graduated in degrees, and three movable arms carrying mirror, etc. 5096
  - Price, complete, mounted on heavy foot with levelling screws—•
  - £5 10 0
  - 2752
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.378 - vue 397/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 379
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - REFLECTION AND REFRACTION
  - 2753
  - 2755
  - 2755.—Glass Cubes, for
  - refraction experiments, polished on all sides, edges slightly bevelled. 6103
  - Each.
  - A. 25 mm. square (approx.) 1 /-
  - B. 38 „ „ „ 2/-
  - C. 50 „ „ „ 2/6
  - D. 64 „ „ „ 6/6
  - 2753.—Reflection and Refraction Apparatus, “ University ” pattern. This apparatus is of superior construction and finish, and is highly recommended to those requiring an instrument of the highest possible finish at a reasonable price. 5097
  - Price, complete .. .. .. .. £11 15 0
  - {Fully described in Ganot’s “ Physics.”)
  - 2754.—“ Fountain of Fire ” or “ Luminous Cascade ” Apparatus, large size, superior make and finish. 5102
  - Price................................£3 10 0
  - {Forfull instructions see Lewis Wright’s book on “ Light.”)
  - 2756
  - 2756.—Semicircular Glass Slab, measuring approximately 3^ in. long x if in. high x f in. thick. 5107
  - Price.................... .. 2/3
  - 2757
  - 2757.—Rectangular Glass Slabs, polished on all sides, for showing refraction. Size 4! X 2| X | in. 5104 ..' ............each 2/-
  - 2758 .—Ditto, cheaper quality, about half thickness of No. 2757 5105 .. .. ... .. each 1 /6
  - 2754
  - 2759
  - 2759.—T r i a ngular Glass Slab, angles 90°, 6o° and 30°, half size of No. 2757.
  - Each..........2/6
  - For Glass Prisms, see pages 386 and 387.
  - For Lenses, see pages 380 to 382.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.379 - vue 398/555
- - 380 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LENSES
  - 2760.—Spectacle Lenses, double convex, rough edges. Diameter, 40 mm.
  - Focus.. 10 15 20 26 30 50 cm.
  - Each .. 1/4 1/4 11d. 9d. 9d. 9d.
  - Dozen.. 14/- 14/- 10/- 8/- 8/- 8/-
  - 2762.—Double Convex Lenses,
  - guaranteed best quality, edges ground and polished. Diameter, 25 mm. Focus .. 5 10 15 20 cm.
  - Each .. 1/3 1/2 1/- 10d. Dozen .. 13/6 12/6 11/- 9/6
  - Focus 26 30 50 cm.
  - Each .. 10d. 10d. 10d.
  - Dozen .. 9/6 9/6 9/6
  - 2763 .—Ditto, but 50 mm. diameter.
  - 2762-2766
  - Focus 10 15 20 26 cm.
  - Each .. 2/4 2/2 1/9 1/7 2768. —Ditto, but 50 mm. diameter.
  - Dozen .. 26/- 22/- 19/6 17/6 Focus 10 15 20 cm.
  - Focus 30 5o 100 cm. Each 2/6 2/4 1/11
  - Each 1/7 1/7 1/7 Dozen .. 28/- 26/- 21/6
  - Dozen .. 17/6 17/6 17/6 Focus .. 26 30 50 cm.
  - 2764. —Ditto, but 65 mm. diameter. Each .. 1/10 1/10 1/10
  - Focus 10 15 20 26 cm. Dozen .. 20/- 20/- 20/-
  - Each Dozen
  - Focus .. .. 30 .. 50
  - Each 2/9 .. 2/9
  - Dozen .. .. 31/- .. 31/-
  - 2765 .—Ditto, but 80 mm. diameter. Focus .. .. 15 .. 20
  - 3/6 3/- 3/- 2/9
  - 40/- 35/- 35/- 31 -
  - 100 cm. 2/9 31/-
  - Each Dozen Focus Each Dozen
  - 2766 .—Ditto, but 102 mm. diameter.
  - A. Focus 10 cm.
  - B. „ 15 cm.
  - 4/6
  - 52/-
  - 30
  - 3/9
  - 43/-
  - 4/6
  - 52/-
  - 50
  - 3/9
  - 43/-
  - 26 cm.
  - 4/6
  - 52/-
  - 100 cm.
  - 3/9
  - 43/-
  - each
  - 8/6
  - 7/6
  - 2761 .— Spectacle Lenses, double concave, rough edges. Diameter, 40 mm.
  - Focus.. 10 15 20 26 30 50 cm.
  - Each.. 1/6 1/6 1/- 10d.10d.10d.
  - Dozen.. 16/6 16/6 11/- 9/- 9/- 9/-
  - 2767.—Double Concave
  - Lenses, guaranteed best quality, edges ground and polished. Diameter
  - 25 mm.
  - Focus . Each . Dozen. . Focus Each Dozen
  - 5 10 15 20 cm.
  - 1/6 1/4 1/2 1/1
  - 16/6 14/- 12/- 11/-
  - 26 30 50 cm.
  - . V- V- V-
  - 2769 .—Ditto, but 65 mm. diameter.
  - Focus 10 15 20
  - Each .. 4/- 3/6 .. 3/4
  - Dozen .. 46/- .. 40/- .. 38/-
  - Focus 26 .. 30 .. 50
  - Each .. 3/- .. 3/- .. 3/-
  - Dozen .. 34/- .. 34/- .. 34/-
  - 2770.—Ditto, but 80 mm. in diameter.
  - Focus 10 15 20
  - Each .. 5/- .. 4/9 .. 4/9
  - Dozen .. 58/- .. 55/- .. 55/-
  - Focus 26 30
  - Each . . 4/9 .. 4/-
  - Dozen . . 55/- .. 46/-
  - cm.
  - cm.
  - Our stock of pure Chemicals and Acids is very considerable j hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.380 - vue 399/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 381
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LENSES
  - 2771.—Plano-Concave Lenses,
  - guaranteed best quality, edges ground and polished. Diameter, 63 mm.
  - Focus .. 20 26 30 cm.
  - Price .. .. 2/6 2/6 2/6 each.
  - 2772.—Plano-Convex Lenses,
  - guaranteed best quality, edges ground and polished. Diameter, 63 mm.
  - Focus .. 20 26 30 cm.
  - Price .. .. 3/- 3/- 3/- each.
  - 2771
  - 2773. — Cylindrical Lenses, plano-convex, best quality, with smooth edges. Size about 40 mm. square.
  - 2773 Each .....................4/6
  - 2774.—S phero-Cylindrical Lenses, convex, best quality, with smooth edges. Size about 40 mm. square.
  - Each.......5/6
  - 2772
  - 2774
  - (When ordering, please mention focal length.)
  - (When ordering, please mention focal length.)
  - 2775
  - (When ordering,
  - 2775. — Cylindrical Lenses, plano-con-
  - cave, best quality, with smooth edges. Size about 40 mm. square.
  - Each................4/6
  - mention focal length.)
  - 2776.—S phero-Cylindrical
  - Lenses, concave, best quality, with smooth edges. Size, about 40 mm. square.
  - Each.........5/6
  - 2776
  - (When ordering, please mention focal length.)
  - 2.777
  - 2777.—Prismatic Lenses,
  - convex, best make, with smooth edges, as used for stereoscopes.
  - 2778
  - 2778.—Prismatic Lenses,
  - concave, best make, with smooth edges. Size about 40 mm. square.
  - 2779
  - 2779.—Prismatic Lenses,
  - piano, best make, with smooth edges. Size about 40 mm. square.
  - A. 30 X 33 mm. .. each 4/6 A. i° and 20
  - B. -35 X 35 - • • „ 6/- B. 3° to 50
  - C. 37 X 39 » •• „ 7/6 C. 6° „ 10°
  - D. 4i X 4i „ 8/6 D. ii° „ 15°
  - E. 45 X 45 „ „ 10/6 E. 160 » 24°
  - each
  - n
  - 3/-
  - 5/-
  - 6/6
  - 8/6
  - 12/-
  - A. i° and 2° .. .. each 3/-
  - B. 3° to 5° •• • • „ 5/-
  - C. 6° „ 10° .. „ 6/6
  - D. ii° „ 15° .. 8/6
  - E. O VO H „ 24° .. „ 12/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.381 - vue 400/555
- - 382 F. E. BECKER & CO., IMIVOC HOUSE, HATTON,WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LENSES
  - 2780.—Cylindrical Lenses, double convex, best quality, with smooth edges.
  - 2780
  - Length •• 39 47 54 60 66 74 81 88 94 IOI 108 ii5 mm.
  - Width .. 27 30 34 40 44 47 50 54 56 61 67 73 >>
  - Focus .. 130 135 148 163 176 190 205 230 270 297 325 350 cm.
  - Price.. .. 6/- 7/- 7/6 8/- 9/- 9/6 10/- 10/6 11/- 13/- 15/- 18/- each
  - 2781.—Hollow Lenses, plano-convex, with
  - hole for filling.
  - Diameter .. 50 80 100 130 160 mm.
  - Price ... 13/6 15/- 17/6 22/6 24/- each.
  - 2782. — Hollow Lenses, double convex with hole for filling.
  - Diameter .. 50 80 105 130 155 mm, Price .. 13/6 15/- 17/6 22/6 24/-each,
  - 2783
  - 2783.—Set of 6 Lecturer’s Lenses, comprising one each of the following :— double convex, double concave, plano-convex, planoconcave, meniscus - convex, and meniscus-concave; mounted in circular frame fitted to brass upright, as figured. 5134
  - A. Diameter of Lenses, 50 mm. Price, with stand £2 2 0
  - B. Diameter of Lenses, 70 mm. Price, with stand £2 12 6
  - C. Diameter of Lenses, 80 mm. Price, with stand £3 10 0
  - 2784. —Set of Lecturer’s Lenses, as described in the Laboratory Note-Books of Professor Wilberforce and Rev. T.
  - C. Fitzpatrick, M.A. This set consists of four whole lenses, and two half lenses all of which are fitted in ebonite holders.5131
  - Price complete .. .. 9/6
  - 2785. —B rass Clamp, sliding on upright pillar, for holding ebonite handle 5132
  - 2786. —Upright Pillar, on heavy metal base, as
  - figured 5133 .. .. .. .. .. each 3/-
  - 2787
  - 2787.—Set of 6 Lecturer’s Lenses, each
  - 50 mm. diameter, best quality, double convex, double concave, plano-convex, plano-concave, meniscus-convex, and meniscus-concave, in velvet-lined case, per set 6126 .. .. .. .. .. .. 18/-
  - 2788 .—Ditto, but lenses 65 mm. in diameter, per set.
  - 22/6
  - 2789 .—Ditto, but lenses 80 mm. in diameter, per set.
  - 37/6
  - 2790.—Set of Lecturer’s Lenses, as No. 2788, but with 6 half lenses added. Price, complete, in velvet-lined case .. 30/-
  - 2784/5/6
  - each 4/-
  - 2791
  - 2791.—Set of 36 Assorted Spectacle Lenses, rough edges, for optical students’ use. 6146 Per set..............................8/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.382 - vue 401/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 383
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LENS HOLDERS
  - 2792
  - 2792.—C heap Metal
  - Holders, for Spectacle Lenses.5147
  - Each.....................4d.
  - Per dozen .. .. .. 3/6
  - 2793.—W ooden Lens Holders, consisting of two, upright hinged supports on wooden base, with rubber ring, as figured. 5149
  - Each
  - 2/-
  - 2795.—Wooden Lens
  - Holder, on base, for taking lenses up to 80 mm. in diameter, as mentioned in Clay’s " Practical Exercises in Light.” 5148
  - Each .............1/6
  - 2795
  - 2793
  - I HI
  - 2794.—“ N i voc” Lens Holder, consisting of a brass ring with two supports for lens and rod passing through top, mounted on brass rod sliding in another rod having an adjusting screw. 5150
  - Price, mounted on heavy foot, as figured .. .. .. 15/-
  - This Holder will take lenses up to 3 inches in diameter.
  - 2796.—Improved Lens
  - Holder (Dr. T. J.
  - Baker’s Patent).
  - The edges of the lens are gripped between the opposed faces of the vertical steel strips, and slipping is entirely prevented by means of short pieces of india-rubber tubing which slide on the steel strips. The strength of the grip which the strips exert on the lens may be increased to any desired extent by sliding the metal bands towards the lens.
  - Any lens up to 3 inches diameter is held firmly by this contrivance, and the range of Vertical Movement is very considerable.
  - Each ...............5/6
  - 2796
  - LENS MEASURES
  - 2797.—L ens Measure,
  - “ Watch Form,” Registered Pattern. Registers the curves of any form of lens and also approximately indicates the axes of cylindrical lenses. Nickel-plated and highly finished.
  - ..............27/6
  - 2799. — O p t i c a I Lever, cheap pattern, for measuring thickness of cover slips, etc., by the optical method. Complete in velvet-lined case. 6168 Each...................9/6
  - .2799
  - 2798. — Birch’s Tangent LensGauge. The illustration shows the way in which the two glasses are to be tilted to one another. The two inclined plates will touch the lens at two points, and a small system of Newton’s rings will be formed at each point of contact. The apparent distance between these points of contact can be measured by means of a reading microscope.6173
  - Price
  - (jFurther details will be found in Clay’s “ Practical Exercises in Light.”)
  - 2798
  - 8/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the ptmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.383 - vue 402/555
- - 384 F. E. BECKER & CO., 1MIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SPHEROMETERS
  - 2800.—Sphero meter, Students’ pattern, for
  - measuring concave and convex surfaces, silvered scales showing ro^th part of a millimetre. 6174
  - Each ..............................8/-
  - Per dozen .. .. .. .. ..£476
  - 2802
  - 2802.—S p h e r o meter,
  - standard pattern, reads to the roVoth of a mm. Accuracy guaranteed. Highest quality and finish.172
  - Price, complete, in polished mahogany case, with plain glass plate .. £5 10 0
  - 2801.—Spherometer. This in-
  - strument is furnished with a table 5 cm. wide, which is divided into 100 parts by a scale furnished with two sets of figures reading in opposite directions, and reads to mm. The pitch of the screw is \ mm. There is a vertical brass scale at the side to indicate complete revolutions of the screw. 5175 Price................£12 6
  - 2803. Large Demonstration Spherometer, with coarse screw. Radius about 1 inch. Diameter of dial about 4 inches, and reading to-ooi inch... .. .. .. .. .. .. .. each £6 0 0
  - MODELS OF INSTRUMENTS
  - 2804.—Model of Terrestrial Telescope,
  - complete with lenses and screens, mounted on table, with lines marked to show the path of the rays. 5161 Price .. .....................£112 6
  - 2805
  - 2805.—Model of a Microscope, complete with lenses, screens and stage, mounted on table, with lines marked to show the path of the rays. 5162 Price......................£17 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.384 - vue 403/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 385
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MODELS OF INSTRUMENTS
  - (See also previovs page.)
  - 2807.—Model of Galilean Telescope. This model gives at once a direct image, and consists of an object glass and a diverging lens mounted on a table with lines marked to show the path of the rays. 5159
  - Price, as figured .. .. £12 6
  - 2806
  - 2806.—Tele-Microscopical Apparatus, for
  - showing the construction and principle of the different telescopes and microscopes, consisting of four lenses (only three are shown in the illustration) and two ground glass screens. A splendid piece of apparatus for the lecture table 5158 .. .. .. .. £2 17 6
  - 2808.—M o d e I of Astronomical Telescope, with lenses and screens mounted on table, with lines marked to show the path of the rays. 5160
  - Price, complete as figured.
  - £12 6
  - 2807
  - 2808
  - PRISMS, Etc.
  - 2809
  - 2809.—Indigo Prism, consisting of a prismatic bottle, nicely cut and polished, and fitted with ground-in cut stopper. This prism, which is used for examining the colours of flames, measures about 9 in. in length and about 2 in. at its greatest width.5217
  - Price .. .. .. .. .. 4/6
  - 2810. —Carbon Bisulphide
  - Prism, cheap quality and small size, made of moulded glass and having polished faces 5218 each 2/9
  - 2811. —Carbon Bisulphide
  - Prisms, superior quality, with sides ground off and closed by means of special patent plate-glasses, which are cemented on at 590° Centigrade. These prisms will not only withstand the action of carbon bisulphide, but also acids, ethers, ammonia, water, etc. 5219
  - Height of faces 57 66 mm.
  - Width of faces .. 26 33 „
  - Price .. .. 7/6 9/6 each.
  - {Other sizes supplied to order.) 2811
  - 2812
  - 2812.—Set of Coloured Glasses, for use with prism, to show absorption. 5215 Per set .. .. .. .. .. .. 3/3
  - spar and glass, to show absorption; mounted with aperture and eye-lens. Length over-all about 75 mm., and diameter about 22 mm. 5216 Price .. .. .. ..£226
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.385 - vue 404/555
- - 386 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GLASS PRISMS
  - 2814. —Cheap Glass Equilateral Prisms, angles 6o‘ D, 6o°, 6o°, for
  - students’ use. 5178
  - Length 25 50 38 75 90 100 127 38 75 100 50 mm.
  - Face .. 20 20 25 25 25 25 25 38 38 38 50 „
  - Each .. 9d. 11d. V- 1/2 1/6 1/8 1/10 1/6 1/10 2/6 2/10
  - Dozen.. 8/- 10/- 11/6 13/- 17/- 18/6 21/- 17/- 21/- 28/6 33/-
  - 2815.—Cheap Glass Equilateral Prism, angles 6o°, 6o°, 6o°, large size, for lecture work, 3! in. face 5179 .. .. .. .. .. .. each 9/6
  - 2816
  - 2816.—Dense Glass Equilateral Prisms,
  - angles 6o°, 6o°, 6o°, guaranteed highest quality and finish and optically worked. Refractive index, 1-6204.
  - Length 25 30 40 50 60 80 mm.
  - Face .. 25 30 40 25 30 40
  - Price . . 19/6 22/6 33/6 39/6 42/6 67/6 each.
  - 2817.—Extra Dense Glass Equilateral
  - Prisms, angles 6o°, 6o°, 6o°, of very great dispersive power. Optically worked. Refractive index, 1-6786.
  - Length .. 25 32 40 mm.
  - Face .. .. 25 32 40 „
  - Price............. 28/6 31 /- 47/6 each.
  - 2819
  - 2818.—Cheap Glass Right-Angled Prisms,
  - angles 90°, 450, 450, for students’ use. 5182
  - Hypotenuse
  - Faces
  - Length
  - Each
  - Dozen
  - 25 25 35 35 50 50 90 mm.
  - 20 20 25 25 35 35 65 „
  - 25 50 40 75 35 100 92 „
  - 9d. 11d. 1/3 1/8 1/3 2/6 7/6
  - 8/- 10/- 14/- 18/6 14/- 28/6 85/-
  - 2819.—Crown Glass Right-Angled Prisms,
  - angles 90°, 450, 450, guaranteed finest quality and optically worked. 6183
  - Hypotenuse 35 45 50 57 65 70 mm.
  - Faces 25 30 35 40 45 50 „
  - Length 25 30 40 45 45 50 „
  - Price 17/- 21/- 28/6 42/6 55/- 62/6 each.
  - Our stock of pure Chemicals and Acids is very considerable ,* hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.386 - vue 405/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 387
  - W. & -J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GLASS PRISMS
  - 2820/2821
  - 2820.—Cheap Glass Right-Angled Prisms,
  - angles 90°, 6o°, 30°, for students’ use. 5184
  - Hypotenuse • • 50 50 mm.
  - Face • • 45 • • 40 „
  - Edge • • 25 • • 25 „
  - Length . . 40 • • 75 „
  - Price 1/9 .. 2/5 each.
  - 2821.—Crown Glass Right-Angled Prism,
  - angles 90°, 6o°, 30°. Guaranteed finest quality and optically worked. Hypotenuse, 57 mm. ; face, 50 mm. ; edge, 28 mm. ; and length 30 mm. ; as per illustration. 5185
  - Each.........................................19/6
  - {Other sizes to order at proportionate prices.)
  - 2823
  - 2822.—Cheap Glass Prisms, with angles 750,750, 30°, for students’ use. 5186
  - Faces 20 20 45 mm.
  - Edge 12 12 25 „
  - Length 25 50 45 „
  - Price 9d. .. 17- 1/9 each.
  - 2823.—Crown Glass Prism, angles 75 °, 75 °,
  - 30°, guaranteed finest quality and optically worked. Illustration shows actual size. 5187
  - Each .. .. ... .. .. .. ..11/-
  - (Other sizes to order.)
  - 2825 .—Ditto, finest quality and optically worked. 5189
  - Price..................................................13/6
  - {Other sizes to order.)
  - 2826
  - 2826.—Obtuse Angled Prism, cheap quality, for students’ use 5190 .......each 1/10
  - 2827. —Ditto, finest quality and optically true. 5191 Each .................................................13/6
  - 2828
  - 2828.—Fresnel’s Bi-Prism,
  - optically worked. 5192
  - A. 20 mm. x 30 mm.
  - B. 30 mm. x 40 mm. ..
  - C. 40 mm. x 50 mm.
  - best quality,
  - .. each 13/6 „ 18/6
  - „ 24/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.387 - vue 406/555
- - 388 F. E. BECKER & CO., IMIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2829
  - GLASS
  - 2829.—P a i r o f Flint and Crown Prisms (Complementary Prism), optically worked. 5193
  - Price .. .. 19/6
  - 2830.—P air of Achromatic Prisms, optically worked (may be used together or apart), mounted on brass support furnished with universal joint. 5212
  - PRISMS
  - 2833
  - 2833.—Nicol’s Prism, for polarizing light or analysing it when polarized. This prism is constructed by slitting a specially selected rhomb of Iceland spar along a diagonal plane and then cementing the two pieces together in their natural position by means of Canada balsam. 5230
  - Aperture .. 6 7 8 10 mm.
  - Price 21 22/6 25/- 31 /6 each.
  - Aperture . . 12 14 16 18 mm.
  - Price .. 36/- 48/- 72/6 112/-each.
  - Aperture .. 20 22 25 mm.
  - Price 180/- 240/- 450/-each.
  - (.Prices are subject to the fluctuations of the market.)
  - 2834.—Large Wooden Model of a IMicol’s Prism, in four parts 5231 .. each £1 17 6
  - Open.
  - Price for best quality—
  - £3 15 0
  - Closed.
  - 2831.—E q u i I a t e r a I Prism of clear crystal glass, cemented in brass trough, having universal movements, and which is adjustable at various heights by means of a thumb-screw. 5206
  - Price, mounted on heavy foot as figured .. .. 19/6
  - 2832
  - 2832.—Polyprism, angle 6o°, of four different kinds of glass. 6205
  - Each ................£2 7 6
  - 2835.—Fresnel’s Rhomb, for obtaining circularly polarised light. This rhomb is made of glass and its acute angle is 540, and its obtuse angle 126°. 5234 Each..............................22/6
  - {For further details see Ganot’s “ Physics ” and other standard works.)
  - 2836.—Pair of Fresnel’s
  - Rhombs, mounted in frame as figured. The over all dimensions of this apparatus are about 65 X 60 mm. 5235
  - Price for best make and finish—
  - £3 15' 0
  - {This apparatus is demountable.)
  - 2836
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.388 - vue 407/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 389
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - GLASS PRISMS,
  - 2837
  - 2837.—Quartz Prisms,
  - angles 6o°, 6o°, 6o°, guaranteed best quality. 5194 Length
  - of side 15 20 25 mm.
  - Price.. 38/- 46/- 60/-each. Length
  - of side 30 35 40 mm.
  - Price 80/- 98/-135/-each. {Other sizes to order.)
  - 2838.—Fresnel’s Mirror, for interference of light, mounted on nicely finished brass stand, as figured. 5228 .. £2 2 0
  - 2839. —Ditto, superior make and finish, with optically true mirrors, micrometer screw adjustment, and mounted on heavy brass stand. 6229
  - Size of mirrors.
  - Each.
  - 2838
  - A. 30 mm. x 40 mm. .. .. £3 10 0
  - B. 40 mm. x 50 mm. .. 3 17 6
  - C. 50 mm. x 60 mm. .. 4 17 6
  - 2840.—Fresnel’s Bi-Prism,
  - guaranted best make and finish. 5222
  - Price, complete, mounted on heavy foot as figured .. £2 7 6
  - 2841
  - 2841.—Silbermann’s Prism, for showing that the angle of deviation increases with the refracting angle of prism. 5227
  - Price for best quality .. .. •. . • £5 10 0
  - CONES, Etc.
  - 2842.—Cone, made of cheap quality glass, for producing a circular spectrum. 5220
  - Each........4/6
  - 2842
  - 2843.—C one, made of finest crystal glass, for producing a circular spectrum. Can be placed at various angles and heights, and is fitted in a brass ring having a swivel joint sliding in a brass pillar. 5221
  - Price, mounted on heavy foot as figured .. .. .. £117 6
  - 2843
  - 2844.—Hollow Prism, with
  - movable sides for varying angle, mounted on brass stand, with metal basin, best quality 5225 £3 5 0
  - 2845 .—Ditto, but with graduated arc and levelling screws. 5226
  - £4 10 0
  - {For further details see Ganot’s “ Physics.”)
  - 2846.—Oscillating Prism,
  - for mixing the colours of the spectrum. 5224
  - Price, complete, with whirling table, as illustrated .. £4 15 0
  - 2846
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.389 - vue 408/555
- - 390 F. E. BECKER & CO., NIVOC HOUSE, HATTON] WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - HOLLOW GLASS PRISMS, GLASS BOXES, Etc.
  - The hollow prisms and glass boxes described below are made of plates of the best quality patent plate-glass cemented together in a muffle furnace at a temperature of 6oo° C They resist high temperatures and the destructive influences of water, alcohol, acids, etc. Possessing plane surfaces without bubbles or other defects and yielding images free from distortion, they offer special advantages as light filters, absorption boxes, etc.
  - 2847
  - 2847.—Hollow Glass Prisms,
  - angle 6o°, superior quality, made of patent plate-glass and cemented together with a special cement which will allow of prisms being filled with acids, alcohol, ether, water, etc., as described above.
  - 2850.—HollowGIass Prism, as No.
  - 2847, but with partition in centre, for holding two liquids, length 100 mm., face 60 mm.
  - Each ..................£4 5 0
  - 2850
  - Length .. 35 75 60 90 100 105 mm.
  - Face .. 30 35 60 60 80 105
  - Price .. 19/6 23/6 31/- 33/6 40/- 72/-each.
  - 2848.—Hollow Prism, walls made of quartz, best quality .. .. .. .. £8 15 0
  - 2851. —Glass Boxes, cube si
  - Height 30 40 50 60 mm.
  - Length 30 40 50 60 „
  - Width 30 40 50 60
  - Price 6/- 7/- 9/6 10/6 each,
  - Height 70 80 90 100 mm.
  - Length 70 80 90 100 „
  - Width 70 80 90 100 „
  - Price 15/- 21/- 30/- 32/6 each.
  - 2851
  - 2849.—Hollow Prisms, Trough form, special quality, made of patent plate-glass; the cement used in the manufacture of these prisms will stand very high temperatures, acids, alcohol, etc. Each compartment measures 50 mm. long x 55 mm. side. Prices include knobbed covers.
  - 2852
  - 2852.—Prismatic Troughs, in equal
  - pairs ; any angle or size up to 180 mm. long and 45 mm. high. Two of these troughs, placed as shown in the illustration, form an absorption box with parallel walls, the breadth of which can be immediately changed by altering position of the different troughs.
  - Number of Compartments Price
  - 1234
  - 30/- 48/- 54/- 72/-
  - Length Height Per pair
  - 100 140 180 mm.
  - 40 45 45 „
  - 40/- 55/- 66/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.390 - vue 409/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 391
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ICELAND SPAR
  - 2853
  - 2853.—Iceland Spar, specially selected piece? . for showing double refraction. 5245 Side .. .. 15 20 25 15 20 25 30 20 mm.
  - Length .. .. 30 30 30 40 40 40 40 50 „
  - {Prices fluctuate. Lowest prices quoted on application.)
  - 2854
  - 2855
  - 2855.—Cubes of Iceland Spar, worked perpendicularly or parallel to the optic axis. 5248 {Prices fluctuate. Lowest prices quoted on application.)
  - 2856
  - 2854.—Rhombs of Iceland Spar, with two
  - opposite angles worked perpendicularly to the optic axis and having eight faces polished. 5246 Approximate
  - length of edge .. 20 25 30 40 50 mm.
  - {Prices fluctuate. Lowest prices quoted on application.)
  - 2856.—Rhombs of Iceland Spar, with two
  - opposite angles worked perpendicularly and two others worked parallel to the optic axis, and having 10 faces polished. 5247
  - Approximate
  - length of edge .. 20 25 30 40 50 mm.
  - {Prices fluctuate. Lowest prices quoted on application.)
  - NEWTON’S RINGS
  - 2857
  - 2857.—Glasses, ground and polished for showing Newton’s Rings.
  - Diameter .. 50 65 80 mm.
  - Price .. .. ..15/- 17/6 22/6 per pair.
  - 2858
  - 2858.—Apparatus for showing Newton’s
  - Rings, comprising pair of glasses, one plane and the other slightly convex, mounted in a brass frame having three adjusting screws for applying pressure.
  - Price............................ . 18/6
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.391 - vue 410/555
- - 392 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - NEWTON’S COLOUR DISCS
  - 2859. — New-ton’s Colour
  - Disc, large size, “ University ” pattern. This apparatus is fitted with a disc 30 cm. in diameter, mounted on whirling stand. 5252
  - Price, complete—
  - 35/-
  - 2859
  - 2860
  - wheel and handle, as figured
  - 2860. — Newton’s Colour Disc, in
  - the form of a slide for use with lanterns. 5257 Price, fitted with turning
  - 25/-
  - 2861.—Newton’s Colour Disc,
  - with spindle, for use on any of the whirling tables listed in this Catalogue (see pages 153 and 154)- 5256
  - 2861
  - .. each 6/6
  - 2862.—Newton’s Colour
  - Disc, i8| cm. in diameter, mounted on strong iron upright, complete with driving wheel and belt, as figured. 5250
  - Each.................13/6
  - 2862
  - 2863.—Set of 7 Coloured Glasses, red,
  - orange, yellow, green, blue, indigo, and violet. 5261
  - Per set.. .. 3/3
  - 2863
  - DIRECT VISION
  - 2864. —P o c k e t 40 ------
  - Direct Vision W Spectroscope, small size, with fixed slit.
  - Each £110
  - 2865. —Pocket Direct Vision Spectroscope,
  - with fixed slit, achromatic object glass and 3 element prism, in case ................£1 10 0
  - 2866. —Pocket Direct Vision Spectroscope,
  - with adjustable slit, achromatic object glass, and 3 element prism, in case .. .. .. £2 5 0
  - 2867. —Pocket Direct Vision Spectroscope,
  - with adjustable slit, comparison prism, achromatic object glass and 3 element prism, in case £2 12 6
  - 2868. —Pocket Direct Vision Spectroscope,
  - with adjustable slit, comparison prism, mirror, achromatic object glass and 3 element prism, in case.
  - £3 15 0
  - 2869. —Pocket Direct Vision Spectroscope,
  - large size, with adjustable slit, comparison prism, mirror, micrometer scale, achromatic object glass and 3 element prism, in case ... .. .. .. £5 15 0
  - SPECTROSCOPES
  - 2870. — Spectroscope,
  - best quality, with adjustable slit, photographed micrometer scale, right-angled prism for showing two spectra in the field of view at the same time, achromatic lens, etc. Price, complete in nicely finished morocco case, velvet-lined.. £6 15 0
  - This instrument will show Fraunhofer’s lines, bright lines of the metals and gases, and the absorption bands in coloured gases, crystals, or liquids, and may be used for many experiments in spectrum analysis.
  - 2871. —Direct Vision Spectroscope, extra
  - large size, on stand, with adjustable collimator and telescope, adjustable slit, with micrometer screw and divided drum to -oi mm., comparison prism, mirror, micrometer scale, 5 element prism, in case.. £12 0 0
  - 2872. —Stand, simple pattern, for use with Spectroscopes Nos. 2865 to 2869 .. .. .. £110 0
  - 2873. —Stand, superior quality, for use with Spectro-
  - scopes Nos. 2869 to 2867. Price complete, with adjustable holder, stage for absorption boxes and tubes, and mirror .. .. .. .. .. ..£350
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.392 - vue 411/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 393
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SPECTROSCOPES
  - 2874.—Table Spectroscope, for use in schools, comprising prism 6o° of dense flint glass ; collimator and telescopes of 18 mm. aperture and 180 mm. focal length ; collimator provided with an adjustable slit and a reflecting prism for showing two spectra in the field at the same time; scale tube provided with a photographic fine scale. Price, mounted on heavy metal foot, as figured .. .. .. .. £7100
  - 2875. —Mahogany Case, with lock and key. .
  - Extra £17 6
  - 2876. —Table Spectroscope, as No. 2874, but without comparison prism and photographic scale.
  - Price, complete .. .. .. .. £6100
  - 2877.—Table Spectroscope, “Science School" pattern. In this instrument the prism is enclosed in a brass drum to which the telescope, collimator and scale tube are attached. A gas burner is fixed to the scale tube. The dense glass prism is i| in. high, and is permanently fixed to the metal box.
  - Telescope and collimator are provided with object glasses having an aperture of 25 mm., and a focal length of 250 mm. The collimator is provided with an adjustable slit and a reflecting prism for showing two
  - spectra in the field at the same time. The scale tube is provided with a photographic fine scale and achromatic lens. Price..................£7 10 0
  - 2878. —Box, with handle, etc., as figured, extra 16/-
  - 2879. —Telescope, made adjustable either to right or
  - left by means of screws............extra 16/-
  - 2880. —Rack and Pinion Motion fitted to either
  - telescope or collimator .. .. .. extra 16/-
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.393 - vue 412/555
- - 394 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C/lv
  - W. & J. QEORQE (LONDON), Ltd., PROPRIETORS.
  - SPECTROSCOPES
  - 2881. —Table Spectroscope, best quality and finish. This instrument is provided with a dense glass prism, i£ in. high, telescope and collimator. It has achromatic object-glasses i£ in. diameter, adjustable slit fitted with a reflecting prism, by means of which two spectra can be shown in the field of view at the same time, sliding adjustment to eye end of telescope, and Huyghenian eye-piece. The circle is divided to £ degrees, and reads by a vernier to i minute, enabling angular measurements to be taken.
  - Price, in polished case..................................................................................£15 10 0
  - 2882. —Ditto, with rackwork adjustment to" eye end of telescope .. .. .. .. .. .. 16 5 0
  - 2883.—Table Spectroscope, “College”
  - pattern, with circle 6 in. in diameter, divided to read by vernier to r minute of arc. The telescope and collimator are provided with achromatic object-glass, 12 in. focus, i£ in. aperture. The telescope is provided with crosswires, rack-motion clamp and fine adjustment.
  - The collimator is provided with adjustable slit, comparison prism, and wedge for varying the length of slit. The prism is adjustable by means of three levelling screws and is rotatable. Complete adjustments are provided for both telescope and collimator. The scale tube has complete adjustments and is detachable from the instrument. Two eye-pieces and one dense flint or crown glass prism, of suitable size, are supplied with the instrument.
  - A. With case .. .. .. .. .. .. .. .. •• .. price £15 0 0
  - B. Hollow prism f-in. hole .. .. .. .. .. .. .. .... .. .. ,, 1176
  - C. Rack-motion to collimator .. .. .... .. .. .. .. .... ,, 0160
  - D. Micrometer symmetrical slit to o-ooi mm. .. .. .. .. .. .. .. •. ,, 5 12 6
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.394 - vue 413/555
- - F. E. BECKER <& CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 395
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SPECTROSCOPES
  - 2884.—Table Spectro-
  - scope, superior quality, “ Board of Education ” type. May also be used as a Goniometer. The circle is 6 in. in diameter, and divided to read by vernier to i minute of arc. I The rotating prism table is fitted with a clamp for the prism, and a division for setting the prism. A movable reader is supplied for reading the vernier. The prism, which is i^- in. high with if in. long face, can be of either light or dense flint as desired. The collimator is provided with a well-made adjustable slit having non-corrosive jaws, wedge for reducing the aperture, comparison prism, and protective cap. A screw
  - adjustment is provided for correcting the parallelism of the jaws should this at any time require correction. The telescope has rack and pinion focussing, high and low-power eye-pieces with spider webs for measurement, and tangent screw for slow motion. The objectives of both telescope and collimator are good achromatics of 12 in. focal length and 1J in. clear aperture. Price mounted on a heavy iron tripod stand as figured, in case .. .. .. .. £15 15 0
  - 2885. —Photographic Fine Scale, adapted on a third tube uniform in design with telescope and collimator.
  - extra 3 15 0
  - 2886. —Rack Motion to Collimator ....................................... 0 15 0
  - 2887. —Hollow Prism, with i-in. hole .. .. • .. .. .. .. .. .. ,, 2 5 0
  - 2888.—Model Spectroscope, for showing deviation and dispersion of light. This apparatus consists of 1 glass prism ; 2 convex lenses of 10 and 15 in. focus ; stands for same ; metal screen with a slit in it; screen to receive the spectrum ; gas flame arid 2 blocks. Price, complete as
  - figured.................................£1 12 6
  - {For further details, see Clay’s “ Practical Exercises in Light.”)
  - 2889. — The Rafferty Wave Length Spectroscope. This instrument is made with the well-known Thorp replica of the Rowland Grating, and is so constructed that the positions of the lines in the spectrum are read direct on a revolving drum in wave lengths (Angstrom Units).
  - It is inexpensive and yet gives remarkably accurate results ; with the ordinary eye-piece it gives an apparent dispersion of about 30°, the whole of the spectrum being included in the field of view at once. By the addition of a high-power eye-piece the dispersion is increased to 90 °, and about one-third of the spectrum is included in the field at one time.
  - The Spectroscope consists of a Collimator, with an adjustable slit (A) at one end, an Object Glass (B) at the other, and a Thorp Diffraction Grating (14,500 lines) (C) fitted into the same tube. Hinged on to this tube is a telescope, with an object glas (D) at one end and crosswires (E) and eye-piece (F) at the other. The centres on which this telescope is hinged are on the level of the grating, and the telescope is moved by a micrometer screw divided into 100 parts. This screw moves the telescope on a true sine motion so that the positions of the lines in the spectrum as they travel across the
  - cross-wires are read in wave-length measurements, each division being equal to 10 Angstrom units. An index gives the number of turns of the screw.
  - The instrument is supplied for use in the hand, as a portable Spectroscope, or on a fully adjustable table stand.
  - Prices.
  - A. Rafferty Wave Length Spectroscope for use in hand,
  - with low-power eye-piece, in case .. £8 10 0
  - B. Ditto, on tripod table stand .. .. 9 5 0
  - C. High-power eye-piece, extra .. .. 0 17 6
- p.395 - vue 414/555
- - 396 F. E. BECKER & CO., IUIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SPECTROMETERS
  - 2890.—Students’ Auto-collimating Spectrometer.
  - The essential feature of this class of Spectrometer is, that the telescope performs the functions of both telescope and collimator. This is effected by placing the slit in the field of the telescope, covering the lower half of it. The slit is adjustable from the outside by means of a milled-head screw on the right of the telescope. A hole on the left of the telescope admits light, which is reflected by a prism on to the slit. ~An image of the slit is thrown by the object-glass on to the 30° prism placed on the prism table of the instrument, and reflected by the posterior face of this prism back upon its own path, the object-glass forming an image of the slit in the upper half of the field.
  - The telescope has an object-glass of 1 in. clear aperture and of about 9 in. focal length, and is provided with rack-motion focussing arrangement. The circle is 5 in. in diameter and is read by two opposite verniers to 1 minute, and is provided with clamp and fine adjustment. The prism table is adjustable by means of three levelling screws, and can be raised or lowered to any convenient position. The whole instrument is strongly constructed, and is packed in a neat case.
  - Price, complete with prism
  - 2891. — Students’ Spectrometer, S.x.
  - Pattern. This instrument was designed to meet the demands of those requiring a cheap, yet reliable Spectrometer. It has a protected 5-in. circle, read by vernier to 1 minute. The circle and telescope are attached to the outer centre and move together. The telescope is counterpoised and provided with cross-wires, rack-motion focussing arrangement, clamp and fine adjustment. The collimator has a protected adjustable slit and clamping ring, so that it can be set for verticality and focal distance once for all. The prism table is adjustable by means of three levelling screws, and can be raised or lowered to any convenient height; it can be clamped to the inner centre, which carries the vernier, and which is provided with clamp and fine adjustment. The object glasses of both telescope and collimator are about 7 in. in focal length, and have a clear aperture of | in. Adjustments are provided for setting the optical axes of telescope and collimator at right angles to the vertical axis of the instrument. One eye-piece, grating-holder, prism clamp and reader are supplied with the instrument.
  - .. £9 0 0
  - Prices of Students’ Spectrometer, No. 2891.
  - A. With case £9 0 0
  - B. Without rack-motion and fine adjust-
  - ments .. .. .. ' .. 7 10 0
  - C. With two verniers, extra 11/6
  - D. Rack-motion to collimator 15/-
  - E. With 9-in. telescope and collimator, extra 8/6
  - F. Comparison prism attached to slit 11/6
  - G. Extra dense flint glass prism 15/-
  - H. Ordinary dense flint glass prism 13/6
  - K. Crown glass prism 13/6
  - L. Hollow prism, with f-in. hole 16/-
  - M. Copy of Rowland’s grating 22/6
  - N. Illuminating attachment to eye-piece .. 11/6
  - 0. Plane parallel mirror, silvered both sides 15/-
  - P. Large ordinary dense flint glass prism,
  - suitable for the 9-in. telescopes 24/-
  - Q- Ditto, crown glass 24/-
  - R. „ extra dense flint glass .. 25/6
  - SPECTROSCOPES AND SPECTROMETERS OF ALL OTHER MAKES SUPPLIED AT CURRENT LIST PRICES.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.396 - vue 415/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 397
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SPECTROM ETERS
  - 2892. — Students’ Spectrometer, S.N.
  - pattern. The circle of this instrument is about 5 in. diameter, and read by two opposite verniers to i minute. The circle and verniers are well pro- I tected. The telescope is counterpoised and provided with cross-wires, rack-motion focussing arrangement, clamp and fine adjustment. The collimator has a protected adjustable slit and clamping ring by which the slit can be set for verticality and focal distance once for all. The object glasses are about 7 in. in focal length with a clear aperture of § in. Adjustments are provided for setting the optic axes at right angles to the vertical axis of the instrument. The prism table is adjustable by means of three levelling screws, and can be raised or lowered to any convenient height; it Gan be clamped to the inner centre, which carries the verniers and which is provided with clamp and fine adjustment. One eye-piece, grating holder, prism clamp, and reader are supplied with the instrument. The uprights which support the telescope and collimator are thrown out sufficiently to give ample room for the attachment of polarizing apparatus. These consist of (1) a Nicol prism polarizer and analyser, each mounted in a rotating circle read by vernier to 5 minutes, and fitting the object ends of telescope and collimator (an adapter is supplied by which the analyser may be attached to the eye end of telescope) ; (2) a rotating circle, reading to 5 minutes, and fitting the object end of telescope or collimator, to which may be fitted a £ wave plate, Babinet compensator, etc. ; and (3) an extra Nicol and mount for the Babinet compensator, when used at the eye end of telescope. The Babinet compensator is fitted with micrometer screw and scale reading to -oi mm.
  - Prices.
  - A. With case .. .. £10 10 0 L. Illuminating attachment to eye-piece .. £0 11 6
  - B. Rack-motion to collimator, extra 0 15 0 M. Plane-parallel mirror, silvered both sides 0 15 0
  - C. 9-in. telescope and collimator, extra 0 8 6 N. Nicol prism polarizer and analyser (the
  - D. Comparison prism to slit, extra 0 11 6 Pair) 6 0 0
  - E. Extra dense flint-glass prism .. 0 15 0 0. Divided circle to 5 minutes 2 5 0
  - F. Ordinary dense flint-glass prism 0 13 6 P. J-wave plate and stage 0 12 0
  - G. Crown glass prism 0 13 6 Q. Babinet compensator with extra Nicol
  - H. Hollow prism, f-in. hole 0 16 0 and mount 6 15 0
  - K. Copy of Rowland's grating 12 6 R. Eye-pieces, each .. 0 11 6
  - 2893.—College Spectrometer, T.N. pat-
  - tern. This instrument is constructed on similar lines to those of the Students’ Spectrometer,
  - No. 2892, with the exception of the centre work.
  - In this, the inner axis carries a 5-in. circle and the prism table, while the outer socket carries the telescope and verniers. The circle is well protected and read by two opposite verniers to 1 minute. The prism table and telescope are both provided with clamp and fine adjustment. The prism table can be raised or lowered, is adjustable by means of three levelling screws and can be detached from the instrument, and other apparatus used in its place. The object lenses of telescope and collimator are achromatic, and have a focal length of 9 in. and a clear aperture of nearly 1 in.
  - The telescope is provided with rack-motion focusing arrangement and cross-wires ; and the optic axis can be set radially and at right angles to the
  - vertical axis of the instrument. The collimator is provided with a protected adjustable slit, comparison prism and wedge for reducing the length of the slit; and it can also be set radially and at right angles to the vertical axis of the instrument. One eye-piece, grating holder, prism clamp and reader are supplied with the instrument.
  - Prices.
  - A. With case .. £15 0 0 G. Hollow prism, f-in. hole £1 7 0
  - B. Divided on silver, extra.. 1 10 0 H. Copy of Rowland’s grating, about 14,500
  - C. Rack-motion to collimator 0 16 0 lines 1 2 6
  - D. Dense flint-glass prism 12 6 K. Illuminating attachment to eye-piece .. 0 11 6
  - E. Crown glass prism 12 6 L. Mirror, silvered both sides 0 15 0
  - F. Extra dense flint-glass prism .. 16 6 M. Eye-pieces, each .. 0 11 6
- p.397 - vue 416/555
- - 398 F. E. BECKER <& CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - SPECTROM ETERS
  - 2894.—College Spectrometer, T.E. pattern. The circle of this instrument is fixed. The movement of the telescope is read by two opposite verniers on the lower edge of the circle ; and the movement of the prism table is read by two opposite verniers on the upper edge of the circle. Two small microscopes (not shown in the figure) for reading the verniers are supported on an arm which moves concentrically with the circle, and can be set to read either edge. Both edges of the circle are protected. The telescope is counterpoised, and provided with cross-wires, rack-motion focussing arrangement, clamp and fine adjustment. The collimator is provided with a protected adjustable slit, comparison prism and fixing ring, by means of which the slit can be set for verticality and focal distance once for all. The slit has means for setting the jaws parallel and an arrangement for varying its length. The prism table is adjustable by three levelling screws, and can be raised or lowered to any convenient height, and is provided with clamp and fine adjustment. The lenses of telescope and collimator have a focal length of about io in. and a clear aperture of i in. Adjustments are provided for setting the optical axes of the telescope and collimator at right angles to the vertical
  - axis of the instrument, and also for setting the axes radial, or otherwise, to the circle. The prism table can be detached from the instrument, and crystal holder and other apparatus used in its place. One eye-piece, grating holder and prism clamp are supplied with the instrument. The whole is packed in a neat case.
  - A. With 5-in. circle, reading to i minute. .
  - B. „ 6 „
  - C. „ 6 ,, ,, ,, 30 secs.
  - D. „ 7^,, „ ,, 10 ,,
  - E. If divided on silver, extra
  - F. Rack-motion to collimator, extra
  - G. Dense flint glass prism, ij x if face
  - H. Crown glass prism, same size
  - K. Extra dense flint glass prism do.
  - L. Hollow prism, with f-in. hole
  - M. „ ,, ,, brass case
  - N. Copy of Rowland’s grating, 14,514 lines to the
  - inch
  - O. Illuminating Attachment to eye-piece (a modified
  - form of Gauss’ eye-piece)
  - P. Plane parallel mirror, silvered both sides
  - Q. Extra eye-pieces, each
  - R. Nicol prism polarizer and analyser to fit over the
  - object end of collimator and telescope—the analyser fitted with divided circle, reading to 1 minute, with clamp and fine adjustment ..
  - Prices.
  - £18 0 0 S.
  - 18 15 0
  - 19 10 0
  - 21 15 0 T.
  - 1 10 0
  - 0 16 0 U.
  - 1 8 0
  - 1 8 0 V.
  - 1 17 6 w.
  - 1 17 6 X.
  - 2 12 6
  - 1 2 6 Y.
  - 0 11 6
  - 0 15 0
  - 0 11 6 Z. Zi. Z2.
  - 7 5 0
  - The above, with divided circle to 1 minute, clamp and fine adjustment to both polarizer and analyser .. .. £10 2 6
  - Divided circle to 5 minutes, to carry J-wave plates, etc. .. .. .. .. 250
  - J-wave plate and stage .. .. .. 0120
  - Babinet compensator, with Nicol and eye-lens 6 15 0
  - Micrometer symmetrical slit, reading to -ooi mm. 5 5 0
  - One right-handed and one left-handed 30° quartz prism, and one right-handed and one left-handed quartz lens to fit in telescope and collimator .. .. .. .. .. 550
  - Crystal holder, consisting of 2 curved and 2 plane slides with screw adjustment .. .. .. 5 12 6
  - Crystal holder, simple construction . . .. 12 6
  - Liebisch total reflectometer, adapted to take the place of the prism table .. .. .. 7 10 0
  - Kohlrausch total reflectometer, adapted to take the place of the prism table .. . . .. 7 10 0
  - 2895. — Repeating Spectrometer, “University” pattern. The construction of this instrument is such that the telescope can be rotated and accurately set independently of either circle or verniers, and it can also be clamped to the circle in such a manner that the telescope and circle move together; so that in measuring the angular movement of the telescope, the angle can be read step by step all round the circle, thus eliminating any error due to eccentricity. The circle is divided on silver and read by two opposite verniers to 10 seconds. There are four concentric axes—the inner one carries the verniers and the prism table, etc. ; the second one is attached to the base of the instrument; the third carries the circle, and the fourth the telescope. Each axis is provided with clamp and fine adjustment. The focal length of telescope and collimator is about io in. The telescope is provided with rack-motion and cross-wires, and an adjustment for setting the cross-wires. The collimator is also provided with rack-motion and a symmetrical slit. An adjustment is provided for setting the telescope and collimator radial or otherwise.
  - Price, with case
  - £37 10 0
  - (Accessories, the same as for Spectrometer, S.N. pattern, see page 397, No. 2892.)
- p.398 - vue 417/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 399
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ANALYSIS APPARATUS
  - 2898
  - 2896
  - 2896.—Flask, with parallel walls, for examining absorption band in liquids. Capacity about 2 cc. Each .................................2/-
  - 2897
  - 2897.—Rectangular Tubes, for examining absorption band in liquids.
  - Length 2 5 10 15 20 cm.
  - Price .. 3/6 5/6 7/6 9/6 10/6 each.
  - 2898.—Set of Reagents, for Spectrum Analysis, consisting of 10 bottles containing salts of the following metals : Ba, Ca, Na, K, Sr, Sn, Tl, Cs, Li, and Rb. Price, including 10 platinum wires with glass rods and polished stand .. .. ..£220
  - 2899 .—Ditto, consisting of 6 reagents only. Price, complete .. .. .. ..£176
  - 2900.—Lantern Slide, showing diagram of the Solar Spectrum .. .. .. .. each 15/-
  - 2901.—Plates of Crystal, for showing absorption phenomena .. .. each, from 10/6 to 25/-
  - 2902.—Brass Spectroscope Stand, on
  - heavy iron foot and provided with adjustable slider for holding three platinum wires fused into glass tubes.
  - A. Without platinum wires .. .. each 3/9
  - B. Platinum wires fused into glass tubes, for use with
  - above, extra .. .. .. .. each 2/-
  - 2902
  - 2903.—Brass Spectroscope
  - Stand, with adjustable slider, carrying
  - 2904
  - a rotatable six-way platinum wire holder.
  - A. Price, mounted on heavy iron foot,
  - as figured .. .. .. 15/-
  - B. Platinum wires fused into glass tubes,
  - extra .. .. .. each 2/-
  - FOR VACUUM TUBES CONTAINING GASES, ETC., FOR SPECTRUM ANALYSIS, SEE PAGES 336 AND 337.
  - 2903
  - 2904.—Brass Spectroscope Stand, mounted on heavy iron foot, fitted with spring clips for making electrical contact with spectrum tubes, otherwise same specification as No. 2903.
  - A. Price, complete, as figured—
  - £1 7 6
  - B. Platinum wires fused into glass tubes, extra .. each 2/—
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the complete furnishing of the largest laboratory.
- p.399 - vue 418/555
- - 400 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2905/2906
  - MERCURY VAPOUR LAMPS, Etc.
  - 2905. —D elachanal and Mermet’s Spark Tube for
  - obtaining the spectra with an induction coil. 5325
  - Price of tube only .. .. 9/6
  - 2906. —Stand for holding ditto.5326
  - Extra ....................15/-
  - 2907.—Grimlich’s Mercury Arc Lamp, modified by Lum-mer & Straubel. 5314
  - Each .. £3 15 0
  - 2908 .—Ditto, ready for exhausting. 5315
  - Price, including pure mercury, each .. . . ..£370
  - 2907
  - These Mercury Arc Lamps require a pressure of 25 to 30 volts for working ; it is inadvisable to go above 30 volts.
  - 2909.—Mercury Spectral
  - Lamp, electrical current 5 amps ; voltage 5,000 volts, plete as figured .. each
  - These lamps generate an intense light well adapted for optical purposes, are worked by a not too small induction apparatus and require no water cooling.
  - The lamp is arranged so that only the cross-section of the capillary tube is utilised ; the luminous source then shines as a small circular spot of great- intensity.
  - TRANSMISSION DIFFRACTION GRATINGS
  - The magnificent rulings of Rowland gave to the scientist a new tool of great perfection which proved of invaluable assistance for spectrum analysis. They were, however, costly and could only be employed where expense was a matter of but little importance. It was reserved for the ingenuity of Mr. T. Thorp to discover a method by which they could be cast in celluloid, and thus duplicated at a moderate cost. In the early days great difficulties were encountered, which have finally been all overcome. Very few Rowland's Gratings are produced which will yield satisfactory results, as some peculiar quality in the nature of the ruled line is required to enable a perfect copy to be produced.
  - The above process copy of a photograph of the spectrum of iron obtained from these gratings by C. P. Butler, Esq., A.R.C.S., Royal College of Science, London, speaks for itself as to the excellence of their performance.
  - These diffraction gratings are supplied either on parallel plates of glass, on prisms, or as portions of spectroscopes, a complete line of which have been designed, and which cover the whole range of spectrum analysis.
  - Diffraction gratings produce a pure spectrum, and are for this reason superior to any arrangement of prisms. The effect of glass upon light, as is well known, is of an irregular character, and thus when light is spread out into a spectrum by means of a glass prism the rainbow colours do not occupy their normal positions. The red is always cramped into much too small a space, and the relative appearance of the other portions of the spectrum vary according to the particular sample of glass of which the prisms are made. In the red end of the spectrum the B group is readily seen with the smaller diffraction spectroscopes, whereas a prism spectroscope requires the use of a train of prisms to resolve it.
  - Diffraction gratings spread out or disperse the light into its constituent colours with exactitude in the true ratio of the wave-lengths, and thus measurements made with Diffraction Spectroscopes correspond to definite wave-length values, while measurements made with Prismatic Spectroscopes are arbitrary, and only apply to the particular instrument with which they were made.
  - 2910.—Transmission Diffrac-
  - tion Gratings, in velvet-lined cases. 5348
  - A. Best quality, ruling 25 mm. X 25 mm.,
  - on worked glass.. .. £2 4 0
  - B. Ditto, ditto, on selected plate glass—
  - £1 13 0
  - The above gratings are suitable for work of the highest class, both for visiial and photographic, as well as for projection purposes, and give brilliant spectra.
  - Each grating has the actual number of lines per inch marked upon it, so that the measurement of the wave-length of light may by their means be accurately determined.
  - 2911.—Adjustable Brass Stands, for holding the diffrac-tion gratings 5349 .. each 5/6
  - 2912.—Circular Diffraction Grating, with ruled surface 3 in. in diameter, and ruled 5,000 lines to the inch 5351 each £3 10 0
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.400 - vue 419/555
- - F. E. BECKER <& CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 401
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - POLARISATION OF LIGHT
  - 2913.—Becker’s Educational Polarised
  - Light Apparatus. This is intended to encourage the elementary study of that beautiful branch of Optics, which has hitherto been so difficult, without the aid of elaborate and costly apparatus.
  - As want of space prevents any treatise on the theory of polarised light, we must refer the reader to Pereira’s “ Lectures on Light,” published by Messrs. Longmans, and afterwards to Spottiswoode’s and Tyndall's works on the same subject. 5366
  - Price complete .. .. . . £3100
  - For full directions for use refer to page 796 of our Physical Apparatus Catalogue, 1913 Edition.
  - 2913
  - POLARISCOPES
  - 2915
  - 2915.—IM oerrenberg’s Polariscope,
  - “ University ” pattern, guaranteed highest quality and finish, and of the most solid construction. The polariser consists of two reflecting glass plates. Three analysers are supplied, viz., Nicol prism, black mirror, and a pile of glass plates. The analyser holder is divided into eight parts 450 apart. The stage is rotatable, and is divided to degrees. A metal and a glass plate, which fit the stage, are supplied. The lower arm can be swung out of line with the instrument, when not required, or for the insertion of lenses, etc. One illuminating lens and two convergent lenses are supplied. Polariser of glass plate and mirror fitted, if desired. 5372 Price, complete in case, as figured .. .. £14 10 0
  - 2914
  - 2914.—IMoerrenberg’s Polariscope, of brass,
  - highly finished and of solid construction, with one Nicol prism and one double-refracting prism, divided circle, adjustable mirror with divided arc, rotatable table, one black glass mirror, three lenses, one pile of glass plates, three unannealed glasses, five crystals mounted in cork, viz. : quartz, calcspar, aragonite, bichromate of potassium, and sugar. 5371 Price, complete . . . . .. .. £12 10 0
  - 2916. —Large Nicol Prism Polariser, with
  - two illuminating lenses to render rays parallel. 5373 Extra .. .. .. .. .. £3 7 6
  - (Made specially for use with No. 2915.)
  - 2917. —Two Sets of Three Highly-Con-
  - vergent Lenses 5374 .. extra £2 10 0
  - (Made specially for use with No. 2915.)
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
  - cc
- p.401 - vue 420/555
- - 402 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - POLARISCOPES
  - 2918.—N oerrenberg’s Polariscope, simple form, consisting of two uprights mounted on a base about 6 in. square, a stage with hole in centre, horizontal glass plate to act as platform, and another glass plate is hinged near bottom of apparatus. 5367
  - Price, including silvered mirror and black card, as Fig. 141 in Clay’s “ Practical Exercises in Light,” 1906 edition.. .. £115 0
  - 2918
  - 2919.—School Polariscope. This is a simple form of instrument mounted on an iron stand, in which a two-decimetre tube can be used, and by means of which practical work can be done in the elementary physical laboratory, where it is inadvisable to use an expensive instrument.
  - Price ......................................£6 5 0
  - 2920.—Set of Fittings, including Nicol prism, for use with polariscope No. 2918.
  - Extra .......................................£2 5 0
  - 2921.—Polariscope, best quality and finish, constructed on Laurent’s half shadow principle. The polariser consists of a rotatable Nicol prism, the position of which can be read to one degree by divided arc and index, and a Laurent half-shadow plate. In front of the polariser is placed a small chamber for the reception of a liquid colour filter, usually bichromate of potassium. The analyser consists of a Nicol prism, carried by a protected divided circle read by vernier to -i degree, and an observing telescope. Two solution tubes, 10 and 20 cm. long, are supplied—these are placed in a piece of tube which lies concentrically with the axis of the instrument.
  - Price, complete in case .. .. .. .. .. £12 0 0
  - 2922
  - 2922. —Polariscope, elbow form, for table use or for projection, highest quality and finish, with polarising glass plates, Nicol’s prism, and focussing lenses, mounted in brass, with rack-work adjustment.5377
  - Price, complete in case .. .. .. .. .. £18 15 0
  - 2923. —Crystal Stage for ditto 5378 .. extra £15 0
  - 2924. —Converging System of Lenses, for showing
  - axes of wide angle crystals in above polariscope 6379 £8 8 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.402 - vue 421/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 403
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - POLARISCOPES, Etc.
  - 2925.—Polariscope, “College” pattern, guaranteed highest quality and finish. All parts are of the most solid construction and will withstand a great deal of wear and tear. This instrument is so constructed that the various methods of measuring the rotation of the plane of polarisation can be carried out in the same instrument. It is thus possible to compare the different methods and to show the student any advantage one method may have over another for any specific purpose. The transforming of the instrument from one type to another is rapidly and easily made. Starting with the plain instrument, the accessories listed below can be added, so as to obtain any type of polariscope or sac-charimeter in current use, and this without sacrifice of accuracy. The polariser and analyser are mounted at the ends of a strong iron bar, which slides up or down, and can be clamped to a stout vertical pillar, supported by a heavy iron tripod. A stout draw-tube slides within the vertical pillar, and can be clamped thereto—it carries the supports for solution tubes, troughs, etc. At one end of the iron bar are fixed the Nicol-prism polariser and collimating lens ; at the other end are fixed the Nicol-prism analyser and observing telescope. The analyser is mounted in a vertical circle read by two opposite verniers to -oi degree ; provided with clamp and fine adjustment and two small reading microscopes. Two solution tubes are supplied with the instrument.
  - Pkices.
  - A. Price, in case ..................£19 5 0
  - B. Biquartz, fitted to the above .. .. 1.40
  - C. Laurent half-shadow quartz plate, with index and
  - graduated arc, fitted to the above .. £2 0 0
  - D. Poynting’s quartz plate, fitted to the above £1 12 0
  - E. Lippich two-prism polariser, fitted to the above—
  - £5 12 0
  - F. Soleil quartz wedges and compensation plate, with
  - scale and vernier and rack-motion adjustment, fitted to the above .. .. .. .. £8 0 0
  - G. Solution tube io, 15, 20, 25, 30 cm. each 0 12 0
  - H. Glass troughs, price according to size.
  - J. Apparatus to convert the instrument into a Wild’s
  - polaristrobometer .. .. .. £4160
  - K. Light filter, to fit over collimating lens 0 12 0
  - 2926
  - 2926.—Plates of Crystals,
  - mounted in cork, for use with Tourmaline Tongs or Noerrenberg’s Polariscope. 5401
  - Each .........................9/6
  - A. Calcspar. G. Brucite {from Texas).
  - B. Arragonite. H. Pot. Ferrocyanide.
  - C. Quartz. K. Sodium Nitrate.
  - D. Nitre. L. Ammon. Phosphate.
  - E. Borax. M. Topaz.
  - F. Pot. Bichrom.
  - {Other crystals supplied to order. Details and prices on application.)
  - 2927.— Metal Clamp and Screw, for
  - showing temporary double refraction imparted to glass by pressure, with glass to fit. 5403
  - Price .. .. 30/- 2927
  - 2928. —Tourmaline Tongs, for ex-
  - amining plates of crystals for coloured rings, best quality 6397 .. .. .. 22/6
  - 2929. —Plates of Tourmaline, unmounted, for showing polarised light 6398—
  - from 10/- to £10 0 0
  - 2930. —Black Glass Plates, optically
  - worked 6399 .. .. .. each 9/6
  - 2931. —Pile of Glass Plates 5400—
  - from 19/6
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.403 - vue 422/555
- - 404 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - w- & J- GEORGE (LONDON), Ltd., PROPRIETORS.
  - POLARISATION BENCH
  - 2932.—Polarisation Bench,
  - “ University " pattern, guaranteed highest quality and finish, and of the most solid construction, 21 in. (53 cm.) long, of cast-iron, and supported on three feet. Five carriages slide along the bench, and can be clamped thereto. The two end slides have only longitudinal motion, and carry the Polariser and Analyser. The other three slides have transverse slides at right angles to the length of the bench, and carry the various accessories, such as rotating stage, Soleil quartz wedges, solution tubes, Babinet compensator, £-wave plates, Mach’s rotating apparatus, etc. Biquartz, Laurent’s half-shadow plate, Poynting's plate, etc., fit in the Polariser support. The Analysers are mounted to fit into the centre of a divided circle, read by two opposite verniers to 1 minute, with clamp and fine adjustment. The Polariser is provided with a graduated arc and index.5029
  - Pricks.
  - A. The Bench, including five slides (three of
  - which have transverse slides), Nicol prism polariser, Nicol prism analyser in divided circle, and supports fitted in the three transverse slides ; two solution tubes, 10 and 20 cm. ; and support for solution tubes .. . . £19 10 0
  - B. Soleil quartz wedge and compensation
  - plate, with scale and vernier and rack motion adjustment fitted to the above—
  - Bench as Soleil Saccharimeter.
  - c.
  - D.
  - E.
  - G.
  - H.
  - J-
  - K.
  - L.
  - M.
  - N.
  - O.
  - P.
  - Q-
  - R.
  - S.
  - T.
  - U.
  - £8 10 0
  - Biquartz fitted to the above 15 0
  - Laurent’s half-shadow plate, fitted to the above .. .. . . £110 0
  - Poynting’s quartz plate, fitted to the above .. .. £110 0
  - Lippich two-prism polariser, fitted to the above .. .. .. £5150
  - Lippich three-prism polariser fitted to the above . . .. .. £8 5 0
  - Solution tubes : 10,15, 20, 25 and 30 cm.
  - each £0 13 6
  - Glass troughs, price according to size.
  - Observing telescope, fitted to analyser
  - £15 0
  - Calcspar plates, etc., to show the principle of Wild’s polaristrobometer (with this apparatus the analyser is to be used as polariser) .. £4 5 0
  - Rotating stage, with clamp and fine divided to 5 minutes, with support ..
  - Black mirror analyser, to take the place of the Nicol
  - £0 19 6
  - Pile of thin glass plates, as analyser, to take the place
  - of the Nicol .........................£0 19 6
  - Plate of tourmaline, as analyser .. 12 6
  - Double image prism .. .. .. 15 0
  - Pair of lenses, mounted to give parallel rays 0 16 6 Two convergent lenses .. .. .. 0 16 6
  - Two sets of three highly convergent lenses 2 10 0 Red and blue glasses, mounted in rotating plate .. .. .. .. .. 0 13 6
  - adjustment
  - £4 18 6
  - Bench as Polarimeter.
  - V.
  - w.
  - X.
  - Babinet compensator, with extra Nicol and mount, and adaptor, to fit either in front or behind the analyser .. .. .. . . £7 10 0
  - £-wave plate and stage .. .. .. 0 14 0
  - Dovetail slide, with rack and pinion movement, to
  - carry wedges of quartz, selenite, etc... £15 0
  - Y. Quartz wedge .. .. .. .. 220
  - Z. Selenite wedge .. .. .. .. 0166
  - Zi. Two quartz plates, to show Airy’s spirals 0 19 6 Z2. Two quartz plates, to show Savart’s bands 0 19 6 Z3. Press for glass .. .. .. .. 110
  - Z4. Mach’s rotating apparatus .. .. 8 5 0
  - Z5. Divided circle to 1 degree, to carry Babinet compensator and |-wave plates .. .. £2 10 0
- p.404 - vue 423/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 405
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - THE
  - 2933. —Eyeball, enlarged five times, dissectable, with
  - attachment of the muscles, divisible into cornea, choroida, etc. .. .. .. .. each £1 15 0
  - 2934. —Eyeball, as No. 2933, but enlarged ten times
  - each £2 2 0
  - 2935. —Eyeball, enlarged five times with microscopic representation of the layers of the retina.
  - each £2 10 0
  - 2936. —Eyeball, entirely dismountable. Best scientific execution.. .. .. .. each £2 10 0
  - 2937. —Eye, vertically dissected, on board. Enlarged ten times. A most instructive model for teaching each 17/6
  - 2938. —Eyeball, in the orbit, vertical section, enlarged five times, showing all the muscles, dissected arteries and nerves.
  - When the sphincter is removed the lachrymal glands are visible below .. . . .. .. each £7 15 0
  - 2939. —Large Demonstration Model of the Human Eye, “University ' model. Most perfect construction. Dissectable to show the complete formation of the eye, its coats, humours, muscles, nerves and vessels,
  - Price £5 5 0
  - 2940
  - 2940.—Glazebrook’s Apparatus, for experiments on the eye and vision. 5461 Consisting of a long rectangular glass trough, one end of which is convex outwards. This convex glass represents the cornea in the eye. Within the trough is a ground-glass screen, which can be made to slide backwards and forwards, and represents the retina. In front of the screen hangs a convex lens of glass, which can also slide backwards and forwards ; this represents the crystalline lens. The trough is filled with water containing a little eosine, to represent the aqueous and vitreous humours .. .. .. £15 0
  - (For full details see Glazebrook’s elementary text-book “ Light.”)
  - 2941.—C ontrast of Colours Apparatus.
  - This apparatus consists of a thin vertical board painted white and a base painted black, on which are painted circles about # in. in diameter, black and white respectively.
  - A sheet of coloured glass is inclined at an angle of 450 ; if now the eye be so held that the image of the white circle (reflected from the under surface of the glass plate) is looked at in front of the circle on the vertical board, the image appears of a colour complementary to that of the glass. Thus with a green plate a red spot is seen on a green ground. 5462
  - Price ...................................£12 6
  - (See Ganot’s “ Physics.”)
  - 2942
  - 2942.—Holmgren’s Set of Coloured Wools,
  - as used by railway and naval authorities for detecting colour blindness ; greatly improved. 6460
  - Price, complete with full directions for use .. 11/6
  - 2941
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.405 - vue 424/555
- - 406 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - HELIOSTATS
  - 2943.—Heliostat, best make, comprising clockwork (in box), dial for reading the hours, and spirit level on base, with three levelling screws. The mirror support is fitted with a declination circle and one black and one silvered mirror. 6499
  - Price, for best make.............£19 10 0
  - 2944
  - 2944.—Hel iostat, window-shutter pattern, on bronzed brass plate, for attaching to openings in blinds and walls ; with rack adjustment, adjustable slit and revolving screen. 6500
  - Price....................................£11 10 0
  - 2945.—Heliostat, simple
  - construction, with clockwork in brass drum, and fitted with accurately-graduated arc for directing the axis to latitude. 6501
  - Price, complete, mounted on heavy metal foot, with three levelling screws—
  - £8 0 0
  - 2946.—Heliostat,
  - after Fuess, guaranteed highest quality and finish, and furnished with all latest improvements, as figured. 5497 Price
  - (Further details on application.)
  - 2946
  - £25 0 0
  - 2947
  - 2947.—Hel iostat, Silbermann’s construction ; accurate clockwork, with escapement and compensation balance ; size of mirror, 2\ X 4 in. 5496 Each......................................£75 0 0
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.406 - vue 425/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 407
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MISCELLANEOUS OPTICAL INSTRUMENTS
  - 2948.—Wheel of Life, or Zoetrope, comprising polished steel-blue drum, with spindle for use on whirling table.
  - Price, including 12 pictures—
  - £110
  - 2948
  - 2949. — Kaleidoscope,
  - “ University ” pattern, comprising nicely-finished metal body, with nickel-plated fittings, turning wheel and polished wooden base and pedestal.
  - This instrument gives excellent colour effects. Height, 13 in. ; length. 10 in. ; diameter, 3 in. 5470
  - Price..................15/-
  - 2950. —Ditto, not quite so large, and cheaper pattern. Height, 10 in. ; length, 8 in. ; diameter, 2\ in. 5471
  - 2949
  - 2951
  - 2951.—Pinhole Camera, consisting of a polished wooden box having a pinhole in front and a ground-glass screen at back. 5472 Price ...............8/-
  - 2952.—Camera Obscura of
  - polished mahogany with sliding brass tube and lens.
  - Price, complete .. £15 0
  - 2952
  - 2953. —Hand Stereoscope, improved pattern with folding handle and extra large prisms. 5478
  - Each...............................12/-
  - 2954. —Stereoscopic Slides.
  - Each
  - 11/6
  - Opaque, all countries or groups
  - each 1/-
  - 2955. —Wollaston’s Reflection Goniometer,
  - with 5-in. circle, reading by vernier to 1 minute. Clamp and fine adjustment to circle. The inner axis, which carries the crystal holder, may be rotated by hand independently of the circle ; and can be clamped to the circle, when both move together.
  - Both crystal holder and mirror have complete adjustments. The whole is mounted on cast-iron tripod, with levelling screw. 5494
  - A. Price, including case .. .. .. .. £8 15 0
  - B. If divided on silver .. .. .. extra 15 0
  - C. If fitted with observing telescope instead of mirror—
  - extra 1 15 0
  - 2956. —Wollaston’s Reflection Goniometer,
  - as No. 2955, but without fine adjustment and fitted with simple crystal holder and a fixed mirror. 6495
  - Price, including case .. .. .. .. .. £7 5 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.407 - vue 426/555
- - 408 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. OEORGE (LONDON), Ltd., PROPRIETORS.
  - MAGNIFIERS
  - 2957. —Single-Power Lens, folding,
  - mounted in horn, best make ; diameter, i in.
  - Each ..........................1/3
  - Per dozen . . . . .. . . .. ISA-
  - 2957
  - 2958. —Double-Power Lens, folding,
  - mounted in horn, best make ; diameter, i in.
  - Each ..........................2/-
  - Per dozen .. . . .. 21 /-
  - 2958
  - 2961.—P o w e r f u I Magnifier, in vulcanite mount.
  - Each.............1/9
  - 2961
  - 2959.—Triple-Power Lens, folding,
  - mounted in horn, best make ; diameter, 1 in.
  - Each . . 2/6
  - Per dozen . . .. .. .. 28/-
  - 2959
  - 2960
  - 2960.—D o u b I e Convex Lenses, commonly called liner pro vers ; folding brass case.
  - Size of opening £ x \ X | 1 X1 in.
  - Price, each . . 2/- 3/6 5/-
  - 2962.—Reading Glasses, comprising double convex lens, mounted in a nickel-plated brass mount fitted in ebonized handle.
  - each 2/6
  - 3/-
  - 3/3 3/6
  - 4/-
  - 4/6 5/9 6/9 7/6 9/6 12/6
  - A. Diameter, 1# in. .
  - B. » 2w in. .
  - C. 2f in. .
  - D. 2-& in. .
  - E. ,, 2f in. .
  - F. » 3 in. .
  - G. 3* in. .
  - H. 3! in. .
  - J- 4 in. .
  - K. >> 4~& in. .
  - L. 4i in. .
  - 2963.- -Reading G
  - quality achromatic lenses, highly finished, and mounts oxidized.
  - each
  - A. Diameter, i| in.
  - B. ft 2f in.
  - C. ft 2§ in.
  - D. y> 3i in.
  - E. >> 3! in.
  - F. in.
  - 4/6
  - 5/-
  - 6/-
  - 8/6
  - 9/6
  - 11/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.408 - vue 427/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 409
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TELESCOPES
  - 2964.—The “ Science School ” Terrestrial and Astronomical Telescope. This telescope will
  - be found suitable for ordinary terrestrial work, and at the same time do all that is required for an elementary study of the heavenly bodies. It is constructed of brass, of substantial workmanship and finish, and mounted on a pillar stand with universal movements and folding claw feet. The achromatic object glasses are of superior quality. The object end extends 3 in. beyond the object glass, forming a dew-cap and sunshade. The brass body is provided with sliding tubes and rack-work focussing adjustment. 5679
  - A. u “ Science School " Telescope, as described above, with achromatic object glass, 3 in. in diameter, which will easily
  - stand a power of 180 X, and fitted with one astronomical eyepiece, magnifying 80 diameters, with tinted glass for observing the sun, one terrestrial eyepiece, magnifying 40 diameters ; complete in strongly made polished pine case, having receptacles for all the telescope parts, thus affording perfect protection when not in use £11 0 0
  - B. Tall Pine Tripod Stand for outdoor use .. .. .. .. .. . . .. .. .. .. 2 10 0
  - C. Tall Mahogany Tripod Stand for outdoor use .. .. .. .. .. .. .. .. .. 376
  - ACCESSORIES FOR TELESCOPES, Nos. 2964, 2971 and 2976
  - 2965. —Astronomical Eyepieces of highest quality and best construction. Each eyepiece complete (with tinted sun cap, 4/6 extra)
  - High powers
  - Extra high powers, in. and $ in. focus
  - 2966. —Day or Terrestrial Eyepiece, 1 in., equivalent focus.........................
  - 2967 .—Ditto, having larger field, giving greater illumination
  - 2968 —Ditto, pancratic, giving variable power ....
  - 2969 —Ditto, larger size pancratic
  - 2970.—Barlow Lens. To increase power of telescope eyepieces
  - {Continued on next page.)
  - 16/6
  - 21/-
  - 25-
  - 35/-
  - 45/-
  - 45/-
  - 50/-
  - 25/-
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.409 - vue 428/555
- - 410 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 2971
  - COPY OF UNSOLICITED TESTIMONIAL FROM THE SCIENCE MASTER OF THE LUCTON SCHOOL, HEREFORDSHIRE.
  - To Messrs. F. E. Becker & Co., Hatton Wall, London.
  - 30 /i /22.
  - Gentlemen,—
  - Please accept my best thanks for the astronomical telescope which reached here in perfect order.
  - I have never had the good fortune to see an instrument that comes anywhere near it before, the workmanship is absolutely perfect, and the optical arrangements deserve the very highest praise, to say that we are delighted with it is only to express ourselves mildly ; it is a wonder to me how you can turn out such a perfect instrument at the price.
  - Will you please let me have a solar diagonal, and a low power astro eyepiece (about x 30 or x 40) at the earliest possible moment. I should like also to know if you could supply sun glass to fit the finder ; I thought that a dark glass mounted in a light metal frame to slip on the object end might meet the case, but I will leave it to you to advise me as to the best thing to do.
  - If you will kindly let me have your account when sending the extra eyepieces, etc., it shall be settled at once.
  - Again offering you my best thanks for all the trouble you have taken.
  - (Signed) JOHN L. A. SILLEM.
  - A FURTHER LETTER RECEIVED FROM THE SAME QUARTER READS AS FOLLOWS:
  - To Messrs. F. E. Becker & Co., Hatton Wall, London.
  - 4/2/22.
  - Gentlemen,—
  - I have to thank you for your letters of 1st and 3rd inst. re Solar Diagonal, Low Power Eyepiece and Sun Glass for Finder. I shall be obliged if you will kindly put the matter in hand at once.
  - Since my letter of the 30th ult. we have had another very clear night, and the telescope has had another severe test upon certain close doubles, all of which it split with the greatest ease.
  - I was extremely pleased with its performance upon Polaris, which is, as you know, considered to be a very difficult test for a yinch glass, but it showed its companion far more clearly than a 4-inch glass by another maker that I sometimes use.
  - You may depend upon it that in future all my requirements will be sent to you.
  - (Signed) JOHN L. A. SILLEM.
  - 2971,—The ‘‘ Nivoc ” Telescope. Designed to meet the demands of those requiring a really high-class instrument at a reasonable price; The brass body is fitted with a high-grade achromatic object glass, 3 in. in diameter, two astronomical eyepieces giving magnifications of 80 and 120 diameters, one terrestrial eyepiece of 40 diameters, star-finder and vertical steadying rod with rack adjustment. Focussing is actuated by means of a rack and pinion movement. The object glass being mounted inside the tube acts as a dew-cap and sunshade. 6680
  - Price, mounted on table stand, which is quite rigid when in use, and polished pine case having receptacles for all the telescope parts .. .. .. .. .. .. . • • • • • • • • • • • • • • • £19 10 * 6
  - 2971a.—Solid Mahogany Tripod Garden Stand, for above..........................................£3 7 6
  - ACCESSORIES FOR TELESCOPES No. 2964, 2971 & 2976.
  - (iContinued from previous page.)
  - 2972. —Comet or Kellner Eyepieces. These are low power, and give a very large field of view. For clusters,
  - comets, nebulae, and other faint objects they are unsurpassed. Price, complete .. .. .. .. .. 45/-
  - 2973. —Sll n Diagonals, which enables a telescope to be used without risk when viewing objects at, or near the zenith,
  - by its means the image only is reflected to the eye, the heat rays passing out through the reflector .. .. .. 45/-
  - 2974. —Star Diagonals. To avoid neck strain when viewing objects at or near the zenith, by means of a prism
  - the rays are directed out at right angles to the main tube .. .. .. .. .. .. .. .. 55/-
  - 2975. —Combined Sun and Star Diagonal. The one diagonal can be interchanged for both sun and star
  - use .. 82/6
  - All Eyepieces, etc., are fitted with the Standard Astronomical Screw.
  - Our stock 'of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.410 - vue 429/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 411
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - TELESCOPES
  - 2976.—F. E. Becker & Co.’s Astronomical and Terrestrial Telescope of guaranteed quality and finish, having brass body fitted with a 3 in. aperture achromatic object glass. Provided with sliding tubes and rack-work focussing adjustment; two astronomical eye-pieces, with tinted glasses for observing the sun ; one terrestrial eye-piece ; brass dew-cap and star-finder with cross wires. Mounted on a substantially built tall mahogany stand which is quite rigid when in use. The top of the tripod is fitted with trunnion bearings, thus providing universal movements and causing the telescope to be evenly balanced. 5682
  - Price, packed in polished pine case having receptacles for all the telescope parts, thus affording perfect protection when not in use.. .. £27 10 0
  - B. Ditto, but fitted with 3|-in. aperture object glass .. .. 40 0 0
  - C. Telescope, same as above, but fitted with a 4-in. clear aperture object glass—
  - £55 0 0
  - D. Ditto, but fitted with a 5-in. clear aperture object glass, large size star-finder.
  - Complete, with massive open frame mahogany stand .. .. £88 0 0
  - E. Ditto, but fitted with 6-in. clear aperture object glass .. £132 0 0
  - Customers can select their own Astronomical Eye-pieces to suit their particular
  - requirements.
  - 2976
  - 2977.—Astronomical and Terrestrial Telescope, brass body, two draws, on dismountable brass tripod stand, with brass movement, the whole fitted in walnut box, with handle and hooks ; magnifies twenty-five and fifty times, object glass 43 mm. diameter, one terrestrial eye-piece, and one astronomical eye-piece. 5715
  - Price, complete .. .. - • • • • • • • • £5 17 6
  - 2978. —Ditto, but with object glass, 50 mm. diameter—
  - £8 10 0
  - 2979. —Ditto, but with object glass 56 mm. diameter—
  - £12 7 6
  - 2980.—Field Telescopes of highest quality and finish, three draw tubes, mounts of brass ; the body is of brass with morocco leather covering.
  - A. Length opened, 17 in. ; length closed, 6 in. ;
  - magnifying power, 15 diams.—
  - each 25/-
  - B. Length opened, 23 in.; length closed, 6 in.;
  - magnifying power, 18 diams.—
  - each 32/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from3 a test tube to the
  - complete furnishing of the largest laboratory.
- p.411 - vue 430/555
- - 412 F. E. BECKER & CO., IMIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Lid., PROPRIETORS.
  - FIELD AND MARINE GLASSES
  - 2981. —Field Glasses with fixed bars, three times magnification, leather-covered bodies, achromatic lenses, complete in strongly made leather tan case.
  - Price .. .. .. .. .. .. each £1 10 0
  - 2982. —Field Glasses with fixed bars, three and a half times magnification, light-proof cup eye-pieces, leather covered bodies, achromatic lenses, complete in strongly made leather tan case.
  - Price .. .. .. .. .. .. each £2 5 0
  - 2983. —Field Glasses with bending bars, three and a half times magnification, leather covered bodies, achromatic lenses, complete in strongly made leather tan case, as illustrated.
  - Price . . . . .. .. . • . each £2 10 0
  - 2984.—Marine Glasses, fixed bars, two and a half times magnification, large object glasses, leather covered, achromatic lenses, complete in strongly made leather tan case.
  - Price .. . . .. .. .. .. .. . . . • .. each £3 2 6
  - PRISMATIC BINOCULARS
  - 2985. —Prismatic Binoculars, stereo
  - model giving improved stereoscopic effect and having eight times magnification, wheel focussing arrangement, adjustable eye-head, pegamoid covered body, complete in strongly made leather tan case.
  - Price .. .. . . each £3 2 6
  - 2986. —Prismatic Binoculars, stereo model as above, but with tapered object glasses giving increased magnification, covered with morocco leather, complete in strongly made leather tan case.
  - Price..........................each £3 15 0
  - Our Balances and Weights have achieved World-wide Reputation ; vide Opinions of the
  - Leading Scientific Press.
- p.412 - vue 431/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 413
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ASTRONOMICAL SLIDES
  - (RACKWORK MOTION).
  - 2987.—Rackwork Astronomical Slides, for illustrating the science of physiography. These slides are carefully made and the movements are accurately timed so as to work in correct ratios. The slides have 3 in. diameter pictures carefully coloured, and carried in mahogany frames ; the rack-work adjustment works smoothly, and each slide is fully described. 6221
  - A. The solar system, showing the revolution of all the planets with their satellites round the sun
  - B. The earth’s annual motion round the sun, showing the parallelism of its axis, producing the seasons
  - C. To illustrate the cause of spring and neap tides, and shows the moon’s phases during its revolution
  - D. To illustrate the apparent direct and retrograde motion of Venus and Mercury ; and also their
  - stationary appearance
  - E. To prove the earth’s rotundity .. .. .. . . .. .. .. .. .. ;.
  - F. To illustrate the eccentric revolution of a comet round the sun, and shows the appearance of its tail
  - at different points of its orbit
  - G. The diurnal motion of the earth, showing the rising and setting of the sun, illustrating the cause
  - of day and night
  - H. To illustrate the annual motion of the earth round the sun, with the monthly lunations of the moon
  - K. To show the various eclipses of the sun, with the transit of Venus
  - L. To show the various eclipses of the moon ..
  - 2988.—Complete Set of Ten Slides, as above, in box
  - Price £1 12 6 0 19 6 0 10 6
  - 0 10 6 0 10 6
  - 17 6
  - „ 0 10 6
  - 1 10 0 0 10 6 0 10 6
  - „ 8 5 0
  - forall LANTERN SLIDES referto
  - ---- COMPLETE LIST AT END OF THIS CATALOGUE. -
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.413 - vue 432/555
- - 414 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CAMERAS
  - 2989.—Magazine Plate Camera, a thoroughly well made camera for use with plates, size 4I x 3j in., with rack and pinion focussing extension, two brilliant view finders, and twelve numbered sheaths for plates.
  - A. As above, with achromatic lens f/11, three portrait magnifiers and
  - speed indicator, time and instantaneous shutter—
  - each £15 0
  - B. Ditto, focussing model with rectimat lens f/11 and iris diaphragm—
  - each £1 15 0
  - C. Canvas Cases for above Camera.. .. .. each 0 7 0
  - 2990.—Single Extension Folding Plate and Film Camera.
  - A good camera for all round work, takes roll films 3^ x z\ in. or plates 3J x z\ in. Fitted with reversible brilliant view finder, focussing scale with infinity catch, detachable back with plate carrier, wire release and one single metal slide.
  - A. As above, fitted with single achromatic lens f/11 and synchro shutter for
  - time, bulb and instantaneous exposures .. .. .. £3 2 6
  - B. Ditto, but fitted with Aldis Plano lens f/77 and shutter giving from 1/5 to
  - 1/100 second exposures .. .. .. £5 10 0
  - C. Ditto, but fitted with Dalmeyer lens f/67 8 7 6
  - 2990
  - 2991.—Folding Camera for use with Plates of Film Packs. An excellent practical camera for all round work giving good results for both near objects and large scale photographs, double extension with rack and pinion, rising and cross front, reversible brilliant view finder, hooded focussing screen, engraved focussing scale, wire release and two single metal slides.
  - A. As above, for plates or film packs 4J X 3i in. shutter, giving from 1/5 to 1/100 second exposures. Plutar Rapid Aplanat leps f/8.
  - £5 10 0
  - B. Ditto, but fitted with f/77 lens .. .............6100
  - C. Ditto, but fitted with Aldis f/6*3 lens .. .. .. 8 0 0
  - 2991
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.414 - vue 433/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 415
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - REFLEX CAMERAS
  - The advantages that the Reflex camera places in the hands of most workers are very obvious. First and foremost the camera, although no larger than an ordinary small box-form hand-camera, enables the worker who is an indifferent judge of distance to depend upon getting his pictures accurately composed and perfectly sharp without any difficulty at all. The picture can be watched and focussed on the screen right up to the instant of exposure, with the assurance that the composition as seen on the focussing screen will be faithfully recorded on the plate. No other type of camera offers this great advantage.
  - 2992.—Reflex Camera, as above. Thoroughly well made of the smallest dimensions and weight, with a focal-plane shutter that is absolutely reliable, and anastigmat lenses of exceptional covering power, working at f/4'5, complete with three dark slides.
  - A. Reflex camera, |-plate size (4^ x 3| in.) with anastigmat lens f/4-5
  - £16 10 0
  - B. Ditto, postcard size (5! X 3J in.) .. . . .. 22 0 0
  - These are the two standard outfits ; any standard make of lens can be fitted, however, at extra cost.
  - 2992
  - FIELD CAMERAS
  - 2993.—The “ King ” Field Camera. A well made field
  - camera outfit, built on practical lines, compact and light in weight, embodying all the essential movements for general purposes and quite simple to operate. Case of polished mahogany with lacquered brass fittings, rack and pinion double extension, wide angle rack movement, rising front, swing back, reversing frame, turn table and leather handle. Complete with roller blind shutter, giving time and instantaneous exposures with indicator and release, suitable tripod stand, and one double plate holder.
  - 2993/2994
  - 2993.—With “ Beck ” Symmetrical Lens, f/8 ..
  - 2994— „ " Aldis ” Anastigmat Lens, Series III., f/77
  - 2995 .—Camera and one double slide only (without lens and shutter)
  - 2996 .—Extra Double Slides .. .. .. .. .. .. each
  - 2997 .—Flexible Canvas Case 2998.—Tripod Stand for Turntable
  - A B c
  - J-Plate. FPlate. i /1-Plate.
  - £5 15 0 £8 0 0 £12 10 0
  - — 9 0 0 14 0 0
  - 2 12 6 4 10 0 6 15 0
  - 0 15 0 0 15 0 0 15 0
  - 0 5 6 0 7 6 0 10 6
  - 0 9 0 0 18 0 1 4 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.415 - vue 434/555
- - 416 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SANDERSON CAMERAS
  - Open ready for use as a Hand Camera.
  - The “ Sanderson ” Hand Camera. —The “ Sanderson ” still holds an unrivalled position as the most useful and valuable camera for all-round work. Combining, as it does, the manifest advantages of a field camera with the portability and “ instantly ready ” character of a hand camera, it is the ideal instrument for a skilled worker. Its simplicity is unequalled. The universal swing front, the movement that has made the “ Sanderson ” famous, provides for the rising and swinging of the lens front in any direction, and yet allows the action to be entirely governed by a single pair of locking nuts. All the actions of the “ Sanderson ” are controlled from the back. The lens swings on its axis and travels upwards, forwards or backwards on a pair of struts slotted in their full length. The action is always steady, smooth and regular, and there is no danger of the lens “ dropping ” and necessitating refocussmg.
  - The “ Sanderson " movement is quite unique and is covered by a large number of patents. It must be understood, however, that in the “ Sanderson ” all these movements are held in reserve, and need only be brought into action when wanted.
  - THE “SANDERSON” REGULAR (2999) AND TROPICAL (3000) MODEL.
  - Complete with three Double Plate Holders and Shutter giving exposures from 1/5 to 1/100 second, size 4^ X 3^ in.
  - A B C D E Regular. Cat. No. 2999. Tropical. Cat. No. 3000.
  - With Aldis Plano Anastigmat Lens 6 in. f/77 ,, Cooke-Luxor ,, ,, 5 in. f/6-8 ,, Ross Homocentric,, ,, 5 in. f/6-3 ,, Ross Xpres ,, ,, 5J in. f/4\5 ,, Cooke-Avair ,, ,, 5^ in. f/4'5 £14 0 0 14 17 6 18 5 0 23 5 0 24 0 0 £17 15 0 18 12 6 22 0 0 27 0 0 27 15 0
  - Ditto, ; as above, but postcard size, i.e. 5|- x 3^ in.
  - Regular. Tropical.
  - Cat. No. 3001. Cat. No. 3002.
  - A With Aldis Plano Anastigmat Lens 6 in. f/77 £16 0 0 £20 15 0
  - B ,, Cooke-Luxor ,, ,,5 in. f/6-8 17 7 6 22 2 6
  - C ,, Ross Homocentric ,, ,, 5 in. f/6-3 . . i 21 0 0 25 15 0
  - D ,, Ross Xpres ,, ,, 5! in. f/4‘5 I 27 17 6 32 12 6
  - E ,, Cooke-Avair ,, ,, 5-^ in. f/4'5 29 15 0 34 10 0
  - Note.—The Tropical Model “ Sanderson " has been specially manufactured to withstand the climatic conditions of tropical climates, and can be thoroughly recommended for use in India, etc.
  - 3003.—THE “SANDERSON” JUNIOR CAMERA.
  - Complete with three Double Plate Holders and Shutter giving exposures from 1/5 to 1/100 second, size 4^ X 3^ in.
  - A I With Plutar Aplanat Lens, f/8 £10 15 0
  - B ,, Aldis Plano ,, f/77 6 in. 11 15 0
  - C ,, Cooke-Luxor ,, f/6-8 5 in. 12 12 6
  - 3003. The “ Junior ” Model.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.416 - vue 435/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 417
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PHOTOGRAPHIC APPARATUS
  - 3004.—Metal Telescopic Tripod Stand for small cameras.
  - Compact, light and rigid, closing up into a small space. Automatic closing and fitted with a spring catch which can be replaced if damaged.
  - Constructed of circular brass tube, the outer section being neatly
  - blackened and fitted with a fixed circular nickel top with camera screw.
  - Sections. Extended. Closed. Each.
  - A 3 44 in. jyb in. 8/6
  - B 4 48^ in. 15-2- in. 10-
  - C 5 49 2 14I m. 11/6
  - D 7 • • 48 in. ii|- in. 13/6
  - 3004
  - 3005.—Wooden Tripod, two fold, varnished pine sliding leg, length : open, 51 in. ; closed, 29-i in. .. . . .. each 8/6
  - 3006 .—-Ditto, three fold, ebonized beech, self-locking and sliding leg, with 3-inch fixed top and fixed T-screw. Length : open, 51 in. ; closed, 21 in. .. . . .. . . .. .. each 15/-
  - 3007. —Ditto, ash, self-locking and sliding leg, with 3-inch cloth-covered ash top, two straps and handle. Suitable for hand cameras. Length : open, 48 in. ; closed, 19 in. . . . . . . each 18/-
  - 3008.
  - The “Presto” Dark Room Lamp. Solid metal base, ruby and orange glasses which can be used together or separately, or opened to admit white light. Outside winder, paraffin chimneylcss burner, and large shade.
  - 3008
  - Price
  - 12/-
  - 3009. — Dark Room Lamp.
  - Black japanned D-shape body with ruby glass front, 5 x in., eye-shade, oil burner and light trap.
  - Price
  - 3 6
  - 3009
  - 3010.—R uby or Amber
  - Globe, with brass fittings. Can be attached to any ordinary incandescent lamp-fitting. The ruby globe is sufficiently large to be used with the ordinary metallic filament lamps.
  - Ruby or orange
  - each 4/6
  - - 3010
  - {The price does not include incandescent lamp.)
  - 3011.— Dark Room Lamp, latest pattern, for use
  - with oil, gas, or electricity. Reflected light only. Scientific
  - light filter, size 10 x 8 in. Absolutely safe.
  - A. Price, fitted with incandescent gas burner and spectro-
  - scopically tested light filter .. . . . . .. 22/6
  - B. Price, fitted with electric lamp-holder, plug, and length
  - of flexible wire .. .. .. . . .. ., 22/6
  - C. Price, fitted with paraffin oil burner and outside winder 22/6
  - 3011
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
  - DD
- p.417 - vue 436/555
- - 418 F. E. BECKER & CO.,' NIVOC HOUSE, HflTTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PHOTOGRAPHIC APPARATUS
  - A.
  - B.
  - C.
  - D.
  - E.
  - F.
  - G.
  - H.
  - 3012.
  - For Plates.
  - 4i X 3i in. 5X4» 5i X 3 2
  - X 4f „ 8i X 6± „
  - 10 x 8 ,;
  - 12 X 10 15 X 12 „
  - 3012. — Porcelain Dishes, made in the celebrated Staffordshire potteries, of the finest porcelain.
  - each
  - Shallow.
  - 1/6
  - 1/9
  - 1/9 2/6 4/-4/9 7/-15/6
  - each
  - Deep.
  - 1/9
  - 2/-
  - 2/-
  - 2/ 4/ 5/
  - 8/-
  - 18/6
  - /9
  - /6
  - /6
  - 3013. —Graduated Glass Jugs.
  - A. 1 pint.. . . . . each 1/6
  - B. 1 quart . . . . ,, 3/-
  - 3014. —Ditto, but graduated in metric system.
  - Capacity, 1000 c.c. .. each 4/-
  - 3015
  - 3015. —The “Waterloo” Washing
  - TrOUgh. Black japanned zinc tank, fitted with overflow syphon, which withdraws the water at bottom of tank, but never allows the plates to be uncovered. Movable combination zinc rack for J, 5 X 4 and |-plates .. .. .. .. .. each 5/-
  - 3016. —The “Popular” Washing Trough. A cheaper model, with syphon and combination rack for |-plate, 5x4 and |-plate each 2/6
  - 3017.
  - The “Rollo” Print Washer.
  - Black japanned outside, white inside.
  - For Prints.
  - A. 3i x 2-1
  - B. 4\ x
  - C. 6i x 4!
  - Each.
  - 2/6
  - 3/6
  - 7/6
  - 3018.— Xylonite Dishes. Substantially made of stout xylonite with ribbed bottom and spout, supplied in different colours. The large sizes are extra stout, but without spout.
  - 3°r8
  - For Plates. Each. For Plates. Each.
  - A. 3-2 X2|- in. 8d. E. 8£x6|- in. 2/3
  - B. 4±X3| in. 9d. F. 10x8 in. .. 3/6
  - C. 5iX3l in. • V- G. 12 X10 in. 4/6
  - D. 6iX4f in. 1/6 IT 15x12 in. .. 8/-
  - 3019.—Conical Form Measures for Laboratory and Photographic work.
  - Capacity 1 2 4 8 dr.
  - Each., iod. nd. i/r 1/3 Dozen 9/- 10/- 12/- 147-
  - Capacity 12 4 6 8 oz.
  - Each nd. 1/2 1/4 1/6 1/9
  - Dozen 10/- 12/6 15/- 17/- 20/-
  - 3019
  - 3020.—Cup
  - sures.
  - Form Mea-
  - Capacity 4 6 8 10 oz,
  - Each i/4 1/6 i/9 i/n
  - Dozen 15/- 17/- 20/- 22/-
  - Capacity 16 20 32 40 oz,
  - Each 2/3 2/9 3/3 3/9
  - Dozen 25/- 27/- 35/- 42/-
  - 3020
  - 3021.—P orce-I a i 11 Fixing Trough. Specially made of the finest porcelain to withstand photographic chemicals.
  - For Plates. 6 Grooves. 12 Grooves.
  - Each. Each.
  - A. 41 X 3i.................... 7/6 .. 12/6
  - B. 5h X 3l.................... 8/6 .. 15/-
  - C. 6I-X4I.................... 11/6 •• 16/-
  - D. 8| X 6£................... 17/6 .. 25/-
  - E. Combined to hold 12 ^-plates or 10 J-plates 18/6
  - F. Combined to hold 18 |-plates or 12 |-plates 35/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.418 - vue 437/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 419
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PHOTOGRAPHIC APPARATUS
  - 3022
  - 3022.—The “ Vento ” Draining Rack,
  - thoroughly well made, extremely rigid. The grooves hold twelve negatives of any size up to whole-plate. The negatives get perfect ventilation and dry quickly. No metal comes into contact with the plates.
  - Each ......................... .. .. 2/-
  - 3023.—A well-
  - made Nonslipping Printing Frame,
  - of well seasoned wood, lined with cloth, strong brass clamps.
  - 3023
  - Size. Each. Size. Each.
  - A. 3i X 24 1/1 D. 5i X 34 1/5
  - B. 4i X 3i 1/2 E. 64 X 4| 1/10
  - C. 5x4 1/10 F. 84 X 64 5/6
  - 3024.—The “ Dualite ” Electric Enlarger. The simplest form of artificial light enlarger, can be used from the ordinary house supply (two 30-watt metal filament lamps should be used). The light is reflected from the inner sides of the lamp house through the negative on to the sensitized paper. The effect of this illumination is to give soft and pleasing pictures, hard lines are softened, faults are minimized and flaws or scratches on the negative practically eradicated. Made in the following two models :—
  - No. 1. Complete, working in conjunction with a J-plate or smaller camera, with all electric fittings (except lamps), special white reflector, negative carrier for ^-plate negatives, with adapter for 34x24 in. film negative holder, two yards of electric flex and plug (as illustrated) £2 2 0
  - No. 2. Complete enlarger with lens, lens front, bellows, etc. .. 3 3 0
  - Model No. i. 3024
  - 3025.—Artificial Light Enlargers. Well designed of solid oak with extending base, truncated bellows, reversible carrier. Iron lamp body with ruby window, light excluding curtain and mounted compound condenser.
  - A. For enlarging from Opiate negatives with 54-in. condenser and portrait lens .. .. .. .. .. £8 10 0
  - B. Ditto, but with Aldis lens i/6 .. .. .. .. .. .. .. .. .. .. .. 1050
  - 3026.—The “ King ” Enlarger for Artificial Light.
  - A practical enlarger possessing all the features for producing the finest enlargements. Made of solid oak with rack and : pinion base with rising and falling lens front. Truncated bellows, reversible carrier with rising and falling movement. The large lamp body which is of iron has rack adjustment for the light, triple condenser cone, ground glass diffusing screen, light excluding curtain and mounted compound condenser.
  - A. For enlarging from |--plate negatives with 54-in. condenser
  - and f/6 Aldis lens .......................£12 5 0
  - B. Ditto, but for 5 X 4 in. negatives with 7-in. condenser—
  - £15 10 0
  - C. Ditto, but for 54 X 34 in. negatives with 7-in. condenser—
  - £15 10 0
  - D. Ditto, but for 64 X 4f in.'negatives with 84 in. condenser—
  - £19 10 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.419 - vue 438/555
- - 420 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PROJECTION LANTERNS
  - 3027
  - 3027.- The “ Junior ” Lantern.
  - A well-made inexpensive lantern suitable for school use, comprising all the essential elements for projecting crisp, sharp and well-illuminated pictures.
  - SPECIFICATION.
  - BODY.—Well-made japanned tin with panelled door, fibre handle and sight-hole, well-ventilated base. Size of body, 8J x 9J X 5| in.
  - FRONT.—Well-ventilated condenser-stage, with spring carrier frame, brass sliding front tube.
  - OBJECTIVE.—No. 1 double achromatic with focussing.
  - CONDENSER.—4 in. (103 mm.) plano-convex compound mounted in brass cells.
  - PRICES.
  - A. Fitted cowl and tray £2 5 0
  - B. ,, inverted incandescent gas outfit . . 2 14 0
  - C. ,, “ Meta ” spirit lamp 3 13 6
  - D. ,, Stocks’ pattern, 4-wick lamp 4 7 6
  - 3028
  - 3028.—The “ York " Lantern.
  - A well-designed and roomy lantern, suitable for almost any form of illuminant. The feature is the large ventilating roof, which keeps the body perfectly cool.
  - SPECIFICATION.
  - BODY.—Well made in japanned iron, with large side door, fibre handle and brass sight-hole. The roof is hinged to form a ventilating shaft which keeps the body particularly cool. Back curtain and rod is provided. Size of body, 9I X 9 x 6£ in. Height of centre, 5 in.
  - FRONT.—Brass front draw-tube, well-lacquered, vent lated, spring carrier stage and brass sliding tube.
  - OBJECTIVE.—No. 2 double achromatic of good quality, with large diameter back lenses in rack and pinion focuss'ng mount.
  - CONDENSER.—4 in. plano-convex compound in brass cell.
  - PRICES.
  - A. Fitted tray . £4 4 0
  - B. ,, inverted incandescent gas outfit . . 4 13 0
  - C. ,, “ Meta ” spirit lamp .5 12 6
  - D. ,, parallel arc lamp 5 17 6
  - 3°29
  - 3029.—The “ Comet ” Lantern.
  - An exceedingly compact lantern of very smart appearance.
  - A favourite with the traveller on account of its solid design
  - and portability.
  - SPECIFICATION.
  - BODY.—Well-made and well-vent lated Russian iron body of new design, panelled door with fibre handle and sight-hole. Size of body, 8 X 4$ X 8 in. Height of centre, 5 in.
  - FRONT.—Open stage with plates of stout brass and solid tubes accurately fitted to ensure rigidity. The front end is supported by a cast-brass standard, the whole lacquered and finished in first-class style.
  - The condenser sleeve and cover are pierced with holes to correspond with those in condenser, giving perfect ventilation.
  - OBJECTIVE.—Best double achromatic, large diameter back combination, with flashing shutter and rack and pinion.
  - CONDENSER.—4 in. (103 mm.) plano-convex compound in brass cell.
  - CASE.—Japanned tin with carrying handle.
  - PRICES.
  - With 4 in. (103 mm.) condenser and 2 in. (43/52 mm.) diameter
  - lenses.
  - A. Fitted cowl and tray £5 0 0
  - B. ,, incandescent gas outfit 5 9 0
  - C. ,, inverted incandescent gas outfit 5 10 0
  - D. ,, “ Meta ” spirit lamp 6 8 6
  - E. ,, parallel arc lamp 8 13 6
  - F. ,, arc lamp 8 18 6
  - 3030.—The “ Iron Duke ” Lantern.
  - A lantern of distinctive design, built in a most substantial manner and suitable for occasional use with arc light.
  - SPECIFICATION.
  - BODY.—Handsomely made in best quality stout Russian iron, with large side door fitted with flashing shutter, covered sight-hole and fibre handle. The back door is hinged, and a sliding brass rod, which can be withdrawn from interior of lantern, carries a curtain. Size of body, 10 x 6 X 11 in. Height of centre, 5^ in.
  - FRONT.—Open stage design in solid brass, with massive square plates, and front tubes made to ensure accurate fitting. The tubes are mounted on cast-brass cradle divided in centre, so that the quick-thread adjustment screw fitted to the front can readily be operated for the rapid adjustment of the width of carrier stage to any thickness.
  - T1LTER.—New patent design adjusted by archimedean screw, giving a graduated rise to front of lantern up to 2J in.
  - OBJECTIVE.—Best quality double achromatic, of 2 in. (43/52 mm.) diameter, mounted in interchangeable tube, massive double pinion jacket with tinter slot and flashing shutter.
  - CONDENSER.—“ Empire ” patent 4% in. (115 mm.).
  - CASE.—Russian iron with leather handle for carrying and lock and key.
  - PRICE.
  - Complete, with three draw telescopic tubes.. .. £14 0 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.420 - vue 439/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 421
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SCIENCE DEMONSTRATION LANTERN
  - ~ -V
  - The “ Science Demonstration ” Lantern in its latest and complete form, as shown, presents perfection in optical lantern construction, both in design and workmanship, and is suitable for all kinds of projection, slides or scientific apparatus.
  - The Objectives fitted are of the best manufacture, and are theoretically designed to give perfect definition, flatness of field and freedom from colour.
  - The Lamp Llouse is large and allows of high candle power illuminants, the door being full size of the body allows of easy and full access to the illuminant. It is constructed of a substantial wrought-:ron framework, the front, side and door being made of blued sheet steel, asbestos lined. A fireproof curtain of woven asbestos is also provided.
  - Condenser lenses are all removable—the back condenser lens being held in position by means of a bayonet cap, the full size lamp house door allowing of quick removal.
  - The lantern is arranged for both horizontal and vertical projection. When projecting horizontally, the light passes through the condenser lenses and objective in the usual manner. When using the vertical projection, the light, having passed through the back condenser lens is intercepted by a mirror swung at an angle of 450; this is accomplished in a moment by drawing out the mirror hinge knob, which instantly allows the mirror to fall into position. The position is located by a cam stop, which can be adjusted to give the correct angle ; the light is then reflected vertically through another condenser lens, and objective upon which is mounted an adjustable 90° silvered prism which allows the light to be projected on to the screen in coincidence with the horizontal projection.
  - For packing, the front slide is pushed home into the body, and the vertical objective holder racked down into the body, the whole lantern being very compact. The extreme convenience and adaptability of this lantern for all kinds of projection will be self evident.
  - 3031. —The “Science Demonstration”
  - Lantern, 4^- in. condenser lenses, silvered prism to vertical, pair of 8 in. focus objectives, rack jacket to horizontal, injector jet, revolving and sliding carriers, steel lamp house and woven asbestos curtain—
  - £22 0 0
  - 3032. —Travelling Case, made of seasoned
  - white wood, polished black, steel corner plates, carrying handles, lock and key . . .. .. £2 10 0
  - 3033. —Adjustable Iron Stand, with pair of
  - mahogany clamp bars, for attaching lantern to stand
  - £8 10 0
  - 3034. —Front Erecting Prism and mounting
  - £3 0 0
  - 3034a—Reversible Table .. £10 0
  - 3042
  - 3035. —Adjustable Clamp .. ..£060
  - 3036. —Slit and Prism for Spectrum £3 10 0
  - 3037. —Adjustable Mirror, mounted and fitted to prism frame to obviate swivelling lantern—
  - £10 0
  - 3038. —Opaque Projection, simple attachment.
  - £2 0 0
  - 3039. —Lantern Microscope, complete with fin.
  - micro objective .. .. .. .. £8 8 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.421 - vue 440/555
- - 422 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DEMONSTRATION LANTERN
  - 3040.
  - THE “UNIVERSAL DEMONSTRATION OPTICAL LANTERN
  - FOR HORIZONTAL AND VERTICAL PROJECTION
  - Designed to meet the requirements for a thoroughly satisfactory and self-contained Demonstrating Lantern, for use in Science Schools, Technical Institutes, etc. It can be used for horizontal projection, vertical projection, or for projecting opaque objects.
  - 3040
  - HORIZONTAL PROJECTION.
  - *When used horizontally or vertically, the stage is entirely open, which is a sine qua non for scientific work and experimental illustrations. Moreover, it can be changed from one adjustment to another in a few seconds. When projecting diagrams or maps, the open stage permits of a pointer, e.g., a knitting needle being used. The stage is sufficiently large to take a gold leaf electroscope. When in a vertical position, diagrams can be drawn on a smoked glass plate placed on the horizontal half of the condenser, the entire process being projected on the screen. In this position such experiments as magnetic curves, etc., can be demonstrated to great advantage. A further advantage is its adaptability for projecting opaque objects, and for demonstrating such experiments as the nodal lines in a vibrating plate, etc.
  - VERTICAL PROJECTION.
  - To alter from horizontal to vertical projection, the catch is released and the stage pulled forward and raised. The edge of the mirror frame rests on a brass ledge fixed to the front plate. By this means it will be seen that the mirror is brought into position at an angle of 450 with the condenser, the stage plate is removed and the lantern slide plate, which is also key-holed, substituted. This plate has a ridge for taking an ordinary size lantern plate, and is held firmly by a side spring. The adjustable objective mirror is then placed in position. The mirror is hinged to a metal ring and is provided with a long milled head screw for adjusting the angle to a nicety. The side doors can then be closed to prevent any leakage of light.
  - PROJECTING OPAQUE OBJECTS.
  - In order to exhibit Opaque Objects, the end of the large mirror is placed within the brass groove on the base and the lantern slide plate is removed. The front half of the condenser lens must also be removed. This is held on the stage plate by studs, and is easily detached by giving the lens cell a twist, this will release the lens which is held to the studs by a circular key way. The front part carrying the objective is lowered so as to allow it to be within focal range of the object placed on the table. The table made of brass, bronzed and lacquered, and covered with velvet, can be raised or lowered, and clamped in any position by a binding nut, and is mounted on a heavy iron stand. The mirror is also adjustable to any angle. As already mentioned there are two swing side doors attached to the body, which are wired along the edges When closed they connect the sides of the lantern with the upright mirror, thus enclosing the space occupied by the adjustable table.
  - (Continued on next page.)
  - Oup stock of pure Chemicals and Acids is very considerable ,* hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.422 - vue 441/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 423
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - “UNIVERSAL” DEMONSTRATION LANTERN
  - {Continued.)
  - SPECIFICATION.
  - Body.—Made of Russian iron, strengthened and wired throughout, in order to make it as strong as possible, and being made entirely of metal, and only the best material procurable entering into its construction, there are no parts that can warp or get out of adjustment. The door is large and when closed fits into a frame, thereby making it perfectly lighttight. The size allows the operator to put both hands inside the body for changing the carbons or limes. The eyepiece, whilst being in the optical axis, is placed forward so that the operator is enabled to look back, so to speak, on the carbons or limes.
  - Stage.-—The front of the body is fitted with a brass plate, bronzed and lacquered, which carries a cell for taking one half of the condenser. A second brass plate, bronzed and lacquered, is fixed to it by brass columns and bolts. To this is hinged, by a long pin with a milled head, another brass plate carrying the second half of the condenser. This plate is fitted with a long polished brass rod on which the objective slides when using various foci lenses, and is locked by means of a large clamping screw at the side of the plate which carries the jacket or rack-mount. This is a distinct advantage over the old type of demonstrator, as the slide is much more accessible when being used in the vertical position. At the end of this sliding rod is a clip which holds the large bottom mirror up when the lantern is projecting ordinary slides. There is a stage plate with adjustable brass springs, with milled head screws, for taking an ordinary slide carrier or chemical tank. This stage plate is attached by “ key-hole ” fittings so that it can be easily removed. Hinged to the front plate is a large mirror, mounted in brass, the back of which forms the foot of the stage when projecting apparatus. Should a higher centre be required, the mirror can be removed by releasing the front catch and withdrawing the hinge pin when the base of the lantern may be used as a table on which to stand the apparatus. The front bracket to which the light shield is attached, is threaded to take the jacket or rack-mount.
  - Condenser.—Double Convex and Meniscus, 4-in. diameter, but each half mounted in separate cell.
  - Prices.
  - 3040. —Demonstrator Science Lantern, complete as specified, with No. 2D Lens Cylinder (any focus)—
  - 3041. —Ditto, ditto with No. 4D Lens Cylinder
  - 3042. —Prism, fits No. 2D Lens Cylinder
  - 3043. —Parallel Beam Nozzle
  - 3044. —Pencil Beam Nozzle
  - 3045. —Electrolytic Tank
  - 3046. —Chemical Trough
  - 3047. —Alum Trough ..
  - 3048. —Projection Microscope
  - 3049. —Lantern Kaleidoscope
  - 3050. —Aphengescope ..
  - £24 10 0
  - 25 10 0
  - 6 6 0
  - 0 15 0
  - 0 7 6
  - 0 15 0
  - 0 5 0
  - 1 0 0
  - 2 5 0
  - 3 3 0
  - 0 15 0
  - Every requisite fdr Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.423 - vue 442/555
- - 424 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - THE FOCUSLITE SLIDE LANTERN
  - The Focuslite Slide Lantern is specially designed for lantemists who require a compact, handy and thoroughly reliable slide lantern.
  - It is designed for use with ioo watt lamps, and for projecting pictures not exceeding 8 ft. wide and at distances not exceeding 30 ft., it will take a 250 watt lamp, but these should not be employed unless the performance is of short duration owing to the greater heat.
  - The outfit is exceptionally well finished and handsome in appearance. It takes ordinary standard size 3^ x 3| lantern slides, and is supplied complete with double slide carrier, 4J in. plano-convex condensers, and good quality projection lens in interchangeable rack and pinion mount, with lamp holder, 12 ft. of cable and adaptor.
  - 3051
  - Prices.
  - 3051. -
  - 3052.
  - 3053.
  - 3054.
  - 3055.
  - 3056.
  - 3057.
  - 3058.
  - -With 6 in. or 8 in. focus projection lens -With extension tube and 10 in. focus lens
  - -With extension tube and 12 in. focus lens ...........................
  - -With extension tube and 14 in. focus lens .. .. .. ..
  - Note.—We do not recommend any longer focus lens than 14 in. with this outfit -No. 0 Series Lamps for the above, 100/120 volts, 100 watts
  - - „ „ „ „ „ „ „ 250 „ ...............
  - - „ ,, ,, ,, ,, 200/250 volts, IOO ,,
  - 5J J? ” ” 250 ,,
  - When ordering state the voltage of supply on which it is to be used.
  - £6 17 6 7 5 0 7 10 0 7 15 0
  - £0 11 3
  - 110 0 11 3
  - 13 6
  - THE PROJECTOSCOPE
  - 3060
  - Prices.
  - A. Projectoscope, as described (without lamps)—
  - £4 17 6
  - B. Lamps (when ordering please state voltage of
  - main) .........................each 7/6
  - C. Reversing Mirror .. .. .. ..10/6
  - 3060.—The Projectoscope, designed for the simple and easy projection of picture postcards, originals, etc., on to a screen, placed at a distance of some 10-12 ft.
  - Such postcards or other objects can be effectively displayed to an audience of some twenty to thirty persons without incurring the expenses of making lantern slides, and for lectures, demonstrations, etc., it will be found to be an extremely useful piece of apparatus.
  - For schools and colleges it will be found to be of great service, enabling lectures to be readily illustrated by the projection of original diagrams or illustrations.
  - When used in the ordinary way, the Projectoscope reverses pictures from right to left ; in many cases this does not matter and is readily understood by an audience, but if it is considered objectionable a reversing mirror can be fitted.
  - The Projectoscope is fitted with two electric lamp holders to take 100 watt gas-filled lamps. Behind each lamp is a silvered glass reflector which must be carefully focussed.
  - Oup Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.424 - vue 443/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 425
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CINEMATOGRAPHS
  - 3061.—The “Empire” Cinematograph, No. 1,has been specially designed for use in the lecture room, and for commercial demonstration purposes. It has a large lamphouse, of sufficient size to take any of the standard illuminants, and in addition to cinematograph projection, is fitted for showing lantern slides. The machine is most simple to use, and it is possible with very little experience to project pictures as perfect as those shown in the cinema.
  - Everything is standard ; the condenser and lens are the same as fitted to the professional machine, and the spool-holders, etc., take the standard size film.
  - Specification.
  - BODY.—Russian iron, extra large and well ventilated, with sliding door and back curtain.
  - MECHANISM.—Maltese Cross movement, running in grease box, gear wheels accurately cut and meshed, sprocket wheels with solid steel spindles, jockey rollers flanged to prevent the film running off the sprocket wheels. Masking is effected by a fine adjustment screw.
  - AUTOMATIC CUT-OFF.—Rises and falls as the film is started or stopped ; prevents the light falling on the film when stationary.
  - SPOOL ARMS.—Long enough to take 12 in. spools ; fold up when not in use. The top spool is fitted with rewind gear.
  - SPOOLS.—Two 8 in. diameter, holding approximately 650 ft. film.
  - CONDENSER.—Four-inch Meniscus and Bi-Convcx in well-ventilated brass cell.
  - CINE LENS.—Standard size iL' in. diameter, interchangeable tube form. Rack and pinion focussing jacket.
  - LANTERN SLIDE LENS.—10 in. focus, in rack and pinion focussing jacket.
  - CASE.—Each machine sent out in packing case, which is convenient for storing when not in use.
  - Prices.
  - A. Complete (without stand and fire-proof boxes) . . . . . . . . £21 0 0
  - B. Adjustable iron legs for fitting to baseboard, making a strong serviceable stand which
  - can be adjusted for height or tilted .. .. .. .. .. 330
  - C. Extra spools, 8 in. . . . . . . . . . . . . 0 5 0
  - D. Fireproof spool boxes for 8 in. spools . . . . . . . . per pair 2 10 0
  - E. Extra spools, 12 in. . . . . . . . . . . . . . . . . 0 7 0
  - F. Illuminants. The “ Klimax ” Parallel Arc Lamp .. .. .. 3 15 0
  - G. The “ Empire ” Arc Lamp . . . . . . . . 6 0 0
  - 306X
  - The “ Empire ” No.
  - with Standard Lamphouse.
  - 3062.—The “Empire” Cinematograph, No. 2.—
  - In this projector the illuminant is electricity, obtained either from the main supply or from accumulators.
  - This forms an ideal school cinematograph ; it is compact and portable, and because the light is always centred, ever ready. It gives a bright picture 5 to 6 ft. wide, according to the distance the machine is placed away from the screen.
  - Specification.
  - The mechanism and general details are identical with those specified for the “ Empire ” Model 1. There is no lamphouse, and the lantern slide attachment is not supplied. The additional features are as follows :—
  - ELECTRIC SUPPLY FOR HALF-WATT LAMP.—The price includes a resistance wired to break down the ordinary house current to feed the small high-power lamp provided. When ordering state whether for use on 220 or no volt circuits.
  - ACCUMULATORS.—For use where the electric current is not laid on, a set of 12-volt accumulators can be substituted for the resistance. This gives excellent results. The accumulators have been specially selected for projection purposes, and give approximately 22 ampere hours.
  - LAMP.—Is a 12-volt J-Watt type contained in a cylinder fitted to the mechanism and moving with the film-gate and lens for masking purposes. The lamp can be replaced instantly when necessary.
  - Prices.
  - A. For use off the electric light supply, complete with resistance
  - and lamp . . . . . . . . . . £16 16 0
  - B. *For use with accumulators, complete with lamp and
  - 12-volt accumulators (not charged) in anti-sulphuric painted white wood boxes, with strap handles—
  - £22 0 0
  - Accessories.
  - C. Adjustable iron legs with iron baseboard which can be
  - adjusted for height or tilted in any direction £3 15 0
  - D. Extra 12-in. spools .. .. .. .. each 7/-
  - * Accumulators are always supplied uncharged. These can be quickly charged
  - locally for a small cost.
  - 3062
  - The “ Empire ” No. 2, for Electric Light.
  - Our stock of pure Chemicals and Acids is very considerable; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.425 - vue 444/555
- - 426 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - Exterior view. Note its extreme compactness and portability.
  - The simplicity of construction and operation has made this machine practical, and any one following the printed instructions and the illustrations on the. inside of the case door can operate and positively get perfect results with a little practice-
  - CINEMATOGRAPHS
  - 3063.—The “ Acme ” Portable Cinematograph Projector, designed
  - for use in schools, colleges, and educational institutions, providing an entertaining and instructive adjunct to existing apparatus. Weighing only 24 lb. and closely resembling a suitcase in size and external appearance, it will be found indispensable to the demonstrator who wishes to proceed from place to place without being unduly encumbered.
  - It is used direct from the electric light main by simply using the rheostat which connects in series to the cord that is attached from lamp socket to the machine.
  - Can be used on alternating or direct current without any changes whatever,
  - the motor being universal. The machine can be hand operated, however, if desired.
  - Illumination is provided by a nitrogen filled lamp of the concentrated filament stere-opticon type, and may be used on either of above currents..
  - Illustration showing interior of the “ Acme ” Portable Projector.
  - The mechanism is equipped with an automatic shutter which cuts the light rays from the film while the machine is standing still. This is necessary on account of the wonderful illumination obtained from the special lamp and condensers used in this machine.
  - DESIGNED TO TAKE THE STANDARD i,oco FT. REELS AND WILL PROJECT A PICTURE OF FROM 7 TO 9 FT. SQUARE AT A DISTANCE OF ABOUT 50 FT. FROM THE SCREEN.
  - Price complete, as above, with handle, two spools, and 15 ft. lead for working on no volts—
  - £60 0 0
  - Rheostat, no to 250 volts . . .. 4 10.0
  - 15 ft. Lead for 250 volts .. .. 0 10 6
  - Extra lamps, 400 watt .. each 1 18 0
  - Extra 10-inch spools .. . . ,, 0 4 6
  - This illustration shows the rapid and efficient way in which the projector can be connected to the ordinary light
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.426 - vue 445/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 427
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ILLUMINANTS FOR LANTERNS, Etc.
  - The “ Focuslite ” Outfits for Lanterns, Cinematographs, and general use. The lamp is self contained. There is no exposed filament and the light can be immediately switched on. These outfits are undoubtedly a great improvement on the “ IMernst ” lamps.
  - Voltage of lamp supplied, 50 fo 55 ; approximate amps, 4 ; candle power of lamp with mirror reflector, 1,000 c.p.
  - A. Outfit (without lamp) on plain tray
  - B. ,, ,, „ ,, mechanical tray
  - C. Lamps
  - 3064.—“ Focuslite ” Outfit, No. 1.
  - This outfit is recommended to those who require a powerful concentrated light which can be used on any ordinary house lighting circuit without risk to the installation.
  - The illumination with mirror is approximately 1,000 c.p., and this is equal to an arc lamp consuming the same amount of current. The bulb is only 3 in. diameter and this enables the outfit to be used in almost any lantern body. The filaments are tough and well concentrated and a good life can be expected from this lamp if treated properly and not overloaded. The resistance is of an improved pattern with roller contact which enables the same lamp to be used on any circuit from 50 to 250 volts. A locking ring to prevent the lamp being overloaded by accident is also provided. The resistance has guards on both sides to prevent the wires being touched when working in the dark.
  - .............................£3 12 6
  - ............................. 500
  - each 0 17 6
  - “ Focuslite ” Outfit, No. 2.
  - These outfits have a very fine point of light and are specially designed for those who desire to possess equipment capable of being used on various electric circuits (A.C. or D.C.) with resistance to regulate the voltage and control the candle power of the lamp. Some clients only need equipment to control low voltages, whilst others require control up to 250 volts. Some require a low power outfit, and others need a powerful outfit. The price therefore depends on what customers may choose from the table below. We strongly advise a Mechanical Tray for high power outfits and in all cases where frequent adjustment is necessary.
  - Prices and Particulars.
  - Type of Outfit. Voltage of Lamp. Approx. Candle Power Measurements. Outfit without Lamp. Price
  - Amps. of Outfit. T toF Min. Max. F to L On Plain Tray. 20/120 V. 20/250 V. Mechanical Tray. 20/120 V. 20/250 V. ot Lamps.
  - 3065 20/30 2 250/400 3i in. 7 in. ij in. 63/- 70/- 90/- 98/- 1 7/“
  - 3066 20/30 5 500/750 4i in. 8 in. 3 in. 70/- 78/- 97/- 105/- ! 12/6
  - 3067 20/30 10 900/1200 4i in. 8 in. 3 in. 78/- 115/- 105/- 142/- 20/-
  - 3068 20/30 20 1800/2200 in. 9 in. 4 in. 120/- 190/- 148/- 218/- 30/-
  - 3069 20/30 30 2500/3000 6 in. 9 in. 4 in. 165/- 243/- 192/- 270/- 45/-
  - Note.—No adaptor is supplied with No. 3067. No adaptor or cable is supplied with No. 3068 and No. 3069, as these outfits cannot be used of lighting circuits as illustrated.
  - The lowest efficient working pressure is 20 volts and the Maximum pressure at which the lamp must be run is 30 volts. The resistances are marked for all voltages, allowing for 25 volts at the lamp. The life and candle power varies according to the pressure at which customer works.
- p.427 - vue 446/555
- - 428 F. E. BECKER & CO., INI I VO C HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - “POINTOLITE” LAMP OUTFIT
  - The “ Pointolite is a new departure in electric lamps, being a direct-current arc burning in a glass bulb filled with an inert gas at a low pressure.
  - The lamp has an unique combination of advantages. The light source is of a point nature, far superior in intense concentration and uniformity to anything previously obtainable in incandescent lamps.
  - The light is perfectly steady, ideal for focussing and requires no attention when in use, a fact that makes it far superior to various types of arc lamps used for projection purposes.
  - The colour of the light is the nearest approach to daylight yet obtained by artificial illumination.
  - 3070/3071
  - 3070.—Complete “ Pointolite ” Outfit, for projection work
  - A. “ Pointolite ” lamp, 100 c.p., 1-35 amp.
  - B. Reflector for 100 c.p. lamp
  - C. Tray
  - D. Clip ,, ,, ,. . . .... . . ..
  - E. Holder ,, ,, ,, ..............................
  - £1 10 0 1 17 6 0 4 0 0 9 6 0 9 0
  - 3071.—Standard Universal Resistance, adaptable to all circuits, with plug, switch, holder, adaptor and flexible for 100 c.p. lamp .. . . .. . . . . .. . . . . .. . . . . ..£500
  - “ Pointolite ” Lamps are for use on direct current only, and can be run from an ordinary lampholder by inserting the adaptor connected to the resistance box. Three wires'and a three-pin plug connect the lamps to the resistance. These three wires connect a heater circuit to start the arc, and the arc circuit proper which maintains the light from the tungsten ball.
  - The standard pattern of resistance is capable of being used on all voltages, that is 100 volts to 250 volts direct current. Care must be taken to use the proper resistance, which is clearly marked, by placing the two-pin plug into the correct holes corresponding with the voltage of the supply.
  - The available supply of current having been connected to the resistance box, and the lamp also connected by means of the plug and adaptor, all that is necessary to light the lamp is to close the switch which is fixed on the resistance box.
  - The switch should be released as soon as the lamp is seen to light up, and if the arc does not strike very quickly the adaptor should be taken from the holder and turned round so as to change the polarity.
  - When the polarity is correct the arc will strike immediately the switch is released.
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.428 - vue 447/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 429
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 3072. —Electric Arc Lamp,
  - simple form, comprising pair of carbons with sliding motion and terminals, etc., mounted on polished stand, as figured—
  - £15 0
  - 3072
  - ARC LAMPS
  - 3073.—E I ect r i c Arc
  - Lamp, new pattern with horizontal positive carbon and vertical negative carbon. Each carbon can be fed separately or simultaneously. This lamp is well made in gun-metal and cast-iron, and adjustments are provided for horizontal and vertical centring. A steel shield is also fitted to cut off any extraneous light.
  - Price £3 17 6
  - 3074.—Electric Arc Lamp for bayonet-holder of house supply, comprising:—Scissors type Arc lamp, with both arms adjustable. The carbons are fed by means of a screw having a wood-fibre milled head. The jaws open sufficiently wide to take 10 mm. carbons. The lamp is carried on a mechanically-controlled tray, as figured, and can be used on any ordinary light main from 100 to 250 volts, either alternating or direct current. The resistance enables fine adjustments to be made and ensures a steady burning and non-hissing arc.
  - 3°74A
  - A. Complete outfit as illustrated with Arc lamp, Wire Adaptor, Resistance and supply of Carbons.
  - 5 mm. solid and 6 mm. cored for direct current, or 6 mm. cored for alternating current .. . . £3 15 0
  - B. Ditto on mechanical tray . . . . . . . . . . . . . . . . . . . . 4 17 6
  - C. Spare carbons, per 25 0 3 0
  - D. Resistance only .. .. .. .. 250
  - E. Arc lamp only .. .. .. .. .. .. .. .. .. .. .. .. .. 150
  - 3075.—Electric Arc La m p, “Scissors” type, suitable for currents up to 20 amperes, made in gun-metal, and highly finished. The base, which is made of cast-iron and enamelled, is 4I in. wide. As will be seen by the illustration, this lamp is fitted with all movements for centring the arc.
  - Price £3 17 6
  - 3075a .—Ditto, plain model without arrangement for centring horizontally and vertically.
  - Price ......................................£2 15 0
  - FOR ARC LAMP RESISTANCES SEE PAGE 257.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.429 - vue 448/555
- - 430 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ARC LAMPS
  - 3076.—Electric Arc Lamp, “ University ” pattern-This lamp is provided with all the latest improvements and adjustments; it is substantially' built and beautifully finished. The tray is of iron, enamelled, and is of standard width, 4}-^ in. ; the remainder of the lamp is mainly constructed of best quality gun-metal and steel. All the pinions are of steel cut from the solid, the racks are also machine-cut from solid drawn brass. Carbon holders are massive, and insulated from the body with mica ; the leads to the terminals are asbestos covered. It is capable of carrying up to 50 amperes. The width between carbon holders at full extension is 8| in., and when closed up 11 in., which provides for a lengthy lecture without recarboning. The centre of the lamp is adjustable from 4f in. to 6 in., and even greater range can be obtained by using the angle adjustment.
  - Commencing from the top of illustration, the first fibre knob allows of the adjustment of the crater of the positive carbon ; the second knob is for striking the arc ; the third knob is for adjusting the angle of the carbons—this is operated by a steel-cut worm working into a worm-wheel segment, which is cut on the main body casting. The third knob gives vertical movement, and the fourth knob horizontal movement. The weight of the complete lamp, as illustrated, is 8 lb. Price £8 10 0
  - L_; ..
  - 3077
  - ARC LAMP CARBONS
  - 3077.—Arc Lamp Carbons, specially developed for projection work, and are unequalled for light and steadiness. The arc burns absolutely without noise, and is easier to control than with any other carbons; the arc settles down immediately on striking or re-striking.
  - The Carbon, No. 3077B, is the smallest diameter Negative Carbon ever put on the market. The diameters advised carry the current without stripping, tapering or overheating. The small diameter of the negative carbon ensures entire absence of screen shadow, and therefore encourages economy in current consumption. The success of these carbons induced foreign carbon manufacturers to copy them.
  - PRICES (STANDARD SIZES) PER 25 PIECES.
  - FOR DIRECT CURRENT.
  - C. FOR ALTERNATING CURRENT.
  - A. Positive Carbons. B. Small : Dia. Negative.
  - Diameter. 8 in. 12 in. Diameter. 6 in. long.
  - 16 mm. 6/2 12/4 8 mm. 4/11
  - 18 „ 8/6 17/- 10 „ 5/6
  - 20 „ 10/8 21/6 11 „ 7/-
  - 22 „ 13/2 26/4 12 „ 7/9
  - 25 „ 17/6 35/- 14 „ 9/6
  - Diameter. Length 6 in. Length 12 in.
  - 16 mm. 9/2 18/4
  - 18 „ 12/7 25/2
  - 20 „ 14/6 29/-
  - 22 „ 16/- 32/-
  - 25 „ 19/7 39/2
  - Correct combinations of carbons for use with direct current :— For currents under—
  - 20 amps. 16 mm. cored positive and 8 mm. small dia. negative. 20 to 40 „ 18 „ „ - „ 10 „
  - 40 „ 60 „ 20 „ „ „ 11 „
  - 60 „ 85 „ 22 „ „ „ 12 „
  - 85 „ 100 „ 25 „ „ „ 14 „
  - Correct combinations of carbons for use with alternating current :—
  - Both carbons.
  - From 40 to 50 amperes .. .. 16 mm.
  - „ 50 „ 60 „ .. .. 18 „
  - » 60 „ 70 „ .. .. 20
  - Over 70 ,, .. .. 22 „
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.430 - vue 449/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 431
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ILLUMINANTS FOR LANTERNS
  - 3078.—The “Meta” Methylated Spirit Lamp, specially suitable where gas or electric light is not available. It is portable and safe. Ordinary methylated spirit is used, and under slight pressure it is vaporized at the burner, and by the medium of a gas mantle a very brilliant light is produced, which will brilliantly illuminate an 8 ft. circle. Well made of polished brass. Complete with rubber ball and tube. One mantle, lantern tray, asbestos lighting fork, and instructions for use, in cardboard box .. £110 0
  - Extra balls and tubes .. .. each 0 4 0
  - ,, mantles .. .. .. ,, 0 10
  - 3079.—S t o c k s’
  - Pattern Lamp.
  - For paraffin. Made of Russian iron and stout tin. Four wicks, 2 in. wide, adjustable reflector, and 4-draw chimney, adjustable by rack and pinion.
  - This is the most powerful paraffin oil lamp made. 3079
  - The system of combustion is perfect, and all parts can be regulated to obtain the maximum amount of light .. ,......................£2 5 0
  - A. Lamp wicks, the “Primus” .. per box 1/-
  - LIEVIE
  - 3080.—I n j ecto r.
  - Entirely supersedes mixed gas jets, will work with coal gas at low pressure, acetylene generators, or compressed acetylene, ether saturators, petrol gas, etc. Oxygen in every case should be at a pressure of 5 to 10 lb. per inch, specially constructed for use with pastilles, but limes can also be used.
  - LIGHTS
  - 3083.—Thorium Pastilles. A new lime made from the rare oxides of earth. Gives a splendid light, and requires no turning from start to finish of the show. Will last for at least twelve to fifteen lectures if handled with care.
  - Without tray Mechanical tray
  - £2 2 0 1 15 0
  - 3081 .—Blow-Through. Excellent
  - quality, with cog-wheel arrangement for turning, raising or lowering the lime, with backward and forward adjustment of the lime, recessed nipple in solid cast head. Fine adjustment taps giving the best light obtainable from a safety jet ... ... £1 5 0
  - 3082.—Mixed. Superior quality, fitted with fine adjustment taps instead of the ordinary turn-off tap, and mechanical backward and forward adjustment of the lime. Gives a powerful light, easily controlled .. .. .. .. £110 0
  - 3083
  - A. Size, 20 X 15 mm. each 2/6
  - B. Size, 20 X 20 mm. • • * * » 3/-
  - C. Pastille Holder .. • * * * 55 1/9
  - 3084. —The “ Excelsior ”
  - Trilby. One doz. limes in each tin. Size, i| X 1 in. per tin 4/-
  - 3085. —“Excelsior Trilby” Cinematograph. Specially recommended for high power jets. Larger size, i| X i| in. Six limes in each tin .. per tin 3/-
  - 3085
  - 308 6. —The Mabor Limes.
  - A lime that laughs at moisture, and needs no tin. Once used, always used. Indestructible. Can be carried in the pocket.
  - 3086
  - They are boxed in well-made card boxes, containing six limes, and are made in the two usual sizes, 1 in. diameter and 11 in. diameter.
  - A. Price, 1 in., per box of 6 .. .. .. 2/6
  - B. „ i| in. „ „ ................3/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.431 - vue 450/555
- - 432 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - ACETYLENE GENERATORS AND JETS
  - 3087
  - 3087.—The “ M.S.” Triumph Jet (with fine
  - adjustment valves).
  - A. 2 Burner .. . . .. . . £10 0
  - B. 3 „......................... 15 0
  - C. 4 „......................... 19 0
  - he “ M.A.” Generator. A cheap generator for using ordinary lump carbide that will work steadily without over-make or escape of gas.
  - A great feature of this generator is that the height of gasholder is a sure indication as to how far the carbide is used. It does not rise and fall, but steadily sinks as the charge is used.
  - Note the plugs PP for clearing gas passages.
  - A. 7 in. dia. 18 in. high. 1 lb. charge £2 10 0
  - B. 8 „ „ 19 „ „ ih ,, 3 0 0
  - C. 9 „ »> 20 ,, 21 ” >> 3 10 0
  - 3088
  - 3088.—The “ M.S.” Triumph Jet (with tap
  - to each burner).
  - A. 2 Burner . . £0 18 0
  - B. 4 ........................... 15 0
  - 3090.—T he Square “ M.A.” Generator.
  - A. i-lb. charge, 18 in. high, 7 in.
  - square .. £2 17 6
  - B. i|-lb. charge, 19 in. high, 8 in.
  - square .. £3 5 0
  - C. 2|--lb. charge, 20 in. high, 9 in.
  - square .. £3 15 0
  - 3090
  - 3091
  - 3091.—The “ Klimax ” Acetylene Generator and Jet.
  - Strong and beautifully finished in nickel-plated brass. It consists of a cylinder in two sections clamped together by lock nuts. The upper section is the water cistern and the lower one the carbide chamber. A water valve with engraved scale for regulating supply is fitted at back, and the rubber bag is to serve to regulate the pressure of gas and also as a water trap for any moisture that may be carried over. A reflector is also supplied, and is capable of being adjusted in any direction.
  - The container or carbide chamber can be placed at any distance from the lantern, the lepgth of tubing governing same. The jet is fitted with four burners and reflector and the tray is of cast iron with detachable brass upright.
  - It is delivered complete with generator, 4-burner jet, tray and 3-ft. rubber tubing.
  - It is the simplest generator to use, and will work for two hours with 1 lb. of carbide and with four Ceto burners.
  - A. Price complete with instructions . . . . .. £3 3 0
  - B. Price of generator and bag only . . . . . . 2 7 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.432 - vue 451/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 433
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDE MAKING APPARATUS
  - 3092.—Lantern Slide Making Apparatus.
  - This Instrument has been designed for making lantern slides quickly, accurately and cheaply from book illustrations, diagrams, drawings, negatives, etc. By means of specially graduated scales, the operations are reduced to a simple mechanical process, so simple that one may become quite proficient in a few minutes. The apparatus, briefly described, consists of a—
  - Railway, on one end of which is fixed the book-holder, as shown to the left of illustration; this is made removable to facilitate packing, etc.
  - Book-Holder.—This is in the form of a box, open at the front, and provided at the back with a pair of sliding vertical boards. These boards are connected together so as to move simultaneously and to an equal distance towards or away from the centre. It is provided with a pair of incandescent gas burners, situated one in either of the front corners. The inside is lined with a special white fire-proof material, which at the same time forms a reflector.
  - Camera is so constructed that it can be raised or lowered in a wood frame, the latter being firmly fixed to a carriage which is movable along the railway, and by means of a thumb-screw it is rigidly fixed without any trace of vibration, which is of vital importance.
  - Dark Slide is of the double book form, constructed to carry a quarter plate in one side, and a lantern size plate in the other side. Quarter plate size plates are the most suitable for producing the negatives ; when reproducing from negatives, however, the lantern size enables one to immediately obtain the required transparency.
  - Scales are engraved and separately graduated for each instrument. The largest illustration, etc., permissible is 12 in. square, and the reduction scales are to 2f in. squares.
  - The apparatus is constructed of selected and seasoned mahogany, French polished. The fittings are of lacquered brass, scales are of black wood, engraved and filled in white, the whole forming an apparatus of handsome appearance. The outfit consists of adjustable book-holder, with pair of incandescent gas burners, board for holding diagrams, etc., superior anastigmat lens, 6 in. focus i/yy, and one double book-form dark slide, taking quarter plate and lantern size plates.
  - A. Lantern Slide Making Apparatus, complete as specified above .. .. .. .. .. .. £23 0 0
  - B. Lantern Slide Making Apparatus, as above specification, but fitted for electric light, pair of B.C. holders
  - wired to outside of book-holder, 3 ft. of flexible wire and plug .. .. .. .. .. .. 25 0 0
  - C. Nest of three carriers for holding negatives 8| X in., 6|- X 4f in., and 4J X 3J in., to fit in front
  - opening of book-holder .. .. .. .. .. .. .. .. .. .. .. .. 200
  - 3092
  - INSTRUCTIONS FOR WORKING.
  - Suppose that it is required to photograph a book illustration, and that it measures io in. in the direction of the height of the page, and 8 in. in the direction of the width of the page.
  - The sliding boards should now be set to io in. as indicated by Scale B, and the book placed on the book-holder, as shown in the illustration. The carriage should now be moved along the railway, and clamped with the Index D opposite io on the Scale C (io in. being the longest measurement of the illustration assumed to be photographed). The camera is now at the correct distance to give the required reduction.
  - Now set Index I to io on Scale H, and the camera is then correctly focussed.
  - Next note, by means of Scale A, the numbers opposite the top and bottom edges of illustration, presuming that these are 3 and 11, add these two numbers together, the resultant number being 14, and set the camera by Index G, Scale F to 14. The camera is now central with the illustration.
  - All is now set, and exposure is the next procedure ; this, however, varies according to the light, plate speed, and aperture of lens. Generally half to one minute exposure is found sufficient, but the worker should ascertain the absolute correct exposure for himself, by photographing-an average line picture in section upon one plate. This is done by opening the shutter of slide at J, J, and full opening, and at each position exposing for quarter minute. The plate will now be exposed in four sections, varying from quarter to one minute exposure ; by developing the plate, it will at once show the correct exposure required.
  - Transparencies are printed in the usual way from the negatives so obtained.
  - To prepare transparencies direct from negatives of 8£ x 6£in.,6J x 4J in., and 44 x 3J in. plates, the negatives are held in carriers, which, in turn, fit in the front opening of book-holder, and a white sheet of paper is placed at the back to reflect the light through the negative. The Scales are used as before, except that Index E must be used with Scale C, and Index G set to 12 on Scale F, which is the central position.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.433 - vue 452/555
- - 434 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDE MATERIALS
  - 3093
  - 3093.—Lantern Slide Binding Outfit. A
  - very useful outfit, containing 50 cover glasses, a box each binding strips, assorted masks, numbered spots, and a bottle of white ink. The whole packed in a draw-box with divisions and brass handle, so that it can be used for storing the slides when finished.
  - Price .... .. .. .. .. 7/6
  - 3097.—The Allsize. By the aid of a pocket knife openings of any desired shape and size may easily be cut.
  - Price .. . . . . . . . . . . per box 2/-
  - 3094.—Combination Cover Glass and Spot
  - Binder. Makes the neatest possible lantern slides. Slides may be mounted and finished ready for exhibition at a moment’s notice.
  - Price, per box, 12 covers . . . . .. .. 2/-
  - 3098.—Painting Outfit. Contents—5 tubes of colour, one cloth pad, one brush rack, one tube of medium, one tube of varnish, one metal point, two camel hair brushes, one conte stump, two palettes. With instructions by an expert.
  - Price, complete . . .. . . . . .. .. 4/-
  - 3095. — Ordinary Binding Strips.
  - These strips are made from specially-prepared black paper, which is very flexible 3095
  - when wetted, and being coated with the finest gum obtainable, are readily adhesive. With each box is enclosed full instructions on the best method of binding slides.
  - A. Price, per box, containing 6 dozen strips .. 9d.
  - B. „ „ 200 „ .. 1/6
  - 3096.—Spot Binding Strips. Made in short strips, long enough to bind one edge of a slide. The spots show the top and which side of the slide is to face the condenser, and in the spaces the title can be written.
  - Price per box, sufficient for 100 slides .. .. 2/-
  - Supplied in colours—black, blue, green, red or brown.
  - 3099.—Ink for Lantern Slides,
  - white, for naming lantern slides; useful for ruling and decorating photo mounts .. Price, per bottle 9d.
  - 3100 •—Black, for writing on plain glass ; useful for making notice slides, etc. .. .. Price, per bottle 9d.
  - I, Photographic i
  - W’HITE INK
  - UTOE WHITE lor IU*» WTERN SLIDES,mllrf! •ntMln? Photo Mounts,«•
  - iT-——~
  - 3099
  - 3101.—Lantern Slide Printing Frames, to take any size negative from 3-J x 3J to 1/1 plate. Made in satin walnut, with polished brass springs and screw eye for hanging up .. .. .. 2/6
  - Registered Design, No. 225,080.
  - 3101
  - Our stock of pure Chemicals and Acids is very considerable j hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.434 - vue 453/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 435
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDE ACCESSORIES
  - 3102.—The “ Systematic ” Box for lantern Sl ides. Polished pine, with numbered grooves, and a tablet in lid for keeping a register.
  - To hold 12 slides 5/-50 „ 6/-
  - „ ioo „ 127-
  - SI 03. — Transit Boxes, white wood, blacked outside, rubber padding, brass-bound ends and strap handle, to hold 8o slides.
  - Each .. .. 10/-
  - 310 4. —The “Handy” Box for Lantern Slides, designed so that in use slides can be placed in the top after exhibition and the box closed without disturbing the slides or their order. In blackened white wood, and strong leather carrying handle.
  - To hold 6o slides .. . . . . . . .. 7/-
  - 3104
  - 3105
  - Lantern Slide Carrier.
  - 3105.—Ordinary lightning pattern in mahogany (as illustrated) .. .. • • • • • • • • 3/-
  - 3107
  - Carriers with Automatic Raiser.
  - 3106, —Lightning pattern, mahogany . . .. 3/-
  - 3107. —Lightning pattern, substantially made in
  - stained walnut, very suitable for use with high-class lanterns .. .. . . .. .. .. 4/-
  - 3108
  - 3108.—Brass Carriers, made of polished brass throughout, strongly riveted ; of standard size, suitable for optical lanterns or cinematographs .. .. 21/-
  - 3109.—AphengeSCOpe. An instrument which, when attached to a lantern, will exhibit opaque objects, etc. Made of japanned tinned iron, and fitted with a brass flange to carry the objective. In use, the objective is unscrewed from the lantern body and the aphenge-scope screwed into its place. The objective is then fitted into the second tube of the instrument and the lantern body is turned round so that the objective shall face the screen.
  - Price .. .. .. .. .. . . .. .. . . .. . . .. . . 15/-
  - 3109
  - AN EXTENSIVE RANGE OF M M M M M
  - LANTERN SLIDES
  - ON VARIOUS SCIENTIFIC SUBJECTS
  - WILL BE FOUND AT THE END OF THIS CATALOGUE.
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.435 - vue 454/555
- - 436 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SCHOOL ORRERY
  - 3110.—Improved School Orrery.
  - Latest pattern and designed expressly for use in Elementary and Secondary Schools, etc.6222
  - The Improved Orrery consists of Pedestal,
  - Central Disc, and accompanying mechanism, by means of which motion is produced, together with the following parts which may be readily attached for the purpose of illustrating particular lessons :—
  - Lamp, with glass, reflector and lamp rod ; earth with screw to fit axis ; moon with arm of adjustable length ; moon’s orbit for showing the inclination of orbit to the plane of the ecliptic ; support for plane of ecliptic, plane of ecliptic and floating plane of ecliptic ; suspension wire for floating plane of ecliptic ; four pins with hinged pointers for showing the varying altitude of the sun at noon according to the latitude and the season of the year; tidal wave ; metal framework containing disc of ground glass to illustrate solar eclipses —total, annular and partial; metal protractor.
  - Improved Orrery, packed in strong wooden box, with illustrated handbook, giving full information how to use the apparatus and suggestive helps to teachers.
  - A. Price.................£6 15 0
  - B. Ditto, fitted in case suitable for
  - carrying and storing—
  - £10 5 0
  - For a full description of the various uses of this Orrery see our Physical Apparatus Catalogue, 1913 Edition, pages 909 to 911.
  - Orrery arranged to demonstrate the Moon’s Orbit and the Floating Plane of the Ecliptic.
  - Orrery arranged to show Spring and Neap Tides, etc.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.436 - vue 455/555
- - 437
  - SECTION 12
  - HEAT.
  - EXPANSION OF SOLIDS.
  - 3111.—Ferguson’s Pyrometer, for showing the linear expansion of solids. In this apparatus a metal rod is fixed at one end by means of a screw, while the other end presses against a lever operating the index needle. The rods —copper, brass and iron respectively—are heated by an oblong metal spirit burner. 6232 Price, complete as figured .. .. .. .. .. .. .. .. .. .. .. .. £3 10 0
  - ‘LONDON. -
  - 3112. —Ferguson’s Pyrometer, as No. 3111, but
  - cheaper make. Price, complete with spirit burner and three metal rods 6233 .. .. .. .. 37/6
  - 3113. —Ditto, with gas burner .. .. .. 39/-
  - 3114
  - 3114.—P yrometer, cheap form, mounted on wooden support, with card scale and aluminium pointer, and one each iron, copper, and brass rods. 6235
  - Price, without burner.. ..... .. 16/6
  - Our stock of pure Chemicals and Acids is very considerable j hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.437 - vue 456/555
- - 438 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - EXPANSION
  - 3115
  - 3115.—Bar and Gauge, to show expansion of a metal bar along its length and diameter 6236 .. 4/9
  - 3116. — Grave-sande’s Ball and Ring, for
  - showing the cubical expansion of solids, consisting of a brass ball 1 in. in dia., attached to a ring by a chain. The ball will pass through the ring at the ordinary temperature, but on being heated it expands, and cannot be passed through the ring. 6237 Price, complete .. .. .. .. .. .. 4/9
  - 3116
  - OF SOLIDS
  - 3121.—Compound Bar of Iron and Brass, with
  - divided scale and index pointer, to show unequal expansion when placed in a vessel containing warm or cold water. 6243
  - Price................27/6
  - 3117.—Gravesande’s Ball and Ring, for showing the cubical expansion of solids. As will be seen by the illustration, this apparatus consists of a brass ball passing freely through a metal ring. Both ball and ring are adjustable. On ball being heated it expands, and cannot be passed through the ring. 6238 Price, including strong iron support
  - 10/6
  - 3118 .—Ditto, large size, “ University " pattern on mahogany base, and fitted with a 2J in. brass ball. 6239
  - 3122. — Bar Breaking Apparatus,
  - for showing the enormous force called into playl( when the contrac-jf tion of a rod is resisted by mechanical means.
  - The thick iron bar is provided with a hole at one end, through which the bar to be broken is passed. The large nut at the other end is for tightening up the small bar against the knife edges. The thick bar should be first heated in a fire, or over a gas burner, and then placed in the iron cradle, and tightly screwed up. 6244 Price, complete, with twelve small bars to be broken 12/-
  - 3122
  - 3117
  - Price, complete . . .. 18/-
  - 3119
  - 3119.—Compound Bar of Brass and Iron,
  - 14 in. x 11 in., to show the curvature resulting from unequal expansion 6240 . . .. .. each 2/9
  - 3120 .—Ditto, but consisting of a copper and iron bar. Length 12 in., width 2\ in. 6241 .. .. each 7/6
  - 3123
  - 3123.—Bar Breaking Apparatus, as No. 3122,
  - but of improved pattern, with gas burner arrangement for heating the iron rod. (With this apparatus bars may be broken either by contraction or expansion of the rod.) 6245
  - Price, including twelve bars to be broken .. 21 /-
  - 3124
  - 3124.—Compound Bar of Brass and
  - Iron, superior quality, 15 in. X 1^ in., mounted in handle. 6242
  - Price .. .. .. .. .. .. 10/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.438 - vue 457/555
- - F. E. BECKER & CO., IMIVGC HOUSE, HATTON WALL, LONDON, E.C.1. 439
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - EXPANSION OF SOLIDS
  - 3125
  - 3125.—Brequet’s Metallic Thermometer.
  - This sensitive instrument consists of strips of gold, platinum and silver rolled into a thin ribbon, and afterwards made in the form of a spiral, one end of which is fixed to the top of the bent support and the other end to a needle moving round a scale empirically graduated in Centigrade degrees by comparing its readings with those of a standard mercury thermometer. Brequet’s thermometer depends on the -unequal expansion of metals, and is fully described in “ Ganot’s Physics ” and other well-known textbooks. 6246
  - Price, for best make .. .. .. .. £5 5 0
  - 3126. — Pullinger’s Apparatus for determining the Coefficient of Expansion of a Metal Tube. 6247
  - This apparatus, which is about 1 metre in height, consists of a metal tube A B, having three lateral openings, two of which serve for the inlet and outlet of steam or water, and a thermometer is fixed to the third by means of a short piece of india-rubber tubing.
  - The metal tube is supported in a wooden framework at the top of which is placed a glass plate C D, upon which rests a spherometer. The top of the tube passes through a hole in the glass plate, and the lower end of the tube is supported on a steel spike projecting from the wooden base.
  - Further details of this useful instrument are given in Robson’s " Practical Exercises in Heat,” and other textbooks.
  - A. Price, not including spherometer and thermometer—•
  - 38/6
  - B. Price, complete with spherometer, but without ther-
  - mometer.. .. .. .. .. .. 46/6
  - C. Extra Tubes : Brass, Copper, Iron, Aluminium, Zinc—
  - extra, each 8/6
  - D. Thermometer, o° C. to no° C. in -J degrees each 3/-
  - 3127.—Pullinger’s Apparatus, as No. 3126, but provided with solid metal rod surrounded by brass steam jacket having inlet and outlet tubes for steam, and tube for thermometer. 6248
  - A. Price, not including spherometer and thermometer .. .. .. .. .. ..47/6
  - B. Price, complete, with spherometer, but without thermometer .. . . .. .. 55/6
  - C. Extra Rods : Brass, Copper, Iron, Aluminium, and Zinc .. . . .. extra, each 8/6
  - D. Thermometer, o° C. to no0 C. in | degrees .. .. .. . . .. .. ,, 3/-
  - 3128.—Fry’s Apparatus for determining the Coefficient of Linear Expansion of Solids. 6249
  - A rod of material 50 cm. long, 3 mm. diameter, with hemispherical ends, is mounted in the centre of a horizontal brass steam jacket covered with nonconducting material. The jacket is supported on a cast-iron base 60 cm. long by 12 cm. wide, and has a tube for a thermometer soldered into it near its centre. One end of the rod presses against a glass disc which is fastened to an adjusting screw, which goes through a pillar rigidly fixed to the base.
  - The other end of the rod presses against a small glass rod attached to a metal diaphragm, the diaphragm forming the face of a metal box which is filled with mercury. The mercury is in connection with a graduated glass capillary tube 15 cm. long and about 1 mm. diameter. When steam is passed through the jacket, the rod expands and presses in the diaphragm of the mercury box, forcing the mercury up the capillary tube. The Coefficient of Expansion can then be determined from the amount of mercury displaced.
  - Price, complete with interchangeable rods of Copper, Iron, and Glass .. .. .. .. •• .. £3 10 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.439 - vue 458/555
- - 440 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS. '
  - EXPANSION OF SOLIDS
  - 3129.—Gunther's Improved Apparatus for Determining the Coefficient of Linear Expansion of IVIetals. 6250
  - (Provisionally Protected.)
  - This apparatus possesses the following advantages
  - Each instrument is fitted with two rods of different metals enclosed in the same jacket. The jacket containing the rods can be rotated on its supports, thus enabling the expansion of these metals to be accurately measured in the course of one and the same experiment. This measurement is effected by means of an ordinary spherometer, but this spherometer is mounted and used in an entirely novel manner. There is no polished and slippery platform on which the spherometer rests, and from which it is only too liable to slip. In place of such there is a specially-designed clamp which holds the spherometer rigidly in position, but from which it can be easily removed if desired. The point of contact of the spherometer with the rods is determined in a manner exactly analogous to that used in setting a Fortin’s barometer.
  - The end of each rod is ground perfectly plane, and brightly silvered, thus the moment of contact can be very sharply defined?. Brass terminals are also provided, by means of which contact can be determined electrically, and, with the help of a suitable galvanometer, rendered visible to a whole class.
  - Results obtained—Brass, -0000188 to -0000189 ; iron, -0000127 to -0000128.
  - A. Price, with thermometer and spherometer complete . . .. . . .. .. .. . . ..£330
  - B. Ditto, but without spherometer .. .. .. .. . . .. .. .. .. .. .. 2 15 0
  - 3130
  - 3130. — Harrison's Compensated Pendulum. This instrument is sometimes called the gridiron pendulum and its elongation, when the temperature rises, is so compensated that the distance between the centre of suspension and the centre of oscillation remains constant. 6252
  - Price, for best quality—
  - £2 10 0
  - 3131.—Money’s Apparatus for determining the Coefficient of Linear Expansion of Solids by Direct Reading.
  - This apparatus consists essentially of a micrometer screw gauge, in which the screw and stop are about 1 metre apart, fixed on a perfectly flat enamelled slate base. The metals to be experimented with are in the form of tubes closed at ends, but with suitable inlet and outlet tubes, through which feteam may be passed.
  - (1) The measurement of the alteration of lengths is made on contracting, thus needing only two readings in which the screw is moving forward and-avoid-ing possible errors due to backlash.
  - (2) The determinations are made very quickly.
  - (3) Very accurate results may be obtained. 6251
  - Price, packed in wooden case, including three tubes of different metals—•
  - ________________________£4 17 6
  - 3132.—Trevelyan's Rocking Bar, with lead block.6253
  - A. Superior quality .. each 17/6
  - B. Ditto, cheaper make and smaller— each 12/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.440 - vue 459/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 441
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - EXPANSION OF SOLIDS
  - 3133.—Glazebrook’s Apparatus for Determining the Coefficient of Linear Expansion Of Solids. In this form of apparatus a stout wire about a metre long is firmly fixed near the top of the wooden upright. A long horizontal lever is attached to the other end of the wire. The special arrangement which supports the lever is so constructed that when the wire expands the reading on the scale is one hundred times that of the part near the fulcrum. The wire passes through a glass or brass jacket having two lateral openings for the inlet and outlet of steam. For further details see Glazebrook’s Elementary Text-Book—“ Heat.” 6254
  - Price, complete, as figured
  - £2 2 6
  - 3133
  - 3134
  - 3134.—Rupert’s Drops. These are small glass pear-shaped globules which have been allowed to cool suddenly. On breaking off the thin tail the whole globule breaks up into a powderish mass. 6255
  - Price .. .. .. .. per dozen 1 /9
  - 3135
  - 3135.—Bologna Phials. These are small
  - thick-walled glass bottles which have been allowed to cool quickly. Drop one or two sharp-edged pieces of flint inside and then shake them about when the bottom of the bottle will fall out. 6256
  - Price.
  - Each .. .. .. .. .. .. 5d.
  - Per dozen .............4/6
  - CONDUCTION AND CONVECTION
  - 3136
  - 3136.—Apparatus for Showing the Different Conducting Powers of Solids, consisting of four bars—copper, iron, zinc and brass—fitted to a wooden ring so that all the bars meet at the centre. At the end of each bar is an excavation into which phosphorus is to be placed. 6267 Price, complete, with support and spirit lamp, as figured............ ..............£12 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.441 - vue 460/555
- - 442 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CONDUCTION OF METALS, Etc.
  - M3137.—A pparatus for Showing the Different Conducting Powers of Solids, consisting of four bars of different metals fixed on a ring, with cups for wax, phos-
  - 3137 Each .. . . . . . . 6/-
  - 3138.—Science Lantern Apparatus for
  - showing that decrease of temperature depends upon the distance from the source of heat. This apparatus consists of a metal bar to which is screwed two spring clips carrying a glass scale and three accurate thermometers. 6260
  - Price, complete, on stand with spirit lamp £2 2 0
  - 3139.—Compound Cyl-inder of Brass and Wood, for showing their different conducting powers.6261
  - Each..
  - .. 2/6
  - 3140.— Iron and Copper Bar of same length and thickness, riveted together to show the difference in their conducting power. This compound bar is about 14 in. in length and is provided with an excavation at each end for wax, phosphorus, etc. 6262 Price .........................................3/6
  - 3141
  - 3141.—Iron and Copper Wire of same length and thickness, bound together, to show the difference in their conducting power 6263 .. .. .. .. .. 1/6
  - 3142
  - 3142. —Copper Wires, 12 in. long x I in. diam. 6264
  - per doz. 3/-
  - 3143. —Iron Wires, 2 in. x £ in. 6265 „ 2/-
  - 3144.—Set of Six Rods, for
  - conductivity experiments. Copper, Glass, Wood, Iron, Bone, and Brass, 12 in. long, | in. diameter. 6266
  - Per set
  - 2/-
  - 3^44
  - 3145.—Set of Six Metal Cylinders for showing conduction of metals.
  - Each cylinder measures i£ in. x \ in., and the following are supplied to the set : Iron, Copper, Brass, Aluminium,
  - Lead and Zinc. 6267
  - Per set.........................5/-
  - (See Tyndall’s “Heat.”) 3*45
  - 31 46.—Bismuth Cylinders, ijin. x 1 in.6268
  - (Price varies) each 6/-
  - 3147.—Tin Cylinders, ditto 6269 „ 1/6
  - 3148.— I ngenhousz’s Apparatus, consisting of zinc vessel with six openings, each fitted with bars of different substances. 6270
  - Each............8/6
  - 3148
  - 3149.—I ngenhousz’s Apparatus, Lecture pattern, with screen to protect rods from heat of flame, mounted on strong metal stand. 6271
  - Price, complete as figured 25/-
  - 3149
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.442 - vue 461/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 443
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - THERMAL CONDUCTIVITY
  - 3150.—Searle’s Apparatus for the Absolute Measurement of the Thermal Conductivity
  - Of Copper. This apparatus, which is fully described in Philosophical Magazine (January, 1905), consists of a stout rod of copper about 12 in. in length, surrounded by a copper steam jacket, having an inlet at one end for steam, and a spiral tube at the other, through which a stream of water is kept flowing, in order to keep that end of the rod cool. The apparatus is fitted in a felt-lined box with removable front, as figured. 6276
  - A. Price, complete, with four thermometers, two of which are accurately graduated in fifth degrees and two in
  - half degrees .. .. .. .. . . .. . . .. . . . . . . .. . . £7 5 0
  - B. Ditto, but without thermometers .. .. .. .. .. .. .. .. .. .. .. 676
  - 3151.—Glazebrook’s Apparatus for Comparison of Thermal Conductivities. This apparatus consists of two long bars of copper and iron, each about 40 in. in length and provided with excavations at distances of 4 in. apart, each excavation being just large enough to contain the bulb of a thermometer. One end of each bar is fixed inside an iron vessel which holds the melted lead. For full details see Glazebrook’s Elementary Text-Book “ Heat.” 6273
  - A. Price, complete as figured . . £5 10 0
  - B. Ditto, without Bunsen burner, clamps and
  - delicate thermometers .. £3 15 0
  - 3152.—Forbes’ Apparatus for Comparison of Thermal Conductivities. This apparatus consists of an iron bar about a metre in length and having excavations at distances of 2\ cm. apart, each excavation being just large enough to contain the bulb of a narrow thermometer. One end of the bar is bent so that it can be dipped in the iron crucible containing melted lead or solder. A screen serves for protecting rod from heat of Bunsen flame. We also supply with each apparatus a short length of bar (having one excavation) for determining the cooling curve. 6274
  - Price, complete with tripod, but without thermometers and Bunsen burner .. .. .. .. .. £2100
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.443 - vue 462/555
- - 444 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - EXPERIMENTS IN CONDUCTIVITY
  - 3153.—Lees* and Chorlton’s Apparatus for Determining the Relative Conductivities of Thin Layers of Materials. 6281
  - This apparatus is fully described in Philosophical Magazine (June, 1896), and in Robson’s " Practical Exercises in Heat,’
  - published by Macmillan & Co., Ltd. It consists of a flat cylindrical box 11-5 cm. diameter, and 5 cm. deep, through which steam can be passed. The bottom of the box is formed of a circular brass plate 12 mm. thick in which a radial hole is bored to the centre. This vessel is supported on a circular plate of the material under test, which in turn is supported on a brass disc of exactly the same dimensions as the base of the steam box. The lower disc is suspended by three strings from the ring of a retort stand. A screened thermometer, placed horizontally under the apparatus, registers the temperature of the air ascending to the disc. The two surfaces of the discs in contact with the substance are electro-plated, while the under surface of the circular brass plate is highly polished so that the heat radiated may be constant. In most cases of powders and liquids, the thickness of the layer of material may be made constant by placing on the lower plate three discs made from a microscope slide, and squeezing out any superfluous substance with the upper plate. If the liquid is very mobile it is enclosed in a thin ebonite ring placed on the lower plate. Having placed a
  - 3153
  - layer of material between the upper and lower plates, suspend the apparatus as shown and pass steam through the inlet. Heat flows through the material to the lower brass plate, and when the steady stage is reached the loss of heat from the lower plate is equal to the heat received from the material under test. Read the thermometers in the upper and lower plates and note the temperature of the air. Price, not including thermometers £2 10 0
  - s
  - 3154.—Edser’s Apparatus for Determining the Relative Thermal Conductivities of Metal Rods. 6283
  - This apparatus consists of a brass vessel, closed at the bottom, to which rods of different metals are firmly soldered. The left-hand rod is of copper, the middle one of brass, and the right-hand one of steel, and each is furnished with a metal index. The brass vessel is inverted as shown in the illustration, an index is slipped on each rod, the single ring being left in contact with the bottom of vessel, and a very small amount of paraffln wax is melted round the rings. When the vessel is supported with the rods downwards the solid wax holds the indexes in position. Customers will find fuller details in Edser’s “ Heat for Advanced Students,” published by Macmillan & Co., Ltd.
  - Price, complete as figured .. .. .. .. .. 8/6
  - SENSITIVE
  - PAPER
  - Special Qualify
  - for
  - LECTURES
  - ON
  - HEAT
  - U tfantJ in a dsmppbce)
  - Becker, london 4 Birmingham
  - amieson’s Sensitive Experiments in Radiation, etc.,
  - 3155.—A pparatus for Illustrating the Low Thermal Conductivity of Water. 6287
  - This consists of an air thermometer which is to be surrounded by water, as explained in Glazebrook’s Elementary Text-Book—•“ Heat.”
  - Place a small quantity of methylated spirits in the porcelain capsule and ignite it ; the upper layers of water are heated, but it is some time before any effect is observed on the thermometer, and when a rise of temperature is noticed, it will be found to be very slight indeed. In consequence of the low conductivity of the water, the heat reaches the thermometer very slowly. On mixing the water in a bell jar with a stirring rod, a considerable rise of temperature is observed, showing that the temperature of the upper layers can be raised by the heat applied without much affecting those below. If the water be replaced by mercury and the experiment repeated, the rise of temperature will be much more rapid.
  - Price, complete .. .. .. .. .. 12/6
  - 3156.
  - Paper for Conduction,
  - etc.6282 ___________
  - For full details, see “ Heat Shadows,” by Walter Jamieson, Esq., B.Sc., A.M.I.E.E., and published by Messrs. Blackie & Sons (price 6d.) ; also several interesting experiments are described in “ A Second Year’s Course in Practical Physics,” by James Sinclair, Esq., M.A., B.Sc., published by Messrs. George Bell & Sons (price 1/6).
  - A. Jamieson’s Sensitive Paper, 7 in. x 5£ in.
  - per doz. sheets 3/6
  - B. „ „ ,, 11 in. x 3! in.
  - per doz. sheets 3/6
  - C. Set of three wires—copper, iron and brass,
  - for conductivity experiments per set 9d.
  - D. Radiating Screen .. .. each 3/6
  - E. Metallic Powder .. per bottle 1/-
  - F. Dead Black Paint .. „ 1/-
- p.444 - vue 463/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 445
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CONVECTION OF HEAT, Etc.
  - 3157.—Apparatus to Demonstrate the Feeble Conductivity Of Water, as described in Ganot’s “ Physics.” This apparatus consists of a strong white glass cylinder at the bottom of which is placed a delicate thermoscope, and over the top is placed a japanned tin vessel for holding the oil, which must have a temperature of two or three hundred degrees. Glass cylinder is filled with water at the ordinary temperature. 6293 Price, complete, as figured .... 10/6
  - 3i59
  - 3159.—G lazebrook’s Apparatus to show Convection in Air, consisting of a lamp chimney, glass basin and thin metal dividing screen, as mentioned in Glazebrook’s Elementary Text-Book—“ Heat.” 6285
  - Price, complete .. .. .. .. 2/6
  - 3160. — Ventilation
  - Apparatus, for
  - demonstrating that both by law and circumstance it is necessary to produce sufficient ventilation in a mine in order to supply fresh air for breathing and also to prevent accumulation of fire-damp.
  - This apparatus consists of a wooden box, having two openings on top over which glass cylinders are placed 3160 and a glass front to show
  - candle burning. A piece of smouldering brown paper held over the top of the cylinders will show that there is a steady current of air down the right-hand cylinder, through the box, and up the other cylinder. 6286 Price, complete with candle-holder .. .. .. .. 8/6 |
  - 3163.—Hot Water Circulation Model. This apparatus illustrates the circulation of water in a house. Below, on the right-hand side, is a boiler, from this the hot water circulates through the house and into the various rooms, having its exit eventually in the cold water cistern at the top. From this cistern the boiler is filled with cold water to replace the cold water entering by pipe at the bottom of the boiler. In the top of the boiler is placed a second pipe, the opening of which is some inches below the surface of the water. If the pressure on the boiler should become too high, the steam accumulating forces the water up through this vent pipe into the cistern above, thus being relieved of excessive pressure. The various sinks, baths, etc., with their accompanying taps are not shown, but we can provide these if desired, at a slight extra cost. To show a class the actual circulation of the heated water, parts of the pipes are in glass at different stages, and a little sawdust put in the water makes the circulation very evident; a model of this kind is of the greatest service to those engaged in teaching, as the explanation of the heating system at once becomes self-evident. The dimensions are approximately as follows :—20 in. x 30 in. 6290 Price................................................£5 10 0
  - 3158.—Apparatus to Illustrate the Convection of Heat, consisting of bell jar, flask, corks, straight and bent tubes as described in Glazebrook’s Elementary Text-Book—” Heat.” 6288
  - Price, complete as figured .. 6/6
  - 315a
  - 3162
  - 3162.—Right-Angled Bent Glass Tube, to show the Circulation of Water. 6289
  - A. Small size .. .. .. .. each 3/6
  - B. Large size . . *. . .. .. ,, 5/6
  - 3163
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.445 - vue 464/555
- - 446 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - EXPANSION OF LIQUIDS
  - 3164.—Empty Thermometer Tubes, size of bulb, i-5 cm., length of stem, 29 cm. .. per doz. 4/-
  - 3165 .—Ditto, medium, size of bulb, 3-5 cm., length of stem, 45 cm. .. per doz. 5/-
  - 1
  - 3167.—Empty Thermometer Tu bes,
  - enamelled back, with funnel end for filling, size of bulb 1-5 cm., length of stem (including funnel) 33 cm.
  - 3168.—U n g r a d u-ated Thermometers, filled with mercury .. each 1 /6
  - 3169 —Ditto, filled with
  - 3166 .—Ditto, large, size of bulb, 5-5 cm., length of stem, 70 cm., each, 8d. ; per doz. 6/6
  - Each .. Per dozen
  - 6d.
  - 57-
  - spirit
  - each
  - 3170.—Rintoul’s Tube and
  - Flask, for experiments on the expansion of liquids, consisting of a graduated thermometer tube 30 cm. long and 1 mm. bore, fitted by means of a piece of india-rubber tubing into a small glass flask having a volume of about 3 c.c.
  - Price, complete, as figured—
  - Each .. . • • • • • 2/6
  - Per dozen ................27/-
  - For details regarding the experiments that can be carried out with this apparatus, see Rintoul’s “ Introduction to Practical Physics,” published by Macmillan & Co., Ltd.
  - 3173.—IVIodel Thermometer
  - to illustrate the expansion of liquids by heat, consisting of a 40 oz. flask fitted with tube and scale.
  - Price, complete ..
  - each 5/-
  - 3171.—M o d e I T h ermometer,
  - to illustrate the expansion of liquids by heat, 40 oz. flask, with tube and scale.
  - Each .. .. 5/6
  - 3172.—W eight Thermometers,
  - globular pattern, for finding the co-efficient of dilation of a liquid relative to glass.
  - Each .. .. 3d.
  - Per dozen ... 2/9
  - 3174.—Weight Thermometers, cylindrical pattern, for finding the co-efficient of dilation of a liquid relative to glass.
  - Each .. .. .. 5d.
  - Per dozen .. .. 4/9
  - (Price does not include support.)
  - 3175.—Weight Thermometers, for
  - finding the co-efficient of dilation of a liquid relative to glass. These are similar to No. 3174, except that the stem is bent twice at right angles. Many scientists prefer this pattern. For further details, see “ Elementary Lessons in Heat, Light and Sound,” by D. E. Jones, B.Sc. (Lond.).
  - Each .................................6d.
  - Per dozen .. .. .. .. .. .. 5/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.446 - vue 465/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 447
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - EXPANSION OF LIQUIDS
  - 3176.—Weight Thermometers, made of transparent fused silica, for finding the coefficient of dilation of a liquid relative to glass .. .. . . .. .. . . .. each 3/-
  - Extractfrom “ School World,” October, 1908.—“ The use of fused silica for making weight-thermometers offers many advantages. The co-efficient of expansion of this material is so low that the correction for it becomes of very slight importance. Also the fact that it is unaffected by even the most sudden changes of temperature, makes it possible to fill the thermometer with any liquid in a small fraction of the time required to fill a glass thermometer. I had some made about a year ago, and although they have been several times in use there has been no case of breakage. It is necessary, of course, to use the transparent variety of the material.’'
  - Brighton College. W. Bennett.
  - 3177.—Dilatometer, with open top and having a fine mark etched round the neck to indicate the position of the liquid in the bottle. The amount of the expansion of the liquid is determined by taking out the excess with a small pipette and running it into a weighed crucible.
  - Each, 9d.; Per dozen, 8/-
  - 3179.—Pyknometer, for
  - Determining the Expansion of a Liquid.
  - This consists of a cylindrical glass bulb, having two horizontal tubes of fine bore. A mark is made round the centre of the right-hand horizontal tube, and the liquid is drawn in as far as this mark by means of a piece of india-rubber tube. On heating the Pyknometer, the liquid will flow out in both directions, and it is again adjusted to the mark.
  - A. 5 c.c...........each 1/6; per dozen 17/-
  - B. 10 „ .. .. „ 1/6; „ 17/-
  - 3181.—Weight Thermometer, for Determining the Cubical Expansion of a Solid.
  - Fully described in Edser’s book “ Heat for Advanced Students.”
  - This thermometer is filled by placing the end of the drawn-out tube below the surface of some clean mercury, and driving out some of the contained air by heating; mercury subsequently enters as the instrument is allowed to cool. This process is repeated till all the air is expelled, when the mercury is boiled for a short interval in order to remove the gases condensed on the inside surface of the glass. If a solid body be enclosed in a glass vessel of which the co-efficient of expansion has been determined, and if some liquid, such as mercury, of which the absolute expansion is known, be introduced so as to fill the space not occupied by the solid, the expansion of the latter may be easily determined by finding the apparent expansion of the mercury. Price .. each 2/9
  - 3178.—Weighted Glass Bulb, for
  - determining the expansion of a liquid.
  - This bulb is weighted with shot so that it will just sink in cold water. It is provided with a hook so that it can be suspended by means of a horse hair from the beam of a balance, and weighed. A small specific gravity stool is placed across one of the balance pans, and on this a beaker of hot water is supported, so that bulb is entirely immersed when the beam is swinging.
  - 3178
  - Each........................................1/2
  - Per dozen .. .. .. .. . . .. 12/6
  - 3180.—Dilatometer, for Determin ing the Expansion of a Liquid.
  - Improved form, as described in Profs. Poynting and Thomson’s " Text-Book of Practical Physics.” This consists of a bulb with a fine graduated stem and open at the top. Below, the bulb is connected with a fine bore tube over which is sprung a screw stopper, which on being screwed up causes a pad to effectually close the opening. This dilatometer is very readily cleaned and filled.
  - Price .. .. .. .. .. each 5/-
  - 3182.—Hope’s Apparatus, to show the Temperature of Water at its Maximum Den-sity, consisting of a tall metal cylinder 12 in. x 4 in., having a circular trough round its centre in which the freezing mixture is placed.
  - A. Price, without thermometers .. .. .. 8/-
  - B. Price, including two special narrow-stemmed
  - thermometers of low range and graduated in
  - £ degrees ..............................13/6
  - (See also No. 3190, page 449.)
- p.447 - vue 466/555
- - 448 F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - EXPANSION OF LIQUIDS
  - 3183
  - 3183.— Apparatus for showing the Difference in the Expansibility of VariousLiquids,
  - consisting of 5 glass tubes, with bulbs of equal capacity, mounted on a support, with scales and trough to hold hot water. 6332
  - 3184.—Weinhold’s Apparatus for Determining the Co-efficient of the Absolute Expansion of Liquids.6335
  - Price, complete as figured—•
  - £1 12 6
  - Price complete .. 27/-
  - 3185.—Apparatus for Determining the True Co-efficient of Dilation of a Liquid. 6334
  - This apparatus consists of a bent tube, with its vertical limbs surrounded by steam jackets. Insert a plug of cotton wool in the horizontal tube and fill the two limbs with the liquid to be experimented upon—say turpentine ; the plug checks currents which may be set up in the tube. Fill the right-hand jacket with cold water, or better, pack it with small pieces of ice. The temperature of the liquid in the limb will then be zero. Pass steam through the jacket surrounding the other limb, allowing it to enter gradually ^ (so as to avoid cracking the glass) at the upper end of the jacket. The temperature of this tube rises to ioo°. When the whole has become steady it will be found that the liquid in the left-hand limb stands at a con-3i85 siderably greater height than that in the
  - right-hand limb. Further details will be found in Glazebrook’s Elementary Text-Book—“ Heat.”
  - A. Price, not including metal stand and clamps .. 12/6
  - B. Ditto, but with thermometers fitted in the upper corks 15/6
  - C. Price of the apparatus complete, with stand and clamps
  - as figured .. .. .. . . . . .. 21 /-
  - D. Ditto, but with thermometers fitted in the upper corks 24/-
  - 3x86
  - 3186.—Regnault’s Apparatus for the Determination of the Absolute Expansion of a Liquid.6338
  - This apparatus consists of two vertical tubes fitted in steam jackets having inlet and outlet tubes as figured. Steam is passed through the left-hand jacket and cold water through the right-hand jacket. Thermometers are attached to each of the tubes. The horizontal tube connecting the two vertical tubes is provided with a small opening on its upper side. The two short vertical tubes in the centre of the apparatus are fitted with a glass stopcock in order that air can be forced into the apparatus by means of a small hand-pump. These short tubes are about 10 in. in height and are accurately graduated in millimetre divisions.
  - Pour the given liquid down the long vertical tubes, and by opening the glass stopcock and blowing in air, arrange the liquid so that it just rises slightly above the level of the horizontal tube at the top of the apparatus, and in the two short vertical tubes to one-half their heights. The horizontal tube and the two short vertical tubes are kept at the same temperature as the water in the right-hand jacket by means of cotton wick connected to the inside of the latter. Close the stopcock, start the supply of steam and water through the apparatus until the temperatures registered on the thermometers are quite steady. The hot column will expand, and any excess liquid flows out of the opening on the upper side of the horizontal tube. For details as to experiments, see Robson’s “Practical Exercises in Heat” (Macmillan & Co., Ltd.).
  - Price, complete........................................................................£2 17 6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.448 - vue 467/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON,. E.C.1. 449
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - DENSITY OF WATER, Etc.
  - 3187-3189
  - 3187.—Apparatus for the Determination of the Freezing Point, consisting of a tin vessel, with perforated conical bottom, mounted on three iron feet 6322 .. each 5/6
  - 3188 .—Ditto, larger size, and ice container made of zinc 6323—
  - each 7/6
  - 3189 .—Ditto, superior make and
  - finish, made of stout copper, and provided with cross-piece at top for holding stem of thermometer 6324 .. .. each 12/-
  - 3190
  - 3190.—Hope’s A p-paratus to show the Temperature of Water at its Maximum Density, consisting of a tall white glass cylinder having two apertures for the thermometers, and fitted with a brass ice trough round its centre. 6325 -
  - Price, including two accurately-graduated thermometers of low range, and divided in degrees—
  - £1 18 6
  - (See also No. 3182, page
  - 447-)
  - 3192
  - 3191.—Glazebrook’s Apparatus to show that Water has a Maximum Density at about 4° C., consisting of lead spiral turned up so as to be vertical when resting on table. Open end is fitted with rubber cork through which passes a long glass tube of about 1 mm. bore 6327 .. .. 4/-
  - 3192 .—Ditto, but with boxwood scale attached to glass tube 6328 ................. 5/-
  - (See Glazebrook’s Elementary Text-Book—
  - “ Heat.”)
  - 3193.—Science Lantern Apparatus, consisting of two glass vessels, thermometer, and metal worm condenser, to explain the phenomena of water when freezing ; when ice is melting; and to show the condition of water when boiling. 6326
  - Price, complete .. . . • • • • • • £1 19 6
  - 3194.—M a x i mum Density of Water Apparatus for use with Projection Lantern. On a glass strip divided into degrees are fixed a thermometer and a glass tube, the bulb of the thermometer and the end of the tube dipping equally into a glass vessel, which is provided with a tubulure closed with a cork through which passes a glass rod. 6329
  - Experiment.—Fill the vessel a with water and close the tubulure with cork d, the excess of water escapes up the tube ; now place the apparatus in a vessel of water and lower the , temperature until the thermometer registers + 40 C.', the water in the tube is then lowered by drawing out the rod in the cork until it is level with the mercury in the thermometer. By the unequal expansion of the water and glass at the same temperature an error will arise, which can be diminished by placing a drop of mercury in the bottom of the vessel. By further cooling of the vessel a, the water in the tube will rise. In order to make the experiment more interesting, the apparatus, after adjusting the height of the column of water, can be placed in a warmer fluid, and this again cooled by the introduction of ice to o° C. Price, complete.......................£12 6
  - 3195.—Cold Water Float, a hollow brass ball which floats in cold water and sinks in hot 6330 .. 10/6
  - 3196.—Ditto, made of glass 6331 .. .. .. 5/-
  - Oup stock of pure Chemicals and Acids is very considerable , hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
  - FF
- p.449 - vue 468/555
- - 450 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PROPERTIES OF VAPOURS
  - 3197.—Apparatus for Determining the True Coefficient of Dilation of a Liquid.
  - 3197
  - This apparatus consists of a continuous glass tube having its left and right limbs surrounded by steam jackets as figured. Both jackets are fitted with inlet and outlet tubes passing through india-rubber corks. An accurately-divided millimetre scale engraved on a piece of mirror glass is fixed behind the two upright tubes. The whole apparatus is suitably mounted. It is fully described in Edser’s “ Heat for Advanced Students.” 6337
  - Price, complete .. .. £1 19 6
  - 3198.—Apparatus for
  - Experiments on Vapour Pressure, consisting of an accurately graduated tube having two stopcocks and a glass funnel at the top. When the upper stopcock is open, the short piece of tubing between the two stopcocks may be filled with water, or any other liquid which is to be examined. Further details will be found in Glazebrook’s Elementary Text-Book “Heat.” 6341 Price 9/-
  - 3199.—Ditto, but fitted with a glass steam jacket and two rubber corks, so that temperature of vapour can be varied, and the laws of the variation of its pressure with temperature measured. 6342 Price .. 12/6
  - 3198
  - 3200
  - 3200.—Weinhold’s Ether Apparatus, for Measuring the Elasticity of Steam in a Space filled with Air.
  - This apparatus consists of a cylindrical glass tube having two stopcocks and a tube at the side about 20 in. long. The upper stopcock is only drilled halfway, and on being turned carries with it a small quantity of the ether in the funnel above it. Before introducing the ether see that the air in the apparatus is at atmospheric pressure.
  - The side tube is partially filled with mercury, which rises as the pressure increases until saturation point is reached.6339
  - Price, not including mercury .. .. .. 15/-
  - 3201
  - 3201.—Apparatus as No. 3200, but for use with Water Vapour.
  - This apparatus consists of two narrow glass tubes, one of which is closed and surrounded by a steam jacket. The wide tube is filled with air and water. Cord can be tied to the hook ends and passed over a pulley for raising and lowering. The tube on the left answers the purpose of a manometer. 6340
  - . Price, including 3 ft. of thick-walled pressure tubing .. .. ..16/6
  - 3202.—Apparatus for Measuring the Pressure of saturated
  - Water Vapour at different temperatures (below 100°
  - Centigrade).
  - This apparatus consists of an inner barometer tube, which is to be filled with mercury and afterwards immersed in the trough containing mercury. An outer glass steam jacket is connected up to a water tank so that water at different temperatures may be passed in. This jacket rests on a wooden ledge at its lower end, while the upper end is fastened near the top of the board in such a way that it can easily be taken out. A thermometer attached to the barometer tube registers the temperature of the enclosure. Pass a few drops of water into the barometer by means of a curved pipette, being careful to prevent air passing up with the water. Note the height of the mercury above the level of the mercury in the trough by means of a metre scale. Read the barometer and also the temperature of the room.
  - Gradually heat the water in the boiler and when its temperature is about 250 C. allow the water to run through the steam jacket.
  - Note simultaneously the temperature of the water in steam jacket and the height of the mercury column in barometer tube. Repeat these observations when the temperature of the enclosure is 350, 45°-ioo° C.6346
  - Price, complete, with thermometer, mercury reservoir, etc., as
  - figured ............................... .. 27/6
  - (See Robson’s “ Practical Exercises in Heat.”)
  - 3202
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.450 - vue 469/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 451
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PROPERTIES OF VAPOUR
  - 3203.—Apparatus to show that the Pressure of Water Vapour when Boiling is equal to the Atmospheric Pressure.6345
  - This apparatus consists of a thick-walled barometer tube surrounded by a wide glass steam jacket fitted with corks and inlet and outlet tubes for steam.
  - Fill barometer tube with mercury, as described in Glazebrook’s Elementary Text-Book, “ Heat.” Introduce some water above the mercury, and then fit tube in steam jacket. Admit steam gradually into the jacket. As the temperature rises, the pressure of the water vapour in the tube increases and the mercury column is depressed, until when the whole has become steady the level of the mercury is the same inside the tube and in the cistern. The pressure exerted by the water vapour is equal to the atmospheric pressure.
  - 3203
  - A.
  - B.
  - Price of Apparatus as figured (glass parts only) .. 67-Stand and Clamp only, for above................8/~
  - 3204.—Apparatus for Ex-periments on the Vapour - Pressures o f different Liquids.6353
  - This apparatus consists of two barometer tubes placed side by side, with their lower ends in a glass trough, and their upper ends in a vessel containing water which serves as a constant temperature bath. The front of this vessel is glazed, so that the levels of the mercury in the two tubes may be observed by a catheto-meter. A spirit lamp is used for raising the temperature of the water and a stirrer for keeping the temperature uniform throughout. A small quantity of water having been introduced into one of the barometer tubes, the vapour from it depresses the column, and after correcting for the pressure due to the small excess of water, for the effect of the water on the capillary depression and for the temperature of the mercury, the difference in level in the two tubes gives the vapour-pressure at the temperature of the bath.
  - Price, complete as figured .. 30/-
  - (Described in Poynting & Thomson’s Text-Book of Physics—“Heat.”)
  - 3205.—Apparatus to
  - show the Formation of Vapour in a Vacuum.6347
  - This apparatus consists of four barometer tubes suitably mounted on a polished stand, as figured. The tubes, after being filled with mercury, are immersed in the glass trough containing mercury. One of the tubes serves as a barometer, and a few drops of water, alcohol, and ether respectively are introduced in the other tubes. When the liquids reach the vacuum, a depression of the mercury is at once produced, .4!i and as this depression cannot !l|§ be caused by the weight of the liquid (which is an extremely
  - m
  - 3205
  - small fraction of the weight of the displaced mercury), it must be due to the formation of some vapour whose elastic force has depressed the column of the mercury.
  - Price of Apparatus as figured but without mercury—
  - £1 12 6
  - (For further details see Ganot’s “ Physics.”)
  - 3206. —Apparatus to
  - show the Formation o f V a pour in a Vacuum. Improved form. 6348
  - This apparatus is used in the same manner as No. 3205, except that the mercury can be poured through the funnels of the barometer tubes, the glass stopcocks afterwards being turned off.
  - Price, complete as figured—
  - £2 17 6
  - 3207. —Curved Pipette,
  - as used for introducing small drops of liquids into narrow tubes. This form of pipette is mentioned in the following Catalogue references Nos. 3203,- 3205, etc.
  - Price .. .. each 6d.
  - 3206
  - 3207
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.451 - vue 470/555
- - w>
  - 452 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - the bath, up with a
  - VAPOUR DENSITY APPARATUS
  - 3208.—Dumas’ Apparatus for Determining the Density of an Unsaturated Vapour.
  - A large glass flask, provided with a neck drawn out to a fine tube, was partially filled with the liquid the vapour-density of which was required, and then immersed in a bath of oil or molten metal which could be maintained at a temperature considerably above the boiling point K of the liquid. In order to keep the flask immersed, it was held in a heavy metal frame, which also supported thermometers to indicate the temperature of the bath.
  - During the ebullition of the liquid in the flask, the vapour formed issued in a small jet from the drawn-out neck. This continued until the liquid was completely vaporised, at which instant the issue of the vapour abruptly ceased. The flask was then full of vapour 3208 at the atmospheric pressure and the temperature of
  - The barometer was then read, and the mouth of the flask was sealed blowpipe. Price .. £112 6
  - (See Edser’s “ Heat for Advanced Students.”)
  - 3209.—Hofmann’s Apparatus for Deter-
  - mining the Density of an Unsaturated Vapour. This apparatus is used in the Science Laboratories of Harrow School, and was made specially by us. It consists of an accurately graduated mercury tube about a metre in length, enclosed in a wide glass
  - tube, which is connected to a round-bottomed flask, and an “ all-glass ” Liebig’s condenser, the latter fitting
  - loosely into a round:bot-
  - tomed receiver.
  - 3209
  - . Price, complete, as figured .. .. £2 2 6
  - ,, glass parts only .. .. .. 12 6
  - C. ,, of graduated tube and jacket only 0 15 0
  - 3210.— Dumas’ Vapour- Density Bulbs, as
  - used in apparatus No. 3208.
  - Each .. .. 8d. Per dozen .. 7/6
  - 3211
  - 3211.—Dr. Lehfeldt’s
  - Apparatus for Comparing the Vapour-Pressures of T w o Liquids. This apparatus, which is more fully described in Edser’s " Heat for Advanced Students,” consists of a glass tube bent round so that two portions of it lie parallel to each other, and very close together, their continuations being bent twice at right angles, and ending in bulbs. Pieces of thermometer tubing are sealed on to the bulbs, and another piece is sealed on to the main tube. 6356
  - Price, without mercury .. 9/6
  - 3209/1.—Victor Meyer’s Apparatus for Determining the Density of an Unsaturated Vapour. Ordinary pattern.
  - A. Price of inner vessel .. .. .. each 4/-
  - B. Price of outer glass jacket for ditto .. ,, 5/6
  - C. Price of outer jacket for ditto, made of brazed copper
  - each 37/6
  - D. Small stoppered bottles for use with above ,, 6d.
  - per dozen 5/6
  - 3209/1
  - 3212. — Victor Meyer’s Apparatus for Determining the Density of an Unsaturated Vapour. “ Stoppered ” Pattern.
  - This improved form of Victor Meyer’s apparatus is fully described in Poynting and Thomson's Text-Book of Physics—" Heat.”
  - A. Price of apparatus, as figured .. .. .. 10/-
  - B. „ outer jacket for ditto.. .. .. 5/6
  - C. ,, outer jacket for ditto, made of brazed
  - copper................. ...................37/6
  - D. Small stoppered bottles for use with above—
  - each 6d. ; per dozen 4/6
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.452 - vue 471/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 453
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - HYGROMETRY
  - 3213.—Regnault’s Hygrometer for Determining the Dew
  - Point. This apparatus consists of two glass tubes, D and E, about 2 cm. in diameter, terminating in polished silver thimbles. Each tube contains a thermometer. A bent tube A, open at both ends, passes through the cork of the tube D, and reaches nearly to the bottom of the thimble. There is a lateral horizontal tube, fused into the tube D, by which the latter is put in communication with the aspirator G. The tube E is not connected with the aspirator ; its thermometer simply indicates the temperature of the atmosphere.
  - The tube D is then half filled with ether, and the stopcock of the aspirator opened. The water contained in it runs out, and just as much air enters through the tube A, bubbling through the ether, and causing it to evaporate. This evaporation produces a diminution of temperature, so that dew is deposited on the silver just as on the bulb in Daniell’s hygrometer, but on all parts of it at the same time since all parts of the silver thimble will be equally cooled; the thermometer Tx is then instantly to be read, and the stream from the aspirator stopped. The dew will soon disappear again, and the thermometer Tx is again to be read. The mean of the two readings is taken as the dew-point; the thermometer T2 gives the corresponding temperature of the air, and hence we have all the elements necessary for calculating the hygrometric state.
  - As all the ether in this instrument is at the same temperature in consequence of the agitation, and the temperatures may be read off at a distance by means of a telescope, and as the silver is thin and a good conductor of heat, the sources of error in Daniell’s hygrometer are avoided.
  - The above details are taken from Ganot’s “ Physics,” published by Macmillan & Co.
  - A. Price for superior make and finish, University pattern, thimbles made of pure silver, and with aspirator of strong
  - copper 6366 .............................................................................£8 10 0
  - B. Ditto, cheaper make, with silvered copper thimbles and zinc aspirator .. .. .. .. .. 3100
  - 3214.—Regnault’s Hygrometer, Simple Form.
  - This small instrument consists of a wide glass tube, carrying a rubber cork, through which pass a thermometer and a bent glass tube.
  - The bottom of the wide tube fits into a thin copper cup which is thickly silver - plated. 3214 The thermometer is graduated in half degrees and reads from — io* to 50° C.
  - The wide tube is half filled with ether and air caused to bubble through it by blowing it in with a pair of foot-bellows through the side tube, causing the ether to evaporate and the temperature to fall, until at last the ether and tube are reduced to the dew point, which is shown by the deposit of dew on the silver-plated cup. 6367
  - Price
  - 7/6
  - 3215
  - 3215.—Aluminium Cup for Determination of the Dew
  - Point. This cup, which measures about 2 in. in diameter, and 4 in. in height, is placed on the table and the temperature is taken with a thermometer graduated in tenth degrees. A sheet of glass is placed in front of the cup to protect it from the heat of the observer’s body. After filling the vessel about half-way with tap water, pieces of ice are dropped in and the contents vigorously stirred with a wire-gauze stirrer until dew begins to appear, when the dew point is read off on the thermometer. The water is then poured out and the experiment repeated three or four times, the mean of the results being taken. The dew point can be determined to an accuracy of a fifth of a degree Centigrade within three minutes from the commencement of the experiment. 6368
  - Each.. ....................1/6
  - Per dozen .. .. . . .. 16/6
  - (See Robson’s “ Practical Exercises in Heat.”)
  - 3216
  - 3216.—Glass Vessel for Determining the Density of Atmospheric Air. Made of fairly thick-walled glass tubing and fitted with a well-ground-in glass stopcock at each end. 6365 Each .......................8/6
  - For full description see Edser’s " Heat for Advanced Students.”
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.453 - vue 472/555
- - 454 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - HYGROMETERS
  - 3217
  - 3217.—IVI as o n ’ s Wet and Dry Bulb Hygro-
  - meter, on boxwood Scale, enclosed in well-finished japanned tin case.
  - Each ..9/6
  - 3218.—Daniell’s Hygro-
  - meter, on well-polished stand.
  - 3219
  - 3219.— S t a n d a r d Hyg r o m e t e r, wet
  - and dry bulb, Mason’s pattern, for ascertaining the dew point and amount of humidity in the air. The tubes are engine-divided on stem, and figured on opal slips on brass backs ; neatly mounted on a polished mahogany board.
  - Each
  - .. 17/6
  - Complete..
  - £2 10 0
  - 3220
  - 3220.—Standard Hygrometer, after the style of No. 3219, but cheaper make, smaller size .. .. .. . .£2 2 0
  - 3222
  - 3222.—RegnauIt’s Hygrometer, im-
  - 3221.—Dine’s Hygrometer, best make and finish.
  - proved pattern, with aspirator, etc.
  - £2 19 6
  - Complete, as figured..
  - £3 10 0
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.454 - vue 473/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 455
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BOILING POINT APPARATUS
  - 3223
  - 3223.—Regnault’s Apparatus for the determination of the boiling point of water.
  - This apparatus, which is made entirely of strong copper, consists of a double-jacketed cylinder mounted on top of a tank. The thermometer is inserted in the tubulure at the top of the apparatus. The steam from the boiling water ascends through the inner tube, descends through the space between the inner and outer jackets, and finally escapes through the sloping tube into the air. The apparatus is also fitted with a tube, the bent part of which must be filled with mercury, as shown in the figure, thus serving the purpose of a manometer for measuring the pressure of the vapour. 6381
  - Price, for best make .. £1 5 0
  - 3224
  - 3224.—Regnault’s Apparatus for the determination of the boiling point of water,
  - made of copper and mounted on three iron legs, as figured. 6382 Each...................£110
  - 3225
  - 3225.—Regnault’s Apparatus for the determin-ation of the boiling point of water. Small size for students’ use. 6383
  - A. Made of japanned
  - tin .. each 5/6
  - B. Made of copper—
  - each 14/6
  - 3227.—IVIarcet’s Steam Boiler,
  - to illustrate how the temperature of Steam varies with the pressure. This boiler is fitted with Barometer Tube and Thermometer.
  - Price .. £3 3 0
  - 3226
  - 3226.—G I a z e-brook’s Conical Tins, for the determination of the boiling point of a thermometer as described in Glaze-brook’s text-book on “ Heat.” 6386
  - Each .. .. 2/6
  - 3228.
  - Papin’s Digester, o r Wl a r c e t’s Boiler. Made of strong copper, tested up to 15 atmospheres, fitted with manometer gauge, safety valve and handle. Mounted on tripod. Capacity 4 litres.
  - Price .. £6 15 0
  - 3229
  - 3229.—F I a s k and Tube, fitted with rubber corks, for determining the boiling point of a thermometer. 6387
  - Price, without thermometer .. 2/6
  - 3228
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.455 - vue 474/555
- - 456 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BECKMANN’S APPARATUS
  - (FREEZING POINT METHOD.)
  - 3230.—Beckmann’s Apparatus for the determination of molecular weights. Freezing point method. The apparatus comprises :—
  - A. Cylindrical glass cooling vessel with nickel-plated metal cover Zinc trough with tubulure at side Glass syphon Pure nickel wire stirrer Two freezing tubes with corks Two air jackets One freezing rod with cork Two filling pipettes
  - One ordinary thermometer for taking temperature of the cylindrical cooling vessel.
  - Price complete £2 7 6
  - B. Beckmann’s Thermometer, Range 5-6° C. in
  - Price £15 0
  - The above apparatus is fully described in the Magazine of Physical Chemistry, Vol. VII, page 324.
  - BECKMANN’S APPARATUS
  - (BOILING POINT METHOD.)
  - 3231.—Beckmann’s Apparatus for the determination of molecular weights. Boiling point method, improved form. The apparatus comprises :—
  - Boiling cylinder with platinum wire sealed through the bottom
  - Glass steam jacket or
  - Porcelain steam jacket
  - Set of two spiral condensers
  - Set of two small Liebig’s condensers
  - Set of two small filling tubes, beads and garnets
  - Asbestos heating bath
  - The burners, stand and clamp are not included in following prices.
  - A. Price complete, with glass steam jacket .. ..£276
  - B. ,, ,, ,, porcelain steam jacket .. .. 3 5 0
  - C. Pastille Press, latest improved pattern......18 0
  - D. Beckmann’s Thermometer, Range 5-6° C. in T^° • • 15 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.456 - vue 475/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 457
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 3232
  - BECKMANN’S APPARATUS
  - 3232.—Beckmann’s Freezing Point Apparatus, for determining Molecular Weights by lowering the freezing point of a solvent.
  - This apparatus consists of a test tube A, provided with a side inlet tube D, and a cork through which a thermometer T, and a platinum wire stirrer S2 pass. The test tube is surrounded by a larger tube B, the space between the two forming an air jacket. Both are surrounded by a larger vessel C, which can be filled with a suitable freezing mixture. The latter is kept in circulation by means of the wire stirrer Sx.
  - The method of using the above apparatus is as follows :—Some of the liquid of which the freezing point is required, is introduced into A, by way of the inlet tube D, which is afterwards closed by a cork. A suitable freezing mixture is introduced into C, and the whole apparatus is allowed to stand till the thermometer T indicates a temperature one or two degrees below the probable freezing point of the liquid. The platinum wire stirrer S2 is then moved briskly up and down, when solidification will generally occur. The temperature indicated by T rises and shortly attains a value which remains constant for some time. This temperature is the freezing point of the liquid. 6403
  - (See Edser’s “ Heat for Advanced Students.”)
  - Prices.
  - A. Price of glass cooling jar, with wooden cover, nickel stirrer, freezing tube and india-rubber stopper 17/6
  - B. Ring stirrer for freezing tube .. .. .. .. .. .. .. .. .. .. 9d.
  - C. Beckmann’s thermometer range, 5-6° C. in x^° .. .. .. .. . . .. £15 0
  - D. Thermometer for cooling jar, 20 to + 40° C. in J° .. .. .. .. .. .. 6/6
  - FOR BECKMANN’S THERMOMETERS
  - -------- SEE PAGE 484 ------
  - 3233.—Landsberger’s Apparatus for the determination of Molecular Weights. (Modified by Walker & Lumsden.)
  - For full instructions see “ Introduction to Physical Chemistry,” 1910 edition, by James Walker, LL.D., F.R.S. (Macmillan & Co., Ltd.), also “ Journal of Chemical Society,” 1898, Vol. LXXIII., Part II., page 502. 8411
  - A. Price, including thermometer, 70° C. to 105° C., graduated in
  - tenths and caoutchouc stoppers .. .. .. .. 25/-
  - B. Price, without thermometer .. .. .. .. .. 16/6
  - DIFFUSION, OSMOSE,
  - 3234.—Graham’s Dialyser, for demonstrating the Laws of Diffusion.
  - This form of Dialyser consists of two rings of pure gutta-percha, one 3234 fitting over the other, and between
  - which is tightly stretched a sheet of Dialysis Paper. The mixed solution is poured into this ring, and the latter with its contents is then placed in a glass basin containing a large quantity of water on which it floats. After a period of about two days, a more or less complete separation of the mixed solution will have taken place. Prices are subject to fluctuations of the market.
  - A. Gutta-percha rings 4 6 8 10 in. diam.
  - Price .. .. 3/6 5/- 7/6 10/6 per pair.
  - B. Glass Basins, suitable for above.
  - To rake ring 4 6 8 10 in. diam.
  - Price .. .. 2/- 3/- 5/5 7/6 each.
  - See McEwen’s “Properties of Matter ” (Longmans,
  - Green & Co.).
  - OSMOTIC PRESSURE.
  - 3235.—Dutrochet’s Endosmo-
  - meter. This apparatus consists of an inner cylindrical tube, the bottom of which is closed with a thin bladder. The top of this tube is connected to a thin stem which is accurately graduated. This cylindrical vessel, after being filled with copper sulphate solution up to about a third of the narrow stem, is placed in a glass jar containing pure water. If the temperature remains constant, the liquid in the narrow stem rises, whilst the water in the glass jar sinks to a lower level and acquires a faint bluish tint.
  - Price, complete, as figured .. .. 10/6 3235
  - 3236.—Dialysis Papers, cut into squares—
  - Size .. .. .. 5 6 8 10 in. square.
  - Price ............9d. 10d. 1/3 1/9 per doz.
  - Oup Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.457 - vue 476/555
- - 458 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BUNSEN’S ICE CALORIMETERS
  - 3237.—B u n-s e n’s Ice Calorimeter
  - having cork and accurately graduated tube in the widened end. For method of filling-see Glazebrook’s Elementary Text-Book “Heat.”6418
  - 3237
  - Length 6 8 10 in.
  - A. Price of calorimeter
  - only .. 2/6 3/- 3/6
  - B. Complete, with rubber cork and
  - graduated tube as figured— Length 6 8 10 in.
  - 4/6 5/6 6/6
  - 1
  - 3238. —Bunsen-Reichert’s Ice C a I o rimeter,
  - mounted on polished wooden back, which is graduated in millimetres for observing the rising of the mercury when the water freezes ; also fitted with a special arrangement so that the pure distilled water and mercury can easily be introduced into the large cylindrical vessel.6419
  - 3239
  - 3238
  - Price
  - £17 6
  - 3240.—Bunsen’s Apparatus for determining the expansion of water on freezing, as described in Edser’s Text-Book—“ Heat for Advanced Students.” 6413 Each...............2/-
  - 3241.—Wei n hold’s S u I p h uric Acid C r y o p h o rus, for
  - freezing the water without the aid of a freezing mixture or an air pump.6421 Each...........6/6
  - 3242
  - 3242.—Apparatus for Freezing Water, consisting of a fairly thick-walled test-tube into which is fitted a rubber cork, carrying inlet and outlet tubes and a bulbed tube for holding the water to be frozen. 6422
  - Ether is caused to evaporate in the test-tube by means of air blown into it with a small pair of bellows, and the continued evaporation causes the water to. drop down to freezing point. Price.. .. .. .. 2/6
  - 3239. — Wollaston’s Cryophorus.
  - This apparatus, which is about 15 in. in length, consists of a bent glass tube provided with a bulb at each end. The apparatus is prepared by introducing a small quantity of water, which is then boiled so as to expel all air. It is then hermetically sealed, so that on cooling it contains only water and the vapour of water. The water being passed into the bulb A by tilting the apparatus, the other bulb is immersed in a freezing mixture. The vapour in the tube is thus condensed ; the water in A rapidly yields more. But this rapid production of vapour requires a large amount of heat, which is abstracted from the water in A, and its temperature is so much reduced that it freezes. The experiment succeeds best when the tube connecting the bulbs is of fairly large diameter.6420 (See “ Ganot’s Physics.”)
  - A. Price, not including glass jar .. 3/6
  - B. Ditto, lower bulb of cylindrical shape
  - 4/-
  - 3243
  - 3243.—Apparatus for demonstrating the principle of Carre’s Ice IVIachine, comprising a cylindrical tube, one end of which is fitted by means of rubber-pressure tubing to a Geryk pump, whilst the other end is connected to a Dewar’s Vacuum Vessel, which contains the water to be frozen. The cylindrical tube contains glass wool and concentrated sulphuric acid, which takes up the aqueous vapour as it is formed. 6425
  - After working pump a few minutes the water in the Dewar’s vessel will first boil and then freeze.
  - A. Price of apparatus complete as figured £17 6
  - B. Absorption tube only .. .. .. 13 6
  - C. Dewar’s Vacuum Vessel .. .. .. 8 0
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.458 - vue 477/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 459
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LIQUEFACTION APPARATUS, Etc.
  - 3244.—F. E. Becker & Co.’s Registered Liquefaction Apparatus. (Invented by Paul Wertheim, B.Sc., Hons. Lond., L.C.P., Senior Physics Master, Tiffin’s Boys’ School, Kingston). Will liquefy sulphur dioxide and ammonia. Useful for students, demonstration, and projection on lantern screen. Simple ; effective. Once filled always ready. For chemical and physical laboratories. See McEwen’s “ Properties of Matter ” (Longmans, Green & Co.).
  - Price, without pump (any bicycle pump will do) .. .. .. 10/6
  - This apparatus will liquefy S02 at temperature up to 50° C., and ammonia up to 200 C. It will indicate pressure of liquefaction, the measurement being, obtained by simply applying Boyle’s Law to the change of volume of the air enclosed in tube E. It is designed to allow the limb containing the gas to be surrounded with water at different temperatures, so that the pressure of liquefaction over a range of temperatures may be obtained.
  - INSTRUCTIONS FOR FILLING TUBE WITH GAS.
  - Owing to the difficulty of ensuring the safe arrival—if sent out already filled—the apparatus has been constructed so that it can be filled in the simplest possible manner on arrival—the tubes being constricted ready for drawing off.
  - Having unscrewed the rough board from back (this board is used for safe transit only) proceed as follows :
  - (1) Take out valve A and pour in mercury until it fills about | in. of the
  - wide tubes D and G.
  - (2) Connect H to gas generator, holding the apparatus in a slanting
  - position so that the mercury just covers the elbow C. Pass the dry gas through until all the air is driven out (make sure that the gas is dry, and that the air is completely driven out).
  - (3) Hold the apparatus in an upright position and seal off at BB.
  - (4) Pour in more mercury until it stands half-way up tube D. Replace
  - the valve and pump carefully until a little mercury comes out of the middle tube E, and in this way drive the gas out of this limb.
  - (5) Take out valve again ; this releases the pressure so that the mercury
  - descends in middle tube E and air enters.
  - (6) Seal off at F.
  - (7) Fill tube D to within \ in. of the top with mercury and replace valve A.
  - (8) Screw ordinary bicycle pump on to valve A and pump until gas is
  - shown in liquid form in tube B.
  - 3244
  - 3245.—Cast-Iron Bursting Bottle,
  - with screw stopper, to show the expansive force of ice. 6444
  - To use, fill with water and tightly close bottle by means of its screw stopper. Bottle is then surrounded with a freezing mixture of snow and salt. After some time the water congeals, a loud report is sometimes heard, and the bottle is found to be rent.
  - ............................1/6
  - ............................16/6
  - 3246.—Set of six ditto, one only fitted with a stopper.
  - Per set .. .. .. .. .. .. .. 7/-
  - 3247.—Apparatus for showing the Change of Volume of a Substance on passing from the Liquid to the Solid Condition. 6439
  - Each...........................5/6
  - (See Ganot’s “ Physics.”)
  - 3248.—Carres Apparatus, provided with a small test-tube which is fused in the centre of the vessel. Ether is placed in this tube, after which it is closed with a cork. 6424
  - 3247
  - On exhausting the vessel, the cork is driven out, owing to the evolution of heat, as the water is taken up by the acid.
  - Price ............................................7/6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.459 - vue 478/555
- - 460 F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 3249
  - PROPERTIES OF ICE
  - 3249.—Apparatus to show that Solidification or [Congelation is the Passage of a Body from the Liquid to the Solid State. 6436
  - This apparatus consists of a delicate thermometer, round the bulb of which is a wider bulb containing some water. Before sealing at A the whole outside bulb is filled with water, which is then boiled out, and sealed so that over the water the space contains nothing but aqueous vapour. The tube is clamped in a retort stand, and ether is dropped on it, that which has dropped off, and become colder, being used over and over again. In this way the temperature may soon be reduced to - 6°, and if then the bulb is shaken, part of the water freezes and the temperature rises to zero.
  - Price .. . . .. .. 7/6
  - 3250.—Liquefied Sulphurous Acid, in glass syphons, holding about 3 lb. 6450 .. 9/-
  - Price for refilling .. per syphon 9/-
  - B
  - former, that it bottle details,
  - 3252.—Apparatus for determining the Critical Temperature of Sulphur-Dioxide.6449 This apparatus consists of a thick-walled glass tube (closed at one end and constricted near the top), into which fits a bent capillary tube, which reaches nearly to the bottom of the The other end of the fine tube is widened so can be connected to the delivery tube of a containing sulphur-dioxide. For further see Edser’s " Heat for Advanced Students.”
  - 3252
  - Price ........................................2/6
  - (For bottles containing sulphur dioxide, see No. 3250.)
  - SB nsFf| Price of glass syphon .. 22/6
  - s |j|| 3251.—Glass Syphons (can
  - Iffl II be filled as often as required).6461
  - 3253.—Mousson’s Apparatus for Demonstrating that at Low Temperatures Ice can be made Liquid by Strong Pressure.6440
  - This apparatus consists of a stout steel tube closed at one end by a screw, and with a screw piston at the other. The tube is filled with water and a metal bullet introduced. When the apparatus is closed it is inverted so that the bullet rests on the piston, and is placed thus in a freezing mixture ; the water freezes and presses the ball against the piston. The apparatus is again inverted, and pressure is gradually applied by turning the handle of the screw. When the lower screw is opened the ball falls out, and is followed by a thick cylinder of ice which must have been formed at the moment of opening. The pressure was estimated at 13,000 atmospheres. Hence, at a pressure lower than this, the ice must have been converted into water at about 180 C. Price
  - 3253
  - £3 19 6
  - (See Ganot’s “ Physics.”)
  - 3254.—Wooden IVIoulds for showing the Regelation Of Ice. On powerfully compressing pieces of ice in a boxwood mould, a clear transparent cake of ice is formed. 6442
  - Moulds as A, B, C, D (when ordering, please state which)
  - each 19/6
  - 3255.—Special Hydraulic Press, for
  - compressing the above moulds. 64 48 Price £9 15 0
  - 3254
  - 3256
  - 3256.—Leidenfrost’s Apparatus for showing the “Spheroidal State,” consisting of a silver-plated copper basin, and a metal triangle, as described in Weinhold’s “ Experimental Physics,” and other well-known text-books. 6445
  - Price.......................................6/6
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.460 - vue 479/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 461
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - Air L iquefier A
  - Part sectional View of Top of Air Liquefier.
  - Diagram showing arrangement of Regenerator Coils.
  - Details of Compressors, capable of compressing 14-6 cubic feet of free air per minute with working pressure of 2000 lbs. per square inch, on application.
  - Air Liquefier (Hampson) Standard Size.
  - 3257.—Air Liquefying Apparatus. See Mc-
  - E wen’s " Properties of Matter ” (Longmans, Green & Co.).
  - This apparatus depends upon a method by which a moderate amount of refrigeration, produced by the expansion of a gas, may be accumulated and intensified till it reaches the point at which the gas becomes liquid under atmospheric pressure. The method consists in directing all the expanded gas, immediately after its expansion, over the coils which contain the compressed gas that is on its way to the expansion point. The cold developed by expansion in the first expanded gas is thus communicated to the on-coming compressed gas, which consequently expands from, and therefore to, a lower temperature than the preceding portion. It communicates in the same way its own intensified cold to the succeeding portion of compressed gas, which in its turn is made colder, both before and after expansion, than any that had gone before. This intensification of cooling goes on until the expansion-temperature is far lower than it was at starting ; and the effect is so powerful that even the small amount of cooling due to the free expansion of gas through a throttle-valve may be made to liquefy air without using other refrigerants.
  - The amount of refrigeration due to free expansion was ascertained by Joule and Thomson, and is in the first place proportional to the fall of pressure. Air at o° C. is cooled 0-29° C. for every atmosphere of pressure-drop. This cooling, however, increases with the descent of the temperature from which expansion takes place, and the law is that it is inversely proportional to the square of the absolute temperature. Thus expansion of air from 4^ atmospheres to 1, and from a temperature of o° C., i.e., 2740 Absolute, gives about i° of cooling in the air itself. But when the air expands from | of that absolute temperature, i.e., from 910 C., the cooling for the same pressure drop is £ of i°, or 2%°.
  - (Prices and further information on application.)
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
  - Full length sectional View of Air Liquefier.
  - Sectional Views of Air Liquefier.
  - The efficiency of the method depends upon the arrangement and construction of the coils and chamber forming the interchanger in which the expanded gas takes up heat from the compressed gas. To make this action as perfect as possible, the conditions required are :—To have a large surface of exposure between the compressed and expanded gases ; to have little thickness of material between them, and that little of high conductivity ; to have both compressed and expanded gas in small masses in close contact with the conducting material ; to have the total volume of the interchanger small so as to expose little surface for the entrance of external heat; and to have the total mass of coils and interchanger, which have to be cooled down with the gas, small and of little specific heat. These are all thermal advantages, and the arrangement of parts in the interchanger of the present apparatus is the most efficient hitherto designed for gases.
  - An external view of the liquefier is given above. The high-pressure purifier is seen in the illustration attached to the pillar of the stand on the left hand side ; the low-pressure purifier stands by itself to the left.
  - The apparatus is capable of working continuously with a compressor able to deliver air at a pressure of 100 atmospheres or over. It begins to liquefy air in from 6 to 10 minutes after its admission when the compressor is working at from 120 to 150 atmospheres pressure, and makes about x litre of liquid per hour.
  - It requires no ice and salt, carbonic acid, or other auxiliary refrigerant.
  - It produces a perfectly clear liquid, which requires no filtering.
  - The operator has only one gauge to watch, and one valve to control.
- p.461 - vue 480/555
- - 462 F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - LIQUID OXYGEN
  - Liquid Air consists mainly of oxygen and nitrogen, and when freshly prepared is a nearly colourless liquid, boiling at — 190° C. As the more volatile nitrogen evaporates, the temperature rises and the liquid assumes a bluish tinge—the colour of liquid oxygen.
  - In the liquid state, air occupies ^^th part of its ordinary volume, or, in other words, if liquid air be vaporised and restored to normal temperature it will expand 800 times.
  - Vacuum Vessels.
  - Vacuum vessels are necessary for the storage of liquid air and those gases which only liquefy at low temperatures.
  - Vacuum vessels are either cylindrical or globular in shape, and consist of one glass vessel enclosed within another. The space between these vessels is thoroughly exhausted and sealed under a high permanent vacuum. Heat radiates across the vacuous space very slowly, consequently liquid stored in a vacuum vessel is admirably insulated from the action of external heat and only vaporises slowly away.
  - The efficiency of the vacuum vessel is increased by silvering, as radiation from outside is thus partially reflected.
  - Liquid air evaporates from vacuum vessels at the rate of from 5 per cent, to 15 per cent, per twenty-four hours, according to the size of the vessel, the evaporation from small vessels being more rapid than from large.
  - (For further in formation on liquefaction of gases, see “ The Experimental Study of Gases,” by Prof. Morris W. Travers. Macmillan & Co.)
  - AND LIQUID AIR
  - We are prepared to supply Liquid Air at the following rates, in quantities of not less than 1 litre at a time, delivered ex works—
  - 3258. —Liquid Air.. .. per litre 15/-
  - and 10/- net for every additional litre supplied at the same time.
  - 3259. —Liquid Oxygen is supplied at an increase of 5/- per litre on the above net prices.
  - 3260. —Vacuum Vessels may be hired atarental of 3/- per week, but customers are strongly recommended to purchase their own vessels.
  - NOTE.—We supply the liquid in our own glass vacuum vessels, which are lent free of charge for a period not exceeding seven days.
  - The vacuum vessels are packed in specially constructed wooden boxes, and every effort is made to guard against breakage, but the conditions of sale are that all breakages which occur after the vessels leave the works are debited to the customers. On no account can we hold ourselves responsible for any evaporation which may take place during transit.
  - The railway companies carry liquid air at parcel rates per passenger train at owner’s risk.
  - For the convenience of customers living in the
  - COUNTRY WE WILL DELIVER LIQUID AIR OR LIQUID OXYGEN BY SPECIAL MESSENGER TO ANY LONDON, BIRMINGHAM,
  - Manchester, or Newcastle railway station, to be
  - FORWARDED BY ANY SPECIFIED TRAIN, AND IT IS ADVISABLE THAT THE CUSTOMER SHOULD MEET THE TRAIN ON ARRIVAL.
  - VACUUM VESSELS
  - 3261.—Dewar’s Cylindrical Demonstration Vacuum Vessels, for
  - holding liquid air, oxygen, hydrogen, etc.
  - Internal Dia. Length. Cap. A Clear Glass. B Silvered Glass.
  - 4 Cm. 20 cm. 260 C.C. Each. 7/6 Each. 9/6
  - 4 „ 30 „ 400 „ 9/- 11/6
  - 4 „ 40 „ 500 „ 10/6 13/6
  - 5 „ 20 „ 430 „ 9/- 12/6
  - 5 „ 30 „ 620 „ 12/- 15/-
  - 5 „ 40 „ 850 „ 15/- 18/-
  - Note.- —For demonstration purposes the
  - Clear Glass Vessels are recommended.
  - Any of the above vessels may be hired at a
  - Vrent charge of 3/- per week (at Customer’s risk). Customers are, however, strongly recommended to purchase their own demonstration vessels. For ordinary lecture purposes the 3261 vessel of 400 c.c. capacity is recommended.
  - 3262.—D ewar’s Globular Demonstration Vacuum Ves-
  - sels. A B
  - Capacity. Clear Silvered
  - Litres. Glass. Glass.
  - i •• 6/- each 8/- each.
  - * •• • • 8/- „ 10/6 „
  - 1 •• .. 10/6 „ 13/6 „
  - I .. 12/6 „ 15/6 „
  - 2 .. 22/6 „ 26/- „
  - 5 •• •• 42/- 48/- „
  - 3263.—Polished Wooden Supports, for use with Vacuum Vessels. No. 3262 .. .. 3/- to 5/- each.
  - 3264 .—Ditto, but made for use with the cylindrical pattern, No. 3261.
  - 3/- to 5/- each.
  - See McEwen’s “Properties of Matter” (Longmans, Green & Go.)
  - 3264
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.462 - vue 481/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 463
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - PIEZOMETERS, Etc.
  - 3266.—Double-Walled Vacuum Vessels, wine glass shape.
  - A. 70 mm. diam., clear glass .. each 5/6
  - B. ,, ,, silvered glass ,, 7/6
  - 3265.—Special Low Temperature Thermometer, filled with pentane for liquid air experiments.
  - A. + 30° to — 8o° C. in single degrees, milk glass scale—
  - each 17/6
  - B. + 30° to — 2000 C. in single degrees.. ,, 30/-
  - 3266
  - 3267
  - 3267.—Oersted’s P i e-ZOmeter, for demonstrating the compressibility of liquids. Furnished with all latest improvements. 6478 Price £27 10 0
  - See McEwen’s “ Properties of Matter ” {Longmans, Green & Co.
  - :jii» 3268
  - 3268.—R egnault’s Piezometer20^ £19 0
  - See McEwen’s “ Properties of Matter” (Longmans, Green&Co.).
  - 3269.—Apparatus for Demonstrating the Phenomenon of Critical Temperature, as described in Ganot’s “ Physics,” 1910 Edition (Longmans, Green & Co.) ; also McEwen’s “ Properties of Matter ” (Longmans, Green & Co.). 6452
  - The phenomena of the critical temperature may be conveniently illustrated by the following arrangement, which is also well adapted for projection on a screen for lecture purposes. A short glass tube about 4 mm. internal diameter and 6 or 8 cm. long contains some carbon dioxide and .its saturated vapour, and is supported with the drawn-out end downwards in a large test-tube by means of a wire frame. The test-tube is filled up with water which is slowly heated. Further details are given in the above-mentioned text-books.
  - Price
  - »4«
  - IIP* 3270
  - 3270.—Apparatus to show that when Liquid Carbon Dioxide is allowed to escape into the Air the Absorption of Heat due to its rapid evaporation causes a Portion of the Liquid to solidify.
  - ,___The solid is collected by allowing the
  - (T^ jet of liquid to stream into the round
  - s* metal box, in which it is caused to
  - revolve by being made to impinge upon the curved tongue of metal. The box is furnished with hollow wooden handles, through which the gas makes its escape. Considerable quantities of the frozen carbon dioxide can in this way be collected in a few minutes. 6480 Price of the nickel-plated box, complete with handles, jet and coupling
  - £2 10 0
  - 3271
  - 3271.—Glass Flask, for liquefying gases by cooling them to low temperatures at atmospheric pressure. 6484 Price, complete, as figured .. .. 3/9
  - See McEwen’s “ Properties of Matter ” (Longmans, Green & Co.).
  - 3272.—Andrews’ Apparatus for Determining the Isothermals of Carbon Dioxide. Latest Improved Pattern.
  - Andrews made a series of observations on the behaviour of condensed gases at different temperatures,
  - by means of an apparatus the principal features of which are more fully described in Ganot’s “ Physics ” (Longmans, Green & Co.); also McEwen’s “ Properties of Matter ” (Longmans, Green & Co.).
  - The pure and dry gas is contained in a tube g, which is sealed at one end, and the gas is shut in by a thread of mercury. The tube is inserted in a brass end-piece, E, which is firmly screwed on a strong copper tube, R. At the other end is a similar piece, in which a steel screw works, perfect tightness being ensured by good packing. The tube is full of water, so that by turning this screw the pressure on the enclosed gas can be increased up to 500 atmospheres.
  - The experiment consisted in maintaining the tube containing the gas at a constant temperature and gradually diminishing the volume, the pressure corresponding to any volume being noted. 6453
  - Price
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.463 - vue 482/555
- - 464 F. E. BECKER & CO., IMIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - EXPANSION OF AIR AND GAS
  - 3273.—Apparatus for IVIea-suring the Pressure Co-efficient of a Gas.
  - A cylindrical bulb A, of about 200 c.c. capacity is closed above with a stopcock, and connected below by means of flexible pressure tubing with a movable tube C. The stopcock must be lubricated with a little burnt black or white (not red) rubber.
  - To commence an experiment, pour a very small quantity of mercury into C, so that it just forms a seal at the lower part of the pressure tube. Open the stopcock and force air (or the gas to be experimented with) through A, after it has traversed a drying tube containing calcium chloride and soda lime. While the drying tube is still connected with the bulb, pour more mercury into U,*and raise C till the mercury stands at a mark B in the glass tube below A. Next place water and plenty of ice in the bath surrounding A, stir well, and finally close the stopcock above A. A volume of pure dry air at o° C., and at atmospheric pressure has now been enclosed. Read the barometer, and thus obtain P. The cursor D should be adjusted until its lower edge just coincides with the surface of the mercury in the tube C, and the corresponding reading on the scale at the side of C should be observed.
  - Next raise the tube C until the mercury rises well within the bulb A ; this is done in order that, when the temperature of the bath is raised, the air shall not be able to expand into the rubber tube which connects A with C.
  - Remove the ice syphon off the cold water from the bath, and fill the latter with boiling water. Keep the water boiling by blowing steam through it; when the bubbles of steam rise without collapsing, the water is at its boiling point. When this condition is attained adjust C until the mercury stands at the mark B as before ; then, by the aid of the cursor D, observe the reading corresponding to the mercury surface in C ; subtracting from this the scale reading previously observed, we obtain the value of the increase of pressure p. 6486 Price of glass parts and pressure tubing . . . . 15/-
  - For further details see Edser’s “ Heat for Advanced Students,” also McEwen's “Properties of Matter” (Longmans, Green &> Co.).
  - 3*75
  - 3275.—Apparatus for Determining the Expansion of Air at Constant Pressure
  - consisting of a Cylindrical glass bulb about io c.m. in length, and 2\ c.m. wide, sealed at one end and drawn out to a thin stem at the other. 6488
  - Instructions for Use.—The thin tube is fitted into a piece of ordinary india-rubber connection tubing which can be closed by means of a clip. The glass vessel should be carefully dried to start with, and then, the clip being removed, it is immersed neck upwards in a vessel filled with boiling water, so that all but the neck is below the surface. Keep the water boiling for several minutes, till the contained air has had time to acquire the temperature of the surrounding water. Then it is quite evident that any expansion which takes place has occurred under conditions of constant pressure, since the air in the vessel is, during the process, in free communication with the atmosphere, and therefore subjected to atmospheric pressure. Now close the india-rubber tube with the clip, and remove the experimental tube, plunging its neck as quickly as possible below the surface of some cold water. The whole of the experimental tube should not at once be immersed, as the sudden cooling might produce a fracture. It is best to add ice shavings to the water, until a considerable amount remains unmelted for (See Edser’s “ Heat for Advanced Students,” p. 96, 1901 Edition.
  - 3274
  - 3274.—Apparatus for Deter-
  - mining the Co-efficient of Expansion of Air at Constant Pressure.
  - One limb of a U-Tube, closfcd above with a stopcock, comprises a bulb A, of 27 c.c. capacity, a lower bulb, B, of 9 c.c. capacity, and a tubular portion graduated in c.c.s ; the other limb, C, is tubular. Both limbs have corresponding graduations, as represented in the diagram. The stopcock must be lubricated with a little burnt black or white (not red) rubber ; this is the only lubricant that will stand the temperature of boiling water. The U-tube has a T-joint at D, which is connected by means of flexible pressure tubing with a glass tube E: The U-tube is surrounded by a glass vessel which can be filled with water, to act as a constant temperature bath.
  - The stopcock above A being opened, mercury is poured into E till it rises in both limbs of the U-tube. Subsequently, whenever the mercury stands at corresponding graduations in the two limbs, the pressure of the air in A will be equal to the atmospheric pressure. The tube E is next lowered till the mercury just forms a seal at the bottom of the U ; by the aid of a bicycle pump air is pumped for some time through a drying tube containing calcium chloride and soda lime, and then through the bulbs A and B, escaping past the mercury seal into the tube C. Next, remove the pump, but leave the drying tube connected with the bulb A. Raise E till the mercury stands at the graduation between the two bulbs A and B, add plenty of ice to the water in the bath, and, when the whole has reached the temperature of melting ice, close the stopcock above A. Twenty-seven c.c.s of pure dry air at o° C. have now been enclosed at atmospheric pressure ; hence V = 27 c.c.
  - Remove the unmelted ice, syphon off the cold water, and fill the bath with boiling water. In order to keep the water boiling, blow steam through it by means of a rubber tube the end of which dips down nearly to the bottom of the bath. When the bubbles of steam rise through the water without collapsing, the water is at its boiling point. Next lower E till the mercury stands at corresponding graduations in the two limbs of the U-tube ; the enclosed air is now at atmospheric pressure, and the increase in its volume can be accurately read off from the graduation below B at which the mercury stands. This gives us v. Hence, determine the value v/iooV. 6487
  - Price of glass parts and pressure tubing
  - 17/6
  - For further details—see Edser’s “ Heat for Advanced Students,” also McEwen’s “Properties of Matter ” (Longmans, Green dF Co.).
  - some time after it has been added. We may then conclude that the temperature of the water is o° C. Finally the clip is removed, and the experimental tube entirely immersed neck downwards for several minutes. By this means the temperature of the contained air is brought to o° C. Then quickly raise the experimental tube (holding it by means of a piece of flannel, so that the temperature of the enclosed air is not altered) till the surface of the inside water is exactly level with that of the surrounding water. If this adjustment is carefully performed, the final pressure of the air, which is at a temperature of o° C., is equal to the atmospheric pressure, i.e. to the pressure to which the contained air was subjected when heated to the boiling point of water. Replace the clip, remove the experimental tube, dry it externally, and obtain the mass of the tube and the enclosed water. Finally, fill the tube up to the clip with water, and weigh again. If the tube has previously been weighed when dry, we can, by subtraction, determine the mass of the water which just fills it, and thence the total volume of the tube is known. , .
  - ) Price, without rubber tube and clip
  - 2/6
- p.464 - vue 483/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 465
  - W. ft J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MARRIOTTE’S APPARATUS AND BOYLE’S
  - LAW TUBES
  - 3276—Plain Glass Tubes, closed at top, for Boyle’s Law apparatus. 389
  - each 6d,
  - 3277.—Plain Glass Tubes, open at both ends 390 .. .. .. each 6d.
  - A
  - 3278.—Boyle’s Law Tubes, graduated
  - 50 c.c. in ioths, with glass stop-cock. 391
  - each 6/6
  - 3279.—Vapour Tension Tubes,
  - graduated 50 c.c. in ioths, with 2 stopcocks 392 .. .. .. each 9/-
  - 2380. —Ditto, fitted with steam jacket. 393
  - each 12/6
  - ......rfrri.
  - 3284
  - 3285
  - 3286
  - 3287
  - 3281. —Vapour Tension Tubes, as
  - No. 3279, but provided with funnel top. 394
  - each 10/6
  - 3282. —Ditto, fitted with steam jacket
  - each 13/6
  - 3283
  - 3283.—Glass Reservoirs for Mercury, strongly made. 388
  - Capacity.. 125 250 500 c.c.
  - Each .. 1/8 1/11 2/6 Capacity.. 700 1000 c.c.
  - Each .. 3/6 4/6
  - 3284. —Marriotte’s Apparatus for proving Boyle’s Law.
  - For half-atmosphere pressure. This apparatus consists of a straight thick-walled barometer tube, closed at one end and 36 in. long, and a tall glass cylinder. Fully described in Watson’s “ Elementary Practical Physics ” 383 .. .. .. ..15/-
  - 3285. —Marriotte’s Apparatus for proving Boyle’s Law. For half-atmosphere pressure. Consists of stout bent glass tube, nicely graduated, with 2 stop-cocks. Can be clamped to any stand by means of an ordinary retort stand, clamp, and boss. 384 £110
  - 3286. —Marriotte’s Apparatus for proving Boyle’s Law.
  - For half-atmosphere pressure. Consists of stout bent glass graduated tube, with 2 stop-cocks, mounted on heavy foot, with upright support 385 .. ............. .. .. £2 5 0
  - 3287. —Apparatus for half-atmosphere pressure. This consists
  - of a graduated tube ending in a stop-cock at the top. A wider tube is fixed in the metal stand as figured 386 .. .. £2 19 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
  - GG
- p.465 - vue 484/555
- - 466
  - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BOYLE’S LAW TUBES AND APPARATUS
  - 3292
  - 3292.—Boyle’s Law Tube,
  - superior make and finish. Mounted on nicely polished mahogany support, with boxwood scales. 380
  - Complete as figured—
  - £17 6
  - 3291
  - 3291.—Boy! e’s Law Apparatus, with
  - Jolly’s air-bulb attachment, which can be taken off when not required. Mounted on heavy iron foot.381 £1 17 6
  - See McEwen’s “Properties of Matter" {Longmans, Green &> Co.).
  - 3293.—Boyle’s Law Apparatus,
  - “ University ” pattern, large size. 382 Price £5 10 0
  - This apparatus, which is of substantial make and finish, is provided with a plain glass tube which can be raised to desired height and held there by means of a clamping screw, a graduated tube with stopcock A, a graduated tube with two stopcocks and funnel B, Jolly’s air-bulb C, all of which are fitted with side attachments and pointers. The side of the tall upright carrying A is so arranged that A, B, and C can be fixed at different heights. Pointers can be moved along the tubes to show height of mercury.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.466 - vue 485/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 467
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BOYLE’S LAW, Etc.
  - 3294.—Shakespear’s Apparatus for Demonstrating the Principles involved in Boyle’s Law. As used in the Birmingham University.
  - This apparatus consists of two capillary tubes of glass, about 2 mm. diameter in the bore, one of them about 80 cm. long and open at both ends, the other about 50 cm. in length, and sealed at the upper extremity. A length of about 2 cm. at the lower end of each is bent at right angles to the remainder. To each of these bent parts is wired one end of a piece of india-rubber tube about 18 cm. long and of 5 mm. internal diameter. The two tubes are fixed side by side in a vertical position on a varnished paper scale, which is pasted on an upright board. This board is supported on a base of cast iron, which takes the form of a small rectangular tray, upon which rest the bent ends of the glass tubes, and between these the rubber tube lies as a connecting loop.
  - The accuracy attainable in measurements is such that the error of Boyle’s law, in the case of carbon dioxide, could easily be shown by a competent observer, whereas the ordinary elementary student can make a series of observations giving values for the product PV which do not differ by more than about half per cent. 6504
  - The above details are taken from “ School World,” January, 1909. Price, complete, as figured .. .. .. .. .. ..17/6
  - This apparatus is specially recommended.
  - 3294
  - 3295.—Appa-ratus for Determ in-ing the Coefficient of
  - Expansion of Gases at Constant Volume,
  - consisting of a long tube having a bulb at one end and a well-fitting stopcock at the other for filling with dry air. This apparatus can be connected to our Boyle’s Law Apparatus, and a small quantity of mercury should be allowed to remain just above the stopcock. To prevent mercury escaping, the apparatus should always be kept on the wooden cradle, and the tube should just dip beneath the surface of the mercury, otherwise the mercury may escape or air enter as the temperature changes. 6513
  - Price, complete .. .. .. .. . . .. .. .. . • •. 19/6
  - 3296
  - 3296. — Shakespear’s Constant Volume Air Thermometer,
  - as used in the Birmingham Universally. Specially recommended.
  - This apparatus is made on the same principle as No. 3294, and the mercury is arranged so that the pressure in the tube at o° C. is about 55 or 60 cm. of mercury, the whole apparatus is very compact and very easy to manipulate.
  - Price, complete as figured—
  - 18 6
  - 3297.—Apparatus for Determining the Relation between the Volume and Temperature of a Gas at Constant Pressure.
  - This apparatus, which is fully described in Robson’s “ Practical Exercises in Heat,” consists of a barometer tube carrying a thermometer and surrounded by a steam jacket resting in a wooden cradle.6507
  - Instructions for Use.—(a) Tap the tube C in order to prevent the mercury thread from sticking. Read the temperature on the thermometer (t,0) and with a metre scale measure the distance from the closed end of the tube to the inner edge of the thread of mercury. If the bore is uniform this length will be proportional to the volume of air enclosed in the tube. Call the length (v,).
  - (b) Fit up a flask with a steam tube and connect it to the apparatus. Pass steam through the tube C for ten minutes, and after tapping the tube, again read the temperature (t2°), and length (v2) of the column of air.
  - (c) Calculate the co-efficient from your results.
  - Price, complete, as figured .. .. .. .. 17/6
  - 3298.—Model Air Thermometer, as
  - sometimes used for measuring temperature by the expansion of air or some other gas, consisting of a flat-bottomed flask carrying a bulbed tube, cork and bold scale as figured, large size.
  - Each...........................5/6
  - 3298
  - 3299
  - 3299.—Apparatus to prove Charles’s
  - Law, consisting of a glass sample tube of about 250 c.c. capacity, furnished with a stopcock at each end. 6608 Each
  - .. 8/6
- p.467 - vue 486/555
- - 468 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CALORIMETRY
  - SPECIFIC HEATS OF SOLIDS AND LIQUIDS. LATENT HEAT OF FUSION AND VAPORISATION.
  - 3300.—Copper Calorimeters, spun in
  - piece, without seam. 6521
  - A. 3 in. high x in. diam., spun in one piece
  - B. 3 „ X 2
  - C. 4 „ X 2\
  - D. 4 „ X 3
  - E. 4 „ X 3l
  - one
  - Each.
  - 1/3
  - 1/6
  - 2/-
  - 2/6
  - 3/-
  - 3301.—Silver-Plated Copper Calorimeters,
  - spun in one piece, without seam. 6523
  - A. 3 in. high x i| in. diameter .. . . each 3/-
  - B. 4 „ x 2\ „ „ .. • • „ 4/-
  - Fig. A. Fig. B. Fig. C.
  - 3303.—Tin Vessels. 6525
  - A. 4j in. high x 3| in. diam.
  - B. 6 „ x 5
  - 3303
  - 3302.—Calorimeter (Figs. A, B, and C), as supplied by us to Harrow school. See W. J. R. Calvert’s “ Heat ” XArnold <§ Sons). This calorimeter is only used for rough calculations. Advantages Copper boiler (Fig. C) can be heated quickly over a ring burner, and is not easily upset. Being same diameter as copper calorimeter (Fig. B) the piece of metal (Fig. A), which weighs about 480 grammes, can be quickly transferred from boiler to calorimeter. The piece of metal with wire attached is about 2W to 2f in. diameter, and about § in. thick. 6528
  - Prices.
  - Metal Block, Fig. A—
  - Lead .. .. .. .. .. .. .. 2/6
  - Copper.. . . .. .. .. .. .. 3/6
  - Tin .. .... .... .. .. 4/6
  - Calorimeter, Fig. B............ .. each 2/9
  - Copper Boiler, Fig. C............... „ 3/6
  - 3304.—S chus-ter & Lees’
  - C a I orlmeter,
  - consisting of one inner copper can resting on piece of felt inside outer copper can, which is provided with bent wire for holding thermometer.6527
  - Price, including stirrer,
  - {See Schuster & Lees’ “ Intermediate Course of Practical Physics.”)
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.468 - vue 487/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 469
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - CALORIMETRY
  - 3305.— Glass Cal-o r i m eter,
  - consisting of a double - walled vessel from which the air has been ex-hausted, to prove that when the space be-3305 tween two ves-
  - sels is exhausted of air no heat can pass to the inner vessel by conduction or convection. 6526
  - A. Inside dimensions about 2\ in. x 2 in. 8/6
  - B. „ „ ,, 4 >> X 3i „ 14/6
  - 3306.—Watson’s Copper
  - Calorimeter.
  - This consists of a cylindrical copper vessel 10 cm. in diameter and 12 cm. high. Two small notches are cut in the top edge at opposite ends of a diameter. The stirrer consists of a thin horizontal copper rod, A B, bent as shown in the figure, and resting in the notches.
  - Two thin copper plates, C D, are soldered to this rod, while a small glass handle is cemented to the outside. By giving this handle a to-and-fro motion, the paddles C and D are moved backwards and forwards 33°6
  - through the liquid, and thus stir it. The thermometer T is supported in a clip, so that its bulb is near the centre of the calorimeter. Further details are given in Watson’s “ Text-book of Practical Physics” 6529 .. .. .. .. Price 10/6
  - 3307.—Tyndall’s Apparatus for Showing that Bodies have D i ff e r e n t Specific Heats. In this experiment the metal balls are usually suspended by means of fine wire in a bath of boiling oil so as to get them sufficiently hot to fall quickly through the wax cake. 6518
  - Price, complete, with lifter, wax cake, five assorted balls of equal size and tripod stand .. 10/6
  - 3308.—Tyndall’s Apparatus for Showing that Bodies have Different Specific Heats.
  - Improved pattern as modified by Kolbe. 6519 Price, complete, with heating vessel, new form of lifter, cake of wax, tripod and full directions for use .. £2 12 6
  - 3309.—Sets of Metal Cylinders, of equal weight (100 grammes), for specific heat experiments. Each cylinder is drilled with a hole near the top so that it can be easily 33Q9 suspended. 6520
  - A. Price of four cylinders in polished block .. 9/6
  - B. „ six „ „ „ .. 11/6
  - 3310.—Lavoisier’s and Laplace’s Ice Calorimeter. In this appar
  - metal enclosure, which is entirely surrounded by a chamber packed with broken ice. The heat communicated from the solid melts some of this ice, and the water formed runs off by the lower tap. In order to prevent this ice from being melted by heat received from surrounding bodies, an external chamber, also packed with ice, is provided, from'which water can run away by the side tap.'-‘ When the apparatus has stood for some time before the solid is introduced, water will cease to flow from the lower tap—a steady drip from the side tap being due to the melting of the ice in the guard chamber. The heated solid is then placed in the inner compartment, and the water which now flows from the lower tap is collected. 6530 .. .. .. .. .. .. .. .. ... .. .. Price complete £3 7 6
  - ' (See Edser’s “ Heat for Advanced Students.”) ’
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.469 - vue 488/555
- - 470 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - CALORIMETRY
  - 3311
  - 3311.—Glazebrook & Shaw's Calorimeter.
  - This Apparatus consists of a small copper vessel polished on the outside, and a larger copper vessel polished on the inside, both resting on layers of felt. The larger vessel is placed in a wooden box having slides which run in grooves in the baseboard, hence the box can be pushed easily under the shelf to which heater is attached. When in this position the Calorimeter is under the hole in the shelf, and if the cylinder be turned so that its inner tube may come over this hole, the heated body can be dropped directly into the Calorimeter. A Sliding Screen fitted in the centre of the Apparatus serves to protect the Calorimeter from the direct radiation of the heater. A brass rod carrying a clamp for thermometer is fixed to the back of the box. The Stirrer consists of a perforated disc of copper with a vertical stem. A Wooden Cover with a slot in it through which stirrer and thermometer passes, fits over the box. 6532
  - Price, complete with heater, as figured £4 15 0
  - 3312
  - 3312.—Regnault’s Calorimeter to Determine Specific Heats.
  - The substance to be experimented upon is suspended in a wire basket in the centre of the double steam jacket shown on the left, the aperture at the top is closed and a thermometer inserted ; the cage is suspended by a fine string, which can be lowered. As in Glazebrook’s, the Calorimeter is at the side, and by means of a sliding panel can be pushed under the steamer when necessary. The stand for steam jacket is hollow and is filled with cold water to prevent heating of Calorimeter by radiation. A double sliding shutter is drawn out and the substance is quickly dropped into Calorimeter below. The Calorimeter is of very thin copper and is put in another copper vessel having an open air space around it. Both copper vessels are silver-plated. 6533
  - Price .. .. .. .. .. .. £8 10 0
  - A.
  - 3313
  - Calorimeter 6534
  - 3313.—Joly’s Steam Calorimeter. The method of Calorimetry here employed has many advantages in that it is convenient and involves no tedious preparation. No delicate thermometry is required, and the Calorimeter itself being roomy permits of bodies of various shapes and forms being used.
  - The apparatus is, moreover, simple and durable. The Calorimeter is a slight metal vessel which is placed beneath a delicate balance, so that a wire from an arm of the balance sustains a light wire carrier within the Calorimeter. This carrier is provided with a platinum catchwater below.
  - The substance to be experimented with is placed on the carrier, and on steam being admitted the substance rapidly rises to its temperature, condensing some of the steam which adheres as water to its surface, or dropping into the catchwater below, is estimated without loss by the balance.
  - A substance at the initial temperature of Atmosphere t^ suddenly immersed in a saturated vapour at the higher temperature t2° abstracts from it a quantity of heat equal to W C(t2°-t1°) where C is the thermal capacity of the substance between the limits t^ and t2° and W its weight. There is then a weight w of the vapour precipitated, so that
  - WC (t2° — tx°) = wl
  - X being latent heat of the vapour. By the observations of the weights and temperatures either C or X may be the quantity derived from the equation. The method is applicable to the determination of the specific heat of a substance or the latent heat of a vapour.
  - The Calorimeter can be used for any substances, for liquids sealed in thin glass vessels, for ores, rocks, metals and substances of any shape or form.
  - A simple device prevents escape of steam at the top of the Calorimeter.
  - See “ Proceedings of the Royal Society ” (1889), xlvii., 218, also " Watson’s Text-Book of Practical Physics.”
  - ................................. .............................£10 10 0
  - (Price varies according to the market price of Platinum.)
  - ................................. ............................£450
  - B. Steam Boiler for ditto
  - (Fully described in Edser’s ” Heat for Advanced Students,” and other well-known text-books.)
- p.470 - vue 489/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 471
  - w. & ; j. george; (London), Ltd., proprietors.
  - CALORIMETERS FOR FUEL TESTING
  - 3314.—The Lewis Thompson Calorimeter.
  - In the “ Lewis Thompson ” Calorimeter the fuel to be tested is burnt by combined Oxygen in a small metal diving bell, under the surface of a known weight of water, and the increase in temperature of the water gives the necessary data for the calculation of the calorific value of the fuel. As supplied for commercial purposes, the instruments are graduated for use with the Fahrenheit thermometer, and consequently the latent heat of steam is taken as 967. It follows, then, that if a unit weight of fuel is burnt under the surface of 967 unit weights of water, and if all the heat is imparted to the water and raises it i°, the same amount of heat would have converted a unit weight of water at 2120 Fah. into steam at the same temperature. Two grammes of the fuel in a finely divided condition are mixed with eleven times the weight of a finely powdered mixture of three parts potass chlorate to one of potass nitrate, and the mixture is pressed, a little at a time, into a small copper crucible. A small piece of wick, soaked in potass nitrate, is fixed into the upper surface of the charge, and the crucible is then placed in the combustion chamber, being held in position by means of a brass plate to which three clutch-springs are fitted. After igniting the fuse, the whole apparatus is plunged into the cylinder, which contains 967 x 2 = 1934 c.c. of water at a known temperature.
  - The mixture ignites, and the fuel burns at the expense of the combined oxygen present in the potass chlorate and nitrate, whilst the products of combustion bubble up through the water, escaping through small holes in the
  - base of the chamber. When combustion is complete, the water is admitted to the chamber by opening the tap in the tube of the chamber, and the water is well agitated by raising and lowering the apparatus several times.
  - The apparatus is then withdrawn, and the temperature of the water taken with the thermometer ; 10 per cent, is added to the number obtained as the difference between the initial and final temperatures, to allow for heat absorbed by the apparatus, radiation, etc., and the total is looked upon as giving the number of unit weights of water which a unit weight of the fuel would evaporate. As an example :—
  - Temperature of water before combustion = 62° Fah.
  - ,, ,, ,, after = 75° „
  - Rise in temperature .. 13
  - Add 10 per cent. • • i-3
  - Evaporating power •• 14:3
  - Therefore, as a gramme of the fuel will evaporate 14-3 c.c. of water, 1 lb. will evaporate 14-3 lb.
  - (Vide “Liquid and Gaseous Fuels,” by V. B. Lewes.)
  - A. Price, complete in polished mahogany case, consisting
  - of combustion cylinder, with separate spring clutch, base, 6 cylindrical copper furnaces, 2 short ditto, glass water cylinder, thermometer, balance and weights, iron mortar and pestle, sieve, oxygen mixture, etc., with instructions for use ... each £7 15 0
  - B. As above, but with cheap scales instead of balance—
  - each £6 5 0
  - 3315.—The William Thomson Calorimeter.
  - This apparatus is similar to the Lewis Thompson Calorimeter, No. 3314, but is designed for burning a weighed quantity of fuel in a platinum crucible under water, by directing a slow stream of oxygen from a gas-holder or compression-cylinder upon it.
  - The oxygen passes down the vertical tube, which contains the Stopcock. Wire-gauze baffle-discs are seen around the combustion-chamber ; these serve to break up the escaping gaseous products into small bubbles, and thus to cause them to be more completely cooled by the water.
  - The apparatus is immersed in water contained in a glass beaker, which is again surrounded by a metal vessel with a glass slip let into its side. The fuel is then kindled by means of a small fuse, as has been already described, and the oxygen stream is started by opening the tap as soon as the chamber containing the kindled fuse has been lowered into the water.
  - See Clowes & Coleman’s “Quantitative Chemical Analysis,” 1909 edition (J. & A. Churchill).
  - A. Price, not including platinum crucible .. .. .. .. .. .. £2 2 6
  - B. Price, including platinum crucible.. .. ... .. .. .. .. 5 10 0
  - (Price varies according to the market price of platinum.)
  - 33i5
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.471 - vue 490/555
- - 472 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - THE ROLAND WILD CALORIMETER
  - 3317
  - 3316. —Roland Wild Calorimeter, complete, with sensitive
  - Fahrenheit Thermometer (40 to 1000 in TlD-ths), nickel wire, certificate of water value and instructions 6541 .. . . .. .. £6 7 6
  - 3317. —Roland Wild Calorimeter, improved form for electrical
  - firing and mechanical stirring, as illustrated, with sensitive Fahrenheit Thermometer (40 to ioo° in roths), nickel wire, certificate of water value and instructions 6542 .. .. .. . . . . ..£850
  - It may happen that the intending user has no apparatus for crushing and drying the coal and weighing the amount of coal and sodium peroxide it is necessary to place in the Calorimeter and for measuring the water to be placed in water vessel. We therefore provide :—
  - 3318. —Calorimeter No. 3316, together with balance of novel
  - design in case and made with two special weights, one for the coal and one for sodium peroxide. For drying the fuel a well-made copper oven with gas burner or spirit lamp is provided. In addition there are mortar and pestle, camel hair brush, tweezers, watch glass, sieve, scoop and 1,000 c.c. glass water measuring vessel 6543 .. .. £13 5 0
  - 3319. —Set of Apparatus, but with the Calorimeter No. 3317, or
  - arranged for electrical firing and mechanical stirring 6544 £15 15 0
  - 3320.—Clement and Desormes* Apparatus for Determining the Ratio of the Specific Heats for Air. 6554
  - Price, complete as figured .. .. .. £6 10 0
  - (See Edser’s " Heat for Advanced Students.”)
  - 3321.—Clement and Des-ormes’ Apparatus for Determining the Ratio of the Specific Heats for
  - Air. See McEwen’s "Properties of Matter ” (Longmans, Green & Co.).
  - Price............£5 17 6
  - 3320
  - Our Balances and Weights have achieved World-wide Reputation vide Opinions of the
  - Leading Scientific Press.
- p.472 - vue 491/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 473
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - APPARATUS FOR SPECIFIC AND
  - 3322.—Apparatus for determining the Ratio of the Specific Heats for Air. 6556
  - This apparatus consists of a glass flask A, about 30 cm. in diameter, which is placed inside a wooden box and packed round with cork dust, cotton wool, or other bad conductor of heat. The neck of the flask is closed by a well-fitting rubber cork, which is pierced by three holes through which pass three glass tubes. One of these, E, is closed by a tap, another, F, is attached to a manometer G, while the third, C, is of at least 1 cm. in bore, and is connected by a short length of wide bore rubber tubing with the mercury reservoir H. This rubber tube can be closed by a pinchcock I. Two small shelves, / and K, are attached to the side of the box, and each has a slot of such a size as to allow the flange on the neck of the reservoir H to catch.
  - The quantity of mercury in the apparatus is so adjusted that when the reservoir is on the lower shelf, K, the surface of the mercury in the flask covers the cork to the depth of about 1 cm. A small quantity of concentrated sulphuric acid is then introduced through the tube E, so as to form a layer, L, on the surface of the mercury.
  - This sulphuric acid serves to keep the air within the flask dry, a matter of great importance. Some oil, such as is used in the Fleuss pump, is introduced into the manometer tube, and the apparatus is then ready for use.
  - To perform an experiment in which the air is suddenly compressed, place the mercury reservoir on the lower shelf, and open the pinchcock and the tap E. Then close the pinchcock, and raise the mercury reservoir on the upper shelf. After allowing the apparatus to stand for a few minutes, so that the temperature of the air in the flask may become uniform, close the tap E. Then open the tap, F, on the thermometer, and fully open pinchcock, thus allowing the mercury to flow into the flask and compress the air. Watch the manometer, and as soon as the reading is a maximum, close the tap F. By this preliminary experiment the liquid in the manometer has been adjusted almost to the position which it will occupy at the end of the compression. Leaving F closed, lower the mercury reservoir and allow the mercury to run out from the flask, close the pinchcock, and raise the reservoir on to the upper shelf. Open the tap E and allow the apparatus to stand for a few minutes, then close E. Next open the pinchcock, and when the mercury has nearly all run into the flask, open the tap F, and carefully note the highest reading given by the manometer. If the preliminary adjustment of the manometer has been properly performed there will only be a small movement of the column, and the maximum reading will be obtained 'without oscillations being set up.
  - As the heat developed owing to the compression of the air is dissipated, the pressure will fall and the reading of the manometer when this fall is complete, which will occur after three or four minutes, must be recorded.
  - Price, without mercury .. .. .. . . .. .. .. .. .. .. .. .. £8 5 0
  - Further details are given in Watson’s “ Text-Book of Practical Physics ” (Longmans, Green & Co.), and McEwen’s “ Properties
  - of Matter ” (Longmans, Green & Co.).
  - LATENT HEAT
  - 3323.—Andrews’ Calorifer, for determining the Specific Heat of Liquids. 6558
  - The total length of this instrument is about 30 cm. The two small bulbs are about 6 mm. in diameter. On the stem there are two marks which are about 9 cm. apart. The calorifer is suspended in a metal vessel and heated until the mercury stands some distance above the upper mark, then if the instrument is immersed in a known weight of water the heat given out by the mercury in falling from the higher to the lower mark can be definitely determined. By immersing the calorifer in a known weight of any other liquid the specific heat of the liquid can be calculated.
  - Price ...........................£17 6
  - (Further details are given in Robson’s “ Practical Exercises in Heat.”)
  - 3324.—A pparatus for determining the Latent Heat of Steam, consisting of calorimeter (as No. 3304), stirrer, condensing vessel, wooden support, and flask fitted with cork and tube 6563 .. .. 15/-
  - (See Schuster & Lees’ “ Intermediate Course of Practical Physics.”)
  - 3325. —Glass Steam Trap, for Latent Heat of Steam Experiments.6566
  - Each .. .. .. 1 /-
  - 3326. —Glass Steam Trap, for Latent Heat of Steam Experiments.6565
  - Each................1/6
  - 3324
  - 3325
  - 3326
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.473 - vue 492/555
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  - APPARATUS FOR SPECIFIC AND LATENT HEAT
  - 3327.—Apparatus for the determination of the Specific Heat of a Liquid by Cooling. 6559
  - This apparatus consists of two aluminium calorimeters, each 2 in. x | in., and fitted with a rubber cork carrying an accurately gradu-a t e d thermometer. These calorimeters are placed inside a zinc trough, resting on four supports, which are fixed to an outer zinc vessel. The latter is provided with a 3327 wooden lid, lined
  - on the inside with
  - felt or leather, and through which the two thermometers are passed. The space between the zinc vessels is filled with water, or better, lumps of ice.
  - A. Price, complete, without thermometers £12 6
  - B. ,, ,, with two accurately graduated
  - thermometers, —io° to -j- 50° C. £1 11 6
  - (Full directions for use are given in Robson’s “ Practical Exercises in Heat.”)
  - Fig. A
  - Fig. B
  - 3328.—Apparatus for the determination of Specific Heats by the Methods Of Mixtures, as described in Schuster & Lees’ “ Intermediate Course of Practical Phy-sics” 6567 Each
  - A. Steam Heater, Fig. A ...................5/-
  - B. Calorimeter (without thermometer) Fig. B. 5/6
  - 3329.—Berthelot’s Apparatus
  - for determining the Latent Heat of Steam. 6560
  - In order to avoid the possibility of partial condensation taking place before the steam enters the calorimeter, Berthelot used the apparatus shown in the illustration. - The water or other liquid of which the latent heat is required, is boiled in a glass flask heated by means of a ring burner placed beneath it.
  - The vapour formed is carried down through the heated liquid by way of a vertical tube, the upper orifice of which is above the surface of the liquid. After leaving the flask the vapour traverses a spiral tube immersed in water in the calorimeter. The liquid condensed in the tube is collected in the enlarged bulb at the bottom of the spiral, which communicates with the atmosphere by means of the tube on the right-hand side. The calorimeter is protected from the reception of heat from external bodies by means of a water-jacket, whilst the direct communication of heat from the ring burner is prevented by a slab of wood covered with wire gauze.
  - Berthelot’s determination resulted in a value for the latent heat 'of steam equal to 536-2 therms, per gramme.
  - A. Price, not including thermometer .. .. £4 15 0
  - B. Extra glass vessel and spiral .. .. .. 0 15 0
  - (See Edser’s “ Heat for Advanced Students.”)
  - 3329
  - 3330.—Gunther's Apparatus for determining the Latent Heat of Steam. 6564
  - Steam heater and Calorimeter with a few additional fittings, can be used for finding the latent heat of steam with a degree of accuracy hitherto unattainable, except by somewhat expensive apparatus.
  - Gunther’s steam heater is converted into an apparatus for supplying dry steam by passing steam from the flask of boiling water simultaneously through the inner and outer tubes. Should any steam condense in the inner tube it cannot reach the calorimeter owing 333°
  - to the arrangement of tubes a b shown in the figure. To secure the best results steam should be first passed through both vessels for some time in order that the inner tube may become thoroughly hot. The steam enters the calorimeter through a short length of copper tubing, b, extending a couple of inches beyond the heater. This part of the tube is entirely surrounded by a cork, c, to prevent condensation of steam. The steam is condensed, not in the calorimeter, but in a thin-walled copper tube. This tube (d) fits into a wooden lid, e, specially constructed to hold it in such a position as to fit centrally into the outer copper vessel of Gunter’s calorimeter. The lid is provided with holes for the thermometer and a stirrer, /, of the pattern shown.
  - A. Price of the complete apparatus, including thermometer,
  - as figured ............................£2 5 0
  - B. Ditto, without retort stand, clamps, flasks and thermometer
  - £1 12 6
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.474 - vue 493/555
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - STEAM HEATERS
  - 3331. —Copper Vessels, for use as Steam Boilers, best
  - make, with inlet and outlet tubes and water gauge as figured. 6571
  - A. i litre capacity . . each 12/-
  - B. 2 „ . . „ 15/6
  - C. 3 „ „ 18/6
  - 3332. —Vessels for use as Steam Boilers.6570
  - Each.
  - A. Made of stout tin, i litre capacity v-
  - B. „ ,, ,, ,, 2 „ 1/3
  - C. ,, ,, ,,copper^- ,, ,, 7/6
  - D. ,, ,, „ ,, i „ 10/6
  - E. ,, ,, ,, ,, 2 ,, 13/6
  - 3331
  - 3333.
  - Jacketted Steam Heaters.6569
  - Each.
  - A. Made of tin 6/6
  - B. „ „ brass 12/6
  - 3334.—Zinc Steam Heater,
  - 3 in. diam. x 7 in. deep, fitted with wide cork carrying a i in. • stout test-tube, and a bent tube as figured. The water in the can should not reach to the bottom of the test-tube. In pouring the body into the beaker, grasp the can with a cloth, and tilt the can so that the bent tube points upwards {vide “ A Second Year’s Course in Practical Physics,” by James Sinclair, M.A., B.Sc.).6568.
  - Price.....................3/9
  - 3332
  - 3335.—Steam Heater,
  - consisting of a hollow copper cylinder io in. X 2 in., surrounded by a metal steam jacket, the outside diameter being 3! in. The inside cylinder is closed at the top with a cork through which the thermometer passes. The lower end is closed with a hinged metal disc which can be moved on one side when it is desired to drop the body into the calorimeter. 6572
  - Price, without thermometer 15/-
  - 3336. —Steam Heater, new pattern, with an inner sliding tube arrangement whereby the substance can be run directly into the calorimeter without any loss of heat {vide “ Second Year’s Course in Practical Physics,” by James Sinclair, M.A., B.Sc.). 6674
  - Prices, without thermometer—
  - A. With brass slanting tube and tinned iron steam jacket—
  - each 9/6
  - B. Ditto, but with copper steam jacket .. ,, 15/-
  - C. Ditto, but with two brass slanting tubes and copper steam
  - jacket, allowing of two lots of substances being used at the same time .. .. .. .. each 22/-
  - 3337. —Various Substances, above 6 mm. x 6 mm., for use with above steam heater. 6575
  - A. Iron .. per lb. 1 /8 D. Zinc .. per lb. 3/6
  - B. Lead .. „ 1/8 E. Copper .. „ 4/-
  - C. Brass .. „ 3/6 F. Aluminium „ 5/6
- p.475 - vue 494/555
- - 476 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MECHANICAL EQUIVALENT OF HEAT
  - 3338.—Searle’s Apparatus for determining the Mechanical Equivalent of Heat. 6582
  - This apparatus consists of a machine with a vertical spindle carrying on its upper end a brass cup. In the hollow of this cup is fitted a ring of ebonite, and in this ebonite ring a hollow truncated cone of brass fits tightly. Inside this truncated cone another cone fits, and this second cone is furnished with two steel pins which fit
  - in two holes in a wooden disc. In working the machine the wooden disc prevents the inner cone revolving when the spindle and the outer cone revolve. The mechanical energy supplied is converted into heat by the friction between these two cones. An iron weight placed on the wooden disc gives — the nee(ied pressure between
  - 3338 ^ the two cones.
  - A brass wheel on the spindle, and a leather band working round this wheel and the hand wheel, imparts motion to the machine. A speed counter (continuous registering) is fixed on the spindle above the wheel.
  - Outside the machine, on the left, a bent steel rod is placed. The top of this rod carries a small guide pulley, which is on the same level as the wooden disc. The pulley can be turned freely on its axis vertically. The fine string provided is fastened round the grooved edge of the wooden disc, and then over the guide pulley. A weight of about 200 grammes is suspended from the end of the string. Turning the hand wheel, the speed can be regulated so that the friction causes the weight to remain at a constant level. To keep the string from slipping it is passed through the eye in the guide. An eye is also fixed to prevent the weight being accidentally pulled round the wheel.
  - A thermometer is hung from a support so that it passes through the hole into the inner cone. A stirrer is also placed through this hole and around the thermometer. The outer surfaces of the cover should be perfectly clean, and should have a few drops of oil upon them. All bearings should be kept well oiled.
  - The cones, when cleaned and oiled, are weighed, also the stirrer. The inner cone is then filled with water a little below the temperature of the atmosphere. The cones are then again weighed. One operator manipulates the driving wheel, and another the machine. The water is warmed till it is the same temperature as the room, the experiment then being made.
  - Price, complete as figured . .. .. .. .. .. .. .. .. .. .. .. .. £8 12 6
  - 3339.—Callendar’s Apparatus for the determination of “ J,” the Mechanical Equivalent of Heat. Accuracy obtainable, 0-5%. Time for an experiment, 10 minutes. The apparatus is simple, and a complete experiment can be quickly carried out during a lecture.6583
  - A. Callendar’s Apparatus for Determining the Mechanical Equivalent of Heat.
  - Complete with thermometer (range 10-30° C.)* and two silk belts (one being a spare), but without motor. (Total net weight — 44 lb.)—
  - £16 15 0
  - B. Callendar’s Apparatus complete as in form A, but with the addition of a
  - no volt f D.C. motor mounted on base with reduction gearing, double pole switch and fuse, and driving belt, as illustrated. (Total net weight = 69 lb.) .. .........................£32 10 0
  - C. Spare Silk Belt .. .. . . .. .. .... .. 8/6
  - D. Spare Thermometer 10-30° C., divided every 0-2° C., special bent pattern
  - for use with above .. . . .. . . . . .. .. 10/6
  - E. Spare bent pattern thermometer, range 25-450 C., suitable for hot climates
  - 10/6
  - For full description and instructions see page 991 of our Physical Apparatus Catalogue, 1913 .Edition, also McEwen’s “ Properties of Matter ” (Longmans, Green & Co.).
  - * This is the range of thermometer we usually supply, although, for use in hot countries such as India, we can supply instead a higher range instrument.
  - -1 Motors for other voltages can be supplied, though usually a slight extra charge will have to be made in such cases.
  - Oup Stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.476 - vue 495/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 477
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - VARIOUS APPARATUS FOR HEAT EXPERIMENTS
  - 3340.—Long Cardboard Tube, with
  - cork at each end for students’ use. 6584
  - Instructions for Use.—(a) Take the cardboard tube, which is about a metre in length and 5 cm. in diameter. Fit the two ends with tightly fitting corks and place inside the tube about a pound of leaden shot. Note the temperature of the shot (ti0).
  - (b) Now place the tube vertical and quickly give it half a turn so that the other end comes uppermost. Repeat this ioo times quickly, take out the pellets, and note the temperature (t2°).
  - The kinetic energy of the pellets acquired by falling is suddenly transformed into heat on reaching the bottom of the tube.
  - Price .. .. .. .. .. 1 /3
  - (See “Robson’s Practical Exercises in Heat.”)
  - 3341.—Copper Tube and Pair Of Oak Boards, for boiling water
  - by friction. 6585
  - The small copper tube is fixed on a small wheel.
  - The tube, three
  - parts full of water, is closed by a cork, and is pressed between a pair of oak boards, while the wheel is rotated very rapidly. The water quickly becomes heated by the friction, and its temperature soon exceeding the boiling point, the cork is projected to a height of several yards by the pressure of the steam.
  - Price of copper tube and oak board-, without whirling table .. 8/S
  - 3342.—Pneumatic Fire Syringe. 6686
  - See McEwen’s “ Properties of Matter.” Longmans, Green & Co.
  - This apparatus consists of a glass tube with thick sides, closed hermetically by a leather piston. At the bottom of this there is a cavity in which a small piece of cotton, moistened with ether or bisulphide of carbon, or a small piece of German tinder, is placed. The tube being full of air, the piston is suddenly plunged downwards ; the air thus compressed disengages so much heat as to ignite the cotton, which is seen to burn when the piston is rapidly withdrawn. The compression is adiabatic. The heat does not escape through the thick, badly conducting glass walls. The ignition of the cotton in this experiment indicates a temperature of at least 300 °.
  - The rise of temperature produced by the compression in the above experiment is sufficient to effect the combination, and therefore the detonation, of a mixture of hydrogen and oxygen.
  - A. Large size, with thick-walled glass barrel as figured each £1 17 6
  - B, Small size, with brass barrel .. .. .. .. ,, 0140
  - 3343.—German Tinder, for
  - use with pneumatic fire syringes6587
  - Per box.. .. .. .. 6d.
  - 3344
  - 3344. — Hero’s Steam Engine (Eolipile).
  - This instrument is mentioned by Hero in his “ Spiritalia seu Pneumatica,” written 130 years B.c. It consists of a globular-shaped glass vessel provided with two S-shaped horizontal pipes. The apparatus is filled with water and then heated over a spirit lamp. When the water boils, the steam rushing out strikes against the atmosphere, and the recoil causes the apparatus to revolve with great rapidity. This is in fact a direct-action rotary steam engine, and undoubtedly the earliest mechanical result achieved by steam power.
  - Price, complete, as figured 6588 .. 6/6
  - 3345.—Dr. Wollaston’s Atmospheric Engine.
  - A glass tube with a bulb to hold water is fitted with a hollow piston which is closed by a screw at the top. This screw is loosened to admit the escape of the air. The water is boiled over a spirit lamp or Bunsen burner. When the steam issues freely from the open end of the rod, the screw is tightened, and the pressure of the steam then raises the piston to the top of the tube, the experimenter withdraws the apparatus from the burner, the steam is condensed, and the air pressing on the top of the piston forces it down again ; when the operation may be repeated by again bringing it over the burner. 6589
  - Simple form, all glass, with brass spring holder as figured .. price 4/-
  - 3346.—W iede-mann’s Apparatus, to illustrate the phenomena of geysers.6590
  - In this apparatus the glass tube A represents the funnel of the geyser, the gas flame the internal source^of heat in the earth, and the side tube B leading to the water bottle represents the fissure or crevice through which cold water from the surface reaches the lower end of the geyser.
  - After regulating the gas flame the eruptions repeat themselves at regular intervals without alteration in the apparatus .. .. .. .. £6 10 0
  - 3346
- p.477 - vue 496/555
- - 478 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RADIATION, REFLECTION AND ABSORPTION
  - 3347.—Set of
  - 3 L e s I i e’s C a n i sters,
  - one having two sides painted dull black, one with all sides polished, and the other with all sides painted dull black. Size 15 cm. square. 6602
  - Per set .. 5/6
  - 3348.—Leslie’s Cubical Tin Canister, one side being black, one bright, one covered with paper, and one made rough. Size 15 cm. square 6603 .. .. each 2/-
  - 3348
  - 3349.—Leslie’s Tin Canister, all sides polished, 15 cm. square16604 .. .. each 1/9
  - 3350
  - 3350.—Tin Vessel to prove that the intensity of the radiation at a point, due to a given source, is inversely proportional to the square of the distance of the point from the source. 6605
  - This vessel measures about 50 cm. x 50 cm. x 10 cm. One face is dead-blacked. Full instructions for use are given in Glazebrook’s Elementary Text-book on “ Heat.”
  - A. Size as above .. .. .. each £14 0
  - B. Smaller size, 30 cm. x 30 cm. x 4 cm. „ 0 13 6
  - 3353
  - 3353.—Set of Five Cast-Iron Balls, as
  - used in experiments on reflection of radiant energy. These balls weigh respectively 4, 2, 1, | and £ lb. 6609 Per set .....................' .. .. 7/6
  - 3351.—Wire Pyramid for demonstrating that the intensity of the radiation at a point due to a given source is inversely proportional to the square of the distance of the point from the source.6606
  - Price .. .. .. .. .. .. .. .. 6/-
  - 3352.—D 0 u b I e- '' Becker .London & EJ'ham. ^ I
  - riveted opaque , I l
  - screen, to show that
  - radiant heat travels in i
  - straight lines, consist-
  - ing of two screens j
  - riveted together and '
  - having an air space
  - between them. 6607 i
  - Price .. .. 9/6 A
  - & 0 |
  - 3354.—Ether Thermoscope, consisting
  - of two bulbs, connected by means of a glass tube, the internal space (which contains a quantity of coloured ether), being exhausted of air. The liquid ether acts as a pressure indicator, whilst its vapour
  - fills the two bulbs. The lower bulb is blackened,
  - and when radiations are absorbed by it, a large expansion of the ether vapour is produced. 6608
  - Each .........................................3/6
  - 3354
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.478 - vue 497/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 479
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RADIATION, REFLECTION AND ABSORPTION
  - 3355.—Copper Balls, as used
  - in experiments on reflection of radiant energy. 6610
  - A. Weight 2 lb. .. each 8/-
  - B. Weight 4 lb. .. „ 12/-
  - 3356.—Ad j u stable Metal Stands for
  - holding iron and copper balls. 6611
  - Each
  - 3357.—Iron Cradles
  - for supporting tin tubes, see No. 3358. 6612
  - Each............3/9
  - 3358.—Apparatus to show that Thermal Radiations are reflected from Polished Metallic Surfaces, and obey the same laws as light. 6613
  - Two tin-plate tubes, of about 3 in. diameter and 30 in. long, together with a sheet of polished tin-plate supported in a vertical plane on a suitable stand, are required for this experiment, in addition to the iron ball and the ether thermoscope. Support the tubes in a horizontal plane, so that they are inclined to each other at about 120°, as shown in the illustration. Place the heated ball and the thermoscope in position, the sheet of tin-plate being removed. No appreciable effect will be produced on the thermoscope. Now place the sheet of tin-plate in position, and rotate it till the thermoscope shows the greatest effect. This will occur when the two tubes are equally inclined on opposite sides of the normal to the square sheet of tin. (See Edser’s “ Heat for Advanced Students.”)
  - A. Square sheet of polished tin-plate on stand—
  - each 5/-
  - B. Pair of tin tubes 30 in. X 3 in. .. per pair 8/6
  - C. Four stands for supporting ditto (see No. 3357)—
  - each 3/9
  - D. Iron ball weighing 4 lb. .. .. .. „ 3/6
  - E. Stand for ditto (see No. 3356) .. .. ,, 5/6
  - F. Ether thermoscope (see No. 3354) • • ,, 3/6
  - G. Polished mahogany holder for ditto .. „ 12/-
  - 3359.—Apparatus to Prove that Different Surfaces have Different Absorbing Powers, and to compare their Values. 6614
  - This apparatus, which is more fully described in Glazebrook’s Elementary Text-book “Heat,” consists of two sheets of tin on suitable stands, one coated with lampblack, the other bright. To the centre of the back of each sheet, a piece of bismuth is soldered, and wires are led away to a galvanometer. The plates are connected by a wire at the top and are placed opposite to each other at some 50 or 60 cm. apart.
  - Between the plates a source of radiation such as the hot copper 3359
  - ball, or a gas jet, is placed. A thermo-electric junction is formed by the contact of the bismuth and the tinned iron, and if the junctions on the two sheets be unequally heated a current is produced, and the galvanometer needle deflected. If the ball be midway between the sheets, the temperature of the blackened sheet is raised very considerably above that of the other ; in order that no current may be produced the source must be very considerably nearer the bright sheet. The blackened surface absorbs a much greater proportion of the incident radiation than the bright, and by measuring the distances of the ball from the surfaces when there is no current, squaring these and taking their ratio, a rough estimate of the absorbing power can be obtained.
  - A. Price of Screens on supports as figured—
  - per pair 11/-
  - B. Price complete with iron ball on stand .. 19/6
  - C. „ „ „ copper ball on stand .. 27/6
  - 3360.—Pair of Screens,
  - 10 in. square, made of tin-sheet, one with bright surface and the other dull blacked, and each having small ledge at back upon which to place piece of phosphorus. 6615
  - 3361. —Dead-Black Tin Screen, with hole in
  - centre and mounted on heavy stand 6616 .. each 6/6
  - 3362. —Steam Radiator, 4 in. in diameter, one side
  - dead-blacked. 6617 '
  - Per pair
  - 117-
  - Price on heavy foot as figured
  - 15/-
  - ^62
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.479 - vue 498/555
- - 480 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - RADIATION, REFLECTION AND ABSORPTION
  - 3363.—Ritchie’s Apparatus to show that the Absorbing and Emissive Powers of a Surface are Equal.6618
  - This apparatus consists of two cylindrical metal reservoirs full of air. Between them is a third and larger one which can be filled with hot water. The ends of B and of A, which face the right, are coated with lamp-black ; those of C and of A, which face the left, are either painted white, or are coated with silver-foil. Thus one of the two faces opposite each other is black, and the other white ; hence when the cylinder A is filled with hot water, its white face radiates towards the black face of B, and its black face towards the white face of C. In these circumstances the liquid in the stem does not move, indicating that the two reservoirs are at the same temperature. On the one hand, the greater emissive power of the black face of A is compensated by the smaller absorptive power of the white face of C ; while, on the other hand, the feebler radiating power of the white face of A is compensated by the greater absorbing power of the black face of B. (See Ganot’s “ Physics.”)
  - Price........................................ ................£3 10 0
  - Crooke’s
  - Radiometer.
  - A glass tube (Fig. A), with a bulb blown on it, is fused at the bottom to a glass tube which at one end serves to rest the whole apparatus in a wooden support. In the other end is fused a fine steel point. On this rests a small vane or fly, consisting of four arms of aluminium wire fixed at one end to a small cap, while at the others are fixed small discs or lozenges of thin mica, coated on one side with lampblack. The weight of Lthe fly is not more 'than two grains or *13 gramme. The e n-closed air is reduced by a mercury pump to any desired degree of rarefaction.
  - If a source of light or of heat, a candle for instance, is brought near the apparatus, the fly rotates slowly in a direction showing that the blackened side moves towards the light; this movement, indicating an attraction, depends on a certain state of rarefaction. If, however, the apparatus is connected with an arrangement which allows the pressure to be varied, the rotation of the fly gradually diminishes in rapidity as the air within is further rarefied, until a certain point is reached at which it ceases. If the rarefaction is pushed further, repulsion succeeds to attraction, and the blackened faces of the vanes move in the direction away from the source of heat. In a double radiometer, in which two flies are pivoted independently one over the other, having their blackened sides opposite each other, the flies rotate in opposite directions on the approach of a lighted candle. When a cold body, such as a piece of ice, is brought near, instead of a hot one, the rotations are reversed.
  - Fig. A.
  - Fig. B.
  - (The above details are taken from Ganot’s “ Physics.”)
  - 3364. —Simple Pattern, as Fig. A 6626—
  - each 8/6
  - 3365. — Double Pattern, with vanes rotating in opposite directions, as Fig. B 6627—
  - each 21 /-
  - 3366.—Thermopiles of Bismuth and Antimony,
  - with brass mount, ball and socket joint, support with rising adjustment and silver cone, guaranteed best make and finish. These piles are very carefully constructed from bars of antimony and bismuth connected up in series. The current proceeds from the bismuth to the antimony across the heated junction, the bismuth forming the positive. The insulation is very carefully attended to, and in use very great caution is required, the junctions being, from their nature, very brittle, and a fracture of any one of them renders the pile useless. The pile should be used with a very sensitive low resistance galvanometer, our
  - No. 2102 being specially adapted for the purpose. 4195
  - Cat. Reference.. .. A B C D
  - No. of Pairs .. 12 20 24 40
  - Price . . .. 70/- 90/- 100/- 120/-
  - Cat. Reference.. . . .. E F G
  - No. of Pairs .. . . 54 60 90
  - Price . . .. 140/- 155/- 190/-
  - Note.—Our Thermopiles are guaranteed to be the most sensitive instruments procurable. The warmth from the hand placed within a few inches of the junctions will cause a deflection of from 5 to 10 degrees on one of our cheap low resistance galvanometers. Cheaper and unreliable Thermopiles cannot be recommended^
  - 3367.—Astatic Galvanometers, specially.ma.de for use with thermopiles4196 .. .. .. .. .* each £1 12 6
- p.480 - vue 499/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 481
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - 3368
  - LANGLEY’S BOLOMETER
  - 3368.—Prof. Langley’s Bolometer.
  - The alteration which occurs in the electrical resistance of a platinum wire when the latter is heated has been utilised by Prof. Langley in the construction of an instrument which he has named the bolometer, or actinic balance. This instrument is designed to measure the heat produced by the absorption of light (or, more generally speaking, radiation) corresponding to various parts of the spectrum. The instrument itself consists of a couple of gratings, punched from very thin platinum foil, and covered with a layer of platinum black. The thickness of the foil used only amounted to mm. These gratings form two arms of a Wheatstone’s bridge, and the resistances in the remaining arms are so adjusted that, when both gratings are shielded from radiation, the galvanometer needle is undeflected. When radiation is allowed to fall on one of the'gratings, its resistance instantly increases, and a consequent deflection of the galvanometer occurs. A difference of temperature amounting to C. will produce a readable deflection. Using this instrument, Prof. Langley
  - was able to investigate the heat which reaches us from the moon. 6630
  - Price of the complete instrument mounted on brass upright with sliding rod .. .. .. £4 10 0
  - (See Edser’s “ Heat, for Advanced Students.”)
  - DIFFERENTIAL AIR THERMOMETERS
  - 3369. Front View.
  - 3369. Back View.
  - 3369.—Differential Air Thermometer,
  - “ Nivoc ” pattern, with movable bulbs.
  - This instrument is fitted with a special arrangement by means of which the height of the liquid in the tube can be adjusted to zero at will. The U-tube in the centre contains enough coloured water to fill each limb to a height of a couple of inches. Each limb is connected by a short piece of rubber tubing with a glass tube having a bulb at the end. If one of the bulbs—-say the left-hand one—be warmed, the air in it will expand and force the liquid column or index down in the left-hand limb in the U-tube and up in the right-hand limb. The differential air thermometer gives an easy and delicate means of finding whether there is any difference of temperature between two liquids. If there is any difference, the index moves downwards on the side nearer the warmer liquid; if both liquids are at the same temperature, the index remains at rest.
  - The cross-tube and stopcock are not absolutely necessary, but are useful for equalising the pressure in the two bulbs and levelling the index at any time. 6636
  - Vide “ Heat, Light and Sound,” by D. E. Jones, B.Sc. (Lond.). (Macmillan & Co., Ltd.). Price, complete .. .. .. .. .. .... .. .. £1 18 6
  - 337°
  - 3370.—Leslie’s Differential AirTher-
  - mometer, consisting of a U-shaped tube having two air bulbs and a crosspiece fitted with a well-ground-in stopcock in the centre; the whole mounted on a polished stand, graduated in mms. on one side. 6637
  - A. Price as figured 10/6
  - B. Ditto, but without stop-
  - cock and cross-piece— 5/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
  - HH
- p.481 - vue 500/555
- - 482 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS
  - THERMOMETERS
  - Thermometers, of Jena normal glass, narrow, for passing through corks. Scale
  - engraved on stems.
  - Each thermoneter in cylindrical case, for general laboratory work.
  - Cat. No. Range. How Divided. Price each. Price per doz. Cat. No.
  - 3371 — 10° to 110° C. single degrees 2/6 27/6 3371
  - 3372 0° to 200° C. single degrees 3/- 35/- 3372
  - 3373 — io° to 250° C. single degrees 3/3 37/6 3373
  - 3374 o° to 360°C. single degrees 4/6 52/- 3374
  - 3375 — 5° to 212° F. single degrees 3/- 35/- 3375
  - 3376 — 320 to 240° F. single degrees 3/3 37/6 3376 3377
  - 3377 + io° to 400° F. single degrees 3/6 40/-
  - 3378 o° to 6oo° F. every 2 degrees 4/6 52/- 3378
  - 3379 ! o° to 50° C. half degree 3/- 35/- 3379
  - 3380 — io° to iio° C. half degree 3/6 40/- 3380
  - 3381 0 O O m 0 +-> 0 0 H 1 half degree 4/6 50/- 3381
  - 3382 j o° to 5o°C. fifth degree 4/6 50/- 3382
  - 3383 — io° to iio° C. fifth degree 6/- 70/- 3383
  - 3384 + 50° to 150° C. fifth degree 6/- 70/- 3384
  - 3385 — io° to 50° C. tenth degree 5/6 60/- 3385
  - 3386 — 50 to iio° C. tenth degree 6/6 72/- 3386
  - THE NATIONAL PHYSICAL LABORATORY,
  - KBW OBSERVATORY. RICHMOND. SURREY
  - CERTIFICATE OF EXAMINATION.
  - Centigrade Thermometer—No. ................
  - by.....................JutrjautoLgyik-......................-.......-.......
  - (VERIFIED UNMOUNTED AND IN A VERTICAL POSITION.)
  - Corrections (to the nearest 0- / ) to be applied to the Scale Readings, determined by comparison with the Standard Instruments at the National Physical Laboratory, Richmond.
  - —O' S5 ... ... -/O f 70 .. .... —Q'0
  - —O' 40 ... ... -to / 75 ... .... —0-0
  - s-o «s ... ... -to / 80 .. .... —O'O
  - 50 ... ... —o'0 85 .. .... -o o
  - -to/ 55 ... ... -o o 90 ., .... -O O
  - -to/ 60 ... ... -O f 95 ... .... -to-/
  - -to/ 65 ... ... -0./ 100 ... .... -to-a
  - Note—I.—When the sign of the Correction is + the quantity noted is to be added to the observed scale reading, and when — to be subtracted from it.
  - II. —It is desirable that this instrument should be tested again after some time has elapsed, as Mercurial Thermometers are liable to read too high through age.
  - III. —The Correction attached to any temperature in the certificate applies only when the whole of the glass and the contained mercury possesses that temperature.
  - National ..Physical Laboratory,
  - ..1912.
  - iHl
  - Director*
  - l&UM
  - BEST BRITISH STANDARD THERMOMETERS FOR RESEARCH WORK HIGHEST QUALITY:
  - Scale engraved on stem for experiments requiring great accuracy.
  - Cat. No. Range. Divided to Each. Natl. Physl. Laboratory Certificate.
  - Points Tested. Extra.
  - 3387 — 30 + 30° C. •1° 14/- II 5/-
  - 3388 -5 + 55°C. •1° 14/- II 4/6
  - 3389 -5 + 55°C. *2° 12/- II 4/6
  - 3390 + io -f- 50° c. •1° 14/- 9 4/-
  - 3391 — io + iio° C. •2° 16/- 21 12/-
  - 3392 + 20 -j- 100° C. •2° 15/- 15 10/-
  - 3393 + 50 + 105° c. •1° 16/- II 8/-
  - 3394 + 5o + 1050 C. •2° 14/- II 8/-
  - 3395 + 70 + 130° C. •1° 16/- 7 14/-
  - 3396 + 80 + 150° c. •2° 17/6 7 14/-
  - 3397 + 100 -j- 210° C. •2° 22/- 6 15/-
  - 3398 -j- 140 + 210° C. •2° 22/- 7 15/-
  - 3399 + 200 + 300 ° C. •2° 25/- 6 22/-
  - 3400 - 5 + 155° C. •5° 20/- 8 14/-
  - 3401 - 5 + 205° C. •5° 21/- 9 15/-
  - 3402 0 + 250° C. •5° 21/- 6 18/-
  - 3403 0 -i- 3000 c. •5° 25/- 7 22/-
  - 3404 0 + 360° c. •5° 27/6 8 22/6
  - 3405 100 + 4000 C. *5° 35/- 7 30/-
  - 3406 + 100 -j- 500° c. i° 40/- 9 40/-
  - 3407 0 + 120° F. •2° 14/- 13 6/-
  - 3408 + 20 + 120° F. •5° 10/- 7 3/-
  - 3409 + 20 + 220° F. •5° 16/- 19 10/-
  - 3410 + 120 -j- 220° F. •2° 16/- 10 8/-
  - 3411 + 30 + 300° F. •5° 20/- 8 14/-
  - 3412 + 30 + 400° F. i° 20/- 10 21/-
  - 3413 + 30 + 600 0 F. i° 25/- 7 20/-
  - 3414 + 100 -j- 8oo° F. i° 40/- 8 27/6
- p.482 - vue 501/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 483
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - THERMOMETERS
  - 3415-3428 Paper Scale.
  - Thermometers of Jena normal glass, with paper scale enclosed in outer tube, outside diameter of the thermometer from \ in. to f in., each thermometer in cylindrical case.
  - Cat. No. Range. How Divided. Price each. Price per doz. Cat. No.
  - 3415 — 10° to + 110° C. single degrees 2/3 26/- 3415
  - 3416 0° to 200° C. single degrees 2/9 j 30/- 3416
  - 3417 — io° to + 250° C. single degrees 3/- 34/- 3417
  - 3418 o° to 360° C. single degrees 3/6 40/- 3418
  - 3419 o° to 150° F. single degrees 2/- 22/- 3419
  - 3420 — 5° to + 212° F. single degrees 2/3 26/- 3420
  - 3421 — 320 to + 240° F. single degrees 2/6 27/6 3421
  - 3422 + io° to + 400° F. every 2 degrees 2/9 30/- 3422
  - 3423 0° to 6oo° F. every 2 degrees 3/6 40/- 3423
  - 3424 — io° to + no0 C. half degree 3/- 34/- 3424
  - 3425 — io° to + 250° C. half degree 3/6 40/- 3425
  - 3426 o° to 250° C. fifth degree 5 /- 55/- 3426
  - 3427 — io° to + iio° C. fifth degree 4/6 50/- 3427
  - 3428 + 50° to + iio° C. fifth degree 4/- 45/- 3428
  - Thermometers, of Jena normal glass, with milk-glass scale
  - enclosed in outer tube, thermometer in cylindrical case. outside diameter of tube about f in., each
  - 3429 — io° to + iio° C. single degrees 2/9 30/- 3429
  - 3430 o° to 250° C. single degrees 3/9 j 40/- 3430
  - 3431 o° to 360° C. single degrees 4 /- | 46/- 3431
  - 3432 — 5° to + 212° F. single degrees 2/6 27/6 3432
  - 3433 — 320 to + 240° F. single degrees 3/- j 34/- 3433
  - 3434 + ro° to + 400° F. single degrees 3/6 40/- 3434
  - 3435 o° to 600° F. every 2 degrees 4/- | 46/- 3435
  - 3429-3435 Milk Glass Scale.
  - 3436.—Thermometers, of Jena normal glass, with both Fahrenheit and Centigrade scales, on strip of milk glass enclosed in outer tube, diameter f in.
  - A. 212° F. and CJ 0 0 H .. .. each 3/6
  - B. O 0 and 200° C. •• .. „ 4/-
  - C. 6oo° F. and 360° C. .. „ 5/6
  - 3437.—Special High Temperature Thermometers, of Jena normal glass, filled with nitrogen,
  - graduated on stem, enamelled backs, diameter about 6 mm.
  - A. o° C. to 360° C., in single degrees .. each 5/6 E. ioo° C. to 360° C., in half degrees .. each 11/6
  - B. „ „ 4oo°C., „ „ „ » 8/- F. -f- ioo° C. „ 400° C., „ single „ » »/-
  - C. „ „ „ „ half „ .. „ 9/6 G. o° C. „ 460°C., „ „ „ .. „ 12/6
  - D. -f- ioo° C. to 360° C., ,, single ,, „ 8/6
  - 3438.—Special Low Temperature Thermometers, of Jena normal glass, for liquid air experiments; calibrated with the greatest precision, graduated on stem, enamel backs.
  - Range ................... .. .. + 30° down to — 120° .. .. + 30° down to — 200° C.
  - Divided into ....................... single .. .. single degrees
  - Filled with .. .. .. .. .. Toluol .. .. Pentane
  - Price .............................. 15/- .. .. 28/6 each.
- p.483 - vue 502/555
- - 484 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEOROE (LONDON), Ltd., PROPRIETORS.
  - BECKMANN’S THERMOMETERS
  - Directions for handling Beckmann Thermometers when the upper mercury reservoir has become full.—First turn the Thermometer upside down, and then by lightly knocking the mercury bulb, let the mercury thread run forward so that it unites with the mercury in the reservoir. The Thermometer must now be very carefully placed in a slightly inclined position so that the mercury thread does not break but draws the mercury in the reservoir down with it; this treatment may probably have to be repeated several times. If, however, in spite of this, the mercury cannot be brought back out of the reservoir in this way, the latter must be slightly warmed and then treated as above stated.
  - 3439.—Beckmann’s Thermometers, of Jena normal glass, for the determination of molecular weights, milk-glass scale closed by metal cap at the top.
  - A. Range of scale, 50 to 6° in y^ths.............. .. .. each
  - B. ,, ,, i° in Tj^-jyths ..
  - C. „ ,, io° to 120 in sVths ..
  - D. ,, „ 250 to 30° in Aths ..
  - E. „ „ 50° to 6o° in TVths ..
  - 3440.—Beckmann’s Thermometers, of Jena normal glass, with auxiliary scale..
  - A. Ordinary pattern, range of scale 50 to 6°, divided into T^<yths ; extent of auxiliary scale-division,
  - — io° to + 1200 C. in t°............................................ • • each
  - B. Ditto, new form, shorter in length, and with smaller mercury bulb .. .. .. ,,
  - C. Ordinary pattern, range of scale 50 to 6°, divided into Aths ; extent of auxiliary scale,
  - — io° to + 1200 C. in t°..................................................
  - D. Ditto, new form, shorter in length, and with smaller mercury bulb .. .. .. ,,
  - 3441.—Beckmann’s Differential Thermometer, latest pattern, with fused-in absolute thermometer.
  - Range of scale of the differential thermometer, 50 to 6°, divided into TJ-()ths ; extent of auxiliary scale, — io° to + 120°, divided into -f0 ; range of absolute thermometer, — io° to + 120° in TVths .. .. .. .. each £3 3 0
  - £1
  - 1
  - £1
  - 1
  - 3442.—Powerful Magnifier, with electric lamp complete. Will fit any thermometer. All parts adjustable.
  - The electric lamp is fixed to the clamping arrangement and can be worked with a couple of dry cells.
  - Each ...............21/-
  - 3443. Powerful Magnifier,
  - for reading Beckmann thermometers. Each ..................12/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.484 - vue 503/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 485
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - WORKS THERMOMETERS
  - Thermometers for Chemical Works, having an outside diameter of about f in., and with bold paper scale, suitable for workmen’s use.
  - Catalogue Reference 3444 3445 3446 3447 3448 3449 3450
  - Range ioo° C. 250° C. 360° c. 212° F. 240° F. 400° F. 6oo° F.
  - Price, each 2/- 2/6 2/9 2/6 2/3 2/6 3/-
  - Thermometers, as above, but with bold milk-glass scale.
  - Catalogue Reference 3451 3452 3453 3454 3455 3456 3457
  - Range ioo° C. 250° C. 360° C. 212° F. 240° F. 4000 F. 6oo° F.
  - Price, each 2/6 3/- 3/6 2/6 2/9 3/- 3/6
  - 3458.—THERMOMETERS FOR USE IN FACTORIES.—We are prepared to quote very advantageous prices for all kinds of factory thermometers. Customers are requested to furnish us with details regarding the purpose for which thermometers will be used, also total length, range and length of stem.
  - ANSCHUTZ NORMAL THERMOMETERS
  - 3459.—Complete Sets of Anschutz Normal Thermometers, filled with nitrogen, milk-glass scale in velvet-lined case ; each set consists of the following seven thermometers, over which the complete range of — io° to 360° C. is distributed.
  - No. 1 Thermometer having a range of — 10° to 600 c.
  - „ 2 } 7 + 40° to no° C.
  - „ 3 77 + 90° to 1600 C.
  - „ 4 7) + 140° to 210° C.
  - „ 5 77 + 190° to 260° C.
  - „ 6 77 + 240° to 310° C.
  - » 7 + 290° to 360° C.
  - PRICES.
  - 3460. —Complete set, as above, graduated in single degrees and fitted in velvet-lined case .. .. £3 3 0
  - 3461. — „ „ „ half „ „ „ ....400
  - 3462. — „ „ „ fifth „ „ „ ....500
  - Thermometers, as above, may be had singly, prices as follows :—
  - Catalogue Reference 3463 3464 3465 3466 3467 3468 3469
  - Range (Centigrade) —io°to6o° +4o0tono0 +90°toi6o0 +i40°to2io° -f-1900 to 260° +240° to 310° -j-29o°to36o°C.
  - A. Price, divided in
  - single degrees 5/- 5/- 6/- 6/6 8/- 10/6 12/-
  - B. Price, divided in
  - half degrees 6/6 6/6 8/- 9/- 10/6 12/- 13/6
  - C. Price, divided in
  - fifth degrees 7/6 7/6 10/- 11/6 14/6 16/- 17/6
  - NORMAL THERMOMETERS
  - 3470.—Set Of three Normal Thermometers, with saddle fastening, length about 32 cm., graduated from — 200 C. to + 300° C. in |°, in velvet lined case. The complete range — 20° C. to+ 300° C. is distributed over the three thermometers. Price complete ... ..........£2 12 6
  - INCUBATOR THERMOMETERS
  - 3471.—Incubator Thermometers, with long stem and milk glass scale.
  - A. io° to 50° c. in v .. .. .. .. .. .. .. .. .. .. .. .. .. each
  - B. io° to 8o° C. in ............................................................
  - C. 20° to ioo° C. in |°.. .. ................................................... ”
  - Thermometers of every description supplied. Write for quotations.
  - 8/-
  - 9/-
  - 10/-
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - 486 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1 .
  - w. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BOXWOOD SCALE THERMOMETERS
  - 3472. — Thermo-
  - meters, square-edged boxwood scale, for hanging on walls.
  - Each .. ..1/6
  - 3473.—D o u b I e Scale Thermometers, highly finished, bevelled boxwood, with both Centigrade and Fahrenheit scales.
  - Each .. ..3/6
  - 3474.—Set of 3 Ther-mometers, Centigrade, Fahrenheit, and Reaumur scales respectively, mounted on polished boxwood back for hanging on wall.
  - Each.................12/6
  - 3475.—Set of 3 Ther-mometers, cheaper make, showing Centigrade, Fahrenheit and Reaumur scales, mounted.
  - Each .. .. .. 6/6
  - 3474
  - MAXIMUM THERMOMETERS
  - (For Minimum Thermometers, see next page.)
  - The self-registering maximum thermometer is used by observers to register the extreme heat during the day. It is usually placed in a Stevenson’s screen, together with the minimum thermometer and the hygrometer. If a screen is not available, a board with a sloping top, to screen from sun and rain, will be found useful. The observation is usually taken at 9 a.m. every morning, when the thermometer is also reset. To reset, hold the top of the thermometer by the right hand and give it two or three gentle swings of the arm, which will cause the column of mercury to descend to its starting point.
  - 3476.—Thermometers, maximum, self-registering, boxwood scale, 8 in. .. .. . • each 3/-
  - 3477 .—Ditto, io in........... „ 3/9
  - 3479.—Maximum Thermometer, better
  - quality, boxwood scale, 8 in. .. .. each 6/-
  - 3480 ,—Ditto, io in.......................... „ 7/6
  - 3478.—Standard Maximum Thermometer,
  - self-registering, engine-divided on stem, and figured on opal scale, mounted polished mahogany or oak back.
  - £110
  - 3481.—Maximum Thermometer, self-registering, engine-divided on stem, and figured on opal scale, mounted on polished mahogany frame, as No. 3478, but smaller size ....................... 15/-
  - Evsry requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.486 - vue 505/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 487
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - MINIMUM THERMOMETERS
  - The self-registering minimum thermometer is used by observers to obtain the extreme of cold during the night. It is usually suspended with the bulb end, slightly inclined downwards, in the Stevenson’s screen, with the maximum and the hygrometer. If a screen is not available it may be suspended on a board with sloping top to shelter from sun and rain.
  - The observation is usually taken at 9 a.m. every morning, and the index is reset at the same time. To reset the index, lift the bulb end of the thermometer and allow it to run to edge of the spirit in the tube ; thus set, the instrument may be replaced in its horizontal position.
  - 3482. —Thermometer, minimum, self-registering,
  - boxwood scale, 8 in., as figured .. .. each 2/9
  - 3483. —Ditto, 10 in. .. .. .. .. „ 3/6
  - 3484.—Thermometer, minimum, better quality, boxwood scale, 8 in. as figured .. • .. each 4/6
  - 3485 .—Ditto, 10 in... .. .. .. 7/-
  - 3486. Standard Minimum Thermometers,
  - self-registering, engine-divided on stem, and figured on opal scale, mounted on polished mahogany or oak back................................£110
  - 3487.—Minimum Thermometer, standard pattern, self-registering, engine-divided on stem, and figured on opal scale, mounted on polished mahogany frame, as No. 3486, but cheaper make .. 15/-
  - COMBINED MAXIMUM AND MINIMUM THERMOMETERS
  - 3488.—Thermometer, combined maximum and minimum, 10 in. scales .. .. .. each 17/6
  - 3489.—10 in. Window or Bracket Six’s Thermometer, mounted on oak or mahogany board, opal scale and plain figures, with magnet.
  - Each ....... ................£17 6
  - 3490.—Six’s Self-Registeri ng Maximum and Minimum, boxwood, in well-finished japanned tin frame, complete with grooved magnet, 8 in.
  - Each .. ..6/6
  - 3490a .—Ditto, 10 in.
  - Each .. ..9/6
  - 3491. — Combined Standard Maximum and Minimum Thermometers, self-registering,
  - Six’s principle, engine-divided on stems, and clearly figured on opal scale, in white metal case with magnet, verified at Kew, 10 in., £1 17s. 6d. ; 12 in., as illustration, £2 17s. 6d.
  - For HYGROMETERS, DIFFERENTIAL AIR THERMOMETERS, BECKMANN’S and OTHER THERMOMETERS, see INDEX.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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- - 488 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - COMPLETE LIST
  - LANTERN SLIDES
  - For LECTURES on SCIENTIFIC SUBJECTS
  - COMPRISING:
  - GANOT’S PHYSICS MAGNETISM ELECTRICITY WIRELESS X-RAYS RADIUM MECHANICS MINING HEAT
  - AND THE ENGINE
  - STEAM STEAM SOUND LIGHT GEOLOGY BOTANY ASTRONOMY NATURAL PHENOMENA
  - for PROJECTION LANTERNS, Etc., See pages 420 to 426
  - X-RAY LANTERN SLIDES
  - 3492.—Rontgen X-Ray Photographs. These X-ray lantern slides are printed direct from the original
  - negatives. Strictly copyright. Plain slides, 2/- each.
  - 1 Man’s hand ; index finger shows incipient gout
  - 2 Various objects photographed while inside a
  - wooden box
  - 3 Human foot, showing bones spread as in
  - walking
  - 4 Living human foot in sock, showing bones
  - cramped together by the sock
  - 5 Hand of a lady
  - 6 Cigars in an aluminium fluted case, and various
  - substances showing different degrees of transparency. Left hand column ; Guttapercha, ebonite, slate, sulphur, sealing wax, sal ammoniac, and calc spar. Right hand column: Plaster of Paris, red vulcanised fibre, ebony, carbon, mahogany, resin, and paraffin
  - 7 Human hand, displacement of middle finger
  - 8 Living human hand, showing damaged bones
  - 9 Lady’s hand, showing needle under meta-
  - carpal bone in palm
  - 10 Steel eyeglasses in leather case
  - 11 Lady’s hand, tops of two fingers crushed and
  - healed
  - 12 Gentleman’s hand with ring
  - 13 Working man’s hand
  - 14 Spectacles in shagreen case
  - 15 Man’s broken finger badly set
  - 16 Mr. Rowland’s laboratory ; process of taking
  - a shadowgraph
  - 17 Broken arm badly set
  - 18 Man’s foot
  - 19 Child’s foot, ten years old
  - 20 Child’s ankle, ten years old
  - 21 Child’s hand, six years old, showing partial
  - ossification of the bones
  - 22 Hand of man (Gout)
  - 23 Foot of man (Gout)
  - 24 Infant aged three months, showing vertebral
  - column, ribs, etc.
  - 25 Boy’s hand, showing incomplete ossification
  - 26 Boy’s chest, showing halfpenny he had
  - swallowed
  - 27 Photograph through a man’s chest, showing
  - backbone, and ribs, and heart
  - 28 Man’s foot, side view, showing ankle bones
  - 29 Man’s elbow joint
  - 30 Lead pencil and horn magnifier
  - 31 Man’s hand, showing pieces of iron
  - 32 Lady’s hand, with diamond rings
  - Taken by A. A. C. Swinton, Esq.
  - 33 Man’s skull, the lower portion
  - 34 Woman’s hand, with bullet flattened in the
  - wrist
  - 35 Boy’s tumorous hand showing the particle of
  - bone in the tumours
  - 36 Boy’s forearm, showing protruding bone
  - 37 Women’s hand, needle embedded
  - 38 Young boy’s hand, with bullet in the wrist
  - 39 Hand of mummy, 3,000 years old
  - 40 Foot of mummy (lady)
  - 41 Mummy cat
  - 42 Mummy bird
  - 43 A knee joint, normal
  - 44 Complete skeleton of a boy, fourteen years
  - old. 2 s.
  - 45 Infant injected, showing veins and arteries. 2s.
  - Taken by Cheyne Wilson, Esq., M.D.
  - 46 Pte. B., shot at Gripsville ; Mauser bullet in
  - . hip
  - 47 Pte. E., shot at Pretoria, near the knee, and
  - bullet extracted near the ankle, leaving two small pieces behind
  - 48 Pte. G., wounded at Friedrichstaad, pieces of
  - shell in forearm
  - 49 Pte. B., shot at Pieter’s Hill by a soft-nosed
  - Mauser, which bent on hitting the femur, which is fractured
  - 50 Pte. C., shot at Paardeburg, Cronje’s laager.
  - Bullet entered in front under the clavicle, seen lying on the last rib. Unsuccessful attempts were made at Cape Town to find it
  - 51 Pte. E., shot in the hip with exploding bullet
  - at 20 yards’ range, at Wakerstroom
  - 52 Pte. O. C., shot at Laand’s River in thigh.
  - Bullet flattened and thigh fractured
  - 53 Trooper C., shot in elbow. Fractured joint
  - 54 Bomb. C., shot in thigh. Piece of shell
  - present
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
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- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 489
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - 55 Pte. H., shot in the thigh by exploding bullet
  - at Paardeburg, Cronje’s laager
  - 56 Pte. G., shot in the thigh at Wakerstroom
  - 57 Fracture of an ankle-joint of a soldier who fell
  - nearly 40 ft. and pitched on his foot
  - 58 Pte. G., shot in chest in lower part of sternum
  - at Driefontein. Mauser bullet lying in heart’s shadow
  - 59 Fractured ankle in man
  - 60 Bullet in boy’s femur
  - 61 Fracture of humerus clavicle
  - 62 Fractured femur wired together. Wire in situ
  - 63 Bullet in ulna of boy shot by a toy pistol
  - 64 Penny in oesophagus of a girl
  - 65 Fractured elbow
  - 66 Fractured wrist
  - 67 Jaw with swelling showing the teeth
  - 68 Pelvis of child
  - 69 Needle in the hand, showing eye of needle
  - 70 Fractured (compound) leg pinned together.
  - Taken through the splints
  - 71 Fractured hip of child
  - 72 Small bullet in hand of young man
  - X-RAYS —continued.
  - 73 A soldier’s knee with a piece of shell, shot
  - near Pekin. Shell since removed and patient well. (One of the very few cases taken in England from the war in China)
  - 74 Dislocation of shoulder joint (not often ob-
  - tained, as the dislocation is usually reduced before an X-ray photo can be taken)
  - 75 A fractured thigh
  - 76 A bony tumour growing from the femur
  - 77 Part of a pom-pom cartridge case in a man’s
  - brain
  - 78 Small lead pellet in boy’s eye
  - 79 Fractured finger of man
  - 80 Darning-needle, showing the eye, in a lady’s
  - hand
  - 81 Part of the ulna (forearm) shot away in Boer
  - war
  - 82 Injury to a boy’s elbow joint
  - 83 Needle in a lady’s knee
  - 84 Needle in a lady’s knee
  - 85 Needle in a boy’s hip
  - Taken by Messrs. Coxeter & Son.
  - 86 Coin in oesophagus
  - 87 Exostosis of tibia (showing arteries)
  - 88 Necrosis of radius
  - 89 Bullets in arm
  - 90 Hand with five fingers
  - 91 Ossifying sarcoma (head of humerus)
  - 92 Fracture of tibia
  - 93 Hip dislocation
  - 94 Leg rickets
  - Birds, Animals, Reptiles. Shells
  - 95 Bones in the legs and feet of a living frog
  - 96 Fish, sole, showing bones, etc.
  - 97 Fish, plaice, showing bones, etc.
  - 98 Puppy dog, one day old
  - 99 Frog, showing bones, broken leg
  - 100 Chicken’s foot
  - 101 Young pigeon, ten days’ old
  - 102 Dove, showing bones and feathers
  - 103 Mouse
  - 104 Three live frogs
  - 105 Tortoise
  - 106 Snake, showing all the bones
  - 3493.— Diseases of the Bone. A series of radiographs by Dr. C. Thurstan Holland. This series of photographs has been awarded the Medal of the Royal Photographic Society. Plain slides 2/6 each.
  - 1 Round-celled sarcoma of the ulna (growth
  - expanding and “ eating up ” the bone)
  - 2 Fibro-sarcoma of tibia (growth springing from
  - bone, and bony deposit in the new growth)
  - 3 Acute tubercular disease of tibia and fibula
  - (with necrosis suppuration, repair)
  - 4 Simple periostitis of tibia (showing the swelling
  - below the periostitis)
  - 5 Tubercular knee-joint (showing the bony anky-
  - losis in malposition which follows)
  - 6 Myeloid sarcoma of fibula (the growth en-
  - tirely within the bone)
  - 7 Acute suppuration oskitis and periostitis of
  - tibia (with necrosis, etc.)
  - 8 Central abscess of tibia (showing abscess cavity
  - and the periostitis set up around it)
  - 9 Chronic syphilitic inflammation of radius (due
  - to tertiary syphilis)
  - io Necrosis of radius (showing loss of bone and repair, cavities in bone, etc.) n Early tubercular disease of ulna and phalanx (oskitis and periostitis)
  - 12 Exostosis of tibia (cartilaginous type, long
  - duration extension bony deposit)
  - 13 Exostosis of tibia (ordinary cartilaginous type,
  - pedunculated)
  - 14 Early tubercular disease of phalanx (oskitis,
  - periostitis, abscess around)
  - 15 Small central abscess of tibia (three positions
  - of bones) A
  - 16 Small central abscess of tibia (three positions
  - of bones) B
  - 17 Small central abscess of tibia (three positions
  - of bones) C
  - 18 Exostosis of phalanx (almost entirely cartilage)
  - 19 Exostosis of tibia (almost entirely bone, with
  - broad base)
  - 20 Oskoma of phalanx (entirely bony growth, no
  - cartilage)
  - 21 Sarcoma growing from phalanx of index
  - finger
  - 22 Round-celled sarcoma of femur in the living
  - subject
  - 23 Ditto, after removal
  - 24 Tubercular disease of shoulder joint (affecting
  - the glenoid cavity and the inner side of head of humerus)
  - 25 Myositis ossificans, left thigh
  - 26 Coxa vara, adult, right and left hip joints
  - 27 Coxa vara, adult, right and left hip joints
  - 28 Pess. carus
  - 29 Acute suppuratisi osteitis (recovery with altered
  - •and thickened bone)
  - 30 Coxa vara and rickets, child
  - 31 Acute periostitis of humerus
  - 3494.—X-Rays and their Application. A collection of slides illustrating the many-sided and important present-day applications of X-rays to the arts and industries, see “ X-Rays,” by Dr. G. W. C. Kaye (Longmans & Co.). 3/6 per slide.
  - 1 Two Radiographs of the hand showing the
  - immense improvements in radiography since the discovery of X-rays, (a) By Mr. Campbell Swinton, F.R.S., in 1896, exposure 20 minutes (b) By Dr. R. Knox in 1920, exposure 1/100 second.
  - 2 X-Ray Spectra of., platinum, copper and
  - lead at different exciting voltages showing spectral lines and quantum limit. (Muller.)
  - 3 Radiograph of hand of mummy of Egyptian
  - Princess, 4,590 b.c. (Knox.)
  - 4 X-Ray photograph of finger-prints. (H.
  - Beclere.) _ ,
  - 5 Radiograph of arm inside an artificial arm
  - of aluminium alloy. (B.T.H.)
  - 6 Radiograph of artificial teeth showing con-
  - struction and defects
  - 7 Radiograph of flowers—carnations and ferns,
  - etc. (Knox.)
  - 8 Radiograph of flowers—roses, etc. (Knox.)
  - 9 Radiograph of aeroplane’s pilot’s electrically
  - heated jacket showing break in heating element -
  - 10 Radiograph of motor tyre, showing burst
  - 11 Radiograph of aeroplane tyre
  - 12 Radiograph of corded motor tyre
  - 13 Radiograph of Dunlop Magnum tyre partly
  - dissected. (Dunlop Rubber Co.)
  - 14 Radiograph of perfect and imperfect golf
  - ball
  - 15 Radiograph of high tension electric cable,
  - showing defects
  - 16 Radiograph of defective electric weld in steel
  - plate
  - 17 Radiograph of defective oxy-acetylene weld
  - in i inch steel plate
  - 18 Radiograph showing concealed crack in alu-
  - minium piston of aeroplane engine
  - 19 Radiograph showing defective soldering on
  - part of petrol tank of aeroplane engine
  - 20 Radiograph of tumbler-switch taken through
  - cover
  - 21 Radiograph of watch
  - 22 Radiograph of electrically-heated coffee-pot
  - 23 Radiograph of silver spruce and West Vir-
  - ginia spruce used in aeroplane construction
  - 24 Radiograph of silver spruce showing also
  - aluminium washer and steel wiring plate.
  - 25 Radiograph of silver spruce showing con-*
  - cealed grub holes and remains of grubs
  - 26 Radiograph of multi-plywood used in aero-
  - plane construction showing defects
  - 27 Radiograph of laminated spar, showing large
  - concealed grub hole
  - 28 Radiograph of laminated spar, showing con-
  - cealed knots and grub holes
  - 29 Radiograph of built-up aeroplane spar, showing
  - poor workmanship
  - 30 Radiograph of built-up aeroplane spar, show-
  - ing poor workmanship
  - 31 Radiograph of aeroplane spar of box-type,
  - showing forbidden joints in ply-wood side.
  - 32 Radiograph of box spar, showing badly
  - shaped end-block split by screws.
  - 33 Radiograph showing aeroplane strut not
  - “ bottoming ” into its aluminium sockets
  - 34 X-Rays and Old Masters. St. Jans “ Ma-
  - donna ” (1500), and radiograph revealing the Child in the arms of the Madonna. (Heilbron.)
  - 35 and 36 Engelbrechtsen’s “ Crucifixion,” show-
  - ing alteration detected by X-Rays, and subsequent restoration of picture completely verifying radiograph. (Heilbron.)
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.489 - vue 508/555
- - 490 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES MAGNETISM AND ELECTRICITY
  - 3495.— Magnetism and Electricity. Copied by special permission of the Publishers, from Ganot’s “Physics” (Longmans & Co.); Guillemin’s “ Forces of Nature and Applications of Physical Force ” (Macmillan & Co.); “Discoveries and Inventions of the Nineteenth Century,' ’ and Pepper’s “ Boy’s Playbook of Science” (Routledge); Fonvielle’s “ Thunder and Lightning” (Sampson, Low & Co.) ; “Science for All” (Cassell, Petter & Galpin) ; etc. Plain slides, 2/- each.
  - 1 Dr. Gilbert’s method of making a magnet (old 59
  - pifint, dated 1600) 60
  - 2 Iron filings attracted by a bar magnet 61
  - 3 Hypothetical position of the magnetic fluids 62
  - in a magnet 63
  - 4 Magnetic pendulum 64
  - 5 Attraction of a magnetic bar by iron 65
  - 6 Magnetisation by influence of magnetism 66
  - 7 Magnetisation by influence at a distance 67
  - 8 Magnetism neutralised by the contact of 68
  - opposite poles 69
  - 9 Bar-magnet with consequent points 70
  - xo Magnetisation of a horse-shoe magnet 71
  - 11 Magnetisation by Duhamel’s process and that 72
  - of iEpinus 73
  - 12 Compound magnet formed of twelve bars 74
  - 13 Magnet formed of two compound bar magnets
  - 14 Iron horse-shoe magnet with its armature and 75
  - keeper 76
  - 15 Natural magnet furnished with its armature 77
  - 16 Magnetic needle showing both inclination and 78
  - declination 79
  - 17 Declination compass. Ganot, 543 80
  - 18 Gambey’s declination compass 81
  - 19 Ship or mariners’ compass 82
  - 20 The binnacle of a man-of-war 83
  - 21 Variation compass 84
  - 22 Portable declination compass
  - 23 Surveying compass 85
  - 24 Principle of the mirror declinometer 86
  - 25 Gauss’s bifilar magnetometer 87
  - 26 Leyser’s portable magnetometer 88
  - 27 Lamont’s magnetic theodolite 89
  - 28 Coulomb’s magnetic torsion balance 90
  - 29 Weber’s instrument for observing the earth’s 91
  - magnetism 92
  - 30 Oscillating magnet for determining the earth’s 93
  - magnetism 94
  - 31 Dip circle 95
  - 32 Isogonic lines for the year 1868 96
  - 33 Isoclinic lines for the year i860 97
  - 34 Electricity excited by friction 98
  - 35 Attraction of light bodies 99
  - 36 Phenomena of attraction and repulsion
  - 37 Biot’s experiment 100
  - 38 Proof-plane and hollow sphere
  - 39 Faraday’s experiment 101
  - 40 Electrification by influence
  - 41 Reiss’s induction experiment apparatus 102
  - 42 Diagram of theory of electrical attraction
  - 43 Electrical induction through a series of con- 103
  - due tors 104
  - 44 Tension of electricity at different points of
  - various figures 105
  - 45 Electric wind 106
  - 46 Electric fly
  - 47 Quadrant electroscope 107
  - 48 Gold leaf electroscope 108
  - 49 Gold leaf electroscope in use 109
  - 50 Straw-stalk electrometer
  - 51 Coulomb’s torsion balance electrometer no
  - 52 Dellmann’s torsion balance electrometer
  - 53 Experiment showing-the distribution of elec- in
  - tricity on a surface 112
  - 54 Experiment showing electrification of influ- 113
  - ence. Ganot, 571
  - 55 Experiment with four ice pails. Ganot, 573 114
  - 56 Specific inductive capacity. Faraday’s experi- 115
  - ment 116
  - 57 Electrophorus 117
  - 58 Otto von Guerick’s electric machine 118
  - Ramsden’s plate electric machine Gruel's cylinder electric machine Naims’s electric machine Winter’s electric machine Holtz’s electric machine, front view Holtz’s electric machine, back view Bertsch’s electric machine. Ganot, 587 Carre’s dielectrical machine Armstrong’s hydro-electrical machine Electric sparks Forms of electric discharges Electric brush, after Van Marum Positive and negative brushes Discharge in a Torricellian vacuum Electric egg for showing spark in rarefied air Apparatus for showing the electric light in various gases Electrical chimes Electrical hail Luminous tube Luminous globe Spangled luminous pane Kinnersley’s thermometer and electric mortar Volta’s pistol
  - Cuneus’s experiment, the Leyden jar Charging the Leyden jar Instantaneous discharge of a Leyden jar by the discharger
  - Successive discharges of Leyden jar, chimes
  - Battery of electrical jars
  - Universal discharger
  - Experiment of perforating a card
  - Experiment of perforating glass
  - Franklin’s portrait experiment
  - Fulminating pane
  - Condenser of ASpinus
  - Charging the condenser of /Epinus
  - Leyden jar with movable coatings
  - Lane’s unit jar
  - Reiss’s method of using the unit jar Harris’s unit jar. Ganot, 610 Volta’s condensing electroscope Leichtenberg’s figures, distribution of two kinds of electricity
  - Leichtenberg’s figures, distribution of positive electricity
  - Leichtenberg’s figures, distribution of negative electricity
  - Duration of spark, Wheatstone’s revolving mirror
  - Duration of spark, theory of revolving mirror Diagram of Feddersen’s experiment to measure duration of spark Diagram of Wheatstone’s spark-board Lucas and Cazin’s electric chronoscope. Ganot, 627
  - Reiss’s spark micrometer Reiss’s electric spark air-thermometer Bonhardt’s electric machine for exploding mines
  - Von Ebner’s electric machine for exploding mines
  - Abel’s electric fuse. Ganot, 624-625 Colonel Schaw’s apparatus for blasting Thompson’s needle quadrant electrometer. Ganot, 613
  - A storm on the Pyramids Different kinds of lightning The fire of St. Elmo Electric aureola
  - Photographic reproduction of electric spark
  - 119 Globular lightning seen and sketched by M.
  - Colon
  - 120 Globular lightning
  - 121 Formation of marine waterspouts
  - 122 Sailors firing at a waterspout
  - 123 Tank struck by lightning at Montmartre, ’66
  - 124 Tree scarified by lightning in the forest of St.
  - Germain
  - 125 M. Lanqon struck by lightning
  - 126 Electrified tree
  - 127 Prevention of hail-storms
  - 128 Lightning above a volcano
  - 129 Fish killed by lightning
  - 130 Bell-ringer struck by lightning
  - 131 Lightning attracted by metallic lodes
  - 132 Umbrella and lightning conductor. Comic
  - 133 Bell-glass preserver. Comic
  - 134 Coastguard blinded by lightning
  - 135 Effect of a distant thunderbolt
  - 136 Explosion of Gas
  - 137 Miners struck by lightning
  - 138 Lightning passing down a staircase
  - 139 Franklin’s kite experiment
  - 140 Oak struck by lightning at Wimbledon
  - Park
  - 141 Vertical rod of lightning conductor and gilded
  - copper point
  - 142 Fixing lightning conductors, vertical and
  - oblique rods
  - 143 Limits of protection of a system of lightning
  - conductors on a building
  - 144 Lightning conductor with multiple points
  - 145 Saussure’s atmospheric electrometer. Ganot,
  - 811
  - 146 Aurora borealis in the Arctic regions
  - 147 Aurora borealis seen in the Atlantic Ocean,
  - August 9th, 1849
  - 148 Radiating and curtain aurora
  - 149 Galvani’s frog’s leg experiment
  - 150 Galvani’s experiment on induction
  - 151 Galvani’s researches with contact of metals
  - 152 Galvani’s experiments on animal electricity
  - 153 Repetition of Galvani’s experiment with a
  - frog’s legs
  - 154 Voltaic element. Ganot, 630
  - 155 Voltaic pile
  - 156 Zamboni’s pile, electric perpetual motion
  - 157 Pile electrometer
  - 158 Electricity developed by chemical action
  - 159 Crown of cups
  - 160 Cruickshank’s trough
  - 161 Wollaston’s cell
  - 162 Wollaston’s battery
  - 163 Hare’s deflagrator
  - 164 Daniell’s cell
  - 165 Grove’s cell
  - 166 Bunsen’s cell
  - 167 Bunsen’s battery of five elements
  - 168 Rectangular zinc and carbon battery
  - 169 Callan’s battery. Ganot, 638
  - 170 Batteries of Maire Davy, Callaud, and Min-
  - otto. Ganot, 639, 640, 641
  - 171 Leclanche’s element. Ganot, 642
  - 172 Stohrer’s chamber battery
  - 173 Decomposition of water by voltaic battery
  - 174 Explosion of torpedoes by electricity. General
  - Chazal’s system of defence
  - 175 Bichromate of potash battery for blasting
  - mines
  - 176 Statham’s fuse for exploding, and chambers
  - in mines
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.490 - vue 509/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 491
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - MAGNETISM AND ELECTRICITY—continued.
  - 177 Tunnels and preparatory works for blowing
  - up Hell Gate rock, New York
  - 178 Blowing up of Hell Gate rock, and diagrams
  - of apparatus
  - 179 Formation of metallic magnesium in a tobacco
  - pipe
  - 180 Decomposition of salts
  - 181 Decomposition of potash
  - 182 Davy’s experiment, transmissions effected by
  - current, and Grothus’s hypothesis. Ganot, 669, 670
  - 183 Grove’s gas battery
  - 184 Faraday’s experiment in electrolysis. Ganot,
  - 671
  - 185 Mechanical action of a current. Ganot, 663
  - 186 Lippmann’s capillary electrometer. Ganot,
  - 665
  - 187 Simple apparatus for electro-plating
  - 188 Compound apparatus for electrotyping
  - 189 Electrotyping objects in the round. The
  - mould and finished object
  - 190 Compound apparatus for gold and silver
  - electro-plating
  - 191 Rosleur’s balance for gold and silver electro-
  - plating
  - 192 Oersted’s experiment
  - 193 Ampere’s law
  - 194 Deviation to the left of the vertical current
  - 195 Schweigger’s multiplier (diagram)
  - 196 Schweigger’s multiplier and astatic needles
  - (diagram). Ganot, 644, 645
  - 197 System of two astatic needles (diagram)
  - 198 Nobili’s astatic galvanometer
  - 199 Astatic galvanometer
  - 200 Du Bois’s astatic galvanometer
  - 201 Thomson’s marine galvanometer. Ganot, 647
  - 202 Meissner’s and Meyerstein’s mirror galvano-
  - meter
  - 203 Weber’s tangent galvanometer
  - 204 Sine galvanometer
  - 205 Siemens’s and Halske’s sine galvanometer
  - 206 Ohm’s law, various ways of connecting
  - batteries
  - 207 Wheatstone’s rheostat
  - 208 Poggendorff’s rheocord
  - 209 Resistance pile
  - 210 Resistance measured by Poggendorff’s com-
  - pensation method
  - 211 Diagram of Wheatstone’s bridge
  - 212 Derived current or divided circuit (diagram)
  - 213 Resistance of liquids. Wheatstone’s apparatus
  - 214 Resistance of liquids. Becquerel’s apparatus
  - 215 Resistance of liquids. Horsford’s and an
  - improved trough
  - 216 Polarisation of the electrodes
  - 217 Galvanic polarisation apparatus
  - 218 Poggendorff’s rocker for galvanic polarisation
  - 219 Electric light
  - 220 Duboscq’s and Foucault’s regulators for the
  - electric light
  - 221 Serrin’s regulator for the electric light
  - 222 Electric battery room, New Opera House, Paris
  - 223 Works carried on at night by electric light
  - 224 Browning’s regulator. Ganot, 662
  - 225 Image of the carbon points
  - 226 Divers examining a wreck by electric light
  - 227 Electric light used by the Navy searching
  - for torpedoes
  - 228 Ampere’s experiments. Repulsion of parallel
  - currents in contrary direction. Ganot, 674
  - 229 Ampere’s experiment. Attraction of parallel
  - currents in the same direction. Ganot, 676
  - 230 Ampere’s experiment. Attraction of recti-
  - linear angular currents. Ganot, 677
  - 231 Ampere’s experiment. Repulsion of recti-
  - linear angular currents. Ganot, 678
  - 232 Experiment with charcoal points, showing
  - repulsion of currents. Ganot, 67.9
  - 233 Law of sinous currents. Ganot, 680
  - 234 Weber’s bifilar dynamometer
  - 235 Action of a magnet on a current
  - 236 Rotation of a current by a magnet
  - 237 Rotation of currents round the poles of a
  - horseshoe magnet
  - 238 Bertin’s experiment. Electro-dynamic-rota-
  - tion of liquids. Ganot, 697
  - 239 Bertin’s commutator. Ganot, 698
  - 240 Reusch’s commutator
  - 241 Faraday’s experiment. Rotation of a current
  - by a magnet. Ganot, 696
  - 242 Rotation of magnets by a current
  - 243 Faraday’s experiment. Rotation of a magnet
  - by a current. Ganot, 692, 692A
  - 244 Rotatic. n of a current by a current
  - 245 Directive action of the earth on vertical and
  - horizontal currents. Ganot, 700, 701
  - 246 Astatic circuits
  - 247 Repulsion of successive portions of a voltaic
  - current
  - 248 Structure of a solenoid
  - 249 Action of a current on a solenoid. Ganot,
  - 704
  - 250 Mutual action of solenoids. Ganot, 705
  - 251 Orientation of a solenoid
  - 252 Dip of element of solenoid
  - 253 Ampere’s theory of magnetism. Ganot, 706
  - 254 Magnetisation of steel needle and production
  - of consequent points by a solenoid
  - 255 Electro-magnet with its charge
  - 256 Electro-magnetic chain
  - 257 Horseshoe electro-magnet and opposing
  - spring
  - 258 Electro-magnet with opposing spring
  - 259 Diagram of Wheatstone’s electric chrono-
  - scope, speed of cannon-ball
  - 260 Wheatstone’s electric chronoscope for falling
  - bodies
  - 261 Pouillet’s chronoscopic experiment with
  - pistol
  - 262 Navez’s electro-ballistic apparatus for mea-
  - suring speed of cannon-ball
  - 263 Electro-magnet and commutator
  - 264 Electro-magnet and commutator seen from
  - above
  - 265 Ruhmkorff’s commutator, end view and
  - section
  - 266 Reiss’s magnetic telephone
  - 267 Ritchie’s rotating electro-magnet
  - 268 Induced current by a current
  - 269 Induced current by distinct coil within coil
  - 270 Induced current by the approach of a con-
  - tinuous one. Ganot, 728
  - 271 Induction by the approach of a magnet
  - 272 Induction by magnetisation of soft iron
  - 273 Inductive action of a magnet on bodies in
  - motion. Ganot, 731
  - 274 Inductive action of earth. Delezenne’s circle
  - 275 Inductive action of the earth. Weber’s incli-
  - natorium
  - 276 Rheotome
  - 277 Magnetic hammer
  - 278 Double interrupter
  - 279 Du Bois Reymond’s sliding coil apparatus
  - 280 Reiss’s induction spiral
  - 281 Malleucci’s experiment. Inductive action of
  - Leyden discharge
  - 282 Extra current apparatus
  - 283 Extra current coil and magnetic hammer
  - 284 Extra current apparatus (diagram)
  - 285 Breguet’s magnetic exploder to blast mines
  - 286 Buff’s disjunctor
  - 287 Ruhmkorff’s induction coil for electric light
  - 288 Ruhmkorff’s coil and interrupter
  - 289 Foucault’s interrupter
  - 290 Ruhmkorff’s induction coil, apparatus and
  - experiments
  - 291 Stohrer’s induction coil, apparatus for electric
  - light
  - 292 Stohrer’s mercury interrupter
  - 293 Fizeau’s condenser. Ganot, 759
  - 294 Ruhmkorff’s coil, perforating a glass plate
  - 295 Ruhmkorff’s coil, charging a Leyden jar
  - 296 Ruhmkorff’s coil, charging a battery of jars
  - 297 Faraday’s induction experiment with copper
  - disc and horseshoe magnet
  - 298 Barlow’s rowel
  - 299 Principle of magneto-electric machines
  - 300 Principle of magneto-electric machines
  - 301 Pixii’s magneto-electric machine
  - 302 Clarke’s magneto-electric machines
  - 303 Commutator of Clarke’s machine. Ganot,
  - 74i, 742
  - 304 Stohrer’s magneto-electric machine
  - 305 Details of commutator in Stohrer’s machine
  - 306 Stohrer’s vertical magneto-electric machine
  - 307 Gramm’s magneto-electric Machine for the
  - laboratory
  - 308 Gramm’s magneto-electric machine for met-
  - allic precipitation
  - 309 Gramm’s magneto electric machine for the
  - electric light
  - 310 Gramm’s magneto-electric machine, latest
  - form
  - 311 Construction of Gramm’s armature
  - 312 Wild’s magneto-electric machine
  - 313 Ladd’s magneto-electric machine
  - 314 Ladd’s magneto-electric machine with driving
  - wheel
  - 315 Alliance magneto-electric machine
  - 316 Electric light during the siege of Paris
  - 317 Siemens’s armature, section and commutator
  - 318 Bourbouze’s electro-motor
  - 319 Fromont’s electro-motor
  - 320 Fromont’s electro-motor, diagram and details
  - 321 Foucault’s experiment, copper disc rotated
  - between poles of electro-magnet. Ganot, 772
  - 322 Large induction coil at Polytechnic Institution
  - 323 Stratification of electric light in rarefied air
  - 324 Electric light in Geissler’s tube
  - 325 Rotation of Geissler’s tubes
  - 326 Electric light in various vapours. Ganot,
  - 765, 766, 767
  - 327 Geissler’s tube. Electric light in hydrogen
  - 328 Tube with sheaths for showing electric light
  - in a gas
  - 329 Dumas and Benoit’s electric safety lamp for
  - miners
  - 330 Arrangement for showing change of colour in
  - electric light, produced by a magnet
  - 331 Action of electro-magnet on voltaic arc
  - 332 Action of electro-magnet on spark produced
  - by induction coil
  - 333 Action of electro-magnet on Geissler’s tubes
  - 334 Rotation of electric spark round a magnet
  - 335 Action of magnet on electric discharge
  - 336 Action of magnet on polarised light, Faraday.
  - Ganot, 773
  - 337 Apparatus for diamagnetism experiments
  - 338 Diamagnetism of solids and liquids. Ganot,
  - 774, 775, 776
  - 339 Diamagnetism of flames
  - 340 Gymnotus
  - 341 Electric fish
  - 342 Muscular electricity, Smee’s experiment with
  - a rabbit
  - 343 Du Bois Reymond’s experiment, human mus-
  - cular electricity
  - 344 Seebeck’s experiment,thermo-electric current
  - 345 Thermo-electric-current with one metal
  - 346 Pouillet’s thermo-electric couple
  - 347 Pouillet’s series of thermo-electric couples.
  - Ganot, 779
  - 348 Nobili’s thermo-electric pile
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.491 - vue 510/555
- - 492 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - MAGNETISM AND ELECTRICITY—continued.
  - 349 Becquerel’s thermo-electric battery. Ganot, 389
  - 782, 783, 784
  - 350 Melloni’s thermo-electric' pile 390
  - 351 Becquerel’s electrical thermometer. Ganot, 391
  - 790 392
  - 352 Becquerel’s electrical pyrometer. Ganot, 791 393
  - 353 Peltier’s cross 394
  - 354 Wheatstone’s five-needle telegraph
  - 355 Cooke and Wheatstone’s single-needle tele- 395
  - graph 396
  - 356 Belgian and English vocabularies of the 397
  - single-needle telegraph 398
  - 357 Two-needle telegraph
  - 358 Vocabulary of the two-needle telegraph 399
  - 359 Bain’s I. and V. telegraph 400
  - 360 Indicator of Foy and Breguet’s needle tele-
  - graph 401
  - 361 Manipulator of Foy and Breguet’s needle
  - telegraph 402
  - 362 Vocabulary of Foy and Breguet’s needle 403
  - telegraph 404
  - 263 Manipulator of Breguet’s dial telegraph 405
  - 264 Manipulator of Breguet’s dial telegraph, new 406
  - form 407
  - 265 Indicator of Breguet’s telegraph 408
  - 266 Indicator of Breguet’s telegraph, view of 409
  - mechanism
  - 267 Details of mechanism of Breguet’s telegraphic 410
  - indicator 411
  - ggg A dial telegraph station 412
  - jgg Wheatstone’s letter showing dial telegraph, 413
  - 1840 414
  - 270 Nott and Gamble’s letter telegraph 415
  - 27! Siemens’s and Halske’s dial telegraph 416
  - 272 Manipulator of Siemens’s and Halske’s dial
  - telegraph 417
  - 272 Indicator of Siemens’s and Halske’s telegraph 4x8
  - 274 Froment’s dial telegraph. Ganot, 717, 718 419
  - 273 Morse manipulator 420
  - 275 Morse indicator
  - 277 Diagram of apparatus in Morse telegraphy 421
  - 278 Morse-Digney indicator
  - ^7^ Froment’s relay 422
  - 380 Morse telegraph, with relay
  - gg! Telegraphic station on Morse-Digney system 423 382 Vocabulary of the Morse system 3g3 Hughes’s printing telegraph 424
  - 384 Type anc* printing shafts of Hughes’s telegraph 425
  - 38g Mechanism of keys, etc., in Hughes’s tele- 426
  - graph
  - 386 Diagram of action of Hughes’s telegraph 427
  - 387 Wheatstone’s automatic system, message as
  - sent and received 428
  - 388 Casselli’s pantelegraph
  - Transmitter and indicator of Casselli’s pantelegraph
  - Facsimile of despatch, Casselli’s pantelegraph Diagram of theory of Casselli’s pantelegraph Meyer’s pantelegraph Backwell’s copying telegraph Telegraphic air lines : suspending posts and insulators
  - Mushroom and annular insulators Stretching winches for telegraphic lines English and German stretchers Transatlantic cables from Valencia to Newfoundland
  - Sections of cable from Brest to St. Peter’s-Thomson’s receiving apparatus of telegraph, Brest to St. Peter’s
  - Section of Thomson’s galvanometer of the Brest to St. Peter’s telegraph Electric bell
  - Breguet’s vibrating alarum Aubine’s vibrating alarum Ansell’s fire-damp indicator Breguet’s lightning conductor, telegraphic Electric clock Garnier’s electric regulator Garnier’s electric regulator, connection with indicators
  - Froment’s electric regulator Breguet’s illuminated clock Verite’s electric clock Robert Houdin’s electric clock Froment’s electric clock Hipp’s electric clock
  - Cooke and Wheatstone’s single-needle telegraph, back showing current reverser Telegraphic magnetic needle and coils Instrument coil damaged by lightning Relay, front and side view Voltaic element and galvanometer showing current. Pepper, 161
  - Galvanometer, showing thermo-electric current. Pepper, 162
  - Electric spark produced by a magnet. Pepper, 163
  - Electricity excited in the human body by friction. Pepper, 165
  - Electric repulsion shown by large paper tassel. Pepper, 169 Electric dancing figures. Pepper, 170 Effects of thunder and lightning experimentally shown. Pepper, 177 Simple electrotyping apparatus in a tumbler. Pepper, 186
  - Jacobi’s method of magnetising a horseshoe magnet. Pepper, 198
  - 429 Simple method of showing the rotation of
  - current round a magnet. Pepper, 203
  - 430 Simple arrangement for showing a wire
  - circuit rotated by a magnet. Pepper, 204
  - 431 Simple method of showing a magnet rotating
  - round a current. Pepper, 205
  - 432 Simple current reverser. Pepper, 219
  - 433 Leyden jar and shape of tinfoil spangles.
  - Pepper, 228
  - 434 Boy, evidently shocked, behind doctor’s car-
  - riage provided with coil machine. Pepper, 233 ,
  - 435 Prof. Tyndall lecturing to the young folks on
  - electricity ; original sketch by one of the audience
  - 436 Magnetic needle attracted by bar magnet
  - 437 Magician and his loadstone rock. Pepper
  - 438 Electric chronograph
  - 439 Bright’s bells
  - 440 Box of resistance coils
  - 441 Diagram of relay and local circuit
  - 442 Machinery, etc., making the Atlantic electric
  - cable
  - 443 Machinery for taking the electric cable on
  - board the Great Eastern
  - 444 Stowing the cable in the hold of the Great
  - Eastern
  - 445 Breaking of the Atlantic electric cable on
  - board the Great Eastern
  - 4(46 Preparing for the final attempt to grapple the lost cable
  - 447 Buoys and grapnels used to recover the Atlantic electric cable
  - 448 Receiving messages from the Great Eastern
  - in the instrument room at Valencia
  - 449 Jamin’s magneto-electric machine
  - 450 Electro dynamometer, with Helmholtz’s
  - arrangement of coils
  - 451 Peltier’s electroscope
  - 452 Thomson’s replenisher
  - 453 Marey’s modification of Lippmann’s electro-
  - meter
  - 454 Dewar’s modification of Lippmann’s electro-
  - meter
  - 455 Halley’s first magnetic map. Date, 1700
  - 456 Jablochkoff’s electric candle and lantern
  - 457 Jablochkoff’s electric candle, arrangement
  - for holding the candle
  - 458 Jablochkoff’s electric candle, diagram of
  - lamp, machine, and shunt
  - 459 Jablochkoff’s electric candle, the automatic
  - shunt
  - 460 Gramm’s portable electro-magnetic machine,
  - with locomotive
  - GANOT’S PHYSICS
  - These Slides are all made from the illustrations in Ganot’s “ Physics ” (Ninth Edition) by kind man. In some cases two or three of the figures are put on one slide where they all refer to to decrease the expense.
  - Plain Photographs, 2/- each.
  - 3496.—Magnetism.
  - 461 Fig. 674 Magnet and iron filings
  - 462 ,, 675 Attraction and repulsion between
  - poles
  - 463 ,, 676 Experiments with broken magnets
  - 464 ,, 677, 678 Magnetic induction
  - 465 ,, 679, 680, 681 Lines of force shown by
  - iron filings
  - 466 ,, 682 Magnetising by separate touch
  - 467 ,, 683 Compound magnet or magnetic
  - battery
  - 468 ,, 684, 685, 686 Magnets and armatures
  - 469 ,, 688 Mayer’s floating magnets
  - 470 Fig. 690 Coulomb’s torsion balance
  - 471 ,, 695, 696 Earth’s action on magnet
  - 472 Page 719 Lines of equal variation, 1895
  - 473 Fig. 697 Declination compass
  - 474 ,, 698, 699 Reversal of needle
  - 475 )> 700 Mariner’s compass
  - 476 ,, 701, 702 Prismatic compass
  - 477 Plate V., page 723. Lines of equal dip, 1895
  - 478 Fig. 703 Inclination compass or dip needle ^479 Plate VI., page 727. Lines of equal horizontal force, 1895
  - 3497.—Frictional Electricity.
  - 480 Fig. 705, 706 Electric pendulum
  - 481 Page 736
  - 482 Fig. 707
  - 483 ,, 709,
  - 484 .. 711
  - 485 „ 712
  - 486 „ 7i4
  - 487 „ 7i5
  - 488 ,, 4i7
  - 00 VO 7i7,
  - permission of Messrs. Long-or bear on the same subject,
  - Table of conductors and non-conductors
  - Mascart’s insulator 710 Attraction and repulsion Goldleaf electroscope Quadrant electrometer Faraday’s experiment of equal and opposite charges Coulomb’s torsion balance Coulomb’s method of oscillations No charge inside a conductor 718 Charge passes from inner to outer envelope of a conductor
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.492 - vue 511/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 493
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - GANOT’S PHYSICS (Magnetism and Electricity) —continued.
  - 490 Fig. 719, 720 Distribution of electricity 555 Fig. 820, 821 Magnetic field round a current 616 Fig. 916 Electric bell
  - 49i ». 721 Electric density 556 „ 822 Magnet rotating round a current 617 )> 917, 918 Electric clock
  - 492 ,, 724, 725, 726 Lines of force in the 557 ,, 823 Oersted’s experiment 618 f t 919, 920, 921 Insulation of telegraph
  - electric field 558 ,, 824 Lines of force surrounding current wire
  - 493 ,, 728 Equipotential surface in a circular ring 6x9 yy 922, 923 Wheatstone’s telegraph
  - 494 729, 731 Electrostatic induction 559 .> 825 Tangent galvanometer 620 yy 924 Tapper
  - 495 ,, 730 Charging electroscope by induction 560 ,, 826 Helmholtz tangent galvanometer 621 y y 925 Receiver
  - 496 „ 732 Faraday’s ice pail experiment 561 ,, 827 Sine galvanometer 622 y y 926 Morse ink writer
  - 497 „ 734 Faraday’s chamber 562 ,, 828, 829 Asiatic needles 623 Page 923 Telegraphic alphabet
  - 498 ,, 735 Faraday’s experiment dielectric 563 „ 830 Asiatic needle galvanometer 624 Fig. 927 Morse key
  - polarisation 564 „ 831, 832 Kelvin’s mirror galvanometer 625 y 928 Relay
  - 499 » 736 Plate electrical machine 565 „ 833 Ballistic galvanometer 626 y y 929 Syphon recorder
  - 5oo ,, 737 Armstrong’s hydro-electric engine 566 ,, 834 Current equal at all parts of 627 y y 930 Syphon recorder alphabet
  - 50i „ 738, 740 Electrophorus circuit 628 y y 931 Duplex telegraphy
  - 502 ,, 741 Kelvin’s water dropping collector 567 ,, 835 Illustration of Ohm’s law 629 y y 932 Wheatstone bridge method
  - 503 „ 742, 743 Kelvin’s replenisher 568 ,, 836, 837, 838, 839 Cells connected in 630 y y 933 Record of Cowper’s writing tele-
  - 504 ,, 744 Holtz’s electrical machine series and in parallel graph
  - 505 „ 745, 746 Sections of Holtz’s machine 569 Page 856 Table of resistance of different 631 y y 934, 935 Principle of Wheatstone’s
  - 506 „ 747 Wimshurst’s machine metals bridge
  - 507 ,, 748 Plan of Wimshurst’s machine 570 Fig. 840 Resistances in parallel 632 y 936 Wheatstone’s meter-wire bridge
  - 508 ,, 749 Diagram. Theory of action of 57i 841, 842 Shunts applied (a galvano- 633 y y 937, 938 Wheatstone’s bridge. Post
  - Wimshurst’s machine meter) Office pattern
  - 509 ,, 75o, 751, 752 Electric spark 572 ,, 843, 844 Resistance box and coils 634 y 939 Ohmmeter
  - 5io „ 753 Electric chime 573 „ 845, 846 Rheostat and resistance frame 635 y y 940, 941 Standard condenser and com-
  - 5ii ,, 754, 755 Pith balls and electric whirl 574 ,, 847 Diagram of the heating effects in a parison of capacities of two
  - 512 ,, 756, 757 Electricity blowing out a circuit condensers
  - candle 575 „ 848 Carbon points of electric arc 636 yy 942, 943 944 Callendar’s electric ther-
  - 513 >. 758 Action of electricity in depositing 576 ,, 849, 850 Automatic arc lamp mometer and Langley’s bolo-
  - smoke or fog 577 „ 851 Differential regulator meter
  - 514 ,, 759 Epinus’s condenser 578 ,, 852, 853 Incandescent lamp and holder 637 y 945, 946 Electrolysis
  - 515 >, 760, 761 Discharging condenser 579 ,, 854 Heroult’s electric furnace 638 y 947 Davy’s potassium experiment
  - 5i6 ,, 762, 763 Faraday’s spheres 580 ,, 855, 856 Thermo-electric-currents 639 yy 948 Grothuss’s hypothesis
  - 517 ,, 764 Fulminating pane 581 ,, 857, 858 Thermo-electric couples 640 yy 949 Migrations of ions in an electrolyte
  - 5i8 „ 765 Charging a Leyden jar 582 ,, 859, 860 Nobili’s thermo-electric pile 641 yy 950, 951 Electrolytic action of current
  - 519 ,, 766, 767 Leyden jar, quick and slow 583 ,. 861, 862, 863, 864 Clamond’s thermo- equal in all parts
  - discharge electric battery 865 Becquerel’s electric pyrometer 642 y 952 Faraday’s chloride of tin experi-
  - 520 ,, 768 Leyden jar with movable coatings 584 ,, ments
  - 52i „ 769 Lichtenberg’s figures 585 ,, 866 Thermo-electric needle 643 y 953, 954 Water voltameters
  - 522 ,, 770 Residual discharge 586 ,, 867 Thermo-electric diagram 644 y 955 Silver voltameter
  - 523 ,, 771 Leyden jar battery 587 ,, 868, 869 Peltier’s and Joule’s effects 645 y 956 Resistance of liquids
  - 524 „ 772 Henley’s universal discharger 588 „ 870 Thomson’s effects 646 y 957 Grove’s gas battery
  - 525 ,, 774, 775 Lane’s electrometer and Harris 589 „ 871 Ampere’s experiments on parallel 647 y 958, 959 Plante’s and Faure’s secondary
  - unit jar currents batteries
  - 526 ,, 776, 777 Volta’s condensing electro- 59° .» 872, 873 Details of Ampere’s apparatus 648 y 960 Accumulator
  - scope 59i ,, 874 Roget’s vibrating spiral 649 y 961 Diagram of E.M.F. charing accu-
  - 527 „ 778, 779 Quadrant electrometer 592 ,, 875 Laws of angular currents mulator
  - 528 „ 780 Thomson’s absolute electrometer 593 ,, 876 Laws of sinuous currents 650 y 962 Capillary electrometer
  - 529 „ 781 Electrostatic voltmeter 594 „ 877 Action of a fixed on a rectangular 651 y 964 Electro deposition
  - 530 „ 782, 783 Zero electrostatic voltmeter current 652 y 965 Induced current. Faraday’s ex-
  - 53i ,, 785 Examining electric spark, Felder- 595 ,, 878 Rotation of a vertical by a circular periment
  - sen’s apparatus horizontal current 653 ,, 966 Induction by a continuous current
  - 532 ,, 787 Reiss’s spark micrometer 596 ,, 879, 880, 881, 882 Rotation of magnets 654 y 967, 968 Induction by a magnet and
  - 533 ,, 788 Electric egg by currents diagram of principles of induction
  - 534 789 Heating eflects of spark 597 ,, 883 Ampere’s stand 655 y y 969 Matteucci’s induction
  - 535 „ 790 Reiss’s electric thermometer 598 ,, 884 De la Rive’s floating battery 656 y y 970, 971 Arago’s rotating copper disc
  - 536 ,, 792 Magnetic effects of current 599 ,, 885 Rotation of currents by magnets, and diagram of pi'inciple
  - 537 ,, 793 Spark perforating glass plate Faraday’s experiment 657 y y 972 Faraday’s cube experiment
  - 538 „ 794 Kinnersley’s thermometer 600 ,, 886, 887 Barlow’s stellar wheel and 658 ,, 973 Foucault cui-rent apparatus
  - 539 „ 795 Electrostriction Faraday’s rotating disc 659 y y 974, 975, 976 E. M. F. in absolute
  - 540 „ 796, 797 Electric pistol 601 ,, 888, 889 Directive action of earth on measure
  - 541 „ 798 Ozone apparatus vertical current 660 y y 977 Induction by the earth. Dele-
  - 542 „ 799, 800 Duration of the electric spark 602 ,, 890, 891 Action of earth on currents zenne’s circle
  - 543 t r 801 Velocity of electricity movable about a vertical axis 661 y y 978 Self-induction current
  - 3498. —Dynamical Electricity 603 ,, 604 ,, 892, 893 Solenoids 894 Magnetic action of solenoids 662 663 y y yy 979, 980 Bell’s telephone 981 Microphone
  - 544 Fig. 802 Galvani’s experiment 60.5 „ 895 Ampere’s theory of magnetism 664 y y 982 Hughes’s induction balance
  - 545 ,, 803, 804, 805 Three forms of Voltaic 606 ,, 896 Electro-dynamometer 665 ,, 983 Ruhmkorff’s coil
  - current cells 607 ,, 897 D’Arsonval galvanometer 666 yy 984, 985 Interrupters
  - 546 „ 806 Volta’s pile 608 ,, 898, 899, 900 Weston ammeter 667 y y 986 Commutator
  - 547 „ 807 Voltaic battery 609 ,, 901, 902, 903, 904 Hall’s experiment 668 yy 988, 989 Coil spark piercing glass and
  - 548 „ 808 Local action 610 ,, 905, 906 Electro-magnets, right and charging Leyden jar
  - 549 „ 809, 810 Daniell’s and Minotto’s cells left-hand coils 669 yy 990, 991, 992 Luminous effects of coil
  - 550 ,, 811, 812 Calland’s and Grove’s cell 6ri: ,, 907, 908, 909, 910 Different forms of spark in vacuo
  - 55i ,, 813, 814 Bunsen’s battery electro-magnets 670 yy 993 Stratification in carbonic acid gas
  - 552 „ 815, 816 Bichromate cell, Latimer 612 ,, 911, 912 Evershed’s ammeter 671 yy 994 High and low vacua
  - Clark’s standard cell 613 ,, 913 Magnetisation curve 672 yy 995, 996 Maltese cross tube to show
  - 553 „ 817 Section of the Clark cell 614 ,, 914 Magnetic hysteresis fatigue, and railway tube to show
  - 554 ,, 818, 819 Leclanche’s cell 6i5 ,, 915 Reiss’s telephone mechanical effects
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.493 - vue 512/555
- - 494 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - GANOT’S PHYSICS (Magnetism and Electricity) —continued.
  - 673 Fig. 997 Heating effects of cathode rays 681 Fig. 1,009, 1,010, x.oii, 1,012 Types of 687 Fig. 1,023 Kerr’s electro-optical experiments
  - 674 J > 998 X-ray focus tube dynamos 688 „ 1,024, I,025, 1,026 Hertz’s apparatus-
  - 675 t > 999, 1000 Magneto-electric machine 682 y y 1,013 Siemens’s drum armature machine oscillator, resonator, and re-
  - 676 y y 1,001 Armature of Siemens’s alter- 683 y y 1,014, 1,015 Types of transformers flector
  - nating current machine 684 yy 1,016, 1,017, 1,018 Diamagnetic ex- 689 ,, 1,027 Lecher’s arrangement
  - 6 77 yy 1,002, 1,003 Siemens’s cylindrical arma- periments 690 ,, 1,028, 1,029 Marconi’s transmitter and
  - ture 685 yy 1,019, 1,020 Lines of force passing receiver
  - 678 yy 1,004 Diagram of Gramme ring through magnetic and diamag- 691 ,, 1,030 Motor mercury break
  - 679 y y 1,005, 1,006 Gramme ring and hand netic substances 692 ,, 1,031 Diagram showing arrangement
  - machine 686 y y 1,021 Effect of magnetic field on polar- with transformer in receiving
  - 680 y y 1,007, 1,008 Displacement of brushes ised ray circuit
  - THE TELEPHONE, MICROPHONE, Etc.
  - 3499. —Plain slides, 2/- each.
  - Reiss’s electro-magnetic telephone. See No. 266
  - 671 Diagram of Reis ’s electro-magnetic telephone
  - 672 Reiss’s musical telephone (American form)
  - 673 Gray’s musical telephone, transmitting ap-
  - paratus
  - 674 Gray’s musical telephone, another form of
  - transmitting apparatus
  - 675 Gray’s musical telephone, receiver
  - 676 Gray’s bath-tub experiment
  - 677 Gray’s physiological receiver
  - 678 Gray’s articulating telephone, transmitter;
  - also early form of Bell’s
  - 679 Gray’s articulating telephone, diagram ; also
  - early form of Bell’s
  - 680 Gray’s articulating telephone, as patented,
  - February 14th, 1876
  - 681 Gray’s battery articulating telephone
  - 682 Gray’s articulating telephone with U magnet
  - 683 Bell’s experiment, the human ear as a phon-
  - autograph
  - 684 Bell’s tracings of the vowel sounds
  - 685 Bell’s inoperative telephone
  - 686 Bell’s first articulating telephone, transmitter
  - 687 Bell’s first articulating telephone, receiver
  - 688 Bell’s articulating telephone, with permanent
  - magnet
  - 689 Bell’s articulating telephone, form used in
  - sending message from Salem to Boston
  - 690 Bell’s articulating telephone, powerful form
  - 691 Bell’s articulating telephone, exterior and
  - section
  - 692 Bell’s articulating telephone, section
  - 693 Bell’s articulating telephone, various
  - 694 Bell’s articulating telephone in circuit
  - (diagram)
  - 695 Dolbear’s articulating telephone
  - 696 Dolbear’s articulating telephone, plan
  - 697 Bolbear’s telephone, with paper diaphragm
  - and electro-magnet armature
  - 698 Dolbear’s battery telephone, section
  - 699 Breguet’s telephone
  - 700 French form of telephone
  - 701 Phelps’s duplex telephone
  - 702 Phelps’s telephone, used by the American
  - Telephone Company
  - 703 Phelps’s telephone, magnets, electric call bell,
  - etc.
  - 704 Phelps’s telephone, magno-electric call bell,
  - etc., box open
  - 705 Phelps’s telephone and accessories
  - 706 A proprietor in his office communicating with
  - his manager
  - 707 The telephone in use
  - 708 The telephone applied to the warfare of the
  - future
  - 709 Various uses of the telephone, humorous
  - 710 Portrait of Edison
  - 711 Edison, the boy printer
  - 712 Edison’s experiment, pressure and resistance
  - of a carbon disc
  - 713 Edison’s carbon rheostat
  - 714 Edison’s telephones
  - 715 Edison’s electro-motograph, diagram
  - 716 Edison’s carbon telephone
  - 717 Edison’s phonomotor
  - 718 Edison’s phonomotor, section
  - 719 Edison’s microtasimeter
  - 720 Edison’s microtasimeter and accessories
  - 721 Edison’s microtasimeter, section and diagram
  - 722 Edison’s megaphone
  - 723 Edison’s harmonic engine
  - 724 Edison’s electric pen
  - 725 Edison’s quadruplex telegraph (diagram)
  - 726 Edison’s electro-motograph
  - 727 Edison’s phonograph, simple form
  - 728 Edison’s phonograph, speed vanes and details
  - 729 Edison’s phonograph, with speed governor
  - in use
  - 730 W. H. Preece speaking into phonograph, and
  - instrument speaking to Prof. Tyndall
  - 731 Edison’s phonograph, details of diaphragm
  - and magnified marks on foil
  - 732 Section of phonograph
  - 733 Section of phonograph, early form
  - 734 Simple phonograph
  - 735 Edison and his assistant singing a duet into
  - the phonograph
  - 736 Edison experimenting with microtasimeter
  - 737 Carbon and crown telephone
  - 738 Hughes’ microphone, experiment of pressure
  - and resistance with a tube of white silver powder
  - 739 Hughes’ microphone, experiment, the tube
  - placed on a resonance box
  - 740 Hughes’ microphone experiment with three
  - nails
  - 741 Hughes’ microphone. Three nails in circuit,
  - battery and telephone (diagram)
  - 742 Hughes’ microphone, experiment with lever
  - resting on blocks of various substances
  - 743 Hughes’ carbon pencil microphone
  - 744 Hughes’ carbon pencil microphone
  - 745 Hughes’ carbon pencil microphone in use.
  - Walking of fly rendered audible
  - 746 Hughes’ receiving microphone
  - 747 Pencil and receiving microphone, transmit-
  - ting the ticking of a watch (diagram)
  - 748 Telephone with microphone relay
  - 749 M. du Moncel’s microphone telephone
  - 750 Carbon pencil microphone transmitting the
  - ticking of watch
  - 751 Clock microphone
  - 752 Cooke’s telephone call
  - 753 Hughes’ induction balance. Diagram of
  - ordinary electrical induction
  - 754 Hughes’ induction balance
  - 755 Hughes’ sonometer or audiometer
  - 756 The Gower telephone
  - 757 Edison’s microtasimeter, improved form,
  - exterior
  - 758 Edison’s microtasimeter, improved form,
  - sectional
  - 759 Edison’s shouting telephone. Principle of
  - action
  - 760 Edison’s shouting telephone, exterior
  - 761 Edison’s shouting telephone, interior
  - 762 Edison’s shouting telephone, sectional dia-
  - gram
  - 763 Edison’s shouting telephone. Diagram of
  - circuit, etc.
  - 764 Simple electro-magnet
  - 765 Advertisement bill of electric telegraph, 1843,
  - No. x
  - 766 Advertisement bill of electric telegraph, 1843,
  - No. 2
  - 767 Cowper’s writing telegraph (diagram)
  - 768 Portrait of Sir Humphfey Davy, discoverer
  - of the electric light
  - 769 Jablochkoff’s electric candle
  - 770 Rapiefi’s electric lamp
  - 771 Rapieff’s electric moderator lamp
  - 772 Werdermann’s electric lamp
  - 773 Werdermann’s electric lamp, circuit and
  - experiments
  - 774 Wallace’s electric lamp
  - 775 Siemens’ magneto-electric machine (old form)
  - 776 Siemens’ magneto-electric machine
  - 777 Siemens’ magneto-electric machine, sections
  - 778 Gramm’s magneto-electric machine, normal
  - type
  - 779 Gramm’s magneto-electric machine, distri-
  - butor
  - 780 Brush’s magneto-electric machine
  - 781 Wallace-Farmer magneto-electric machine
  - 782 M. de Meriten’s magneto-electric machine
  - 783 M. Lontin’s dynamo-electric machine, gene-
  - rator
  - 784 M. Lontin’s dynamo-electric machine, divider
  - 785 The electric light on Thames Embankment
  - 786 The electric light in MM. Sautter and
  - Lemonnier’s workshops Paris
  - 787 Dockyard works carried on by night by the
  - electric light
  - 788 Football by the electric light
  - 789 Reading the pigeon post during the siege of
  - Paris by the electric light
  - 790 Electric light in lantern microscope
  - 791 Graphic chart showing the fall in price of gas
  - shares during 1878
  - 792 Edison’s magneto-electric machine
  - 793 Edison’s incandescent electric lamp
  - 794 Edison’s incandescent electric lamp. Plati-
  - num wire and Zircon
  - 795 Edison’s incandescent electric lamp. Carbon
  - 796 Edison’s Faradaic generator
  - 797 Edison’s proposed central station of gene-
  - rators
  - 798 Edison’s electric light meter
  - 799 Edison’s electric motor
  - 800 Edison’s dynamometer for measuring the
  - force of an electric current
  - 801 Edison’s electric lamp, bracket and table form
  - 802 Andre’s electric lamp
  - 803 Ploughing by electricity
  - 804 The audiphone
  - 805 Jamin’s electric light
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.494 - vue 513/555
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - MAGNETIC CURVES
  - 3500.—Photographed from the actual figures made with iron filings by Professor S. P. Thompson, D.Sc. Per slide, 2/-
  - 461 Magnetic curves of bar magnet
  - 462 Magnetic curves of horseshoe magnet y 463 Magnetic lines of force of single pole >*£•464 Curves of attraction of two magnets -*2.465 Curves of repulsion of two magnets
  - 466 Two parallel magnets attracting f 467 Two parallel magnets repelling * 468 Lines of force of dissimilar poles
  - 469 Lines of force of similar poles
  - 470 Horizontal section of electro-magnet
  - 471 Lines of force of electro magnet
  - 472 Action of magnetic field on a small magnet
  - 473 Circular lines of force round a galvanic current
  - 474 Lines of force of current in horizontal wire
  - 475 Magnetic field of a looped conductor
  - 476 Field of two parallel attracting currents
  - 477 Field of two parallel repelling currents
  - 478 Attraction of two parallel horizontal currents
  - 479 Repulsion of two opposed parallel currents
  - 480 Magnetic field of oblique currents
  - 481 Field of horizontal and vertical currents
  - 482 Lines of force of current deflecting a needle
  - 483 Stable position of needle near vertical
  - currents
  - 484 Neutral position of needle near vertical
  - current
  - 485 Unstable position of needle near vertical
  - current
  - 486 Field of force of a galvanometer
  - 487 Field of magnetic needle in a circuit
  - 488 Field of magnet attracting current
  - 489 Attraction of North pole into a simple circuit
  - 490 Repulsion of South pole out of a simple
  - circuit
  - 491 Mutual rotation of current and magnet pole
  - 492 Spiral field of magnet rotated by current
  - running through it
  - 493 Converse spiral field of South pole rotated by
  - current running through it
  - ELECTRICAL DISCHARGES
  - 3501 •—Direct photographs of actual discharges, photographed by A. A. C. Swinton,
  - 1 Ordinary oscillatory discharge from induction 8
  - coil 9
  - 2 High frequency oscillatory discharge from a io
  - Tesla coil
  - 3 Positive discharge from induction coil
  - 4 Positive discharge from induction coil
  - 5 Negative discharge from induction coil
  - 6 Negative discharge from induction coil ii
  - 7 Hand electrified by a Tesla coil discharging on 12
  - to glass plate
  - Electrified Penny 13
  - Single Flash Discharge from large Induction Coil Single Flash Discharge from large Induction 14 Coil, the Spark Gap being within the 15 Magnetic Field set up by the Coil itself.
  - The Spark forms a complete helix between the electrodes.
  - Same as 10 (nearer view)
  - Pocket Book struck by lightning while in a man’s pocket
  - Esq. Plain photographs. Each 2/-
  - A halfpenny split in half and curiously marked by lightning, while in a man’s pocket
  - Spark Electrograph. 2s. 3d.
  - Electric Discharges. Simultaneous discharge from both poles, showing characteristic figure attached to each. Photo by Mr. K. J. Tarrant. 2s. 3d.
  - High Frequency Discharge between Two Bare Conductors. Photo by Mr. K. ^ Tarrant. 2s. 3d.
  - WIRELESS TELEGRAPHY
  - 1 Prof. H. Hertz. Portrait with autograph
  - 2 Standard Hertz resonator
  - 3 Sir Oliver J. Lodge, D.Sc., F.R.S., etc.
  - Portrait.
  - 4 Syntonic Leyden jar experiment
  - 5 Spiral wire coherer
  - 6 Diagram of Lodge’s experiments with receiver
  - enclosed in metal
  - 7 External view of Lodge’s proposed syntonic
  - signalling stations
  - 8 Lodge’s single-point coherer and diagrams of
  - coherer circuits
  - 9 Lodge’s and Muirhead’s improvements in syn-
  - tonic telegraphy, showing all connections for a complete station
  - 10 Sir W. H. Preece, C.B., F.R.S., etc. Portrait
  - 11 Diagram of apparatus for magnetic induction,
  - showing principle of Preece’s system as adopted by the Post Office
  - 3502. —Plain slides, 2/- each.
  - 1.2 Lodge’s magnifying telephone devices showing details of magnet and microphonic relay
  - 13 Complete arrangements of Lodge’s magnifying
  - telephones in series
  - 14 Signor Marconi. Portrait
  - 15 Marconi’s short-distance apparatus
  - 16 Marconi’s receiver and transmitter
  - 17 Receiving apparatus with cover removed
  - 18 Wireless telegraph station at the South Fore-
  - land lighthouse
  - 19 The Marconi transmitter in the lighthouse
  - connected for telegraphing to Wimereux
  - 20 The receiving apparatus at the lighthouse
  - connected up
  - 21 The mast carrying the vertical wire at the
  - South Foreland
  - 22 Receiving a message at the South Foreland
  - station
  - 23 The mast at the Wimereux station
  - 24 Receiving a message from Dover at Wimereux
  - 25 Facsimile and transcription of dot-and-dash
  - message sent by H.M. the Queen from Dover to Wimereux to the Mayor of Boulogne
  - 26 Morse printer
  - 27 Morse Alphabet
  - 28 Diagram showing steady flow of energy
  - 29 Portrait of Signor Marconi, taken at .Poldhu
  - 30 Portrait of Signor Marconi on edge of cliff at
  - Poldhu
  - 31 Signor Marconi at work
  - 32 Signor Marconi on one of the towers at
  - Poldhu
  - 33 Wireless telegraphy station at Poldhu
  - 34 The wireless guidance of torpedoes by electric
  - waves (the Orling-Armstrong torpedo)
  - 35 Wireless telegraphy at sea. The Italian ship
  - Carlo Alberto
  - WIRELESS TELEGRAPHY (POULSEN SYSTEM)
  - 3503.—Plain slides, 2/- each. Lecture notes, 7/6.
  - 1 Clerk Maxwell 20 Dr. Valdemar, Poulsen’s Apparatus 39 Magnetic Circuits
  - 2 The Maxwell Theory 21 System of Connection 40 Method of setting
  - 3 Heinric Hertz 22 Small Size Poulsen’s Apparatus 41 Interior of Transmitter House
  - 4 Hertz Apparatus 23 An anode 42 Map Showing Stations
  - 5 Guglielmo Marconi 24 Cathode Mounting 43 Army Waggon
  - 6 Sir Oliver Lodge 25 System of Connection 44 Army Waggon Near View
  - 7 Map Showing Stations 26 Steel Tower 45 Army Waggon Pack set
  - 8 Masts in Pineapple Field 27 Elwell Wooden Tower 46 Army Waggon Trench Set
  - 9 Honolulu Station from the Sea 28 Six Short Wooden Towers 47 In the Trenches
  - 10 Honolulu anchorage for Stays 29 Method of Constructing The following numbers may be used with extra
  - 11 Honolulu anchorage near View 30 Two Short Towers condensed notes instead of numbers 21
  - 12 Damped and Continuous Waves 31 Stay Wires and 24.
  - 13 Valve 32 Oregon Station 48 Ellwell Poulsen Arc Installation
  - 14 Alternator 33 Admiralty Station. Horsea Island 49 System of Connection
  - 15 Duddell Singing Arc 34 Seaplane in collision at Horsea Island 50 A small sized Arc Generator
  - 16 Static Curve 35 Interior of Long Distance Station 51 An Anode
  - 17 Duddell Arc 36 Tallest Wooden Towers in existence 52 Cathode Mounting
  - 18 Dynamis Curve 37 Base of Tower 53 Small Arc
  - 19 Late Dr. Duddell 38 Electrical Machines 54 Large Arc
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
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  - LANTERN SLIDES RADIUM
  - 3504 .—Set of instructive and unique lantern slides illustrating the action of radium, etc. The experiments illustrated on these slides were performed with 500 MILLIGRAMMES OF RADIUM BROMIDE, VALUE £7,500.
  - No. 1.—Photographic action of Radium produced by a medical applicator
  - ,, 2.—Photographic action of Radium through a penny .. .. .............
  - ,, 3.—Photographic action of Radium through a purse ..
  - ,, 4.—Photographic action of Radium through 15 in. of cast iron
  - ,, 5.—Photographic action of radium through a laundry iron, 1 inch thick . .
  - ,, 6.—Photograph showing the laundry iron experiment arranged
  - ,, 7.—Photograph of a piece of mineral (Fergusonite), showing the contained volume of Helium that the age of the mineral exceeds 240 million years..
  - ,, 8.—Photograph of a tube of Radium Bromide containing 500 milligrammes, value £7,500 ,, 9.—Photograph showing coloration of glass by Radium ,,10.—Photograph of various medical applicators ..
  - each
  - indicating
  - 3/-
  - 3/-
  - 3/-
  - 5/-
  - 3/-
  - 3/-
  - 3/-
  - 5/-
  - 3/-
  - 3/-
  - 3505.—Lectures on Radium.
  - Cwo lantern slides from Sir Oliver Lodge’s drawings of structure of “ atoms ” of hydrogen and radium, with description
  - each 2/6
  - Four lantern slides of Sir William Ramsay working in his laboratory, and his apparatus for collecting the emanations of radium .. .. .. .. .. .. .. .. .. .. .. .. .. . . .. each 2/3
  - One rackwork slide, showing the “Spinthariscope” effect of radium, very effective .. .. .. .. ..17/6
  - Set of five slides showing the characteristic bright light spectra of barium, helium, radium, and emanations of radium, in colours .. .. .. .. .. .. .. .. .. .. .. .. .. .. the set £12 6
  - SOUND, SOUND WAVES, Etc.
  - 3506.—Sound Waves. Professor R. W. Wood, of J.ohn Hopkins University, U.S.A., has succeeded in photographing waves of sound, and has carried his investigations so far that he has photographed sound waves in various successive phases during reflection from different shaped surfaces and during refraction when passing through various media. Lantern Slides made from his negatives are published only by Newton &. Co., Ltd.
  - 1 Sound shadow and diffraction
  - 2 Formation of a wave train, viz., musical note
  - by reflection from steps
  - 3 Reflection of spherical wave from plane
  - mirror.
  - 4 Reflection inside of complete spherical mirror
  - 5 Wave entering hemisphere mirror, Cusps trace
  - the caustic
  - 6 Spherical wave starting at focus of concave
  - spherical wave
  - Plain slides, 2/6 each.
  - Copies of Professor Wood’s paper, 1 /-,
  - 7 Reflection in elliptical mirror
  - 8 Transformation of spherical into plane wave
  - by reflection from parabolic mirror
  - 9 Transformation of spherical into plane wave
  - by C02 lens
  - 10 Reflection of wave from corrugated surface
  - showing secondary wavelets (diffraction grating)
  - 11 Passage of wave through grating showing
  - secondary wavelets
  - 12 Huyghen’s principle passage of wave through
  - two slits showing formation of complete secondary waves
  - 13 Refraction in tank of C02.
  - 14 Refraction in tank of carbonic acid under
  - oblique incidence
  - 15 Refraction by carbolic acid prism
  - 16 Refraction by hydrogen prism
  - 3507.—Chladni’s Sand Figu res. A new series of eleven direct photographs of sand figures, obtained by bowing a Chladni’s plate, by Professor Philip E. Belos, Royal College of Science, Dublin.
  - Plain slides, 2/- each.
  - 3508.—The Fall of a Water Drop. Plain slides, 9/- the set of four.
  - 1 Jet of water falling freely in the air 3 Jet of water before and after application of a 4 Portions of water-jet under the influence of
  - 2 Jet of water broken by a blow on supporting vibrating tuning-fork to the support vibrating fork
  - stand
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  - LANTERN SLIDES WAVES AND RIPPLES
  - 3509.—Flying Bullets. A series of twelve lantern slides, chiefly from photographs taken by Professor C. V. Boys, * F.R.S. Plain slides, 3/6 each. Plain slides, £1 19 6 the set.
  - Reading—Extracts from a lecture by Professor C. V. Boys, F.R.S., price 1/-.
  - 1 Bullet from Martini- Henry rifle, travelling
  - 1,296 ft. per second
  - 2 Magazine rifle bullet, travelling 2,000 ft. per
  - second
  - 3 Diagram to explain cause of air waves pro-
  - duced by bullet
  - 4 Diagram to explain why the waves are visible
  - 5 Bullet passing through ether vapour and car-
  - bonic acid gas
  - 6 Reflection of air waves caused by bullet from
  - flat surfaces
  - 7 Martini-Henry bullet, travelling 1,296 ft. per
  - second, disturbed by reflections of air waves from flat surfaces
  - 8 Shot, Schultz No. 8. Right barrel, showing
  - air waves and wad
  - 9 Magazine rifle bullet striking sheet of plate
  - glass, showing back splash of glass dust
  - 10 Bullet passing through plate glass
  - 11 Bullet, after passing through plate glass, sur-
  - rounded by glass dust. Plate beginning to break up
  - 12 Bullet clear from glass dust. Air waves caused
  - by glass dust, and by piece of glass punched out by bullet
  - 13 Scale showing measurement recorded
  - 3510. —Photographs of Rippl 6S, by Dr. J. H. Vincent; illustrating acoustical and optical phenomena by photo-
  - graphs of ripples on the surface of mercury and water. Messrs. Newton & Co. have the sole right of reproduction of these negatives. Plain photographs, 2/6 each.
  - 3511. —Ripples on Mercury. Illustrating paper in Philosophical Magazine, June, 1897.
  - 1 a Interference. Two point sources same phase. The straight lines are those of minimum disturbance ; they are hyperbolas of which the centres of disturbance are the foci 2a Interference, showing con-focal hyperbolas and eclipses, the latter being the light oval curves in the centre
  - 3a Interference to illustrate Meslin’s experiments
  - 4a Beats. The curved light lines of minimum disturbance rotate towards their convexities 5a Two sets of ripples propagated independently, one four times as rapid as the other 6a One point source and a reflecting line producing Lloyd’s bands
  - ya Virtual image in plane rectilinear reflector 8a Virtual image in concave reflector
  - 9a Spherical aberration in concave mirror 10a Virtual image in convex reflector, showing interference fringes
  - 11a Plane rectilinear waves brought to a focus in concave reflector, showing two series of parabolic interference fringes 12a Reflection of plane (linear) waves in a plane (linear) reflector, showing diffraction
  - 3512.— Ripples on Mercury.
  - 1 b Ripples due to agitation of support of mercury trough by a musical note
  - 26 Ripples due to agitation of support of mercury trough by noise
  - 3b Point source and its image at equal distances from concave reflector, showing conjugate foci
  - 4 b Real image of point source in a concave reflector, showing normal and abnormal foci
  - Philosophical Magazine, February, 1898.
  - 5 b Spurious ripple focus 6b Conjugate foci of ellipse yb Source at centre of ellipse, showing two foci conjugate to the centre near each end of ellipse
  - 8b Plane diffraction grating effect produced by ten equidistant sources 9b Analogous to a zone plate in optics
  - 10b Ripples caused by a card cut to represent a median section of a circular zone plate. This and No. 9b illustrate the fact that the focal length of a zone plate is less for red than for blue light 11b Refraction in a prism
  - 12b Refraction in three circular patches of mercury covered with water
  - 3513.—Ripples on Mercury.
  - ic Doppler’s principle
  - 2c Waves formed by motion of a style along the surface of the mercury Interference between two sources of nearly the same frequency, 190 and 170
  - Philosophical Magazine, September, 1898.
  - (To get wide interference bands in optics, the two point sources must be near together. - The sources in these photo-graphs vibrate in opposite phase. The ^ bright lines of minimum disturbance decrease in number as the sources ap-y proach each other until in No. 6c only the centre band is left
  - 7c Young’s experiment
  - 8c Arago’s experiment to test Newton’s emission theory
  - 9c Rowland’s concave grating 10 sources, frequency 170
  - ioc Interference pattern produced by three point sources vibrating in same phase iic Ripples caused by impact of a shot 12c Ripples caused by a ricochet
  - 3514.—Rippl es on Water Surface. Philosophical Magazine, October, 1899.
  - id Refraction of plane (rectilinear) waves in a plane (rectilinear) surface 2d Refraction through a prism 3d Fringes analogous to those joined by a bi-prism caused by a glass cylinder just submerged, the waves being retarded in passing over the shallow portion
  - 4d [ Refraction in a medium of increasing optical 5d j density
  - 6d Refraction of spherical (circular) waves in a plane (straight line), showing also Lloyd’s bands due to reflection
  - yd Refraction of plane (rectilinear) waves in a lens
  - 8d Refraction of spherical (circular) waves in a lens giving plane rectilinear waves
  - 3515.—Sound. Plain slides, 2/-
  - 494 Propagation of a pulse or wave experimentally
  - shown
  - 495 Propagation of sound from a bell to the ear
  - 496 Bell struck in vacuum
  - 497 Propagation of a pulse or wave in a tube
  - 498 Speaking tube, mouth-piece, and whistle
  - 499 The invisible woman
  - 500 The horn of Alexander
  - 501 Speaking trumpet in the merchant service
  - SOUND
  - each.
  - 502 Ear trumpets
  - 503 Stethescope (Konig’s). Ganot, 187, 188
  - 504 Reflection of sound (diagram). Ganot, 185
  - 505 Reflection of sound. Echo
  - 506 Reflection of sound
  - 507 Reflection of sound by an elliptical roof
  - 508 Echo with seven repetitions
  - 509 Variation of echoes
  - 510 Refraction of sound
  - 511 Diagram of refraction by a sound lens
  - 512 Experiment to ascertain the velocity of sound
  - in air
  - 513 Experiment to ascertain the velocity of sound
  - in water
  - 514 Gyroscope producing series of taps or musical
  - sounds
  - 515 Savart’s toothed wheel experiment
  - 516 Savart’s apparatus for producing low tones
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices; etc., see Chemical Apparatus Catalogue.
  - 11
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  - LANTERN SLIDES
  - 517 Rocking fire-shovel experiment
  - 518 Trevelyan’s rocker
  - 519 Seebeck’s syren
  - 520 Disc of Seebeck’s syren with nine pipes
  - 521 Musical sound produced by tuning-fork
  - 522 Simple method of showing vibration of
  - tuning-fork
  - 523 Graphic method of registering vibrations of a
  - tuning-fork
  - 524 Lissajous’s method of showing vibrations of a
  - tuning-fork on a screen
  - 525 Diagram of sound waves produced by tuning-
  - fork
  - 526 Syren of Cagniard de la Tour
  - 527 Syren section
  - 528 Helmholtz’s double syren
  - 529 Experiment showing the transmission of
  - sounds by liquids
  - 530 Arrangements for sounding a pipe in a liquid
  - 531 Sonometer
  - 532 Weber’s wave can
  - 533 Vibrations and nodes in a string shown by
  - damping the centre
  - 534 Vibrations and nodes in a string shown by
  - damping one-third
  - 535 Vibrations and nodes in a string shown by
  - damping one-fourtli
  - 536 Vibrations and nodes in a string shown by
  - damping one-fifth
  - 537 Melde’s experiment. String attached to
  - tuning-fork
  - 538 Vibrations and nodes produced by string in
  - Melde’s experiment
  - 539 Melde’s experiment with the strain on the
  - string varied
  - 540 Young’s figures of vibrations of wires
  - 541 Transverse vibration of a rod fixed at both
  - ends
  - 542 Transverse vibration of a rod fixed at one end
  - 543 Kaleidophone
  - 544 Pendulum vibrating in two directions
  - 545 Figures produced by the kaleidophone
  - 546 Diagram of vibrations of a wooden ruler
  - 547 Claque-bois
  - 548 Glass harmonicon
  - 549 Vibrations of a tuning-fork
  - 550 Chladni’s sand figures, method of showing
  - vibrations of square plate
  - 551 Sand figures on four square plates held in the
  - centre
  - 552 Sand figures on four square plates held not in
  - the centre
  - 553 Three figures on square plates obtained with
  - sand and gum
  - 554 Three figures on square plates with sand and
  - lycopodium powder
  - 555 Sand figures on square plates
  - 556 Sand figures on plates of various forms
  - 557 Sand figures on membrane, produced by
  - vibration of the air. Ganot, 227
  - 558 Sand figures on membranes
  - 559 Diagram of vibration of bell 550 Proof of vibration of glass bell 661 Vibrations of a metal clock bell
  - 562 Melde’s experiment showing vibration of
  - liquid molecules
  - 563 Faraday’s experiment, vibrations of water
  - impressed on a layer of sand
  - 564 Longitudinal vibration of a rod
  - 565 Diagram of longitudinal vibrations of rods
  - 566 Marloye’s harp
  - 567 Konig’s ocular demonstration of the longitu-
  - dinal vibration of a rod
  - 568 Fracture of glass tube by sonorous vibrations
  - 569 Tube held and rubbed so as to produce its
  - octave
  - 570 Action of sonorous vibrations on polarised
  - light .
  - SO U N D—continued.
  - 571 Resonance experiment, to ascertain the length 618
  - of column that responds to a tuning-fork
  - 572 Jars of different heights which respond each 619
  - to its own rate of vibration
  - 573 Sonorous bell and cardboard resonator 620
  - 574 Helmholtz’s resonator 621
  - 575 Musical note, generated by blowing across 622
  - the mouth of a tube 623
  - ^576 Diagram of vibrations in stopped pipes, fundamental note and overtones 624
  - 577 Pan’s pipes
  - 578 Square organ pipe and round stopped pipe 625
  - 579 Organ pipe responding to excited tuning-fork
  - 580 Hopkins’s experiment to ascertain the posi-
  - tion of nodes in a vibrating column of air 626 581 Organ pipe with gas jets to ascertain the position of nodes
  - ^582 Diagram of vibrations in open pipes, funda- 627 mental note and overtones
  - 583 Free reed 628
  - 584 Organ pipe with free reed, and arrangement
  - for experimentally altering the reed 629
  - 585 Section of organ pipe with striking reed and
  - arrangement for altering the reed 630
  - /.586 Vertical and horizontal section of glottis,
  - vocal cords, etc. 631
  - 587 Vertical section showing the vocal organs 632
  - 588 Muller’s indiarubber imitation of vocal cords 633
  - 589 Kundt’s method of showing vibrations of a
  - glass tube 634
  - 590 Sound figures in glass tubes
  - 591 Savart’s experiment, musical flow of water 635
  - through small apertures /- 636
  - 592 Bunsen burner and tin tube for musical flame
  - experiment / 637
  - 593 Glass tube with paper slide for musical flame 638
  - experiment 639
  - 594 Images of twinkling flame 640
  - 595 Experiment for showing the image of twink- 641
  - ling musical flame 642
  - 596 Blow-pipe flame affected by whistle
  - 597 Sensitive flames, fish-tail burner 643
  - 598 Sensitive flames, bat’s-wing burner 644
  - 599 Experiments with sensitive flames from round 645
  - apertures 646
  - 600 Effect of sound of short duration on sensitive 647
  - flame [condition 648
  - 601 Sensitive flame in its original and affected 649
  - 602 Sensitive smoke jets
  - 603 Sensitive water veins 650
  - 604 Sensitive water jets 651
  - 605 Propagation and x'eflection of liquid waves on 652 the surface of an elliptical bath of mercury 653
  - 606 Propagation and reflection of liquid waves on 654 the surface of a circular bath of mercury 655
  - 607 Diagram of vibrating tuning-forks in a state 656 of coincidence and interference
  - 608 Experiment for dividing a stream of sound 657
  - into two branches 658
  - 609 Method of showing beats with two organ pipes 659
  - 610 Simple method of compounding the vibration
  - of two forks 660
  - 611 Tracings of combination of two parallel
  - vibratory movements 661
  - 612 Tracings of combination of two rectangular 662
  - vibratory movements 663
  - 613 Apparatus for showing the action of beats of
  - flame * 664
  - 614 Lissajous’s method of showing beats of two
  - tuning-forks 665
  - 615 Hopkins’s experiment to show coincidence
  - and interference of portions of a vibrating 666
  - disc
  - 616 Lissajous’s experiment augmenting of sound 667
  - of vibratory disc by holding hands over alternate sectors 668
  - 617 Sounding and quenching a tuning-fork 669
  - experimentally shown 670
  - Lissajous’s method of combining two rectangular vibrations
  - Lissajous’s figures produced by the combination of two rectangular* vibrations Leon Scott’s phonautograph Tracings by the phonautograph Konig’s manometric flame apparatus Manometric flames. Image of flame, fundamental note and octave. Ganot, 241, 242 Manometric flames. Image of flame, note and octave together, and note and third Manometric flames. Image of flame, vowel e sung on note C and its octave. Ganot, 245, 246
  - Manometric flames. Image of flame, vowel o sung on note C and its octave. Ganot, 247, 248
  - Apparatus for the comparison of the vibratory movements of two sonorous tubes Kdnig’s apparatus for the analysis of sound. Ganot, 198
  - Helmholtz’s apparatus for synthesis of sound. Ganot, 199
  - Detail of construction of Helmholtz’s apparatus. Ganot, 200
  - Helmholtz’s vibration microscope Helmholtz’s electro-magnet and tuning-fork Helmholtz’s electro-magnet and tuning-fork breaker
  - Rijkie’s experiment. Glass tube containing heated wire gauze Chemical harmonicon
  - The human ear. Section of the bone and apparatus for hearing The human ear. Labyrinth, cochlea, etc. Section of the cochlea Musical box
  - Sistra of the ancient Egyptians Old arrangements for chimes Modern keyboard carillon at St. Germain, L’AuxeiTois
  - The violin, longitudinal and transverse section
  - Savert’s trapezoidal violin
  - African violin
  - Mechanism of the harp
  - The harp
  - Piano, mechanism of hammers and keys The flute, longitudinal and transverse section of mouth-piece Clarionet and hautboy Trombone Ophicleide
  - Cornet-a-piston and section Forms of pipes of stops in the organ Wind chest furnished with pipes Transversal section of sound board, wind chest, and valve Experimental organ The Barbary organ
  - Wheatstone’s telephonic concert at the Polytechnic
  - Graphic method of registering the vibrations of a violin string Natural gamut Scale of equal temperament Graphic method of representing a sound composed of a note and its octave Graphic method of representing a sound composed of several sounds Phonautograph tracings. The vowels sung on note G; clarionet, trumpet Tracings by the logograph. Stanza from Hohenlinden
  - Tracings by the logograph, faintly, forcibly, ordinary, and loudly Faber’s euphonia Steam syren at South Foreland Portrait of Chladni
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.498 - vue 517/555
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES LIGHT
  - 3516.—Ganot’s Phys ics. These slides are all made from the illustrations in Ganot’s “ Physics ” (Ninth Edition), by kind permission of Messrs. Longman. In some cases, two or three of the figures are put on one slide, where they all refer to or bear on the same subject, to decrease the expense.
  - Plain slides, 2/- each.
  - f 314 Fig. 469, 470 Diagrams shadow and pcnum- 361 Fig. 538 Formulae for lenses 409 Fig. 600 Principle of the Gregorian telescope
  - bra 362 ,, 539, 540 Principal focus and conjugate 410 f > 601 Principle of Newtonian telescope
  - V 315 ,, 471, 472 Solar eclipses, total and partial foci 411 y y 602 Newtonian telescope
  - 316 ,, 473, 474 Annular eclipse 363 ,, 541 Parallel beam 412 y y 603 Principle of Herschelian telescope
  - 317 ,, 475, 476 Images produced by small 364 ,, 542 Virtual foci 4i3 Page 610 Table of notable telescopes with
  - apertures 365 ,, 543, 544 Path of rays through concave sizes of object glasses
  - 318 ,, 477 Velocity of light, Romer’s deductions lenses >4i4 Fig. 604 Camera obscura
  - 319 M 478, 479 Foucault’s apparatus diagram 366 ,, 545, 546 Optical centre and secondary 4i5 y y 605, 606 Camera lucidas, Wollaston’s
  - 320 ,, 480, 481 Laws of intensity of light axis and Amici’s
  - 321 ,, 482 Rumford’s photometer 367 ,, 547, 548 Formation of real virtual ,4-416 y y 607 Magic lantern
  - 322 ,, 483 Bunsen’s photometer images of objects by convex lens 4i7 yy 608 Erecting prism
  - 323 ,, 484 Wheatstone’s photometer 368 ,, 549 Formation of image of object by 418 yy 609, 610 Dissolving views
  - 324 ,, 486 Laws of reflection concave lens 419 y y 611, 612 Solar microscope and diagram
  - 325 ,, 487 Artificial horizon experiment 369 ,, 550 Spherical aberration of path of rays
  - 326 ,, 488, 489 Formation of images by plane 37o ,, 551 Laryngoscope 420 y y 613 Photo electric microscope
  - mirrors >>37i ,, 552 The spectrum, Newton’s original 4-421 y y 614, 615 Lighthouse lenses
  - 327 „ 490 Multiple images from two plane experiment / 422 • y y 616, 617 Photographic camera
  - mirrors 372 ,, 553 Simple spectrum colours 423 y y 618, 620 Troughs for Lippmann’s colour
  - 00 Cl CO 491 Multiple images from two parallel 373 ,, 554 Colours not equally refrangible photography process
  - plane mirrors 374 ,, 555, 556, 557 Recomposition of white 424 y y 619 Lippmann’s method of photograph-
  - 329 ,» 492 Reflection of a ray by a rotating light by a lens, a prism, and a ing the spectrum in natural
  - mirror concave mirror colours
  - ^•330 ,, 493 Diagram to illustrate principle of 375 ,, 558 Recomposition of seven mirrors 425 y y 621 Transverse section of human eye
  - sextants 376 ,, 559, 560 Newton’s white light disc j, 426 y y 622 Path of rays in the eye
  - 331 ,, 494 The sextant 377 „ 561 Complementary colours, Lambert’s 427 y y 623 Optic angle
  - 332 ,, 495, 496 Measurement of small angles method 428 y y 624 Visual angle
  - by reflection 378 ,, 562, 563, 564 Maxwell’s colour discs 429 yy 625 Scheiner’s experiment
  - 333 „ 497, 498 Reflection from concave sur- ^-379 ,, 565 Helmholtz’s method of mixing 430 y 626, 627 Principle of the stereoscope
  - faces colours 43i y 628 The reflecting stereoscope
  - 334 ,, 499, 500, Position of real and virtual t, 380 Page 575 Table showing the results of 432 y 629, 630 Principle of the refracting
  - image mixing pure colours stereoscope
  - 335 „ 501 Reflection from convex surface /<38i Fig. 566 Spectroscope 433 y 631, 632 Irradiation experiinents
  - 336 ,, 502, 503 Formation of real and virtual 382 ,, 567 Diagram showing path of rays in a 434 y y 633 Use of concave lens for myopia
  - images of objects by concave spectroscope 435 yy 634 Use of convex lens for hyper-
  - mirrors 383 ,, 568 Slit and comparison prism metropia
  - 337 ,, 504 Formation of real and virtual 384 ,, 569 Train of nine prisms 436 y y 635, 636 Ophthalmoscope
  - images by convex mirrors 385 ,, 570 Direct vision spectroscope 437 y y 637, 638 Phosphoroscope
  - 338 ,, 506, 507 Determination of focal length 386 ,, 571 Cinnamic ether prism 438 y y 639 Diagram of single refraction
  - of a spherical mirror 387 ,, 572 Apparatus for observing spectra of 439 y y 640 Iceland spar rhomb
  - 339 ,, 449 Calculation of the magnitude of salts 440 y y 641, 642 Fresnel’s interference experi-
  - images 388 ,, 573 Geissler’s spectrum tube ment
  - 340 ,, 509 Spherical aberration by reflection 389 Frontispiece, table of spectra 44i y y 644 Diffraction fringes
  - 34i >, 510, 511 Parabolic mirrors 390 Fig. 574 Reversal of the sodium line, Bun- 442 y y 645 Diffraction of monochromatic light
  - ^ 342 ,, 512, 513 Phenomena of refraction sen’s apparatus by a narrow slit
  - 343 ,, 515 Descartes’ apparatus 39i ,, 575 Double slit for quantitative spec- ^•443 y y 646 Explanation of diffraction by a
  - 344 ,, 516, 517 Apparent shallowness of water trum analysis grating
  - caused by refraction 392 ,, 576 Anomalous dispersion 444 y 647 Comparison of spectra from a
  - 345 > j 518 Cause of visibility of stars when 393 ,, 577 Fluorescence grating and a prism
  - below the horizon 394 ,, 578 Chromatic aberration 445 y 648 Newton’s rings
  - 346 ,, 519 Multiple images from glass mirror 395 ,, 580, 581 Achromatic prism and achro- 446 y 649 Apparatus for experiments on New-
  - 347 „ 520, 521 Total reflection critical angle matic lens ton’s rings
  - , 348 „ 522 Mirage /^396 ,, 582 Simple magnifying glass 447 y 650 Diagram explaining Newton’s rings
  - 349 ,, 523 Wollaston’s poker experiment 397 ,, 583, 584 Simple microscope and Wol- 448 y 651 Polarisation by double refraction
  - 350 ,, 524 Refraction at a curved surface laston’s doublet 449 yy 652 Polai'isation by reflection
  - k- 351 „ 525 Path of ray through a glass plate 398 ,, 585, 586 Apparent magnitude of an 450 y 653 Angle of polarisation
  - ^ 352 ,, 527 Path of ray through a prism object 45i y 654, 655 Noerrenberg’s polariscope
  - 353 „ 528, 529 Polyprism and prism with 399 ,, 587 Measure of magnification 452 y 656 Double image prism
  - variable angle 400 ,, 588 Principle of the compound micro- 453 y 657, 658 Nicol’s prism
  - 354 „ 530 Right-angled prism used as a re- scope 454 y 659 Tourmaline tongs
  - flector 401 ,, 589, 590 Compound microscope 455 Plate II. Rings in uniaxal and biaxal crystals
  - 355 „ 531 Conditions of emergence in prisms 402 ,, 591 Principle of Huyghen’s eye-piece 456 Fig. 660, 661, 662, 663, 664, 665 Unannealed
  - 356 „ 532 Angle of minimum deviation 403 ,, 592 Magnifying power micrometer glass in polarised light
  - 357 „ 533, 534 Refractive index of solids £-4°4 ,, 593 Principle of the astronomical tele- 457 > > 666 Fresnel’s rhomb
  - spectrometer scope 458 y y 668 Biot’s polarimeter
  - 358 ,, 535 Refractive index of liquids, Biot’s 405 „ 594, 595 Telescope with finder 459 yy 669 Soleil’s saccharimeter
  - experiment 406 ,, 596 Principle of terrestrial eye-piece 460 y y 670, 671, 672, 673 Sections and details
  - 359 ,, 536 Refractive index of gases 407 ,, 598 Principle of Galileo’s telescope of saccharimeter
  - 360 ,, 537 Different kinds of lenses, sections 408 „ 599 Gregorian telescope
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
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  - LANTERN SLIDES
  - LIGHT—continued.
  - 3517.—Light. Selected and arranged by the Rev. Philip Sleeman, F.R.A.S., F.R.M.S., etc. Plain slides, each 2/-.
  - 1
  - 2
  - i/ ?>
  - 4
  - 5
  - 6 7
  - jy
  - Part I.
  - Rectilinear propagation of light Experiment illustrating rectilinear propagation
  - Formation of images by small apertures Images of sun through openings in foliage Reversed image of landscape Cone of shadow of opaque body Umbra and penumbra
  - 8 Effect of umbra and penumbra. Chinese shadows
  - Intensity of illumination. Law of inverse squares
  - xo Intensity of illumination. Law of the cosine
  - 11 Rumford’s photometer
  - 12 Bunsen’s photometer
  - 13 Velocity of light. Roemer’s observations
  - 14 Velocity of light. Aberration.
  - 15 Velocity of light. Fizeau’s experiment
  - 16 Velocity of light. Foucault’s experiment
  - 17 Illustration of the law of reflection
  - 18 Experimental verification of the law of
  - reflection
  - 19 Artificial horizon
  - 20 Reflection from plane mirror
  - 21 Lateral inversion by reflection
  - 22 Multiple images by two plane parallel mirrors
  - 23 Multiple images by inclined mirrors
  - 24 Multiple images by two surfaces of mirrors >- 25 The kaleidoscope
  - 26 Scattering of light by irregular reflection
  - 27 The sextant
  - / 28 Explanation of the sextant
  - 29 Goniometer (Babinet’s)
  - 30 Magic telescope
  - 31 Polemoscopc
  - 32 Silbermann’s heliostat
  - 33 Foucault’s heliostat
  - 34 Pepper’s “ Ghost ”
  - 35 Diagrams of foci of concave mirrors
  - 36 Real image by concave mirror
  - 37 Virtual image by concave mirror
  - 38 Caustics by reflection
  - 39 Images formed by convex mirrors
  - 40 Cylindrical mirror. Anamorphosis
  - 41 Experiment illustrating refraction of light
  - 42 Law of refraction and verification
  - 43 Law of sines. Glass and water
  - 44 Phenomena of refraction (bent stick)
  - 45 Explanation of phenomena of refraction
  - 46 Atmospheric refraction
  - 47 Effect of refraction on sunset
  - 48 Total reflection. Limiting angle
  - 49 Phenomena of total reflection
  - 50 Totally reflecting prisms
  - 51 Illustration of total reflection by cut glass
  - 52 The mirage
  - ,• 53 Explanation of the mirage
  - 54 Deviation by refraction (parallel plate)
  - 55 Deviation by refraction (successive media)
  - 56 The prism ^
  - 57 Deviation by prism
  - 58 Explanation of deviation
  - 59 Deviation and retardation
  - 60 Index of refraction. Dulong’s apparatus
  - 61 Index of refraction. Spectrometer
  - 62 Lens considered as an assemblage of prisms
  - 63 Converging and diverging lenses
  - 64 Various foci of converging lenses
  - 65 Principal foci of double and plano-convex
  - lenses
  - ^66 Formation of image by converging lens
  - 67 Fresnel’s lens
  - 68 Lenticular apparatus of lighthouse
  - 69 Diagram illustrating spherical aberration
  - 70 Decomposition of light by a prism
  - 71 Necessity for use of narrow slit
  - 72 Unequal refrangibility of different colours
  - 73 Recomposition of light, No. i ' 74 Recomposition of light, No. 2
  - 75 Deviation without dispersion
  - 76 Anomalous dispersion
  - 77 Achromatic prisms
  - 78 Chromatic aberration
  - 79 Achromatic lenses
  - 80 Spectroscope with reflected scale
  - 81 Solar spectrum (Fraunhofer)
  - 82 Coincidences of Fraunhofer lines with those of
  - sodium, etc.
  - 83 Chart of radiation spectra
  - 84 Chart of absorption spectra
  - 85 Thermal, luminous, and actinic rays in solar
  - spectrum
  - 86 Calorescence. Tyndall’s apparatus, No. 1
  - 87 Calorescence. Tyndall’s apparatus, No. 2
  - 88 Fluorescence
  - 89 Fluorescent spectra
  - 90 Phosphoroscope
  - 91 Phosphorescent spectra
  - 92 Horizontal section of the eyeball
  - 93 Vertical mid-section of the eyeball, No. 1
  - 94 Vertical mid-section of the eyeball, No. 2
  - 95 Diagram of nervous and connective elements
  - in retina
  - 96 Diagrammatic section of macula lutea
  - 97 Pigment cells from the choroid coat
  - 98 The crystalline lens. Structure
  - 99 The crystalline lens. Accommodation
  - 100 Schemer’s experiment on accommodation
  - 101 Formation of image on retina
  - 102 Diagrams explaining long and short sight" ,
  - 103 Ophthalmoscope
  - 104 Illustration of monocular and binocular vision
  - 105 Diagram explaining binocular vision
  - 106 Corresponding points on retina
  - 107 Wheatstone’s reflecting stereoscope
  - 108 Brewster’s refracting stereoscope
  - 109 Helmholtz’s lenticular stereoscope
  - no Analogy between sound and light, illustrated by persistence of vision in Thaumatrope and praxinoscope
  - 112 Optical illusions
  - 113 Subjective colours. Norrenberg’s apparatus
  - 114 Contrast colours. Scina’s apparatus
  - 115 Apparatus for mixing coloured light (Helm-
  - holtz)
  - 116 Apparatus for mixing coloured light (Dove)
  - 117 Complementary colours
  - 118 Dichroscopic lens (Haidinger)
  - 119 The dichrooscope (Dove)
  - 120 Spectra of white and coloured strips
  - 121 Helmholtz’s analysis of compound colours
  - 122 Maxwell’s analysis of compound colours
  - 123 Maxwell’s colour triangle, etc.
  - 124 Colour circle (Von Bezold)
  - 125 Diagram of colour sensations (Helmholtz)
  - 126 The rainbow
  - 127 Explanation of the rainbow
  - 128 Refraction in raindrops
  - 129 Camera obscura
  - 130 Photographic camera
  - 131 Camera lucida
  - 132 Magic lantern
  - 133 Bi-unal lantern for dissolving views
  - 134 Duboscq’s electric lantern
  - 135 Foucault’s and Duboscq’s electric lamps
  - 136 Duboscq’s vertical lantern
  - 137 Enlarged image produced by convex lens
  - 138 Simple microscopes. Magnifying glasses
  - 139 The compound microscope
  - 140 Achromatic eye-piece
  - 141 Binocular microscopes
  - 142 Rosse’s complete binocular microscope
  - 143 Solar microscope
  - 144 Duboscq’s lantern microscope
  - 145 Use of Duboscq’s microscope at siege of Paris
  - 146 Galilean telescope. Opera glass
  - 147 The astronomical telescope
  - 148 The terrestrial telescope
  - 149 Reflecting telescopes, No. 1
  - 150 Reflecting telescopes, No. 2
  - 151 The Rosse telescope
  - Part II.
  - 152 Diagram of plane wave
  - 153 Movement of particles in advancing wave
  - 154 Diagram of pendulum
  - 155 Diagram of harmonic motion
  - /-156 Experimental illustration of wave-motion, No. 1
  - yi57 Experimental Illustration of wave-motion, No. 2
  - 158 Crova’s wave-motion apparatus (longitudinal)
  - 159 Crova’s wave-motion apparatus (transversal)
  - 160 Huyghen’s principle of undulations
  - 161 Huyghen’s construction for reflection and
  - refraction
  - 162 Velocity of light in air and water. Foucault’s
  - experiment
  - >163 Diagrams explaining interference of waves
  - 164 Apparatus illustrating interference of waves
  - 165 Weber’s figure of interfering waves, No. 1
  - 166 Weber’s figure of interfering waves, No. 2
  - 167 Fresnel’s mirror
  - 168 Diagram of interference by Fresnel’s mirror
  - 169 Bi-prisms, etc., for interference experiments
  - 170 Jamin’s interferential refractor
  - 171 Colours of thin plates. Soap bubble
  - 172 Diagram explaining colours of thin plates
  - 173 Newton’s rings
  - 174 Diffraction of light
  - 175 Diffraction fringes. Young’s experiment
  - 176 Diagram of interference by diffraction
  - 177 Diffraction telescope and figures
  - 178 Diffraction figures, No. 1
  - 179 Diffraction figures, No. 2
  - 180 Diagrams explaining diffraction figures
  - 181 Measurement of wave length, No. 1
  - 182 Measurement of wave length, No. 2
  - 183 Table of wave lengths
  - 184 Diffraction spectra
  - 185 Principle of diffraction grating
  - 186 Measurement of wave length by diffraction
  - spectrum
  - 187 Comparison of diffraction with prismatic
  - spectrum
  - 188 Phenomena of polarisation by reflection
  - 189 Reflecting polariscope
  - 190 Polarising angle and diagram of intensities
  - 191 Illustration of meaning of “ polarised ” ray
  - 192 Polarisation by series of parallel plates
  - 193 Polariscope with pile of plates
  - 194 Norrenberg’s polariscope
  - 195 Planes of polarisation and of vibration
  - 196 Polarisation by tourmalin
  - 197 Illustration of “polarity” by iron filings
  - 198 Crystal of Iceland spar, and double refraction
  - 199 Diagram of double refraction in Iceland spar
  - 200 Optic axis and principal section
  - 201 Double image of aperture, projected on screen
  - 202 Effect of rotating the crystal
  - 203 Experiment showing opposite polarisation of
  - the two images
  - 204 Experiment with plate of tourmalin
  - 205 Apparatus for Huyghen’s experiment
  - 206 Phenomena of Huyghen’s experiment
  - 207 Ordinary and extraordinary rays
  - 208 Huyghen’s explanation of double refraction
  - 209 Verification of law of double refraction
  - 210 Ellipsoids of revolution. Positive andnegative
  - 211 Wave surface of positive crystal
  - 212 Wave surface of negative crystal
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.500 - vue 519/555
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  - LANTERN SLIDES
  - 213 Senarmont’s isothermal lines in crystal
  - 214 Sorby’s uni-focal and bi-focal images
  - 215 Achromatic, double-image prisms
  - 216 Senarmont’s, Rochon’s, and Wollaston’s
  - prisms ,
  - 217 Double image micrometer
  - 218 Nicol’s prism, No. 1
  - 219 Nicol’s prism, and Foucault’s modification
  - 220 Arrangement of polariser and analyser
  - 221 “ Depolarisation ” by selenite film
  - 222 Crystal of selenite and ideal structure
  - 223 Diagram of waves within selenite film
  - 224 Effect of rotating ; 1, selenite : 2, analyser
  - 225 Complementary colours shown by double
  - image prism
  - 226 Diagram explaining complementary colours,
  - No. 1
  - 227 Diagram explaining complementary colours,
  - No. 2
  - 228 Wheatstone’s polar clock
  - 229 Sound vibrations in bar of glass revealed by
  - polarised light
  - 230 Presses for heating and compressing glass
  - 231 Phenomena exhibited by compressed glass
  - 232 Diagram explaining phenomena of com-
  - pressed glass
  - 233 Phenomena of unannealed glass, No. 1
  - 234 Phenomena of unannealed glass, No. 2
  - 235 Phenomena of unannealed glass, No. 3
  - 236 Starch grains by polarised light.
  - 237 Sections of wave surface of bi-axal crystal
  - 238 Intersecting wave surface in bi-axal crystal
  - 239 Conical refraction. Theory
  - 240 Conical refraction. External
  - 241 Conical refraction. Internal
  - 242 Tourmalin pincette
  - 243 Norrenberg’s polariscope arranged for con-
  - vergent light
  - LIGHT—continued.
  - 244 Polari-microscope (Hoffman)
  - 245 Phenomena of uni-axal crystal by convergent
  - light
  - 246 Explanation of rings and cross, No. 1
  - 247 Explanation of rings and cross, No. 2
  - 248 Phenomena of bi-axal crystal by convergent
  - light, No. 1
  - 249 Phenomena of bi-axal crystal by convergent
  - light, No. 2
  - 250 Lemniscate
  - 251 Measurement of angle of optic axes
  - 252 Table of angles of optic axes
  - 253 Dispersion of optic axes, No. 1
  - 254 Dispersion of optic axes, No. 2
  - 255 Phenomena of quartz plate in polarised light
  - 256 Diagram of succession of colours on rotating
  - quartz plate
  - 257 Diagram of succession of colours on rotating
  - analyser
  - 258 Diagram of intensity of colours in quartz-plate
  - 259 Diagram illustrating production of circular
  - motion by two rectangular vibrations
  - 260 Vibration phases. Compound
  - 261 Diagram of spiral curve on cylinder
  - 262 Wheatstone’s apparatus for illustrating cir-
  - cular wave-motion
  - 263 Apparatus for illustrating plane and circular
  - wave-motion
  - 264 Right and left-handed quartz crystals
  - 265 Quartz wedges. Badinet’s compensator
  - 266 Bands of colour in quartz wedges
  - 267 Hyperbolas exhibited by quartz plates
  - 268 Amethyst. Superposed laminaj
  - 269 Phenomena of quartz in convergent light
  - 270 Airy.’s spirals
  - 271 Fresnel’s rhomb
  - 272 Wheatstone’s apparatus for circular polari-
  - sation
  - 273 Dislocation of crystal rings by circularly
  - polarised light
  - 274 Explanation of dislocation of crystal rings
  - 275 Stauroscope and Brezina plate
  - 276 Rotation of plane of polarisation. Biot’s
  - apparatus
  - 277 Soleil’s saccharometer
  - 278 Soleil’s saccharometer. Section
  - 279 Wild’s polari-strobometer
  - 280 Hoffmann’s polarimeter
  - 281 Laurent’s saccharometer
  - 282 Laurent’s saccharometer. Section
  - 283 Electro-magnetic rotation of plane of polari-
  - sation. Faraday’s experiment
  - 284 Electro-magnetic rotation of plane of polari-
  - sation. Verdet’s apparatus
  - 285 Arago’s polarimeter
  - 286 Haidinger’s “ brushes ”
  - 287 Polariscope for projection. Reflecting
  - 288 Polariscope for projection. Duboscq’s
  - 289 Polarising apparatus with large Nicol prisms
  - for projection with electric light (Rev. P. Sleeman)
  - 290 Apparatus for spectra of polarised light
  - 291 Bands in spectra of polarised light, No. 1
  - 292 Bands in spectra of polarised light, No. 2
  - 293 Polariscope with rotating analyser (Mach)
  - 294 Selenite plate, seen with rotating analyser
  - 295 Quartz plate, seen with rotating analyser
  - 296 Spiral spectral bands, seen with rotating
  - analyser
  - 297 Identity of light and radiant heat. Reflection
  - 298 Identity of light and radiant heat. Refraction
  - 299 Identity of light and radiant heat. Double
  - refraction
  - 300 Identity of light and radiant heat. Polari-
  - sation
  - 3518.—Refraction of Light. Plain slides, 2/6 each.
  - 1 Photograph of mirage on hot City Pavement. 3 Parallel bundle of Rays coming to successive foci in non-homogeneous
  - 2 Light Ray travelling in line curve in non-homogeneous medium. medium
  - 3519.—Reflection in Mirrors, Refraction by Lenses, etc. By Dr. H. J. Oosting. Plain slides, 2/6 each.
  - 1 Reflection in a plane mirror
  - 2 Reflection in a concave spherical mirror. Luminous point in the centre
  - of curnature.
  - 3 Reflection in a concave spherical mirror. Slightly turned.
  - 4 Reflection in a concave spherical mirror. Incident rays parallel
  - 5 Reflection in a concave spherical mirror. Slightly turned
  - 6 Reflection in a concave spherical mirror. Luminous point coinciding
  - with principal focus
  - 7 Reflection in a concave spherical mirror—ditto—mirror turned
  - 8 Reflection in concave spherical mirror. Luminous point at a distance
  - greater than the radius
  - 9 Reflection in concave spherical mirror. Luminous point at a smaller
  - distance
  - 10 Reflection in concave spherical mirror. Luminous point at a distance
  - smaller than the focal length
  - 11 Reflection in convex spherical mirror. Incident rays parallel
  - 12 Reflection in convex spherical mirror. Luminous point on axis of
  - mirror.
  - 13 Reflection of light rays passing surface of separation between air and
  - water
  - 14 Reflection of light rays passing through glass cell filled with water
  - 15 Reflection of light rays passing through glass cell filled with Carbon
  - Bi-sulphide
  - 16 Total reflection of surface between water and air
  - 17 Refraction of parallel rays by a convex lens
  - 18 Refraction of rays by a convex lens. Luminous point in principal
  - focus
  - 19 Refraction of rays by a convex lens. Luminous point in principal
  - axis at a distance of twice the focal length
  - 20 Refraction of rays by a convex lens. Luminous point at a distance of
  - twice the focal length, but not in principal axis
  - 21 Refraction of rays by a convex lens. Luminous point at a distance
  - from lens greater than twice the focal length.
  - 22 Refraction of rays by a convex lens. Luminous point at a distance
  - greater than one and smaller than two times the focal length.
  - 23 Refraction of rays by convex lens. Luminous point at a distance
  - smaller than focal length
  - 24 Refraction of rays through concave lens. Incident rays parallel
  - 25 Refraction of rays through concave lens.' Luminous point on principal
  - axis
  - 26 Course of rays in astronomical telescope
  - 27 Course of rays in astronomical telescope
  - 28 Course of rays in Dutch or Galilean telescope
  - 29 Course of rays in Dutch or Galilean telescope
  - 30 Course of rays through objective of lantern
  - 31 Spherical aberration
  - 3520.—Polarised Light.
  - The following series of Slides is entirely new, and they are taken in colour direct from the object under Polarized Light. The brilliant colours shown in the originals are as nearly as possible reproduced in the Slides. They are very transparent, and can be shown in conjunction with other slides.
  - They have been taken by T. E. Freshwater, F.R.P.S. The Slides should be very useful to the lecturer who wants to produce the effect of polarised light without the trouble of working the Polariscope. Price 75. 6d. each.
  - Blocks of Chilled or Unannealed Glass of Various Shapes.
  - Showing the permanent polarising structure of glass that has been uniformly heated and suddenly cooled.
  - 1 Star on dark field 4 Cube, showing red spots with blue eyes. 7 Triangle. This shows very curious 9 Square, etc., etc.
  - 2 Star on light field 5 Oval, cross and colour rings markings All the above show the black cross
  - 3 Two bars of glass crossed 6 Circle, cross and colour rings 8 Rose. Very pretty object and colour bands
- p.501 - vue 520/555
- - 502 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - io Natural right-hand Compound, very fine, showing the formation of the Crystal
  - 16 Wedge showing bands of colour
  - 17 Double wedge crossed
  - 18 Concave, worked to show Newton’s
  - Rings on dark field
  - LANTERN SLIDES
  - Polarised Light—continued.
  - Quartz Plates.
  - 11 Bi-quartz, right and left-hand, built 12 Quartz, showing cross crystallisation, up whole section of crystal
  - 13 Bar of crystal, very pretty
  - Selenites.
  - 19 Concave, worked to show Newton’s 20 Plate of uneven film Rings on light field, showing the 21 Plate showing made complementary colour to the one 22 Amethyst, section of, in plane polarised on dark field light
  - 14 Bi-quartz put together at 45 degrees
  - 15 Plate showing formation of a twin
  - crystal
  - 23 Amethyst with red and green selenite
  - superposed
  - 24 Granite [preparation
  - Various rock sections in course of
  - SPECTRUM ANALYSIS
  - 3521.—Spectrum Analys is, including representations of the various instruments and apparatus made use of in recent spectroscopic researches, and descriptive of the results of the application of prismatic analysis to the study of terrestrial substances, and to the physical constitution of the celestial bodies. Selected and arranged by the Rev. Philip Sleeman, F.R.A.S., F.R.M.S., etc. Plain slides, 2/- each.
  - 1 The refraction of light 38
  - 2 The prism 39
  - 3 Deviation of luminous ray by prism 40
  - 4 Explanation of deviation 41
  - 5 Decomposition of light by prism 42
  - 6 Unequal refrangibility of different colours 43
  - 7 Recomposition of light. No. 1 44
  - 8 Recomposition of light. No. 2 45
  - 9 Effect of aperture on spectrum 46
  - 10 Necessity for use of narrow slit 47
  - 11 Use of collimating lens
  - 12 Spectroscope with single prism 48
  - 13 Spectroscope with reflected scale 49
  - 14 Sectional view of spectroscope 50
  - 15 Slit, and comparison prism 51
  - 16 Increased dispersion by series of prisms 52
  - 17 Automatic arrangement for battery of prisms 53
  - 18 Large spectroscope with returning ray 54
  - 19 Anomalous dispersion 55
  - 20 Direct vision prisms 56
  - 21 Miniature spectroscope 57
  - 22 Direct-vision spectroscope 58
  - 23 Micro-spectroscope. Elevation 59
  - 24 Micro-spectroscope. Section 60
  - 25 Solar spectroscope (Secchi) 61
  - 26 Star spectroscope (Secchi) 62
  - 27 Star spectroscope (Huggins)
  - 28 Various classes of spectra 63
  - 29 Chart of radiation spectra. No. 1 64
  - 30 Chart of radiation spectra. No. 2 65
  - 31 Chart of radiation spectra. No. 3 66
  - 32 Chart of radiation spectra. No. 4 67
  - 33 Chart of radiation spectra. No. 5
  - 34 Chart of radiation spectra. No. 6 68
  - 35 Chart of radiation spectra. No. 7
  - 36 Chart of radiation spectra. No. 8 69
  - 37 Chart of radiation spectra. No. 9 70
  - Chart of radiation spectra. No. 10 Double spectra Bunsen’s maps of spectra Projection of spectrum on screen. No. 1 Projection of spectrum on screen. No. 2 Foucault’s and Duboscq’s electric lamps Ruhmkorff’s spectral lamp Apparatus for photographing spectra Slit with several apertures Long and short lines in spectra, with explanation
  - Photographic comparisons of spectra. No. 1 Photographic comparisons of spectra. No. 2 Phosphorescent spectra Fluorescent spectra Apparatus for spark spectra Vacuum tubes
  - Becqucrel’s apparatus for spark spectra Apparatus for spectra of metallic vapours Chart of absorption spectra. No. 1 Chart of absorption spectra. No. 2 Chart of absorption spectra. No. 3 Chart of absorption spectra. No. 4 Chart of absorption spectra. No. 5 Chart of absorption spectra. No. 6 Bunsen’s apparatus for reversal of sodium lines
  - Reversal of sodium lines on screen Solar spectrum (Fraunhofer)
  - Solar spectrum (Kirchhoff)
  - Solar spectrum (photograph by Draper) Coincidences of Fraunhofer lines with those of sodium, etc.
  - Coincidences of Fraunhofer lines with those of iron
  - Telluric lines in solar spectrum General view of chromosphere
  - 71 Typical sun spot (Langley)
  - 72 Spectrum of sun spot (Secchi)
  - 73 Spectrum of sun spot, near D lines
  - 74 Thickening of D lines in sun spot
  - 75 View of total solar eclipse, 1870
  - 76 View of solar prominences
  - 77 Solar prominences, examined with radial slit
  - 78 Spectra of solar prominences (Lockyer)
  - 79 Various spectra of solar prominences
  - 80 Solar prominences : examined with tangen-
  - tial slit
  - 81 Solar prominences : seen entire, by use of
  - wide slit
  - 82 Long and short lines in solar prominences
  - 83 Solar cyclones (Lockyer)
  - 84 “ Motion forms ” (Lockyer)
  - 85 F line, in Sirium and the sun
  - 86 Measurement of velocity by displacement of F
  - line
  - 87 Spectra of sun, corona, and aurora borealis
  - 88 Types of stellar spectra (Secchi)
  - 89 Spectrum of Sirius
  - 90 Spectrum of A in a Herculis
  - 91 Spectrum of b Cygni
  - 92 Spectrum of T Coronaa Borealis
  - 93 Spectra of a Orionis and Aldebaran
  - 94 Spectrum of Uranus
  - 95 Spectrum of a nebula
  - 96 Cometary and carbon spectra
  - 97 Thermal, luminous, and actinic rays in solar
  - spectrum
  - 98 Thermal intensities in spectra of sun and of
  - the electric light
  - 99 Chemical intensity in solar spectrum
  - 100 Influence of solar spectrum on sensitive silver salts
  - 3522.—Bright-Line Spectra. The following special slides have been designed to show on the screen the bright line spectra in correct colours of the various gases and metals. They were first made for the late Sir W. Ramsay, F.R.S., to illustrate his lecture at the British Association. No. 1 is used with each of the others in turn. Price : No. 1, 10/6;
  - all the remainder, 3/ - each.
  - 1 Spectrum slide, coloured, to be 13 Indium line spectrum 27 Bromine 41 Manganese
  - placed in an ordinary single lan- 14 Natrium line spectrum 28 Calcium Chloride 42 Mercury
  - tern with any of the following 15 Lithium line spectrum 29 Carbon 43 Nickel
  - 2 Helium line spectrum 16 Kalium line spectrum 30 Carbon Hydride 44 Oxide of Nitrogen
  - 3 Argon line spectrum 17 Rubidium line spectrum 31 Carbon Oxide 45 Phosphorus
  - 4 Neon line spectrum 18 Casium line spectrum 32 Chlorine 46 Platinum
  - 5 Krypton line spectrum 19 Titan line spectrum 33 Chlorophyll 47 Silicon
  - 6 Xenion line spectrum 20 Radium line spectrum 34 Copper 48 Silver
  - 7 Hydrogen line spectrum 21 Emanations of radium 35 Cyanogen 49 Sulphur
  - 8 Oxygen line spectrum 22 Air. 36 Gold 50 Thorium
  - 9 Nitrogen line spectrum 23 Aluminium. 37 Iodine 51 Tin
  - 10 Calcium line spectrum 24 Ammonia 38 Iron 52 Uranium
  - 11 Strontium line spectrum 25 Arsenic 39 Lead 53 Water
  - 12 Barium line spectrum 26 Bismuth 40 Magnesium 54 Zinc
  - 3523.—Anomalous Dispersion of Sodium Vapour.
  - 1 Sodium flame (coloured) each 7s. 6 d. 3 Spectrum given by prism of sodium vapour crossed by diffraction
  - 2 Spectrum given by Prism of sodium vapour crossed with a glass prism. grating. Each 2s 6d.
  - (coloured). Each js. 6d.
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.502 - vue 521/555
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES OPTICAL PHENOMENA
  - 3524. -—A new series of Slides from negatives made direct from the actual objects, by Mr. W. B. Croft, of Winchester College.
  - These are far superior to those usually made from drawings and book illustrations, and are in considerable demand for those who require really good slides on scientific subjects. Plain slides, 2/3 each.
  - 1 Fresnel’s interference from a Bi-prism
  - 2 Two very narrow slits : the broader has narrower bands
  - 3 Diffraction. Four small circular holes :J a different
  - phenomenon from that of the very narrow openings
  - 4 Diffraction. Arago’s bright centre to the shadow of
  - opaque circular screen
  - 5 Diffraction. Arago’s bright centre to the shadow of
  - opaque circular screen
  - 6 Diffraction of 3d. piece. Argo’s bright centre
  - 7 Diffraction. Needle points : the smaller needle has
  - the larger bright centre
  - 8 Diffraction. Eye of Needle
  - 9 Diffraction. Eye of Needle
  - 10 Diffraction. Wire Gauze
  - 11 Diffraction. Perforated Zinc: to show the bands in
  - the shadow
  - 12 Diffraction. Perforated Zinc : to show the bands in
  - the spaces
  - 13 Arago’s shiftings of bands : the velocity in glass less
  - than air
  - 14 Groups of circles for diffraction screens ; much magni-
  - fied : the original figures are about -fa inch diameter : a part of Bridge’s series
  - 15 Fraunhofer or Schwerd diffraction from three of these
  - figures
  - 16 Fraunhofer or Schwerd diffraction from three of these
  - figures
  - 17 Fraunhofer or Schwerd diffraction from three of these
  - figures
  - 18 Fresnel diffraction from these figures
  - 19 Fresnel diffraction from these figures
  - 20 Fresnel diffraction from these figures
  - 21 Fresnel diffraction from these figures
  - 22 Talbot’s bands : glass film an object glass
  - 23 Talbot’s bands : glass film an eye-piece
  - 24 Conical refraction. Five examples of the phenomenon
  - from five pin-holes of light
  - 25 A Model of the wave-surface
  - 26 Calcite in polarised light : rings and brushes
  - 27 Calcite circularly polarised and circularly analysed
  - 28 Calcite. The dislocated rings of a negative crystal.
  - 29 Concave Selenite : rings in polarised light
  - 30 Quartz : rings and brushes
  - 31 The two spirals of right-handed quartz
  - 32 Quartz. Airy’s spirals, right and left quartz
  - 33 Quartz. Shifting hyperbolas
  - 34 Quartz. Shifting hyperbolae another position
  - 35 Quartz. Savart’s Bands
  - 36 Babinet’s Compensator
  - 37 Nitre : rings and brushes
  - 38 Nitre : rings and brushes, another position
  - 39 Nitre : circularly polarised
  - 40 Nitre: circularly polarised, another portion
  - 41 Nitre : circularly polarised : Lewis Wright’s Spirals
  - 42 Bertrand’s Idiocyclophanous prism of calcite
  - 43 Bertrand’s Idiocyclophanous, another position
  - 44 Idiocyclophanus Topaz
  - 45 Unannealed Glass in polarised light
  - 46 Unannealed Glass in .polarised light.
  - 4 7 Annealed Glass under pressure
  - 48 Newton’s Rings : reflected
  - 49 Newton’s Rings : transmitted
  - 50 Newton’s Rings : reflected, on a larger scale
  - 51 Rings of Tubular calcite \
  - 52 >> »» -four positions
  - 53 ;> »
  - 54 >> »» ' , . ,
  - 55 Star of twenty-four rays : [internal reflection in Canada
  - mica or Phlogopite
  - 56 Micro-photograph showing the internal crystals of the
  - mica
  - 57 The Human Eye. Back part of human eye : showing
  - nerve trunk and fibres and punctum coecum
  - 58 The Human Eye. Crystalline lens of human eye
  - 59 The Human Eye. The lens more highly magnified to
  - show onion structure
  - 60 The Human Eye. The human retina, showing numerous
  - layers
  - 61 The Human Eye. The human retina : to show more
  - distinctly the rods and cones
  - 3525.—Photographing by Ultra-Violet and Infra-Red Rays.
  - These Slides were made from negatives prepared by Prof. R. W. Wood, of the John Hopkins University, to illustrate his Lecture on “ Photographing by Invisible Light.” Copies of the Lecture, revised and brought up to date by him, can be supplied typewritten for 3/6. Plain slides, 3/- each.
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  - Spectrum. (Painted, ys. 6d.)
  - Sky and White Paper by Infra-Red and Ultra-Violet Light
  - Trees at Florence by Infra-Red Rays Willow Tree, Florence Umbrella Pines at Rome
  - Mount I
  - Florence,
  - Florence,
  - Florence.
  - Florence.
  - Florence.
  - Rays
  - Florence.
  - Rays
  - Florence,
  - Rays
  - Florence,
  - Rays
  - Florence,
  - Florence.
  - tna from Taormina, by Infra-Red Rays An Old House, by Infra-Red Rays Trees in the Park, by Infra-Red Rays Cypress Trees, by Infra-Red Rays A Corner of the Park, by Infra-Red Rays View of the Country near, by Infra-Red
  - A Shady Corner in the Park, by Infra-Red
  - A Typical Italian Road, by Infra-Red
  - A Road leading to Florence, by Infra-Red
  - On Mount Oliveto, by Infra-Red Rays Certeosa Monastery, by Infra-Red Rays
  - 17 Florence. A View from behind San Miniato, by Infra-
  - Red Rays
  - 18 Florence. Old Church, by Infra-Red Rays
  - 19 On the Road to Fiesole, by Infra-Red Rays
  - 20 A Ruined House at Pompeii, by ordinary light
  - 21 Hadrian Villa, Odena, by ordinary light
  - 22 A Grove of Pine Trees near Rome, by Infra-Red Rays
  - 23 Old Temple, Girgenti, by Infra-Red Rays
  - 24 Straits of Messina for Taormina, by Infra-Red Rays
  - 25 A Greek Theatre, Taormina, by Infra-Red Rays
  - 26 Palermo. View looking towards Monte Pellegrina, by
  - Infra-Red Rays
  - 27 Palermo. View, Monte Pellegrino, by Indra-Red Rays
  - 28 Palermo. Cactus and Palms, by Infra-Red Rays
  - 29 Syracuse. River Scene with Papyrus, by Infra-Red
  - Rays
  - 30 Syracuse. Almond Trees in Latomia, by Infra-Red
  - Rays
  - 31 Syracuse. The Quarry, Latomia, by Infra-Red Rays
  - 32 The Quarry, Latomia, by Infra-Red Rays
  - 33 The Shadowless Man
  - 34 Landscape seen through Window, by Ultra-Violet and
  - Visible Rays
  - 35 White Flowers, by Ultra-Violet and Visible Rays
  - 36 Bunch of White Flowers, by Visible and Ultra-Violet
  - Rays
  - 37 Reflections from a Mirror by Ultra-Violet and Visible
  - Rays
  - 38 Reflections from Silver and Brass in Ultra-Violet Rays
  - 39 Glass Jar and Silver Jug, by Visible and Ultra-Violet
  - Rays
  - 40 Nickel and Silver Reflecting Surfaces, by Visible and
  - Ultra-Violet Rays
  - 41 Letters in Chinese White, photographed by Ultra-
  - Violet and Visible Light
  - 42 Lunar Photographic Telescope on Bicycle Frame
  - 43 Lunar Photographs by Ultra-Violet and Yellow Light
  - 44 Various Substances by Ultra-Violet and Yellow Light
  - 45 Invisible Ray surrounding an Electric Spark, photo-
  - graphed by Ultra-Violet Light
  - 46 Absorption of Ultra-Violet Light by a Candle-flame
  - 47 Iron Spectrum from Nickel and Silver Mirrors
  - 3526.—Marvels of Modern Photography.
  - This is an entirely new Series, carrying the Science of Photography right up to date, but it is arranged, and the lecture has been written, to suit a popular audience.
  - A glance at the list of subjects will show the comprehensive nature of this set, and while it is purposely kept on such a plane as to interest an ordinary audience, it may safely be concluded that there will not be one man present to whom some point or other will not be new. The set complete, £10 4s. 6d. Lecture, 1s.
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  - Art in Photography
  - Landscape—Summer
  - Landscape—Winter
  - Crowned Pigeon
  - Young Zebra
  - Frilled Lizard running
  - Architectural detail
  - Mrs. Siddons, by Gainsborough
  - Vase of Flowers on ordinary photographic plate
  - Vase of Flowers, orthochromatic
  - Wave Study
  - An artist’s conception of a Galloping Horse A Close Finish
  - Horses going uphill. From the Louterell Psalter Queen Philippa and the Citizens of Calais Queen Victoria at St. Paul’s, at the Diamond Jubilee George V in Westminster Abbey. The only photograph ever taken of an English Coronation Pharaoh Rameses II (Head of)
  - Bacillus Anthracis Bacillus Tuberculosis Zygotes in stomach of Mosquito Filaria in proboscis of Mosquito Nitrifying organisms in soil Photographing from bowsprit
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  - K29
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  - 46 a*’” 47
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  - Photographing under water Living Corals with extended Polyps Photographing under difficulties Purple Heron photographing itself A Flash of Lightning
  - High Frequency Oscillating Electric Discharge Electrified Human Hand Positive discharge from Induction Coil Negative discharge from Induction Coil Rotating form of Spark from Induction Coil Flying Bullet, showing Air Waves Rifle Bullet striking Plate Glass Bullet passing through Plate Glass Bullet after passing through Glass Plate Bullet clear of Glass Plate Exposure scale. Millionths of a second Photograph of an Echo. Sound-wave reflected from plane mirror
  - Visual formation of a musical note
  - The Pleiades Telescopic View
  - The Pleiades Photographic View
  - The Pleiades Prolonged exposure showing nebulae
  - The Pleiades Astrographic Chart
  - Millions of Stars
  - Nova Persei. Photographed’by light rays 300 years old
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  - 62 A" 63
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  - Pin-hole photograph
  - Across the River
  - Across the River. Telephoto
  - Kittiwake leaving nest. Telephoto
  - Telegraphing a picture
  - Moving pictures
  - Head of the Crane Fly
  - Eye of Beetle
  - Snow Mushroom
  - Photograph of Snow Crystal
  - Scene from a balloon
  - Rainbow in the spray of Victoria Falls
  - St. Paul’s Cathedral in Venice
  - The Grand Canal in Regent Street
  - Distortion or True Perspective ?
  - Solar spectrum
  - Photography by Invisible Infra-Red Rays Photography by Invisible Ultra-Violet Rays Photography by Invisible Radium Rays Photography by Invisible X-Rays Photography by Invisible X-Rays, instantaneous Colour Photography, Autochrome (16s.) Three-colour photography (21s.)
  - Photography and Colour (7s. 6d.)
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.503 - vue 522/555
- - 504 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES ASTRONOMY
  - 3527.—Astronomical Sliders
  - 1 Figure of the earth, 8/6
  - 2 Rotundity—movable ship, 11 /-
  - 3 Telescopic view of the moon, 5/6
  - 4 Half-moon, 5/6
  - 5 Moon’s phases, 10/-
  - 6 The sun, showing spots, 4/6
  - 7 Phases of Mercury and Venus, 6/6
  - 8 Planet Mars and moons, 5/6
  - 9 Asteroids and moons, 6/-
  - 10 Jupiter, showing bands, moons, 7/-
  - 11 Saturn, showing broad rings, 7/—
  - (No. i set), a series of thirty-three lecture, 2/6.
  - 12 Saturn, showing edge of rings, 7/-
  - 13 Uranus and moons, 5/6
  - 14 Neptune and moons, 5/6
  - 15 Orbit of comet, 7/-
  - 16 Comets, 1680 and 1858, 7/-
  - 17 Ptolemaic system, 7/—
  - 18 Pythagorean system, .7/-
  - 19 Tychonic system, 7/-
  - 20 Newtonian system, 7/-
  - 21 Shadow of the earth, 8/-
  - 22 Causes of eclipses of sun and moon, 8/-
  - coloured slides £11 11s. Descriptive
  - 23 Eclipses of the sun—movable, 8/-
  - 24 Orbit of moon, 8/-
  - 25 Eclipses of the moon—movable, 8/-
  - 26 Zodiac and seasons, 10/-
  - 27 Spring tides, 6/-
  - 28 Spring tides, 6/-
  - 29 Neap tides, 6/-
  - 30 Constellation of Orion, 7/6
  - 31 Constellation of Ursa Major, 7/6
  - 32 Milky way and nebulas, 5/6
  - 33 Comparative sizes of the sun and planets, 6/6
  - 3528.—Astronomical Sliders (No. 2 set), beautifully painted. 3/6 to 8/6 each.
  - 34 Curvature of the ocean, 4/-
  - 35 The earth’s figure and dimensions, 4/-
  - 36 The terrestrial skeleton globe, 6/—
  - 37 The mariner’s compass, 6/-
  - *38 The winds, table of velocity and forces, 3/—
  - 39 Mountain of the moon, telescopic view, 5/6
  - 40 Planetary motion, No. 1, 5/-
  - 41 Planetary motion, No. 2, 5/—
  - .. 42 Planetary motion, No. 3, 5/—
  - 43 The planet Saturn, as observed from Octo-
  - ber, 1848, to March, 1851, 7/6
  - 44 Comet, Sword over Jerusalem, 7/6
  - 45 Comet of 1680, 7/6
  - 46 Comet with six tails, of 1741, 7/6
  - 47 Comet, Halley’s 1835, 7/6
  - *48 Comet, Halley’s, giving extent of orbit, 3/—
  - 49 Donati’s comet, October, 1858, 8/6
  - 50 Atmospheric refraction, 7/6
  - 51 Atmospherical refraction in the Polar seas, 8/6
  - 52 Parallax of the planets, 6/6
  - 53 Constellation of Draco and Ursa Minor, 7/6
  - 54 Constellation of Hercules, 7/6
  - 55 Constellation of Taurus, 7/6
  - 56 Constellation of Southern Cross, 7/6
  - 57 Various nebulae, 6/6
  - 58 Meteor, falling or shooting star, 9/6 *59 Comparative size of the planets, 3/-
  - 60 Duration of light and darkness, 7/6
  - 61 The sun’s rays, 7/6
  - 62 Sun, partial eclipse, as seen at Dublin, 11.30
  - a.m., March 15th, 1858, 7/6
  - 63 Sun, partial eclipse, as seen at 1.30 p.m.,
  - March 15th, 1858, 7/6
  - 64 Sun, total eclipse, with corona, August 7th,
  - 1869, 7/6
  - 65 Solar eclipse, 1869, as seen in America, 6/6
  - 66 Change in appearance of solar spot, caused
  - by rotation of sun, 6/6
  - 67 Solar spots drawn by Nasmyth, June 5th,
  - 1846, 8/-
  - 68 Solar prominences observed by Zollner,
  - August 29th, 1869, 8/-[
  - 69 Solar prominences observed by Respighi,
  - 1870, 8/-
  - 70 Solar prominences observed by Respighi,
  - 1870, 8/-
  - 71 Solar prominences observed by Zollner,
  - August 29th, 1869, 8/-
  - 72 Solar prominences observed by Zollner,
  - August 29th, 1869, 8/-
  - 73 Solar prominences observed by Zollner,
  - August 29th, 1869, 8/-
  - 74 Diagram of the solar spectrum observed by
  - Secchi, April 13th, 1869, 10/—
  - * Plain slides only.
  - 75 Star spectra as compared with sun, 10/-
  - 76 Nebulae spectra as compared with sun, 3/6
  - 77 The rainbow, 7/6
  - 78 The rainbow, spectrum with prism, 4/6
  - 79 The rainbow, drops of rain, 8/6
  - 80 The rainbow, the double bow, 10/6
  - 81 Lunar rainbow, 8/6
  - 82 Clouds: cumulus, nimbus stratus, and
  - cumulo stratus, 8/6
  - 83 Clouds : cirrus, 8/6
  - 84 Clouds : cirro cumulus and ciro stratus, 8/6
  - 85 Motto : “ The Heavens declare the Glory of
  - God,” designed in stars, 12/6
  - 86 Motto : “ The Heavens declare the Glory of
  - God,” designed in wreath of flowers, 8/-
  - 87 Map of nebulae and clusters of the northern
  - heavens, 6/-
  - 88 Map of nebulae and clusters of the southern
  - heavens, 6/-
  - 89 The great magnetic storm of October 31st,
  - 1903, and its relation to the solar prominences, 6/—
  - 90 The stars in miniature : Practical teaching of
  - astronomy in a Spanish School. Pupils learning the relative positions of the planets on an open-air model at a school in Granada, 10/-
  - 3529.—Hackwork Astronomical Slides.
  - A comprehensive series of mechanical slides for illustrating the science of physiography. They are carefully made, and the movements are accurately timed so as to work in correct ratios. The slides have 3-inch diameter pictures, carefully coloured, and are carried in unpolished mahogany frames. The rackwork adjustment works smoothly, and each slide is fully described. They are supplied either in box or separately, as detailed below.
  - A. The Solar system, showing the revolution of all the Planets with their Satellites round the sun
  - B. The Earth’s annual motion round the Sun, showing the parallelism of its axis, producing the seasons _ ..
  - C. To illustrate the cause of Spring and Neap Tides and shows the Moon’s phases during its revolution ..
  - D. To illustrate the apparent direct and retrograde motion of Venus and Mercury, and also their stationary
  - appearance
  - E. To prove the Earth’s Rotundity ..
  - F. To illustrate the eccentric revolution of a Comet round the Sun, and shows the appearance of its Tail at
  - different points of its orbit
  - G. The Diurnal Motion of the Earth, showing the Rising and Setting of the Sun, illustrating the cause of Day
  - and Night
  - H. To illustrate the Annual Motion of the Earth round the Sun, with the monthly lunations of the Moon
  - K. To show the various Eclipses of the Sun, with the Transit of Venus
  - L. To show the various Eclipses of the Moon
  - Complete Set of 10 Slides as above, in Wood Box...................................................
  - £1 12 6 0 19 6 0 10 6
  - 0 10 6 0 10 6
  - 17 6
  - 0 10 6 1 10 0 0 10 6 0 10 6 8 5 0
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.504 - vue 523/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 505
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - 3530.—Astronomical Work in the Solar Physics Observatory, South Kensington.
  - These are published by the kind permission and under the direction of Sir Norman Lockyer, F.R.S.
  - Plain Photographs, 2/- each.
  - Eclipse Expedition to India, 1898.
  - 1 H.M.S. “ Melpomene ”
  - 2 H.M.S. “ Melpomene ” Officers
  - 3 Approaching Viziadrug Fort, the Station that was
  - occupied
  - 4 Viziadrug Fort
  - 5 Viziadrug Fort Plan
  - 6 The Camp. First day after arrival
  - 7 The Camp. Middle of the first week
  - 8 The Camp. A week after our arrival
  - 9 The Camp. General View, looking East
  - ro The Camp. Panoramic View taken before the Eclipse xi Group of Observers taken after the Eclipse
  - 12 The Eclipse Clock showing how the dial was graduated
  - spirally
  - 13 The 6-in. grating Spectroscope with Professor Pedler
  - and Staff
  - 14 The 3J Telescope with Sir Norman Lockyer
  - 15 The Hut containing Coronograph and Integrating
  - Spectroscope
  - 16 The Kinematograph worked by the Marquis of Graham
  - 17 Siderostat and Cameras as arranged for Meteor Obser-
  - vations. No. I
  - 18 Siderostat and Cameras as arranged for Meteor Observa-
  - tions. No. II
  - 19 Dark slide (running plate) used in the 6-in. Prismatic
  - Camera
  - 20 Apparatus for enlarging Star Spectra
  - 21 Plan or part of the Viziadrug Fort, showing positions
  - of instruments
  - Stellar and other Spectra.
  - 22 Up-and-down Spectra of Sirius taken with the up-and-
  - down motion, showing how oblique are the Spectra produced by this method
  - 23 Comparison of Spectra of Sirius and a Cygni, with
  - enhanced lines added
  - 24 /3 Lyras, one for each day
  - 25 Comparison of Spectra of Procyon and y Cygni, with
  - the enhanced lines added
  - 26 Stellar Spectra, Ascending Series
  - 27 Spectrum of 8 Orionis, showing the lines due to O. N.
  - & C.
  - 28 Comparison of a Cygni and the enhanced lines of cer-
  - tain metals. (Chiefly of the iron group)
  - 29 a Orionis with metallic comparisons
  - 30 Comparison of enhanced lines with Chromosphere (1898)
  - and a Cygni
  - 31 Comparison of Corona Chromosphere (1898) and Sun
  - 32 Comparison of Chromosphere and Sun
  - 33 Bellatrix with the Hydrogen and Cleveite Gases
  - 34 Metals up. Diagram showing the behaviour of metals
  - in stars increasing their temperature
  - 35 Metals down. Diagram showing the behaviour of
  - metals in stars decreasing in temperature
  - Stellar Spectra taken with a 6-in. Prismatic Camera (2 Prisms 45°) :—
  - 36 Arcturus. (18 May, 1898)
  - 37 Procyon. (23 Dec., 1898). 75 min.
  - 38 Sirius
  - 39 Vega. (17 April, 1899) 80 min. exposure
  - 40 a Cygni. (17 April, 1899) 80 min. exposure. Scale
  - 5-o-
  - 41 Definitions of Stellar Genera
  - 42 Stellar Evolution Map. Diagram illustrating the
  - Stellar Evolution as based on spectroscopic observations
  - 43 Constellations near Leo for November meteors
  - 44 Map of Spain with 1900 Eclipse track marked
  - Eclipse Expedition, 1896.
  - 45 H.M.S. “ Volage ” in Bras Haven, Lapland
  - 46 H.M.S. “ Volage ” in)Bras Haven, Lapland, anchored
  - 47 H.M.S. “ Volage ” in Bras Haven, Lapland, casting the
  - anchor
  - 48 H.M.S. “ Volage,” The Volunteer Observer on board
  - 49 H.M.S. “ Volage,” The Ship’s Company
  - 50 H.M.S. “ Volage,” An Officer
  - 51 The 9-in. Prismatic Camera worked by Dr. W. J. S.
  - Lockyer, No. 1
  - 52 The 9-in. Prismatic Camera worked by Dr. W. J. S.
  - Lockyer, No. 2.
  - 53 Group near 9-in. Prismatic Camera, (1) Dr. W. J. S.
  - Lockyer, (2) Lieutenant Martin, (3) Sir Norman Lockyer
  - 54 The 6-in. Prismatic Camera worked by Mr. A. Fowler
  - 55 The 3|-in., with Sir Norman Lockyer
  - 56 The erection of a Disc
  - 57 The erection of a Disc, by Lieutenant Martin, R.N.
  - 58 General View of the Eclipse Camp
  - 59 General View of the Eclipse Camp, nearer view
  - 60 KiO Fjord, Lapland
  - 61 Our Marine Guard
  - 62 Chart of Sky in region about Sun during the Eclipse
  - 63 W hat we saw of the Eclipse
  - 64 The Integrator and its staff of workers
  - 65 Group of Observers, taken after the Eclipse
  - 66 Packing up after the Eclipse
  - Eclipse Expedition to India, 1898.
  - 67 The 9-in. Prismatic Camera
  - 68 The 9-in. Prismatic Camera, worked by Dr. Lockyer
  - and his Naval Staff
  - 69 The 6-in. Prismatic Camera, worked by Mr. Fowler
  - and his Naval Staff
  - 70 Despatch of Instruments for Eclipse, 1898
  - 71 Group on board H.M.S. “ Melpomene ”
  - 72 Eclipse Camp
  - 73 Excursionists from Bombay to Viziadrug to view the
  - Eclipse
  - 74 Government Packers at work
  - 75 Our Police Guard
  - Instruments.
  - 76 6-in. Prismatic Camera with two prisms
  - 77 9-in.Prismatic Camera with one prism
  - 78 9-in. Prismatic_Reflector, two prisms
  - 79 9-in. Prism
  - 80 Eclipse Telescope 6-in. Prismatic Camera with one
  - prism, as arranged for Eclipse work
  - 81 Stand for 9-in. Prismatic Camera, as used in the Indian
  - Eclipse, 1898
  - 82 3-in. Transits at South Kensington
  - 83 Coronograph as used at Novaya Zembya in Eclipse
  - 1896
  - 84 Driving Screw of 36-in. Common Reflector
  - 85 Integrating Spectroscope as used in Eclipses 1896 and
  - 1898
  - 86 Celestial Globe, adjustable for precessional move-
  - ment
  - 87 Stella Spectra of Cygni Arcturus
  - 88 Hammersley Grating Spectroscope, for observation of
  - widened lines in Sun Spots, Solar Physics Observatory
  - 89 Curves of known and unknown line in Sunspot Spectra
  - 3531.—The Moon’s Eclipse. A series of seven photographs, showing the gradual passing of the shadow over the Moon’s surface. Taken by G. J. Newbegin, Esq., May nth, 1892. Plain photographs, 2/- each.
  - 1 Eclipse time, 9.20 p.m. ' 3 Eclipse time, 9.50 p.m. 5 Eclipse time, 10 p.m.
  - 2 Eclipse time, 9.30 p.m. 4 Eclipse time, 10.30 p.m. 6 Eclipse time, 11.30 p.m.
  - 7 Eclipse time, 12 p.m.
  - 3532.—Weather and Weather
  - 1 A Meteorological Station
  - 2 Maximum and Minimum Thermometers
  - 3 Wet and Dry Thermometers
  - 4 Interior of a Thermometer Screen
  - 5 Recording Thermometer—Thermograph
  - 6 Solar Radiation Thermometers
  - 7 Reading the Earth Thermometers
  - 8 Sunshine Recorders
  - 9 Actual Sunshine Records •10 Mercurial Barometers
  - Recording. Plain slides, 2/-. Reading, 1/-
  - xi Aneroid Barometer
  - 12 Barograph
  - 13 A Wind Tower
  - 14 Robinson’s Anemometer
  - 15 Recording Anemometer
  - 16 Dine’s Anemometer
  - 17 A Dine’s Record
  - 18 Measuring the Rainfall
  - 19 A Raingauge
  - 20 Self-Recording Raingauge
  - Beautifully painted views, 7/6. Printed
  - 21 Electrical Self- Recording Raingauge
  - 22 A Week’s Rainfall
  - 23 Three Records of a Gale
  - 24 Evaporation Tanks
  - 25 Cloud Forms—Cirro-Stratus
  - 26 Cloud Forms—Cumulus
  - 27 Measuring Heights of Clouds
  - 28 Lightning Flashes
  - 29 Earthquake Records
  - 30 A Daily Report from the Meteorological Office
  - 3533.—Lantern Slides—Meteorology. These are photographed from the actual instruments. Plain photographs 2/- each.
  - 1 Standard mercurial barometer (Fortius)
  - 2 Aneroid barometer
  - 3 Mountain and surveying aneroids
  - 4 Boiling-point thermometer and apparatus
  - 5 Recording barometer
  - 6 Recording thermometer
  - 7 Standard maximum and minimum thermometers
  - 8 Thermometers ; Fahrenheit] and Centigrade
  - scale. Bath thermometer. Scale of temperature
  - 9 Six’s maximum and minimum registered thermometer
  - 10 Terrestrial radiation and solar radiation maxi-
  - mum with blackened bulb in vacuum thermometers
  - 11 Solar radiation and maximum register ther-
  - mometers
  - 12 Window thermometers on brackets
  - 13 Thermometer screen for holding thermometers
  - 14 Hygrometer, wet and dry bulb
  - 15 Rain gauges with glass measures
  - 16 Sunshire recorders, Jordan’s and Stonyhurst
  - simplex
  - 17 Anemometer or wind gauge with vane
  - 18 Anemometer with cups
  - 19 Differential thermometer
  - 20 Air meter for measuring the velocity of air
  - currents
  - 3534.—Lantern Slides from Ganot’s “ Physics” (9th Edition).—Meteorology.
  - 093 rig.
  - 694 „
  - 695 „
  - 696 ,,
  - 69 7 ,,
  - 1033, 1034 Secchi’s meteorograph.
  - Direction and velocity of wind 1,036 Secchi’s meteorograph reverse 1,035, 1,037 Secchi’s meteorograph.
  - Rain gauge and psychrometer 1,038 Clouds
  - 699 ,, 1,041 Water spouts
  - £.-•700 ,, 1,042 Snow crystals
  - 701 ,, 1,043 Atmospheric electroscope
  - 702 ,, 1,044, 1,045 Kelvin’s apparatus for
  - registering Atmospheric electricity
  - 703 ,, 1,046 Lightning conductor
  - 704 Fig. 1,047 Explanation of rainbow
  - 705 ,, Plate Aurora Borealis, Norway, 1868,
  - painted in colours, 8s. 6d.
  - 706 Fig. 1,048 Aurora, Lapland, 1838
  - 707 Plate VII., Isothermes for the year
  - 708 Plate VIII., Isothermes for January
  - 709 Plate IX., Isothermes for July
- p.505 - vue 524/555
- - 506 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES HEAT
  - 3535.—Lantern Slides for Lectures on Heat. These slides are all made from the illustrations in Ganot’s “ Physics ” (Ninth Edition) by kind permission of Messrs. Longman. In some cases two or three of the figures are put on one slide where they all refer to or bear on the same subject, to decrease the expense. Plain photographs, 2/- each.
  - 176 Fig.
  - 177 ,,
  - 178 ,,
  - 179 ,,
  - 180 ,,
  - 181 ,,
  - 182 ,,
  - 183 ,,
  - 184 „
  - 185 ,,
  - 186 ,,
  - 187 Page
  - 188 Fig.
  - 189 „
  - 190 Page
  - 191 Fig.
  - 192 ,,
  - 193
  - 194
  - 195
  - 196
  - 197 „
  - 198 ,,
  - 199 ,,
  - 200 ,,
  - 201 Page
  - 202 Fig.
  - 203 Page
  - 204 Fig.
  - 205 „
  - 206 ,,
  - 207 ,,
  - 208 ,,
  - 209 „
  - 210 „
  - 211 ,,
  - 212 „
  - 213 „
  - 214 „
  - 215 ,,
  - 298 Linear expension of solids
  - 299 Cubical expansion of solids
  - 300, 301' Expansion of liquids and gases
  - 302 Filing a Thermometer
  - 303, 304 Determining freezing and
  - boiling points on the Thermometer
  - 305 Divided stem Thermometer
  - 306 Matthicson’s Differential Thermo-
  - meter
  - 307 Breguet’s Metallic Thermometer
  - 308 Maximum and Minimum Thermo-
  - meters
  - 309, 310 Six’s Thermometer and detail 311 Contracted boremaximum Thermometer
  - 299 Table of remarkable temperatures 312, 318 Measurement of co-efficient of linear expansion, Lavoisier and Laplace’s method
  - 314 Roy and Ramsden’s method
  - 303 Table of co-efficients of linear ex-
  - pansion
  - 315 Gridiron pendulum
  - 316, 317, 318, 3x9 Compensating strip pendulum and compensating balance wheel
  - 320 Apparent and real expansion
  - 321 Co-efficient of absolute expansion
  - of mercury
  - 322 Weight Thermometer
  - 323 Hope’s Appai'atus showing tem-
  - perature of maximum density of water
  - 324 Co-efficient of expansion of gases.
  - Gay-Lussac’s method
  - 325 Regnault’s method. Hot bath
  - 326 Regnault’s method. Cold chamber
  - 327 Relation between temperature
  - volume and pressure 320 Table of Co-efficients of expansion of gases
  - 328 Determining density of gases 324 Table of 1-elative density of gases 338 Melting point
  - 331, 332 Influence of pressure on melting point, Bunsen’s and Kelvin’s experiments
  - 333; 334 Lowering of the melting point, Musson’s and Helmholtz’s experiments
  - 335 Co-efficient of molecular depression
  - 336 Retardation of the point of solidi-
  - fication
  - 337 Superfusion of phosphorus
  - 338, 339 Change of volume on solidification and liquefaction 340, 341 Vapour pressure and formation of vapour in vacuum 342, 343 Saturated and unsaturated vapour
  - 344, 345 Pressure of aqueous vapour between o° and ioo°. Dalton’s and Regnault’s methods
  - 346 Pi-essure above ioo° Regnault’s
  - method
  - 347 Pressure above and below ioo°
  - Regnault’s method
  - 216 Page 346 Table of pressure of vapours of
  - different liquids
  - 217 Fig. 348 Pressure in two communicating
  - vessels at different temperatures
  - 218 ,, 349, 350 Ebullition and boiling points
  - of liquids
  - 219 Page 350 Table of boiling points
  - 220 Fig. 351 Water at xoo° C. without boiling
  - 221 ,, 352 Influence of pressure on boiling
  - point
  - 222 ,, 353 Franklin’s expeidnxent
  - 223 ,, 354 Measurement of heights by boiling
  - 224 ,, 355 Behaviour of condensed gases at
  - different temperatures
  - 225 ,, 357 Critical temperature
  - 226 ,, 358 Papin’s digester
  - 227 ,, 359, 360 Cold due to evaporation
  - 228 ,, 361, 362 Carre’s freezing apparatus
  - 229 ,, 363 Carre’s Ice-making machine
  - 230 ,, 364 Still
  - 231 ), 365 Liebig’s condenser
  - 232 ,, 366 Apparatus for determining the
  - alcoholic value of wines
  - 233 >) 367, 368 Safety tube
  - 234 >) 369 Liquefaction of gases, Faraday’s
  - Tube
  - 235 ,, 370, 371 Liquefaction of gases, Bianchi’s
  - apparatus
  - 236 ,, 372, 373 Liquefaction of gases, Caille-
  - tet’s apparatus
  - 237 >) 374 Liquefaction of gases, Pictet’s
  - method
  - 238 ,, 375 Liquefaction of gases, Wroblewski’s
  - apparatus
  - 239 Page 374 Table of boiling and melting points
  - 240 Fig. 376 Tube for containing liquid air
  - 241 >, 377 Linde and Hampson’s apparatus
  - for liquefying gases
  - 242 ,, 378 Gay-Lussac’s apparatus illustrating
  - Dalton’s laws
  - 243 )> 379 Leidenfrost’s phenomena
  - 244 ,, 330 Doutigny’s experiment
  - 245 ), 381 Density of Vapours, Gay-Lussac’s
  - method
  - 382 Density of Vapours, Hoffmann’s method
  - 383 Density of Vapours, Dumas’ method
  - 384 Density of Vapours, Meyer’s method 887 Table of Densities of Vapours
  - 385 Chemical Hygrometer
  - 386 Daniell’s Hygrometer
  - 387 Regnault’s Hygrometer
  - 388 Mason’s Hygrometer
  - 389 Saussure’s Hygrometer
  - 390 Conductivity of Solids, Ingenhous’s apparatus
  - 391 Conductivity of Solids, Despretz’s apparatus
  - 400 Table of relative conductiveness
  - 392 Senarmont’s experiment
  - 393 Conductivity of liquids
  - 394 Conductivity, Guthrie’s appai’atus
  - 395 Convection
  - Conductivity of gases, Grove’s experiment 397> 398 Thermo-Electric pairs 399 Melloni’s Thermo multiplier 400, 401 Radiation in vacuo and Intensity of radiant heat
  - 246
  - 247 ,,
  - 248 ,,
  - 249 Page
  - 250 Fig.
  - 251 ,,
  - 252 ,,
  - 253 ,,
  - 254 ,,
  - 255 „
  - 256 ,,
  - 257 Page
  - 258 Fig.
  - 259 ,,
  - 260 ,,
  - 261 ,,
  - 262
  - 263
  - 264
  - 265
  - 266 Fig. 402, 403 Law of Inverse squares
  - 267 ,, 404 Leslie’s experiment
  - 268 ,, 405 Diagram of Angle of Reflection
  - 269 ,, 406 Experimental demonstration of the
  - laws of reflection of heat
  - 270 ,, 407 Expei’iments of the conjugate
  - mirrors
  - 271 ,, 408 Reflection in vacuo
  - 272 ,, 409 Leslie’s cube experiment
  - 273 ,, 410 Ritchie’s experiment
  - 274 ,, 411, 412, 413, 414 Melloni’s researches
  - 275 >> 4*5 Thermal analysis of Sunlight
  - 276 ,, 416, 417 Tyndall’s i-esearches on the
  - heat of the Spectra of Electric and Sun Light
  - 277 ,, 418 Langley’s observations
  - 278 ,, 419 Absorption of heat rays by solids
  - and liquids
  - 279 ,, 420 Absorption by gases
  - 280 ,, 421 Radiometer
  - 281 ,, 422, 423, 424 Relation of l’adiant heat
  - to sound
  - 282 ,, 425, 426 Black’s and Lavoisier’s calori-
  - meters
  - 283 ,, 427,428 Bunsen’s ice calorimeter
  - 284 ,, 429, 430 Specific heat, Regnault’s
  - apparatus
  - 285 ,, 431, 432 Specific heat, Dulong and
  - Joly’s methods
  - 286 ,, 433 Specific heat of gases
  - 287 ,', 434, 435 Latent heat of vapour. Des-
  - pretz’s and Bertholet’s apparatus
  - 288 ,, 436 Latent heat of vaporisation of
  - liquefied gases
  - 289 ,, 437 Favre and Silbermann’s calorimeter
  - 290 ,, 438 Method of graduating the meixury
  - calorimeter
  - 291 )> 439, 440 Cornish boiler, sectional
  - drawings
  - 292 ,, 441 Cornish engine
  - 293 ,, 442 Hoi-izontal engine with Watt’s
  - governor
  - 294 ,, 433, 444 Slide valves, sectional drawings
  - 295 ,, 445 Locomotive
  - 296 ,, 446, 447, 448 Indicator and diagrams
  - 297 ,, 449 Principle of the dynamometer
  - 298 ,, 450 Gas engine 1
  - 299 ,, 45i Tindall’s experiment. Heat due
  - to friction
  - 300 ,, 452 Pneumatic or fire syringe
  - 301 ,, 453 Pyroheliometer
  - 302 ,, 454 Dobereiner’s Hydrogen Lamp
  - 3°3 ,, 455 Heat disengaged during chemical
  - action, Favre and Silbermann’s arrangement
  - 304 ,, 456 Bunsen’s and Bertholet’s methods
  - 305 ,, 458 Draught of fire-places
  - 306 ,, 459 Heating by hot air
  - 307 ,, 460 Heating by hot water
  - 308 ,, 461 Cooling by expansioix of gases
  - 309 ,, 462 Mechanical equivalent of heat,
  - Jule’s experiment
  - 310 ,, 463 Hirn’s expeidment
  - 311 ,, 464, 465 Tyndall’s experiments to show
  - that work and heat are convertible
  - 312 ,, 466, 467 Isothermal and adiabatic lines
  - 313 ,, 468 Carnot’s Cycle
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.506 - vue 525/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 507
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - H EAT—continued.
  - 3536.—Lantern Slides for Lectures on Heat. Selected and F.R.A.S., F.R.M.M., etc. Per slide, 2/-.
  - 1 Simple pyrometer
  - 2 Gravesande’s ring
  - 3 Experiment with platinum wire
  - 4 Unequal expansion of different metals
  - 5 Metallic thermometers
  - 6 Compensating pendulum. No. i
  - 7 Compensating pendulum. No. 2
  - 8 Pendulum with compensating bars
  - 9 Compensating balance wheel
  - 10 Measurement of coefficient of linear expan-
  - sion. No. 1. (Lavoisier and Laplace)
  - 11 Measurement of coefficient of linear expan-
  - sion. No. 2. (Roy and Ramsden)
  - 12 Expansion of crystals
  - 13 Contraction of india-rubber by heat
  - 14 Trevelyan’s rocker
  - 15 Rocking fire shovel experiment
  - ' 16 Expansion of liquids and gases by heat
  - 17 Expansion of liquids projected on the screen
  - 18 Filling a mercurial thermometer
  - 19 Boiling the quicksilver
  - 20 Determination of freezing point
  - 21 Determination of boiling point
  - 22 Thermometer scales
  - 23 Weight thermometer
  - 24 Air thermometer. Absolute zero
  - 25 Differential thermometers
  - 26 Maximum and minimum thermometers.
  - (Rutherford)
  - 27 Maximum and minimum thermometers.
  - (Wolferdin)
  - 28 Apparent and real expansion
  - 29 Pierre’s apparatus
  - 30 Measurement of coefficient of absolute expan-
  - sion of mercury. No. 1. (Dulong and Petit)
  - 31 Measurement of coefficient of absolute expan-
  - sion of mercury. No. 2. (Regnault)
  - 32 Maximum density of water. Hope’s experi-
  - ment
  - 33 Maximum density of water. Graphic illus-
  - tration
  - 34 Graphic charts of expansion
  - 35 Expansion of air by heat
  - 36 Expansion of bladder by heat
  - 37 Draught in fireplace
  - 38 Heating and ventilating stove
  - 39 Hot air heating apparatus
  - 40 Hot air balloon
  - 41 Ventilation of mines, etc., by heat
  - 42 Expansion of gases. Gay-Lussac’s apparatus
  - 43 Expansion of gases. Regnault’s apparatus
  - 44 Expansion and density of gases. Regnault’s
  - apparatus
  - 45 Cold produced by expansion of gases. Ice
  - machine
  - 46 Influence of pressure on melting point
  - (Oersted)
  - 47 Change of volume on solidification
  - 48 Elastic force of vapour
  - 49 Formation of vapour in vacuo
  - 50 Saturated vapours. Maximum of tension
  - 51 Non-saturated vapours
  - 52 Tension of aqueous vapour below zero. Gay-
  - Lussac’s apparatus
  - 53 Tension of vapours (Dalton, Regnault)
  - 54 Tension of vapours (Dulong and Arago)
  - 55 Tension of vapours above 100° (Regnault)
  - 56 Tension of vapours (Magnus)
  - 57 Tension of vapour in communicating vessels
  - at different temperatures
  - 58 Ebullition : water “ singing ”
  - 59 Ebullition : water boiling
  - 60 Donny’s experiment on dissolved air
  - 61 Tension of vapour during ebullition
  - Influence of pressure on boiling point Influence of pressure. Franklin’s experiment Franklin’s pulsometer Hypsometer
  - Diagram of effects of heat upon water Comparative volumes of water and steam Papin’s digester. No. 1 Papin’s digester. No. 2 Picture of geyser. No. 1 Picture of geyser. No. 2 Experimental geyser
  - 73 Diagram explaining geyser
  - 74 Cold due to evaporation The cryophorus
  - Freezing by evaporation of ether
  - 77 Carre’s ice machine. No. 1
  - 78 Carre’s ice machine. No. 2 Latent heat of vapour Distillation. Chemical
  - Liebig’s apparatus Safety tubes Commercial
  - Alcoholic value of wines
  - Faraday’s apparatus
  - 62
  - 63
  - 64
  - 65
  - 66
  - 67
  - 68
  - 69
  - 70
  - 71
  - 72
  - 75
  - 76
  - 79
  - 80
  - ol
  - 82
  - 83
  - 84
  - 85
  - 86 87
  - 88
  - 89
  - 90
  - 91
  - 92
  - 93
  - 94
  - 95
  - 96
  - 97
  - 112
  - 113
  - 114
  - 115
  - 116
  - Distillation. Distillation. Distillation. Distillation. Liquefaction of gases. Liquefaction of gases. Liquefaction of gases. No. 1
  - Liquefaction of gases. No. 2
  - Liquefaction of gases. Liquefaction of gases. Liquefaction of gases. Liquefaction of gases. Liquefaction of gases. Density of vapours. Density of vapours.
  - Pouillet’s apparatus Thilorier’s apparatus.
  - Thilorier’s apparatus.
  - Bianchi’s apparatus Magnus’s apparatus Andrew’s apparatus Cailletet’s apparatus Pictet’s apparatus Gay-Lussac’s apparatus Hofmann’s apparatus
  - Density of vapours. Dumas’s apparatus Mixture of gases and vapours. Gay-Lussac’s apparatus
  - 98 Spheroidal condition.
  - 99 Spheroidal condition.
  - tion. No. 1
  - 100 Spheroidal condition, tion. No. 2 Hair hygrometer Chemical hygrometer
  - 103 Daniell’s hygrometer
  - 104 Regnault’s hygrometer
  - 105 Edelmann’s hygrometer
  - 106 Psychrometer
  - 107 Hoar frost on window, pane.
  - 108 Hoar frost on window pane.
  - 109 Hoar frost on window pane.
  - Globule
  - Experimental illustra-Expcrimental illustra-
  - 101
  - 102
  - no Snow crystals, in Snow crystals. Snow crystals. Snow crystals. Snow crystals. Snow crystals. Snow crystals.
  - No. 1 No. 2 No. 3
  - 117 Snow crystals.
  - No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8
  - 118 Dissection of ice by electric lamp
  - 119 Flowers of ice (Tyndall)
  - Regelation. Bottomley’s experiment Ice moulded by pressure. No. 1 Ice moulded by pressure. No. 2
  - 123 Glaciers. 1—View of the “ Mer de Glace ”
  - 124 Glaciers. 2—Map of the “ Mer de Glace ”
  - 125 Glaciers. 3—Section of the “ Mer de Glace ”
  - 126 Conduction of heat. Ball and rod experiment
  - 127 Conduction of heat. Ingenhous’s apparatus
  - 128 Conduction of heat. Despretz’s apparatus
  - 129 Conduction in crystals (Senarmont)
  - 130 Conduction in wood (Tyndall)
  - 120
  - 121
  - 122
  - arranged by the Rev. P. Sleeman,
  - 131 Conduction in gases (Magnus)
  - 132 Wire gauze over flame
  - 133 Davy’s safety lamp
  - 134 Ice house
  - 135 Norwegian cooking stove
  - 136 Eskimo dress
  - 137 Bad conducting power of liquids
  - 138 Water boiling over ice
  - 139 Convection currents. No. 1
  - 140 Convection currents. No. 2
  - 141 Convection currents. No. 3
  - 142 Conductivity of liquids. Despretz’s apparatus
  - 143 Conductivity of liquids. Guthrie’s apparatus
  - 144 Heating buildings by hot water
  - 145 Oceanic currents : Gulf Stream. Map
  - 146 Oceanic currents : Gulf Stream. Section
  - 147 Convection currents in gases
  - 148 Simple calorimeter. Heated balls
  - 149 Black’s ice calorimeter
  - 150 Lavoisier and Laplace’s ice calorimeter
  - 151 Bunsen’s ice calorimeter
  - 152 Specific heat. Liquids (Regnault)
  - 153 Specific heat. Gases (De la Roche and Berard)
  - 154 Specific heat. Gases (Regnault)
  - 155 Specific heat. Aqueous vapours (Regnault)
  - 156 Latent heat of evaporation (Despretz)
  - 157 Favre and Silbermann’s water calorimeter
  - 158 Favre and Silbermann’s calorimeter. No. 1
  - 159 Favre and Silbermann’s calorimeter. No. 2
  - 160 Favre and Silbermann’s calorimeter for com-
  - bustion
  - 161 Thermo-electric couple
  - 162 Construction of thermopile
  - 163 Thermopile and galvanometer
  - 164 Radiation of heat in straight lines
  - 165 Radiation of heat. Law of inverse squares
  - 166 Radiation of heat. Law of inverse squares
  - and cosine
  - 167 Reflection of radiant heat
  - 168 Reflection of heat by tube and single mirror
  - 169 Burning mirror
  - 170 Reflection of heat by conjugate mirrors
  - 171 Reflection of heat in vacuo
  - 172 Refraction of heat. Burning glass
  - 173 Refraction of heat. Echelon lens
  - 174 Refraction of heat. Bemiere’s lens
  - 175 Refraction of heat. Prismatic dispersion
  - 176 Leslie’s cube and thermopile
  - 177 Melloni’s sources of heat
  - 178 Melloni’s measurement of radiating power
  - 179 Melloni’s measurement of absorptive power
  - 180 Reciprocity of radiation and absorption
  - 181 Reciprocity of radiation and absorption.
  - Ritchie’s apparatus
  - 182 Theory of exchanges
  - 183 Theory of exchanges. Tourmalin experiment
  - 184 Newton’s law of cooling. Dulong’s apparatus
  - 185 Melloni’s measurement of reflecting power
  - 186 Melloni’s measurement of diathermancy
  - 187 Diathermancy of liquids (Tyndall)
  - 188 Diathermancy of air (Tyndall)
  - 189 Diathermancy of gases (Tyndall)
  - 190 Absorption of radiant heat by air (Tyndall)
  - 191 Influence of thickness upon diathermancy
  - 192 Relation of gases and vapours to radiant heat
  - (Tyndall)
  - 193 Radiating power of gases (Tyndall)
  - 194 Linear thermopile and its application
  - 195 Diagram of thermal, luminous, and actinic
  - intensities in solar spectrum
  - 196 Diagram of thermal intensities in sun and
  - electric light
  - 197 Calorescence. Tyndall’s apparatus. No. 1
  - 198 Calorescence. Tyndall’s apparatus. No. 2
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
- p.507 - vue 526/555
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - 199 Calorescence. Experiments with ray filter. No. 1.
  - 200 Calorescence. Experiments with ray filter. No. 2
  - 201 Identity of light and radiant heat. Reflection
  - 202 Identity of light and radiant heat. Refraction
  - 203 Identity of light and radiant heat. Double
  - refraction
  - 204 Identity of light and radiant heat. Polari-
  - sation.
  - 205 The radiometer
  - 206 Solar rays used by Athan. Kircher
  - 207 Pyrheliometer
  - 208 Bunsen’s burner and candle flame
  - 209 Combustion of iron wire in oxygen
  - 210 Oxyhydrogen blowpipe
  - 211 Blast furnaces
  - 212 Animal heat. Dulong’s apparatus
  - 213 Voltaic battery and carbon points
  - 214 Peltier’s experiment
  - 215 Thermo-electric couple (Pouillet)
  - 216 Series of thermo-electric couples (Pouillet)
  - 217 Thermo-electric battery (Becquerel)
  - HEAT—continued.
  - 218 Thermo-electric battery (Clamond)
  - 219 Electrical thermometer (Riess)
  - 220 Electrical thermometer (Becquerel)
  - 221 Electrical pyrometer (Becquerel)
  - 222 Spark obtained by friction. No. 1
  - 223 Spark obtained by friction. No. 2
  - 224 Experiment with whirling table
  - 225 Rumford’s experiment on mechanical heat
  - 226 Heat developed by pouring mercury. No. 1
  - 227 Heat developed by pouring mercury. No. 2
  - 228 Heat developed by compression of air
  - 229 Chilling produced by current of air
  - 230 Chilling produced by bellows
  - 231 Precipitation of clouds
  - 232 Joule’s apparatus for mechanical equivalent
  - of heat
  - 233 Lecture apparatus for mechanical equivalent
  - of heat
  - 234 Hirn’s ballistic pendulum
  - 235 Heat rendered sensible by compression of air
  - 236 Diagram of Carnot’s engine
  - 237 Steam engine indicator
  - 238 Indicator diagram
  - 239 Heat developed in magnetic field
  - 240 Heat developed in magnetic field. Foucault’s
  - experiment
  - 241 The asolipile
  - 242 Savery’s engine
  - 243 Newcomen’s engine
  - 244 Single acting engine (Watt)
  - 245 Double acting engine (Watt)
  - 246 Double acting engine and boiler
  - 247 Double cylinder marine engine. No. 1
  - 248 Double cylinder marine engine. No. 2
  - 249 Locomotive engine, “ Puffing Billy ”
  - 250 Locomotive engine, “ The Rocket ”
  - 251 Modern locomotive engine, elevation
  - 252 Modem locomotive engine, section
  - 253 Rotatory engine, elevation (Behrens)
  - 254 Rotatory engine, section (Behrens)
  - 255 Steam boiler
  - 256 Steam boiler, marine
  - 257 Section of cylinder and slide-valve
  - 258 Giffard’s injector
  - 259 Gas engine (Crossley)
  - 260 Gas engine (Otto and Langen)
  - THE STEAM ENGINE, Etc.
  - 3538.- —Its evolution and application to Locomotion on Land and sea.
  - 1 Hero’s Engine, 120 b.c.
  - 2 Branca’s Engine, a.d. 1629
  - 3 Sir Isaac Newton’s (suggested) Steam Locomotive,
  - a.d. 1680
  - 4 Savery’s Steam Engine, at work pumping, a.d. 1698
  - 5 Papin’s Engine (force-pump with safety valves),
  - a.d. 1707
  - 6 Newcomen’s Atmospheric Engine, at work, pumping a mine
  - 7 Newcomen’s Atmospheric Engine (diagram)
  - •8 Newcomen’s Atmospheric Engine, Model in Glasgow University, repaired by James Watt 9 James Watt’s first experiment 30 James Watt inventing the Steam Engine
  - 11 Watt’s Engine with Sun and Planet gear (photo-
  - graphed direct from one of the last engines made by Watt).
  - 12 Watt’s Single-acting Engine (sectional diagram),
  - a.d. 1775
  - 13 W. Symington’s Model Coach, a.d. 1876
  - 34 Miller & Symington’s Steam Launch, at Dalswinton, a.d. 1788
  - 15 Miller & Symington’s Steam Launch, the Engines
  - 16 Watt’s Double-acting Engine (diagram), a.d. 1782
  - 17 Watt’s “ Waggon ” Boiler (longitudinal section)
  - 18 Watt’s (Adaptation) Centrifugal Governor and Throttle
  - Valve
  - 29 Portrait of James Watt
  - 20 Symington’s Steamer “ Charlotte Dundas ” on Forth
  - and Clyde Canal, a.d. 1803
  - 21 Symington’s Steamer “ Charlotte Dundas ” (section
  - showing machinery)
  - 22 Portrait of Matthew Boulton, F.R.S., of Boulton
  - and Watt, Soho
  - 23 Portrait of Richard Trevithick
  - 24 Trevithick’s Tramway Engine, 1803
  - 25 Trevithick’s (the earliest) High Pressure Steam Road
  - Locomotive, 1801
  - 26 Trevithick’s Model
  - 27 Trevithick’s Engine
  - 28 Murdoch’s Model Engine
  - 29 Fulton’s Steamer “ North River,” or “ Clermont,”
  - on the Hudson, 1807
  - 30 Fulton’s Steamer “ North River,” or “ Clermont,”
  - the Machinery
  - 31 “ The Blenkinsop ” (rack rail locomotive), Middleton
  - Colliery, 1812
  - 32 Bell’s Steamer “ Comet ” on the Clyde, 1812
  - 33 Bell’s Steamer “ Comet,” two views of the machinery
  - by Watt
  - RAILWAY LOCOMOTIVES.
  - 34 Stephenson’s “ Rocket,” 1829
  - 35 Portrait of George Stephenson
  - 36 The “ John Stevens,” 1825
  - 37 The First Locomotive passing Great Grimsby Church,
  - on the Manchester, Sheffield, and Lincolnshire Railway
  - 38 The “ Planet,” 1830, Liverpool and Manchester Rail-
  - way
  - 39 “ Puffing Billy ”
  - Plain slides, 2/- each.
  - 40 The “ De Witt Clinton, 1831, New York Central
  - Railway (and stage-coach train)
  - 41 The “ John Bull ” and stage-coach train, 1832, Mohawk
  - and Hudson Railway
  - 42 The “ George Washington,” 1835
  - 43 Stephenson’s “most recent” (1840) Locomotive
  - (longitudinal section)
  - 44 Stephenson’s “ most recent ” (1840) Locomotive Plan
  - of working parts under boiler
  - 45 Stephenson’s Locomotive of about 1850 (one of fifty
  - ’ sent to Italy)
  - 46 Giffard’s Injector, section showing construction
  - 47 “ The Lord of the Isles,” 1851, G.W.R. (broad gauge)
  - 48 Midland Railway Engine, 1896
  - 49 Midland Railway Train, 1896
  - 50 Train leaving Euston Station
  - 51 L.N.W. Railway Express Train
  - 52 M.R. Train entering St. Pancras Station
  - 53 The new 4-Cylinder Engine, on a Permanent Way
  - Improved for Safety (Germany)
  - 54 L. & N.W.R. Compound Express Passenger Locomo-
  - tive “ Queen Empress ”
  - 55 M.R., 1901, Express Passenger Locomotive
  - 56 10-Wheel Freight Locomotive, American type
  - 57 4-Wheel Tank Locomotive, American type
  - 58 12-Wheeled American Heavy Freight Locomotive
  - 59 8-Wheeled American Express Passenger Loco.
  - 60 Compound “ American ” type Locomotive, by the
  - Baldwin Company
  - 61 Central London Railway, Section of “ Tube,” showing
  - how constructed
  - 62 Central London Railway. Cross-section of “ Tube ”
  - with train “ in situ.”
  - 63 Central London Railway. Platform with train waiting
  - 64 Central London Railway. Platform with Passengers
  - leaving the train
  - 65 Central London Railway. Railway carriage with
  - motor cab
  - 66 Central London Railway. Railway carriage with
  - relay motor cab
  - ROAD LOCOMOTIVES.
  - See also the early Nos. of this set, 3,13, etc.
  - 67 Cugnot’s Steam Car, 1770
  - 68 Cartwright’s Engine (for alcohol vapour or steam)
  - 1797
  - 69 Burstall & Hill’s Steam Coach (3-4 miles per hour),
  - 1824
  - 70 James’s Steam Coach (12-15 miles per hour), 1829
  - 71 Church’s Patent, 1st July, 1832. London and Bir-
  - mingham Steam Carriage Co.
  - 72 William Church’s Steam Carriage, 1832
  - 73 Steam Carriage. The First Motor Omnibus in London,
  - 1833
  - 74 Hancock’s Steam Coach. The “ Era ” Arriving at
  - Greenwich, 1833
  - 75 Hancock’s Steam Omnibus, which ran on the common
  - Roads
  - 76 Mr. Galsworthy Gurney’s Steam Carriage, 1833
  - 77 The Squire and Macerone Steam Coach on the Harrow
  - Road, 1833
  - 78 The Touring Car in i860. Rickett’s Steam Carriage
  - for common Roads
  - 79 Carret’s Steam Carriage, 1862 (15 miles an hour)
  - 80 The “ Advance,” 1870, road Steamer with rubber
  - tyres
  - 81 Parcel-Service Road Locomotive, 1886 (8 miles an
  - hour)
  - 82 Road Locomotive, for haulage, 1890
  - 83 The Progress of the Wheel. The Ousting of the
  - Horse from London Thoroughfares
  - 84 Serpollett’s Motor Car
  - 85 R s and Venables’ Oil Motor, kerosene, not spirit
  - or benzoline
  - 86 Propeller Steam Vehicles, four-wheeled Wagonette,
  - Luggage and three-wheeled Victoria
  - 87 Steam Motor Car, 4J horse-power. Front view show-
  - ing Condenser
  - 88 Steam Motor Car, 4J horse-power. Side view showing
  - steering, water tank, &c.
  - 89 Steam Motor Car, 4J horse power. Comer view
  - showing works
  - 90 The Albone Ivel Agricultural Motor
  - 91 The Albone Ivel Agricultural Motor hauling a mowing
  - machine
  - 92 The Albone Ivel Agricultural Motor working a reaper
  - and binder
  - 93 The Albone Ivel Agricultural Motor drawing a double
  - furrow plough
  - 94 Lord Roberts on a Motor Car at Aldershot
  - 95 Mr. Cecil Edge (cousin of Mr. S. D. Edge) on aj sixteen
  - horse-power Napier Motor Car
  - 96 A 10 horse-power Panhard Motor Car
  - 97 A Motor Car on the Road (4-seater)
  - 98 Gordon-Bennet Race, 1904. The Finish
  - 99 A Taxi Cab
  - 100 A Motor Omnibus
  - 101 An Express Carrier
  - 102 Motor Cycle with Side Car
  - 103 The King’s Coach in the 20th Century
  - 104 Motor arriving at Meet of the Hounds
  - MARINE ENGINES, ETC.
  - 105 The “ Enterprise,” 1825 (first steamer to India, via
  - Cape, 113 days), paddles 15 ft. diam.
  - 106 The “ United Kingdom,” 1826 (“ the wonder of the
  - day ”), 160 ft. long, engines 200 h.p.
  - 107 The “ Robert S. Stockton,” with Ericsson’s screw
  - propeller, crossing the Atlantic, 1839
  - 108 Section showing Ericsson’s Screw Propeller in the
  - “ Robert S. Stockton ”
  - 109 “ Iona.” Elevations and plan of oscillating cylinder,
  - paddle, steam engine
  - no “ Arabia.” Elevation of verticle cylinder, paddle, steam engine
  - in Oscillating Cylinders of the paddles of the “Great Eastern ”
  - 112 “ Barwon.” Sections and plan of marine screw,
  - horizontal engine
  - 113 “ Jura.” Elevation and plan of vertical engine with
  - beam and gear
  - 114 Twin-screw Triple-expansion Engines of H.M.S.
  - “ Edgar.”
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.508 - vue 527/555
- - F. E. BECKER & CO., INIIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 509
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES MECHANICS
  - 3539.—Lantern Slides on IVIechani CS. Including the various properties of SOLIDS, LIQUIDS, AND
  - GASES. 2/- per slide.
  - 1 Action and reaction
  - 2 Measurement of force
  - 3 Parallelogram of forces (diagram)
  - 4 Parallelogram of forces (experimental demon-
  - stration)
  - 5 Parallelogram of forces. The “ knee joint ”
  - 6 Composition and resolution of forces
  - 7 Parallel forces. The arithmetical lever
  - 8 Pressure of wind on sails of ship
  - 9 Equilibrium of two forces
  - 10 The pulley
  - 11 The compound pulley. No. i
  - 12 The compound pulley. No. 2
  - 13 Simple levers (The three orders)
  - 14 The lever, 1st order. No. 1
  - 15 The lever, 1st order. No. 2
  - 16 The lever, 2nd order. No. 1
  - 17 The lever, 2nd order. No. 2
  - 18 The lever, 3rd order. No. 1
  - 19 The lever, 3rd order. No. 2
  - 20 Wheel and axle
  - 21 The windlass
  - 22 Inclined plane
  - 23 Apparatus demonstrating laws of inclined
  - plane
  - 24 The screw
  - 25 Male and female screws
  - 26 The screw-jack
  - 27 The screw-press
  - 28 The wedge
  - 29 Friction (horizontal) .
  - 30 Friction rollers, etc.
  - 31 Friction dynamometer
  - 32 Resistance to motion. Revolving fan
  - 33 Resistance to motion. Parachute
  - 34 Elasticity. Stretched wire
  - 35 Elasticity. Spring balances
  - 36 Elasticity of torsion
  - 37 Porosity. Physical pores
  - 38 Porosity. Filters
  - 39 Crystallisation.
  - 40 Crystallisation.
  - 41 Crystallisation.
  - system
  - 42 Crystallisation.
  - 43 Crystallisation.
  - 44 Crystallisation.
  - 45 Crystallisation.
  - No. 1. Cubic system No. 2. Pyramidal system No. 3. Rhombohedral
  - Experimental determina-
  - No. 4. Prismatic system No. 5. Oblique system No. 6. Anorthic system Hemihedry
  - 46 Gravity shown by tension of a spring
  - 47 Direction of gravity. Plumb-line
  - 48 Plumb-line, vertical to fluid surface
  - 49 Convergence of verticals towards centre of
  - the earth
  - 50 Attraction. Cavendish experiment
  - 51 Centre of gravity
  - 52 Centre of gravity. Experimental determina-
  - tion. No. 1
  - 53 Centre of gravity.
  - tion. No. 2
  - 54 Centres of gravity.
  - 55 Centres of gravity.
  - 56 Different positions
  - 57 Different positions
  - 58 Stable and unstable equilibrium
  - 59 Examples of equilibrium. No. 1
  - 60 Examples of equilibrium. No. 2
  - 61 The balance. Ordinary scales
  - 62 The balance. Centre of suspension
  - 63 The chemical balance
  - 64 The chemical balance. The beam
  - 65 Vacuum balance of Standards Department
  - 66 Leaning Tower of Pisa.
  - 67 Repetition of Galileo’s Pisa experiment
  - 68 Fall of bodies in vacuo.
  - 69 Galileo’s experiment with inclined plane
  - 70 Attwood’s machine
  - 71 Friction pulleys of Attwood’s machine
  - 72 Morin’s machine
  - 73 Parabolic curve
  - 74 Parabolic path of projectile
  - Examples, No. 1 Examples, No. 2 of equilibrium, of equilibrium.
  - No.
  - No.
  - 75
  - 76
  - 77
  - 78
  - 79
  - 80
  - 81
  - 82
  - 83
  - 84
  - 85
  - 86
  - 87
  - 88
  - 89
  - 90
  - 91
  - 92
  - 93
  - 94
  - 95
  - 96
  - 97
  - 98
  - 99
  - 100
  - 101 £"T02 #?I03
  - 104
  - 105
  - 106
  - 107
  - 108
  - Action of gravity independent of motion of the body
  - Centrifugal force apparatus Centrifugal force. Oblateness of earth Centrifugal force. Steam governor Free axis of rotating bodies Foucault’s gyroscope Diagram of- motion of simple pendulum Diagram of harmonic curve The pendulum. Time of vibration not dependent on amplitude The pendulum. Verification of laws Borda’s pendulum. No. 1 Borda’s pendulum. No. 2 Cycloidal pendulum Conical pendulum Inverted pendulum The metronome
  - Application of pendulum to clocks. No. r Application of pendulum to clocks. No. 2 Foucault’s pendulum experiment Compound pendulum (Blackburn)
  - Tisley’s compound pendulum apparatus Curves traced by compound pendulum apparatus
  - Lissajous’ curves of compound harmonic vibration The Vernier
  - Spherometer and micrometer screw The cathetometer
  - Equality of liquid pressure. Pascal’s law Principle of the hydraulic press The hydraulic press Vertical upward pressure of liquids Pressure of liquids on bottom of containing vessels
  - Liquid pressure. Haldat’s apparatus Liquid pressure. Pascal’s apparatus Hydrostatic paradox
  - 3540.—Lantern Slides, from Ganot’s “ Physics ” (9th Edition).
  - ON MATTER, FORCE, AND MOTION.
  - 1 Fig. 1 Vernier
  - 2 ,, 2 Spherometer
  - 3 ,, 3 Demonstration of Sensible Pores
  - 4 ,, 5 Cohesion of Liquids
  - 5 ,, 12 Parallelogram of Forces
  - .6 ,, 19 Simple Lever
  - 7 ,, 20, 21, 22, Simple Pulleys, Block and
  - Tacide
  - 8 ,, 23, 24, Wheel and Axle and Toothed
  - Wheels
  - 9 ,, 25 Inclined Plane
  - 10 ,, 2 7 Wedge
  - 11 ,, 28, 29, 30, The Principle of the Screw
  - 12 ,, 31 Resistance to Motion in a Fluid
  - Medium
  - 13 ,, 34 Motion of Projectiles
  - 14 ,, 36 Diagram of Centrifugal and Centri-
  - petal Force
  - 15 ,, 40, 41, Diagrams of 2 Rectangular
  - Motions
  - 16 ,, 42 Resultant Figure when the Periods
  - are 3.2
  - 17 ,, 43 Compound Pendulum Apparatus
  - 18 ,, 44 Figure traced by Compound Pen-
  - dulums
  - 19 ,, 45 Diagram of Simple Harmonic Motion
  - Plain Photographs, 2/- each.
  - ON GRAVITATION AND MOLECULAR ATTRACTION.
  - 20 Fig. 47, 48, Centre of Gravity
  - 21 ,, 52 Stable, Unstable, and Neutral Equi-
  - librium
  - 22 ,, 54, 55, 56, Delicacy of Balance
  - 23 ,, 58 Jolly’s Balance for determining the
  - constant of Gravity
  - 24 ,, 59 Bodies falling in a Vacuum
  - 25 ,, 60 Water Hammer
  - 26 ,, 61 Attwood’s Machine
  - 27 ,, 62, 63 Morin’s Apparatus
  - 28 ,, 64, 65 Katir’s Reversible Pendulum
  - 29 ,, 66 Pendulum with Escapement
  - 30 ,, 68, 69 Longitudinal Elasticity, Jolly’s
  - Spring Balance
  - 31 ,, 70, 71 Elasticity of Flexure
  - 32 ,, 72 Coulomb’s Torsion Balance
  - ON LIQUIDS.
  - 33 Fig. 73 Oersted’s Piezometer
  - 34 ,, 74 Amagat’s Piezometer
  - 35 u 75, 76 Equality of Pressures. Pascal’s
  - Law
  - 36 ,, 77 Principle of the Bramah Press
  - 37 ,, 78 Upward pressure of Liquids
  - 38 ,, 79 Haldat’s Apparatus
  - 39 Fig. 80 Masson’s Apparatus
  - 40 ,, 81 Pressure not equivalent to weight
  - 41 ,, 82 Why fluid surfaces are always level
  - 42 ,, 83 Equilibrium in communicating
  - Vessels
  - 43 ,, 84 Equilibrium of different Liquids
  - 44 ,, 85 Bramah’s Hydraulic Press
  - 45 ,, 86, 87 Details of Bramah’s Press
  - 46 ,, 88 Water Level
  - 47 ,, 89, 90 Spirit Lbvel
  - 48 ,, 91 Artesian Well
  - 49 ,, 92 Pressure on Immersed Body
  - 5° >> 93 Principle of Archimedes
  - 51 ,, 94, 95, 96, 97 Equilibrium of floating
  - Bodies
  - 52 ,, 98 Cartesian Diver
  - 53 >> 99, 100 Specific Gravity of Solids,
  - Nicholson’s Hydrometer
  - 54 ,, 101 Specific Gravity, Bottle for Powder
  - 55 ,, 103, 104, I05 Specific Gravity, Bottles
  - and Bulbs
  - 56 ,, 106, 107, 108 Hydrometers and Densi-
  - meter
  - 57 ,, 109, no, in, 112 Examples of Capil-
  - larity
  - 58 ,, 113 Mean height independent of form
  - of tube
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.509 - vue 528/555
- - 510 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - IVIECH AN ICS—continued.
  - 59 Fig. 114 Jurin’s Law 78 Fig. 146 Compressibility of Gases 101 Fig. 185 Balloon
  - GO ) 7 ii5 Capillary Curve between inclined 79 y y 147 Weight of Gases 102 y y 186 Parachute
  - plates 80 y y 148 Crushing force of the Atmosphere 103 y y 187 Air pump
  - 6l 7 y ii7, 118 Surface Tension 81 y y 149, 150 Magdeburg Hemispheres 104 y y 188 Section of air pump
  - 62 t 7 120, 121, 122 Consequences of Surface 82 y y 151 Torricelli’s experiment 105 y y 189, 190 Details of air pump
  - tension 83 y y 152, 153, 154 Barometers 106 y y 191, 192, 193, 194 Double exhaustion
  - 63 y y 123, 124, 125 Angle of Contact between 84 y y 155, 156 Fortin’s Cistern and Cimbals stopcock
  - liquids and solids 85 y y 157. 158, 159, 160, 161 Gay-Lussac’s 107 y y 195 Bianchi’s air pump
  - 64 y y 126 Determination of Surface tension Syphon Barometer 108 y y 196 Section of piston
  - 65 y y 127 Surface tension of oil and water 86 y y 162, 163 Wheel Barometer and Reg- 109 y y 197 Section of Fleuss’s pump
  - 66 y y 128 Formation of drops in a capillary nault’s Barometer no y y 198 Single form of Sprengel’s air pump
  - orifice 87 y y 165, 166, 167,168 Apparatus for demon- III y y 199 McLeod’s gauge
  - 67 y y 129 Osmose strating Boyle’s Law 112 y y 200 Bunsen’s Sprengel pump
  - 68 y y 131. 132 Diffusion of liquids 88 y y 169 Dulong and Arago’s Apparatus 113 y y 201, 202 Aspirating action of currents
  - 69 y y 133, 134, Graham’s Dialyser 89 y y 170 Table of Deviations from Boyle’s of air
  - 70 y y 135 Spouting jar 90 y y 171, 172 Manometers [Law 114 y y 203 Principle of Gifford’s injector
  - 7i y y 136. 137 Influence of shape of orifice on 9i y y 173 Volumenometer 115 y y 204, 205 Morin’s Mercury pump
  - efflux 92 y y 174 Aneroid Barometer 116 y y 206, 207 Condensing pump
  - 72 y y 138, 139 Viscosity, efflux through capil- 93 y y 175 Mixture of Gases II7 y y 208 Fountain in vacuo
  - lary tubes 94 y y 176 Absorption by Liquids Il8 y y 209 Pressure of atmosphere
  - 73 y y 140, 141 Form of the jet 95 y y 177, 178, 179 Diffusion of gases 119 y y 210 Hero’s fountain
  - 74 y y 142 Barker’s Mill 96 y y 180 Illustration of the action of diffusion 120 y y 211 Intermittent fountain
  - 75 y y 143 Montgolfier’s Hydraulic Ram 97 y y 181 Effusion of gases 121 y y 212, 213 Syphon and intermittent syphon
  - 76 y y 144 Hydraulic Engine 98 y y 182 Absorption by solids 122 y y 214, 215 Clack valve and conical valve
  - ON GASES. 99 y y 183 Occlusion of gases 123 y y 216 Suction pump
  - 100 yy 184 Archimedes’ principle applied to 124 y y 217 Suction and force pump
  - 77 y 1 145 Expansibility of Gases gases 125 y y 218 Fire Engine
  - 3542.—Coal Mining up to date,
  - coal mine. Plain slides, Nos. i
  - MINING
  - from a series of very fine negatives showing modern methods of working a to 12, 2/6 each; Nos. 13 to 37, 3/- each. Lecture notes, 1/-.
  - 1 Air Compressing Machinery for supplying
  - compressed air to the pumps in the mine
  - 2 Hoisting Engine for raising the Coal from
  - the pit
  - 3 View of the Entrance to a Coal Mine worked
  - by means of a slope
  - 4 Boring with Diamond Drill through a Fault
  - to test its thickness
  - 5 Clearing away Debris, the result of a fall
  - of the roof on one of the main levels
  - 6 Mine box let down from a side gallery ready to
  - be pushed off and added to a train of boxes
  - 7 Train of Boxes being drawn from a side
  - gallery into the main slope
  - 8 Miner Tamping a Charge of Powder prepara-
  - tory to firing
  - 9 Driving a Level in an inclined coal seam.
  - 10 Bank Head Creeper and Tipler for turning out
  - the coal from the boxes on to screens where the fine coal is separated from the lump
  - 11 View of Two Tiplers for turning out the coal
  - from the boxes
  - 12 View of Screens and Picking Tables for
  - removing stone and other foreign materials from the coal
  - 13 Bottom of Shaft
  - 14 Undercutting Coal
  - 15 Driving a Stall
  - 16 Cutting the Bottom Layers of Coal
  - 17 Cutting the Top Coal
  - 18 Boring a Shot Hole in the Top Coal
  - 19 Percussive Hand Boring
  - 20 Drilling with a Machine
  - 21 Loading Large Coal
  - 22 Loading Slack
  - 23 Fixing short Timber Props
  - 24 Fixing long Timber Props
  - 25 Effects of Pressure on Masonry and Timber
  - 26 Building a Cog
  - 27 Self-acting Incline Haulage
  - 28 Endless Rope Haulage
  - 29 Junction on Haulage Plane
  - 30 Testing the Roof
  - 31 Separation Doors between Intake and Return
  - Airways
  - 32 Testing for Gas
  - 33 Intrusion of Basalt in Coal
  - 34 Limestone Mining, showing Pillars.
  - 35 Limestone Mining, view down a Stall
  - 36 Underground Stables
  - 37 Meal-time
  - 3543.— Lantern Slides.—’Mongst Mines and Miners in the Cornish Tin and Copper Mines.
  - Beautifully painted views, 7/6 each. Plain photographs, 2/- each.
  - Descriptive book, “ 'Mongst Mines and Miners,” by J. C. Burrow, 21/- each.
  - These slides are printed from a very fine series of negatives (perhaps the finest set of mining negatives ever produced) taken by Mr. J. C. Burrow, of Camborne, by flash-light in the Cornish Tin and Copper Mines.
  - These negatives have been awarded the medal of the Royal Photographic Society of Great Britain.
  - 1 The chief mining district of Cornwall, view of
  - surface of country
  - 2 Dolcoath Mine, pumping engine on surface
  - 3 Four rock specimens
  - 4 Blue Hills Mine, above the 66 fathom level
  - 5 Blue Hills Mine, heave looking west, 60
  - fathoms level
  - 6 Blue Hills Mine, heave looking east, 6o
  - fathoms level
  - 7 Cook’s Kitchen Mine, end of ground, illus-
  - trating lode structure
  - 8 East Pool Mine, surface of shaft, showing
  - pumping engine, etc.
  - 9 Group of tin miners in working dress
  - 10 Dolcoath, man engine at surface
  - 11 Section of Dolcoath Mine
  - 12 Dolcoath miners ascending by man engine at
  - the 234 fathom level
  - 13 Cook’s Kitchen, man engine at 190 fathoms
  - 14 Dolcoath, balance box at 236 fathoms
  - 15 Dolcoath miners in a gig, and portion of skip-
  - road at 302 fathoms
  - 16 Cook’s Kitchen miners descending in skip at
  - 190 fathoms
  - 17 Dolcoath, 302 new east shaft
  - 18 Cook’s Kitchen, 406 fathoms’ level engine
  - shaft, loading wagon
  - 19 Cook’s Kitchen, Bottom of engine shaft, half-
  - mile below surface
  - 20 Dolcoath, air-compressor engines
  - 21 Dolcoath, Boring machine at work, 326
  - fathoms
  - 22 Cook’s Kitchen. Boring machine at 406
  - fathoms
  - 23 East Pool, Working the boring machine
  - 24 Working the air winch, East Pool
  - 25 Cook’s Kitchen Mine, 355-fathom stope
  - looking west
  - 26 East Pool, an “ Upper ”
  - 27 Cook’s Kitchen, Overhand stoping 355
  - fathoms
  - 28 East Pool, Underhand stoping
  - 29 Hole charged for blasting
  - 30 East Pool “ croust ” time, miners at lunch,
  - 70 fathoms
  - 31 Working on at rich load, Dolcoath, 412
  - fathoms
  - 32 Cook’s Kitchen, Looking up the 355 stopes
  - 33 Cook’s Kitchen, Timbering at 406 fathoms
  - 34 East Pool, Horse of ground between the tin
  - and copper lodes
  - 35 East Pool, 70 stope, showing supports
  - 36 East Pool, Stoping at 70 fathoms
  - 37 Dolcoath Mill or Pass, 412 fathoms, loading
  - wagon
  - 38 Dolcoath Mill or Pass, 400 fathoms level
  - 39 Working in the 412-fathom level, Dolcoath
  - (Steel)
  - 40 Hanging tram-road 375 fathoms, New East,
  - Dolcoath
  - 41 East Pool, 70-fathom tram-road
  - 42 East Pool, 170-fathom level, Tram-road
  - Bridge
  - 43 At work in the 180 fathom level, East
  - Pool
  - 44 Wagon of tinstuff at shaft
  - 45 Wagon of tinstuff tipped
  - 46 Landing the stuff at surface
  - 47 Dolcoath, Interior of the “ Dry ”
  - 48 Dolcoath, Old Cornish stamps
  - 49 Dolcoath, New Californian stamps
  - 50 Dolcoath, Tin dressing frames
- p.510 - vue 529/555
- - F. E. BECKER & CO., IMIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 511
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - MINI NG—continued.
  - 3544.—Lantern Slides. Work in a Wigan Coal Mine
  - Beautifully painted views, 7/6 each. Plain photographs, 2/- each.
  - 1 View of a colliery above ground, showing
  - large wheel and machinery
  - 2 Stokers with apparatus
  - 3 The winder
  - 4 Brakesman and cage
  - 5 Coal-pickers
  - 6 Pit lasses and tub
  - 7 Pit lasses, pay day
  - 8 Two colliers’ widows
  - 9 Pit lasses and barge
  - 10 Canal basin
  - 11 Tally boy shouting numbers
  - 12 Fault, or slip, with the wheel listings
  - 13 Sending props down pit
  - 14 Hand-picked (cannel coal)
  - 15 Different kinds of safety lamps
  - 16 Check-weighman testing weights
  - 17 Dialling party
  - 18 Collier, drawer, fireman trying for gas
  - 19 Collier beginning to hole
  - 20 Drawer and tub
  - 21 Two pit lasses
  - 22 Pit lasses with screen
  - 23 A collier’s wife
  - 24 Mass meeting
  - 25 Pay-day
  - 26 Man in cage
  - 27 Stepping out of cage
  - Direct photographs.
  - 28 Pit lads
  - 29 Working thick seam
  - 30 At work on 4 ft. seam
  - 31 Holeing in 2 ft. scam
  - 32 The knocker-up
  - 33 Colliers’ houses
  - 34 Pitman at home
  - IRON-WORKERS.
  - 35 Shinglers
  - 36 Steam hammer
  - 37 Bell furnacemen at work
  - 38 Group of men (rollers)
  - 39 Rolls
  - 40 Finishing rolls
  - PHYSICAL GEOGRAPHY
  - 3545.—Lantern Slides—Physical Geography.
  - Plain Photographs, 2/3 each. The Complete Set, £12 10s.
  - An Original Series of Slides, selected and arranged for the Oxford University Extension by H. J. Mackinder, Esq. M.A., F.R.G.S., Reader in Geography in the University of Oxford. With Explanatory Notes for the use of Lecturers.
  - Price 1/6.
  - I—METEOROLOGY, ETC.
  - 1 Diagram showing vertical and inclined rays
  - of light, incident on plane surface
  - 2 Diagram of parallel beams of light striking
  - spherical surface
  - 3 Diagram of Barometer
  - 4 Diagram explaining distribution of pressures
  - over a heated surface
  - 5 Diagram of land and sea breezes
  - 6 Mercator’s chart, showing belts of pressure
  - and prevalent winds in January
  - 7 Mercator’s chart, showing belts of pressure
  - and prevalent winds in July
  - 8 View of sphere, showing the curving of the
  - Trades and anti-Trades
  - 9 Map of cyclone
  - 10 Map of anti-cyclone
  - 11 Diagram of wind striking mountain range and
  - producing rain
  - 12 Map of British Isles, showing annual rain-
  - fall
  - 13 View from Darjeeling, showing clouds on the
  - Himalayas
  - 14 Breaking of the monsoon in Ceylon
  - 15 Mercator’s chart, showing the ocean currents
  - 16 Chart of North Atlantic, showing the Gulf
  - Stream
  - 17 Sections through the Gulf Stream
  - II—ICE.
  - 18 View of Mont Blanc, showing glaciers
  - 19 New Zealand glaciers
  - 20 The Rhone Glacier
  - 21 Map of a glacier
  - 22 Map of South Polar Region
  - 23 View of the coast of South Victoria
  - 24 View of Mount Erebus
  - 25 Edge of the Great Southern Ice-sheet
  - 26 Tabular icebergs
  - 27 Decayed icebergs
  - 28 Map of Greenland, showing the inland ice,
  - and currents bearing icebergs
  - 29 View of the inland ice of Greenland
  - 30 Arctic scenes, showing the sea-made ice
  - 31 Ice-scratched rock
  - 32 Map showing former extension of ice over the
  - British Isles
  - III—STRUCTURE AND SCENERY OF MOUNTAINS.
  - 33 Diagram of strata, fiat on sea bottom
  - 34 Diagram of strata, bent into anticline
  - 35 View of Anticline at St. Abb’s Head
  - 36 Section through the N. Island, New Zealand
  - 37 Section through the S. Island, New Zealand
  - 38 Section through the Jura
  - 39 Sections through the Alps
  - 40 Map of mountainous country ; Eastern Alps
  - and Bohemia
  - 41 View of the Limestone Alps
  - 42 View in the Central Alps
  - IV—SCENERY RESULTING FROM THE DENUDATION OF HORIZONTAL STRATA.
  - A^43 The Grand Caiion'of Colorado
  - 44 Interior of canon
  - 45 Interior of marble canon
  - 46 Marble canon platform
  - 47 Cafion within canon
  - 48 Section of canon
  - 49 Bird’s-eye view in canon country
  - 50 Remnant of a tableland, a table mountain
  - 51 Last remnant of a tableland, pinnacles of rock
  - 52 Canon with debris-slopes
  - 53 Debris-cones
  - 54 Cliffs with talus
  - 55 Table mountain with talus
  - ^ | Views in the Rhine Gorge 58 Gorge in the Loess of China
  - V—WIND ACTION.
  - 39 Sand dunes
  - 60 Map showing the Frisian Islands
  - VI—VOLCANOES.
  - 61 Ideal cone, in plan and in section
  - 62 Actual cone, near Auckland, -New Zealand
  - 63 Vesuvius at rest
  - 64 Vesuvius in eruption
  - 65 Ararat (extinct)
  - 66 Fusiyama, Japan
  - 67 Lava, with slaggy surface
  - 68 Lava, sticky, in the Sandwich Islands
  - 69 Lava, fluid, Basalt, Staffa
  - 70 Fingal’s Cave
  - VII—GEYSERS.
  - 71 Spouting geyser
  - 72 Artificial geyser
  - 73 The White Terrace, New Zealand
  - 74 Section through the White Terrace
  - VIII—PLAIN AND MOUNTAIN.
  - 75 Map of Northern Italy
  - 76 Map of South America
  - 77 Map of South-Eastern Asia
  - 78 Sections through the continents
  - 79 Sections through oceans
  - 80 Sections through mountain ranges
  - IX—ISLANDS.
  - 81 Oceanic islands—Volcanic. View, Tristan da
  - Cunha
  - 82 Map of Tristan da Cunha
  - 83 Oceanic island, Coral Atoll
  - 84 Section through Atoll
  - 85 Continental islands ; Map of British Isles
  - showing 100 fathom line.
  - X—RIVERS AND VALLEYS.
  - 86s)
  - 87 !• Model of river basins
  - 88 j
  - 89 River windings ; Mississippi
  - 90 Mississippi delta j
  - 91 Orinoco delta [ Maps
  - 92 Nile delta j
  - 93 Section of raised delta channel
  - 94 Tongues of alluvium at confluence of rivers,
  - map
  - 95 Transverse and longitudinal valleys, Alle-
  - ghanies, map
  - 96 Sections through transverse and longitudinal
  - valleys
  - 97 Sections through different types of longi-
  - tudinal valley
  - XI—RIVER FALLS.
  - 98 Sections through Niagara
  - 99 Bird’s-eye view of Niagara River
  - 100 View of Niagara Falls
  - 101 Gorge below Niagara Falls
  - 102 Shores of a drained lake in Western America
  - XII—LAKES.
  - 103 Volcanic, View of Lake Taupo
  - 104 Fiord, Map of Loch Ewe
  - XIII—TYPES OF VEGETATION.
  - J-Tropical forest
  - 107 Temperate primeval forest
  - 108 Wellingtonias
  - 109 Pampas
  - no Venezuelan flood scene in Bamboos
  - 112 Banyan
  - 113 Sago palms
  - 114 Coco-nut palms
  - 115 Mangrove swamp
  - 116 New Zealand forest
  - 117 Mediterranean flora ; Egypt
  - 118 Cedars of Lebanon
  - 119 Alpine flowers
  - 120 Pines on the Himalayas
- p.511 - vue 530/555
- - 512 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES PHYSIOGRAPHY
  - 3546.—Lantern Slides—Physiography. 2/- per slide.
  - 1 Microscopial structure of quartz
  - 2 Section of rocks at Niagara
  - 3 Section of a mineral vein
  - 4 Diagram to illustrate unconformability out-
  - crop, dip and strike
  - 5 Diagram, geological, to illustrate the progress
  - of life
  - 6 Chart of the earth’s crust
  - 7 Snow crystals
  - 8 Structure of hornblend-schist
  - 9 Section of a barrier reef and an atoll io Structure of sandstone
  - n View of Niagara Falls
  - 12 The spectroscope
  - 13 The theodolite
  - 14 Rainfall map, England and Wales
  - 15 Diagram of mean annual rainfall at different
  - places
  - 16 Diagram of mean annual rainfall of the earth
  - 17 Magnetic chart of the British Islands
  - 18 Diagram to illustrate the processional revo-
  - lution of the North celestial pole around the polestars of different epochs
  - 19 Apparatus to determine velocity of light
  - 20 Diagram to illustrate decomposition of white
  - light
  - 21 Chart of elements of solar system
  - 22 Diagram of the sun’s yearly motion through
  - the fixed stars in the Signs of the Zodiac
  - 23 Diagram to illustrate the cause of lunar eclipse
  - 24 Diagram of parts of a shadow
  - 25 Theoretical effects of the moon’s attraction
  - upon the waters of the earth
  - 26 Comparative diameters of the planets
  - 27 Lunar landscape lit up by light reflected from 55 Isoclinal lines
  - the earth 56 Diagram to illustrate the height of the baro-
  - ^28 The moon, through small telescope meter at different altitudes
  - ( 29 The sun and his family of planets, with their ^57 Approximate section of the world [circle
  - satellites 58 Instrument to illustrate casellas, form of dip-
  - 30 Diagram of the sun’s physical nature 59 Comparative chart of cyclones and anti-
  - 31 Circles of the celestial sphere cyclones
  - 32 Variation of the Pole Star, with altitude and
  - latitude
  - 33 Distance of the planets from the sun /-- 34 Relative sizes of the sun and the earth
  - 35 Phases of the moon
  - 36 Diurnal inequality of the tides
  - l- 37 Relative positions of the sun, moon, and earth at spring tide : and cause of neap tide
  - 38 Altitude of the sun at midsummer and mid-
  - winter
  - 39 Methods of sounding on the Challenger
  - 40 Sounding rods on the Challenger ^41 Diagram of magnetic declination
  - 42 Distribution of oceanic deposit
  - 43 Approximate depth of the ocean
  - 44 Distribution of active volcanoes
  - 45 Map of the world’s depths
  - 46 Map of'mean annual rainfall of the world
  - 47 Rainfall and trade map of Great Britain
  - 48 Form of a lightning flash
  - p. 49 Diagram to illustrate the variation in length of day and night through the year 50-52 Isothermal lines
  - 53 Distribution of atmospheric pressure over the
  - world in July
  - 54 Diagram to illustrate the principle of an
  - artesian well
  - 60 Bright-line and the solar spectrum
  - 61 Diagram to illustrate the cause of priming and
  - lagging of tides
  - 62 The sea-bed around Great Britain
  - 63 Diagram of depths of Atlantic Ocean
  - 64 Section across the Atlantic
  - 65 Section of an Arctic glacier giving off icebergs
  - 66 Floating icebergs in Arctic region
  - 67 Map of currents in the Atlantic
  - 68 Longitudinal and transverse valleys 69-72 Swiss snow scenes
  - 73 Mason’s chemical hydrometer
  - 74 Barometric heights as adopted by London
  - newspapers
  - 75 Forms of lightning flashes
  - 76 Course of tidal wave near the British Isles
  - 77 Section of the Atlantic between Sandy Hook
  - and Bermuda
  - 78 Map of Isogonic lines
  - 79 Diagram to illustrate the change of volume
  - accompanying changes of state of water
  - 80 Diagram to illustrate the polar and equatorial
  - diameters of the earth
  - 81 Thermal curves
  - 82 Perspective views and vertical section of anti-
  - clinal and synclinal beds
  - 83 Diagram of anti-cyclone of March 20th, 1893
  - NATURE STUDY
  - 3547.—Nowadays, when Nature Study is being taken up in our principal schools, we have thought that it would be useful to publish a series of Slides taken from “ Eton Nature Study ” by Matthew Davenport Hill, M.A., F.Z.S., Assistant Master at Eton College, and Wilfred Mark Webb, F.L.S., F.R.M.S. (6/- net, Duckworth & Co.) Many of them are from direct photographs, but a large number are from most beautiful and careful drawings by W. J. Webb.
  - Price : Beautifully Painted Slides, 7/6; Plain Slides, 2/3 each.
  - 1 A specimen left-hand page of the note-book, on
  - which headings and notes have been written
  - 2 A specimen right-hand page of the note-book, on
  - which outline diagrams and water-colour sketches have been made
  - 3 Map showing the method of recording observations
  - by use of flag labels
  - 4 A plum cut through, and showing the seed laid
  - bare by the removal of part of the stone
  - 5 Development of a dwarf Bean Pod.
  - / Fruit of Caper Spurge
  - 6-j Ripened fruit of Caper Spurge bursting and scattering ( its seeds
  - < The fruits of Robin-run-in-the-hedge ' t The head of Burdock (Fruit of Barley Grass
  - 8 -J Fruit of Goat’s Beard
  - ( Fruit of “ Old Man’s Beard.”
  - 9 The fruit of Crane’s-bill.
  - 10 A glass-topped box containing fruits of Willow Herb
  - 11 Swallows collecting round a tower, near Redhill,
  - before migrating
  - 12 Barn Swallows returning in pairs and landing on
  - the Isle of Wight f Apparatus for observing the sun ’ t Part of apparatus for observing the sun
  - 14 A Window showing the method of recording the
  - height of the sun
  - 15 Diagram to show the position of the sun on the
  - longest and shortest days
  - 16 Records of the position of a shadow on the floor
  - (Flower of a dwarf bean
  - Flower of a dwarf bean from which the petals have been removed
  - Young seed pod of a dwarf bean 18 Shadow cast at noon by an erect rod 19 Shadow cast at noon by a tilted rod 20 A figure showing the connection between the angle made by style of a sun-dial, and that representing the latitude of place where it is used
  - 21 A figure showing one method of determining
  - latitude
  - 22 A figure showing how to cut out the style for a paper
  - model sun-dial
  - 23 A Sun-dial; seen from above
  - 24 A Sun-dial; seen from below
  - 25 Clouds. Cumulus indicative of approaching
  - showers
  - 26 Clouds. Stratus pointing to fine weather f A Sea Anemone expanded
  - 7 ( A Sea Anemone contracted
  - 28 A marine aquarium kept without changing the water
  - for many years
  - 29 Back of an ordinary edible crab
  - 30 Underside of an ordinary edible crab (female)
  - 31 The tail of a female edible crab extended to show
  - the swimmerets
  - 32 Web of a garden spider
  - 33 House spider
  - 34 Garden spider
  - 35 A leaf scar on a sycamore twig
  - 36 Diagram showing the leaf arrangement of syc-
  - amore
  - I Spindle Tree leaf
  - 37- Dogwood leaf
  - (Wayfaring Tree leaf (Lesser Maple leaf
  - 38 < Greater Maple leaf (Guelder Rose leaf (Horse Chestnut leaf
  - 39- Elder leaf ( Ash leaf (Lime leaf
  - 40 K Common Elm leaf lWych Elm leaf j Plane leaf
  - 4 ( Spanish Chestnut leaf [ Birch leaf
  - 42 -j Alder leaf l Beech leaf
  - (Hazel leaf
  - 43 -j Hornbeam leaf (Walnut leaf
  - ( Blackthorn leaf
  - 44 •< Bird Cherry leaf (Wild Cherry leaf i' Crab Apple leaf
  - 45 -j Aspen leaf
  - (Black Poplar leaf ( White Willow leaf 46-^ Oak leaf
  - (Wild Service leaf (White Beam leaf 47 •< White Thom leaf (White Poplar leaf , a j Mountain Ash leaf ^ ( Holly leaf
  - i Scotch Pine leaf
  - 49 Larch leaf (Yew leaf
  - 50 A common mould
  - 51 A portion of a mushroom bed
  - 52 A common cultivated mushroom
  - 53 A blind worm
  - 54 The hatching of a blind worm
  - 55 A viper.
  - 56 A smooth snake (Coronella)
  - 57 A viviparous lizard
  - 58 A hedgehog
  - 59 Head of a male wild cat 59a Wild cat and her kittens
  - 60 A hybrid stoat ferret. Fourth generation
  - 61 A hybrid stoat ferret. This specimen was born with
  - a stump tail
  - 62 A dormouse. (Douglas English)
  - 63 A squirrel
  - 64 Mr. A. Heneage Cocks with one of his stoat-ferret
  - hybrids
  - 65 The skeletons of man and horse compared
  - 66 A thoroughbred horse, “ St. Simon ”
  - Our stock of pure Chemicals and Acids is very considerable ; hence all orders are executed with the utmost despatch. For Prices, etc., see Chemical Apparatus Catalogue.
- p.512 - vue 531/555
- - F. E. BECKER & CO., N1VOC HOUSE, HATTON WALL, LONDON, E.C.1. 513
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - LANTERN SLIDES
  - NATURE STUDY—continued.
  - 67 A Shire horse, “ Hiawatha ”
  - 68 Wild horses
  - 69 A hyacinth bulb cut through
  - 70 A hibernating humble-bee
  - 71 The edible snail and its winter lid
  - 72 Nest of a dormouse
  - 73 Oak log cut across
  - 74 Oak bark
  - 75 Bark of Spanish chestnut
  - 76 Section of Elder stem, showing the wide annual
  - rings of wood and pith
  - 77 Section through a piece of Yew
  - 78 Section through a piece of “ stainy ” Willow
  - wood
  - 79 Museum specimens and labels
  - 80 A museum jar
  - 81 Section of a railway cutting and limestone rocks
  - near Ashbourne, Derbyshire
  - 82 Sycamore twig
  - 83 Valley showing the windings of the river which made
  - it
  - 84 Cross section of the stem of a cabbage
  - 85 Section of a cabbage
  - 86 Plane tree in winter
  - 87 Methods of drawing trees
  - g8 f Dwarf sugar bean. (Sutton’s)
  - 00 t Bean with the skin removed o ( Soaked bean beginning to shoot
  - j Soaked bean with one lobe removed.
  - 90 Skeleton leaf of Magnolia
  - 91 Skeleton of an Indiarubber-Plant leaf
  - 92 Young bean seedling
  - 93 Bean seedling bursting skin of the seed
  - ( Bean seedling kept in a tube supplied with air
  - 94 I Bean seedling kept in closely corked tube
  - 95 Development of the feathers of young Robin , J Potato tuber
  - ( Developing “ eye ” of a Potato tuber
  - 97 Geranium cutting
  - 98 Young lily bulbs growing from an old scale
  - 99 Begonia leaf producing new plants
  - 100 Young bryophyllum plaints growing from a detached
  - leaf
  - 101 Frog eggs
  - 102 Crocus
  - ( Trout egg
  - 103 -J Trout egg faintly “ eyed ”
  - (.Trout egg fully “eyed”
  - 104 Trout egg hatching
  - 105 Newly hatched trout or “ Allevin ” showing the
  - yolk sac
  - 106 Young trout in the “ fry ” stage after the yolk sac
  - has been absorbed
  - 107 A Terrarium with accommodation for amphibious
  - animals
  - 108 Nest of the seven-spined Stickleback
  - 109 Potato tuber showing “ sprouts.”
  - no! Fr°S’s efe'gs. eight days old 1 Frog’s eggs, twelve days old hi A developing chick, two days old
  - 112 A closed-in nesting box
  - 113 Nesting box with the side open
  - 114 A series of chickens of the same brood at different
  - ages showing the replacement of the downy covering by feathers (Tadpole just hatched
  - 115 -j Tadpole—underside showing gills and mouth (three l days hatching)
  - 116 A developing chick, three days old
  - 117 Horse-chestnut buds
  - 118 Potato showing young shoots
  - 119 Horse-chestnut bud opening
  - 120 Decaying vegetable matter pulled into the ground
  - by a worm
  - 121 An earthworm
  - (Tadpole, seven days old
  - 122 Tadpole showing the hind limb
  - (. Tadpole showing the hind and fore limb
  - 123 Horse-chestnut bud opening and showing a bunch
  - of young flowers (A pill wood-louse rolled up 4 ( A pill wood-louse crawling
  - 125 Centipede
  - 126 Millipede
  - 127 Lily bud
  - 128 Silkworm eggs
  - 129 “ May ”
  - 130 A dried Fritilaria plant
  - 131 A dried branch of Alder
  - 132 Lily bud swelling
  - 133 Drone bee
  - 134 An observatory hive
  - 135 A nucleus hive
  - 1 6.( Egg of the honey-bee 30 ( Larva of the honey-bee
  - 137 Pupa of a drone in its cell
  - 138 Humble-bee visiting Snapdragon
  - 139 Lily bud about to open
  - 140 A silkworm caterpillar
  - 141 The blind wood-louse that lives in ants’ nests
  - 142 A gallery in ants’ nest with their “ cows ”
  - 143 An ant’s “ cow,” underside
  - 144 Lily bud opening
  - 145 Lily flower
  - 146 Privet hawk caterpillar showing the bands whicn
  - “ break ” the surface of its body
  - 147 A lobster caterpillar g ( A hover-fly
  - 401 Egg of the hover-fly, enlarged
  - 149 Larva of the hover-fly preying on aphides
  - 150 A white butterfly
  - 151 The common snail
  - 152 The underside of a snail
  - 153 The great grey slug
  - 154
  - 156
  - 157
  - 158
  - 159
  - 160
  - 161
  - 162
  - 163
  - 164
  - 165
  - 166
  - 167
  - 168
  - 169
  - 170
  - 171
  - 172
  - 173
  - 174
  - i75
  - 1761
  - 177
  - 178
  - 179
  - 180
  - 181
  - 182
  - 183
  - 184
  - 185
  - 186
  - 187
  - 188
  - 189
  - 190
  - 191
  - A worm-eating slug Egg of a worm-eating slug Newly hatched worm-eating slug Egg of a worm-eating slug broken open to show the . young one inside Spine of Hawthorn Spines of False Acacia Prickles of Wild Rose Gorse shoot
  - Leaf-like branch of “ Butcher’s Broom,” bearing a flower bud
  - Fruit of “ Butcher’s Broom ”
  - Section across a side wound in Ash branch Side wound on an Ash branch Cross section of a recently made Apple graft Cross section through an Apple graft after a year’s growth.
  - Maple tree in winter Maple tree in summer A Bryony tendril A Sundew leaf A Sundew leaf feeding
  - Section showing how a side branch of Walnut joins another
  - Marble gall showing the holes through which the insect inhabitants have escaped Marble gall cut through, showing the cavities occupied by the grub Marble gall-fly
  - A “ lodger ” from a marble gall Sheep’s-wool galls on oak flowers A “ Robin’s Cushion ” on a rose shoot A fairy fly
  - Succession of moorland vegetation on Redbourne Edge, Weardale Wild hyacinths
  - Spore-capsule covers of the Male Fern Silkworm chrysalis
  - Silkworm cocoon from which the moth has emerged
  - Male silkworm moth
  - Female silkworm moth
  - Moss showing capsules
  - Liver-wort
  - A Fern Prothallus
  - Eggs of a twin-spot lady-bird on the underside of a Hollyhock leaf Larva of a lady-bird Pupa of a lady-bird Twin-spot lady-bird Wild duck’s ’nest covered Wild duck’s nest uncovered Nearer view showing the eggs Black-headed gull’s nest and eggs Black-headed gull’s eggs hatching Robin’s nest Young jackdaws
  - “ The Eton NaturerStudy Camera*”
  - NATURAL PHENOMENA
  - 3548.—Lantern Slides. Natural Phenomena; or, the Wonders of the World
  - Beautifully painted, 7/6 to 10/- each. Plain photographs, 2/- each.
  - x Landscape, with rainbow effect
  - 2 Lunar rainbow as seen at Compiegne
  - 3 Halos, or mock suns, Arctic
  - 4 Alpine mountain scene
  - 5 Atmospherical effect
  - 6 Mirage in desert, caravan
  - 7 Mirage in Arctic regions
  - 8 Fata Morgana Reggio
  - 9 Spectre of the Brocken
  - 10 Aurora Borealis, ribbon effect, Snow Village
  - 11 Aurora Borealis, Paris, 1869
  - 12 Aurora Australis, Antarctic
  - 13 Landstorm
  - 14 Landstorm, lightning effect
  - 15 Lightning flash, June 28th, 1892
  - 16 Lightning flash, June 28th, 1892
  - 17 Lightning flash, June 28th, 1892
  - 18 Lightning flash, June 28th, 1892
  - 19 Midnight Sun, Norway
  - 20 Sunrise at sea
  - 21 Sunset at sea
  - 22 Moonlight at sea
  - 23 Cormorants on mast of ship
  - 24 Ignus Fatuus, Will-o-the-Wisp
  - 25 Meteoric shower, falling stars
  - 26 Meteoric stone bolides
  - 27 Whirlwind
  - 28 Whirlwind, lightning effect
  - 29 Sandstorm, whirlwind
  - 30 Monsoons, mouth of Hooghly
  - 31 Simoon in the desert
  - 32 Waterspout at sea
  - 33 Whirlpools
  - 34 Rapids on the St. Lawrence
  - 35 Falls of Niagara, United States
  - 36 Falls of Montmorency, Canada
  - 37 Falls of Montmorency, winter scene
  - 38 Falls of Montmorency, natural steps
  - 39 Falls of Trenton, Canada
  - 40 Falls of Zambezi, South Africa
  - 41 Icebergs, Arctic Regions
  - 42 Icebergs, Floating
  - 43 Glaciers, Grindalwald >
  - 44 Glacier tables
  - 45 Avalanche at Ticino
  - 46 Snow bridges, Mont Blanc
  - 47 Dropping Well, Knaresborough
  - 48 Petrifying springs, San Filippi
  - 49 Great geyser, or boiling spring
  - 50 Geyser, Giantess, Yosemite
  - 51 Hot wells, Gardiner’s River,
  - 52 Mirror Lake, Yosemite Valley
  - 53 Volcano, Vesuvius
  - 54 Volcano, Vesuvius, crater
  - 55 Volcano, Kilauea, crater
  - 56 Volcano, Mount Etna, Sicily
  - 57 Volcano, Cascade of red-hot lava, during
  - eruption of 1771
  - Typed Lecture, 7/6 net.
  - 58 Volcano, Jorullo, Mexico
  - 59 Volcano, Stromboli
  - 60, Volcano, Hecla, Iceland
  - 61, Volcano, Mud,‘ Yosemite Valley -_.62- Volcg.no,- Erebus, Antarctic Ocean
  - 63 ;Volcano, Submarine
  - 64 Volcano, Air, Turbaco, S.A.
  - 65 Earthquake, Lisbon
  - 66 Grotto of Antiparos
  - 67 Cave of Adullam, Holy Land >,•'68 Mammoth Cave, Kentucky
  - 69 Cave of Adelsberg, Austria
  - 70 Staffa, General view
  - 71 Cave, Fingal, Isle of Staffa
  - 72 ,Gignt!s. Causeway, Ireland
  - 73 Giant’s Causeway, Portcoon Cave
  - 74 Blue Grotto, Isle of Capri
  - 75 Natural bridges, Virginia, United States
  - 76 Coral reef, Indian Ocean
  - 77 Coral reef, bird’s-eye view
  - 78 Prairie on fire, North America
  - 79 Landscape, summer scene
  - 80 Landscape, winter scene
  - 81 Map of Atlantic Ocean, showing course of the
  - Gulf Stream
  - 82 Dolomite formation
  - 83 The entrance to the stalactite caverns of
  - Padium
  - Every requisite for Chemical, Physical, and Bacteriological work supplied, from a test tube to the
  - complete furnishing of the largest laboratory.
  - KK
- p.513 - vue 532/555
- - 514 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - BUNSEN’S ABSORPTION!ETER, Etc.
  - 3549.—Bunsen’s Absorptiometer for measuring the Solubility of Gases in Liquids.
  - This apparatus consists of a graduated tube E, into which known volumes of the gas and liquid are introduced. The lower end of this tube is furnished with an iron screw, by means of which it can be securely screwed down upon an india-rubber pad, in order to completely close the tube (seen in the side figure).
  - The tube containing the gas and liquid under examination is lowered into a tall cylinder GG, in the bottom of which is a quantity of mercury. The cylinder is then filled with water, and the cap P screwed down. The thermometer K registers the temperature. The apparatus is then briskly shaken, in order that the liquid in the eudiometer may exert its full solvent action upon the gas, and on slightly unscrewing the tube from the caoutchouc pad, mercury enters to take the place of the dissolved gas. The tube is again closed and the shaking repeated, and these operations are continued until no further absorption results. Finally, the volume of gas is measured, the temperature noted, and the pressure ascertained by reading the position of the mercury within the tube, and deducting the height of the column from B to the surface of the mercury A, from the barometric pressure at the time of making the experiment. The temperature of the water in the cylinder may be varied, and the co-efficient of absorption at different temperatures can thus be determined.
  - Price, complete as figured .. .. ... .. £14 10 0
  - See Newth’s “ Text-book of Inorganic Chemistry ” (Longmans,
  - Green & Co.) ; also McEwen’s “ Properties of Matter ” (Longmans, Green 6* Co.).
  - 3550.—Becker’s il Airtite,” a special preparation only to be obtained from us.
  - Price .. .. .. .. .. .. per pot 1 /6
  - N.B.—The constituents of this grease are mixed in correct proportions, so that the grease is neither too hard nor too soft. There are preparations on the market which look the same as “ Airtite,” but do not give satisfaction in use.
  - 3552.—Barometer Tube, New Pattern, with well-ground-in stopcock and funnel on top.
  - Each .. .. 5/-
  - 3551.—Soft Red Wax, special quality. This will be found generally useful in physical laboratories, especially for fixing small galvanometer mirrors to silk fibre suspensions.
  - Price..................................per lb. 4/-
  - Our Balances and Weights have achieved World-wide Reputation : vide Opinions of the
  - Leading Scientific Press.
- p.514 - vue 533/555
- - 515
  - PHYSICAL LABORATORY MEMORANDA
  - ENGLISH WEIGHTS AND MEASURES.
  - AVOIRDUPOIS WEIGHT.
  - i dram =
  - 16 drams =
  - 16 ounces =
  - 14 pounds =
  - 28 pounds =
  - 4 quarters =
  - 20 cwt, =
  - 1 dram (avoirdupois) =
  - •0625 ounce (oz.).
  - 1 ounce (oz.) = 437-5 grains.
  - 1 pound (lb.) = 7,000 ,,
  - 1 stone.
  - 1 quarter (qr.).
  - 1 hundredweight (cwt.) = 112 lb. 1 ton == 2,240 lb.
  - 27-34375 grains.
  - TROY WEIGHT.
  - 24 grains = 1 pennyweight (dwt.).
  - 20 pennyweights = 1 ounce (oz.) = 480 grains.
  - 12 ounces = 1 pound (lb.)= 5,760 ,,
  - Multiplier.
  - To convert lb. avoirdupois into lb. troy, 1-2153.
  - ,, lb. troy into lb. avoirdupois, 0-82286.
  - MEASURES
  - 1 minim =
  - 1 dram =
  - 2 drams =
  - 4 drams =
  - 60 minims -8 drams =
  - 20 ounces =
  - 1 pint =
  - 8 pints =
  - 16 pints =
  - 64 pints =
  - 512 pints =
  - An Imperial gallon of distilled \
  - OF CAPACITY.
  - 1 drop.
  - 1 teaspoonful.
  - 1 dessertspoonful.
  - 1 tablespoonful.
  - 1 dram.
  - 1 ounce.
  - 1 pint (nearly £ litre).
  - •125 gallons.
  - 1 gallon.
  - 2 gallons.
  - 8 gallons.
  - 64 gallons.
  - rater weighs 10 lb. avoirdupois.
  - CUBIC MEASURE.
  - 1 pint = 34-6829 cubic inches.
  - 1 gallon = 277-463 ,, ,,
  - 1 gallon = 0-1604 cubic foot = 10 lb. of water
  - To convert cubic inches into pints multiply by 0-02883.
  - ,, ,, ,, inches into gallons multiply by 0-003604.
  - ,, ,, ,, feet into gallons multiply by 6-228.
  - Cubic foot = 1,728 cubic inches.
  - Cubic yard = 27 cubic ft., 21-033 bushels.
  - Cubic Cubic Cubic Cubic Metre
  - Inches. Feet. Yard. or Stere.
  - 1 = •0005787 = •00002143 = •000016387
  - 1,728 = 1 = •03704 = •028317
  - 46,656 = 27 = •1 = •764553
  - SQUARE MEASURE.
  - 144 square inches = 1 square foot.
  - 9 ,, feet = 1 ,, yard.
  - 30 i ,, yards = 1 ,, perch.
  - 40 perches = 1 rood.
  - 4 roods = 1 acre.
  - 640 acres — 1 square mile.
  - English mile = 1,760 yards = 5,280 feet, x geographical mile, Admiralty knot or nautical mile = 6,080 feet — 1-151 statute mile.
  - r cable length = 100 fathoms = 600 feet.
  - Acre = 4 roods = 4,840 yards (nearly 70 X 70 yards).
  - 1 quarter acre = 104-35 feet square = 34 yards 2 feet square.
  - Mile square = 640 acres = 3,097,600 square yards.
  - LINEAL MEASURE.
  - 4 in. = 1 hand. 5$ yards = 1 rod, pole or MEASURES OF SPACE
  - 9 = i span. perch.
  - 12,, = x foot. 4 poles = 1 chain. 60 seconds = 1 minute.
  - 3 feet = i yard. 10 chains = 1 furlong. 60 minutes = 1 degree.
  - 5 feet = 1 pace. 8 furlongs = 1 mile. 30 degrees = x sign.
  - 6 feet = 1 fathom. 3 miles = 1 league. 45 = 1 octant.
  - 1-151 miles make 1 knot. 60 ,, = 1 sextant.
  - ANGULAR MEASURE.
  - 90 degrees = 1 quadrant.
  - (a right angle)
  - 180 ,, = x semi-circle.
  - 360 ,, = 1 circle.
  - METRIC WEIGHTS AND MEASURES.
  - WEIGHT.
  - 10 milligrammes = 1 centigramme.
  - 10 centigrammes = 1 decigramme.
  - 10 decigrammes = 1 gramme.
  - 10 grammes = 1 decagramme.
  - 10 decagrammes = 1 hectogramme.
  - 10 hectogrammes = 1 kilogramme.
  - CAPACITY.
  - 10 centilitres = 1 decilitre.
  - 10 decilitres = 1 litre.
  - 10 litres 1 decalitre.
  - 10 decalitres = 1 hectolitre.
  - io hectolitres = 1 kilolitre.
  - LENGTH
  - 10 millimetres 10 centimetres 10 decimetres 10 metres 10 decametres 10 hectometres 10 kilometres
  - 1 centimetre.
  - 1 decimetre.
  - 1 metre.
  - 1 decametre.
  - 1 hectometre. 1 kilometre.
  - 1 myriometre,
  - VOLUME
  - 1,000 cubic millimetres = 1 cubic centimetre.
  - 1,000 cubic centimetres = 1 cubic decimetre.
  - 1,000 cubic decimetres = 1 cubic metre.
  - SURFACE.
  - 100 square millimetres 100 square centimetres 100 square decimetres 100 square metres 100 square decametres 100 square hectometres
  - 1 square centimetre. 1 squai-e decimetre.
  - 1 square metre.
  - 1 square decametre. 1 square hectometre. 1 square kilometre.
  - FACTORS FOR RAPID APPROXIMATE CALCULATIONS. Metric to British.
  - The exact factors are placed within brackets so that the degree of accuracy of the approximate calculation may be seen.::,
  - Decigrammes to grains X i£ (1-543)
  - Grammes to grains X 15^ (15-43)
  - Grammes to ounces X 3i and -f- 100 (0-0353)
  - Dekagrammes to drachms X 2 J (2-57)
  - Hectogrammes to ounces X 3i (3’53)
  - Kilogrammes to pounds X 21 (2-205)
  - Myriagrammes to stones X ii (1-44)
  - Quintals to hundredweights X 2 (1-97)
  - Milliers to tons — (0-984)
  - Decilitres to gills X 7 -7 10 (0-704)
  - Litres to pints X if (1 + i + i) (1-76)
  - Litres to quarts ' x85 + to of this (o-88o)
  - Litres to gallons X 22+ 100 (0-220)
  - Hectolitres to bushels X 11 -f 4 (0-275)
  - Hectolitres to quarters -4- 3 (0-344)
  - Millimetres to eighths of inches X 3 — & (3’io) Centimetres to inches X 4 and -7- 10 (0-394)
  - Decimetres to feet ~ 3 (-F 3-05 or X 0-328)
  - Metres to feet X 3 — to (3-28)
  - Metres to yards + to (1-093)
  - Dekametres to chains — 2 (0-497)
  - Hectometres to furlongs -y 2 (0-497)
  - Kilometres to miles £ + i of the £ (0-621)
- p.515 - vue 534/555
- - 516
  - PHYSICAL LABORATORY MEMORANDA
  - PHYSICAL CONSTANTS OF THE ELEMENTS.
  - Melting Boiling Melting Boiling
  - Point °C. Point °C. Point °C. Point °C.
  - Helium .. — 270b — 268-7 Calcium .. 800
  - Hydrogen — 258-9 — 252-8 Strontium 800a
  - Neon — 253 240a Lanthanum 810
  - Fluorine .. — 223 -T87 Arsenic .. . . ... . . 817-850P sbm
  - Oxygen 219 — 182-9 Neodumium 840
  - Nitrogen — 2IO-5 — 195-7 Barium .. 850
  - Argon —189-6 — 186 Germanium 900a
  - Krypton —169 -.151-7 Praseodymium 940
  - Xenon — 140 109 Silver 960 1955
  - Chlorine . . — 102 — 33-7 Gold 1062-4
  - Nitron — 71 Copper .. 1082-6 23x0
  - Mercury .. 38-85 356-7 Manganese : 1260 1900
  - Bromine .. 7-3 58-7 Glucinum 1280
  - Caesium .. 28-25 670 Zirconium 13003
  - Gallium .. 30-15 Samarium 1350a
  - Rubidium 38-5 696 Silicon 1434
  - Phosphorus 44-1 279-3 Nickel 1452 2340
  - Potassium 62-5 762-2 Cobalt 1478 2415
  - Sodium .. .. .. 97*5 882-9 Iron 1505 2450
  - Iodine 114 184-3 Chromium 1520 2200
  - Sulphur rhombic 112-8 444-7 Palladium 1549
  - Indium . . 155 Vanadium 1720
  - Lithium .. 186 I400g Thorium i7oog
  - Selenium.. 217 690 Platinum 1755
  - Tin 231-9 2270 Titanium 1795
  - Bismuth .. 268 1420 Ruthenium 1900a
  - Thallium.. 301 1515 Rhodium 1907
  - Cadmium 321 765-9 Columbium 1950
  - Lead 326-9 1525 Osmium .. 2200-2500
  - Zinc 419-4 905-7 Iridium .. 2290
  - Tellurium 450 1390b Boron 2000V
  - Cerium .. 635 Molybdenum 2450a
  - Antimony' .. .. 629-2 1440 Tantalum 2910
  - Magnesium 649 1120 Tungsten 3540a
  - Aluminium 658 1800 Carbon .. 35oova
  - Notes.—a. approximately ; b. below ; g. greater than ; p. under pressure ; sbm. sublimates ; v. volatises, Boron at 2,000 to 2,500° C.
  - Melting Points are taken at atmospheric pressure, the melting point is usually slightly raised on increasing the pressure.
  - Boiling Points taken at a pressure of 760 mm. except nickel and cobalt , which are taken at 30 mm.
  - LINEAR EXPANSION OF METALS.
  - Expansion. Expansion.
  - Aluminium, pure 0-0000245 Iron pure . . 01x8
  - Antimony 0115 Lead, cast 0292
  - Bismuth 0135 Nickel, cast . . 0128
  - Cadmium, distilled 0307 Platinum, cast and beaten .. 0090
  - Copper, distilled 0168 Silver, pure 0192
  - Gold 0147 Tin, cast 0223
  - Iron, cast gray 0106 Zinc, cast 0292
  - ,, wrought .. . 0110
  - The co-efficient of cubical expansion is three times the co-efficient of linear expansion.
  - SPECIFIC GRAVITIES OF SOLIDS.
  - Platinum 22-07 Diamond 3-35 Ice at 0° C. 0-93
  - Gold 19-36 Statuary marble 2-83 Oak 0-84
  - Lead .. .. n-35 Aluminium 2-68 Yellow pine 0-65
  - Silver 10-47 Glass 2-48 Common poplar 0-38
  - Copper .. 8-87 Salt 2-22 Cork 0-24
  - Bronze coinage 8-66 Anthracite i-8o Snow ... .. 0-18
  - Iron 7-7 8 Coal 1-32 Pith o-o 7
  - Zinc .. • • 6-86 Amber .. 1-07
  - > SPECIFIC GRAVITIES OF LIQUIDS. - ’
  - Mercury .. 13-60 Sea water 1-02 Liquid oxygen .. 0-89
  - Methylene iodide 3-34 Distilled water at 4° C. I-00 Oil of turpentine 0-87
  - Bromine 2-96 Distilled water at o° C. 0-99 Absolute alcohol o-8o
  - Sulphuric acid .. 1-84 Claret 0-99 Ether 0-72
  - Glycerine 1-26 Olive oil.. 0-91 Pentane .. 0-62
  - Milk 1-03
- p.516 - vue 535/555
- - 517
  - PHYSICAL LABORATORY MEMORANDA
  - UNITS OF ELECTRICITY.
  - THE AMPERE, or unit of strength of current, is defined from Ohm’s law as being that current which would be produced by an electromotive force of a volt acting in a circuit through a resistance of an ohm : or, for instance, what1 is the same, an E.M.F. of io volts through a resistance of io ohms. A milliampere is the Tg\jjj of an ampere.
  - THE COULOMB is the unit of quantity of electricity : it is that quantity which flows in a second of time through a circuit which has a resistance of an ohm with an electromotive force of a volt: or, in other words, it is that quantity which passes in one second with a current of an ampere.
  - THE VOLTCOLUMB, or unit of electric work, is the work done when a coulomb of electricity falls through a difference of potential of a volt: it is precisely analogous to the foot-pound or unit of mechanical work, and is known as the JOULE.
  - THE UNIT OF ELECTRO-MOTIVE FORCE or difference of electric pressure, or electrical potential, exists between two points when i erg per second is necessary to cause the unit current to flow between them. For practical purposes the unit employed is io8 times this quantity and is called the VOLT.
  - THE UNIT OF RESISTANCE is called the “OHM.” If the current is passing from one point to another there must be an electromotive force, or difference of potential between them, and Ohm found that the ratio of potential to a- current in a conductor was constant and therefore unit resistance exists when unit potential is necessary to produce unit current. The “ ohm ” is equivalent to io9 absolute units of resistance, and is equal to the resistance offered by a column of mercury 106-3 cm- long and 1 square millimetre in cross sectional area at the temperature of melting ice.
  - THE UNIT OF CAPACITY (THE FAR AD) is the capacity possessed by a conductor when a charge of 1 coulomb raises its potential 1 volt. Since this unit is extremely large the MICRO-FARAD (equal to one-millionth of a farad) is employed.
  - THE UNIT OF SELF-INDUCTION (THE HENRY) is the induction in a circuit which gives rise to an induced potential difference of one volt in the circuit when the inducing current changes at the rate of one ampere per second.
  - THE BOARD OF TRADE UNIT (B.T.U.) is the commercial unit for purposes of public supply, and is measured by the product of j the power and the time in hours divided by 1,000. Thus 1 B.T.U.
  - | equals 1,000 watt-hours, equals 1 kilowatt-hour, equals 1-34 horse-I power-hours.
  - APPROXIMATE E.M.F.’ S OF VARIOUS CELLS.
  - Cell. E.M.F. Cell. E.M.F.
  - ^Bichromate .. 2-0 volts. Leclanche . .. i*5 volts
  - Bunsen 1‘9 it Obach •• i*5
  - Daniell I-I Clark (Standard) .. •• 1-434 „
  - Grove 1-9 .. Secondary 1-85 to 2-i ,,
  - “NIVOC” PATENT STENCILS
  - -VllVOc-patent stencil
  - F E BECKER & C°. HATTON WALL LONDON.
  - Stencil No. 1 (J Actual Size).
  - v
  - patent stench F EBECKER 8 C?
  - HATTON WAIL
  - LONDON
  - Stencil No. 2 (J Actual Size).
  - Now used all oven the world where Chemistry is taught. Bad Drawings things of the past.
  - Extracted from the Matriculation and Science Programme of the University of London :—
  - ggCandidates taking Chemistry will be permitted, if they desire it, to use a stencil for making drawings of apparatusm"
  - The Indian Authorities have also sanctioned the use of these Stencils•
  - Full instructions for use will be found in our Chemical Apparatus Catalogue, 23rd Edition, pages 270 and 271,
  - 3553.—“ Nivoc ” Stencil IMo. 1 .............................. each 1 /—
  - 3554___“Nivoc” Stencil No. 2 .............................. 1/-
- p.517 - vue 536/555
- - 518 F. E. BECKER & CO., NIVOC HOUSE, HATTON HALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - SECTIONAL INDEX.
  - PAGES
  - ELEMENTARY SCIENCE.......................................................1-27
  - Measurement of Length, Area, Volume, Capacity, Mass, Density, Etc.
  - MISCELLANEOUS LABORATORY APPARATUS .................................28-51
  - Glassware, Stands, Clamps, Burners, Tools, Etc.
  - MATHEMATICAL INSTRUMENTS................................................52-60
  - BALANCES AND WEIGHTS................................................... 61-92
  - MICROSCOPES . 93
  - {See also Chemical Apparatus Catalogue.)
  - METEOROLOGY............................................................94-108
  - MECHANICS: PRACTICAL AND APPLIED................................109-167
  - Hydrostatics, Pneumatics, Steam and the Steam Engine.
  - SURVEYING AND PHYSICAL GEOGRAPHY......................................168-172
  - MAGNETISM AND ELECTRICITY............................................ 173-337
  - Batteries and Storage Cells, Terminals, Wires, Galvanometers, Resistances, Wireless Apparatus, X-Rays, Vacuum Tubes, Etc.
  - SOUND . 338-365
  - LIGHT . 366-436
  - Mirrors, Lenses, Prisms, Spectrometers, Telescopes, Cameras, Lanterns, Cinematographs, Etc.
  - heat..................................................................437-487
  - LANTERN SLIDES . 488-513
  - Ganot’s Physics, Magnetism and Electricity, Mechanics, Heat, Light, Astronomy, Botany, Etc.
  - DETAILED INDEX
  - PAGE
  - ABSORPTIOMETER, Bunsen’s . 514 Absorption of Heat, Apparatus for experiments on . . . . 478-479
  - Accumulator Charging Sets . . . 220
  - •Accumulator Hydrometers . . .218
  - Accumulators.................214-218
  - Acetylene Generators and Jets . . 432
  - Achromatic Prisms....................388
  - “ Acme ” Portable Cinematograph
  - Projector . . . . . . . 426
  - Acoustic Bellows . . . . . . 354
  - Acoustic Radiometers . . : . . . 363
  - Action of Electricity on Points,
  - Apparatus.........................190
  - Action of Wire Gauze on Flame
  - Apparatus . 167
  - Adapters, Horizontal.................295
  - Adapters, Vertical...................295
  - Adapters, Plug.......................265
  - . Adhesion Plates . . . . . .130
  - Adjustable Resistances (Slate Types)
  - 258-261
  - Adjustable Resistances (Tubular
  - Types) .......................262-263
  - Adjustable Resistances (Ventilated
  - Patterns).........................264
  - Adjustable Slits for Optical Bench
  - Experiments..............373~374
  - Adjustable Spark Gap . . . . 305
  - Aerial Insulators....................299
  - Aerial Wire..........................299
  - : Air-bulb Tubes, Jolly's . . . 26,466
  - Air Concussion Apparatus . . .341
  - PAGE
  - Air, Expansion of, Apparatus . . 464
  - Air Liquefying Apparatus. . . .461
  - Air, Liquid ......................462
  - Air Pump Apparatus . . . .164-166
  - Air Pump Plates..............162, 163
  - Air Pump Plates, " Airtite ” for
  - greasing.......................514
  - Air Pumps.....................161-162
  - Air Thermometers, Differential . .481
  - Air Thermometer, Model .... 467 Air Thermometer, Shakespear’s . . 467
  - “ Airtite ”.......................514
  - Airy’s Double Pendulum .... 348
  - Aluminium Cubes....................16
  - Aluminium Cups for Determination of
  - Dew Point......................453
  - Aluminium Cylinders................21
  - Aluminium Foil.....................46
  - Aluminium Leaf.....................46
  - Aluminium Pulleys.................124
  - Aluminium Spheres..................17
  - •Amalgam, Electric................187
  - Amber Globes......................417
  - Amber Specimens...................186
  - Ammeter and Voltmeter Combined 237 Ammeters and Voltmeters Combined,
  - Watch Type . 240
  - Ammeters......................236-240
  - Ampere’s Induced Currents Apparatus ........................183-184
  - Ampere’s Law, Apparatus for Proving..............................182
  - Ampere’s Parallelogram . . . .183
  - PAGE
  - Amplifiers, Power (for wireless) . . 297
  - “ Amplion ” Loud Speaker . . . 296
  - Amsler’s Planimeter...............56
  - Analysis of Sound Apparatus . . 355
  - Andrew’s Apparatus for Determining the Isothermals of Carbon Dioxide 463
  - Andrew’s Calorifer...............473
  - Anemometers . . . . . . .108
  - Aneroid Barometers, Carved Wood
  - Frame..........................99
  - Aneroids, Watch form .... 104
  - Anglemeters......................169
  - Angular Mirrors..................376
  - Anode Ray Tubes .................334
  - Anode Resistances (for wireless) . . 293
  - Anschutz Normal Thermometers . 485 Antimony and Bismuth Thermopiles
  - 302,-480
  - Antimony and Bismuth Bars . . 302
  - Antimony, Bismuth and Nickel Bars,
  - set of 3......................175
  - Aperiodic Coils for d’Arsonval Galvanometers .....................223
  - Aphengescope................... . 435
  - Apparatus for showing Volume and Temperature of Gas . . . . 467
  - Apple Cutter.....................165
  - Aprons, Lead Rubber .... 309 Arago’s Apparatus for illustrating
  - Induced Currents..............184
  - Arc Lamps ....... 429-430
  - Arc Lamp Carbons.................430
  - Arc Lamp Carbons.................267
- p.518 - vue 537/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 519
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Arc Lamp Resistances . . . .257
  - Arc Lamps, Electric .... 266-267
  - Arch, Model of ....................132
  - Archimedean Drill...................48
  - Archimede’s Experiment, Apparatus
  - for...............................22
  - Area of a Sphere Apparatus . . . 18
  - Armature Motor.....................268
  - Aron’s Tubes.......................334
  - Arresters, Lightning...............299
  - Artificial Light Enlargers . . . .419
  - Assorted Spectacle Lenses . . .382
  - Astatic Galvanometer, Thomson’s . 225
  - Astatic Galvanometers .... 302
  - Astatic Galvanometers . . . .231
  - Astatic Galvanometers for use with
  - Thermopiles......................480
  - Astatic Pair.......................177
  - Atmospheric Engine, Wollaston’s . 477
  - Astronomical and Terrestrial Telescopes ......................409,411
  - Astronomical Slides (Rackwork
  - Motion)..........................413
  - Astronomical Telescope, Model of 385
  - Atwood’s Machines . . . .120-121
  - Auto-collimating Spectrometer . . 396
  - Auto-Magnetic Jet..................306
  - Ayrton-Mather’s Universal Shunt . 230
  - Ayrton’s Gold Leaf Electroscope .196
  - Azimuth Compass Box................178
  - BALANCES and Weights . . 61-92
  - Balances, Ballistic . . .122-123
  - Balances, Compression . . .138-139
  - Balances, Coulomb’s Torsion . . . 196
  - Balances, Magnetic, Hibbert’s . . 175
  - Balances, Physical, for Experiments
  - in Mechanics.....................112
  - Balances, Specific Gravity, Joly’s . 25
  - Balances, Spring...............139-140
  - Balance Hydrometer, Bucknell’s . 24
  - Balance Lever and Moments Apparatus ...............................no
  - Balancing Machine . . . . . 155
  - Ball and Ring for showing Expansion
  - of Solids.................... . 438
  - Ball and Ring for use with Whirling Tables. . . ... . . . 154
  - Ball-ended Magnets, Robison's . . 173
  - Ball, Glass, Rotating (Electrical Circus) .......................... . 193
  - Ball, Glass, Rotating, for Air Pump
  - Work.............................165
  - Ball with Weight for use with Whirling Tables.........................154
  - Ballistic Balances.............122-123
  - Ballistic Coils for d’Arsonval Gal- -
  - vanometers.......................223
  - Balls, Brass, for Statical Electricity
  - Apparatus........................194
  - Balls, Brass, for use with Whirling
  - Tables...........................154
  - Balls, Copper, for Heat Experiments 474 Balls, Lead, making simple Pendulums ..............................149
  - Balls, Pith.........................190
  - Balmain’s Luminous Paint . . . 320
  - Bands, India Rubber.................46
  - Bar and Gauge to show Expansion 438 Bar Breaking Apparatus .... 438 4Bark Corks and Shives . . . .34
  - ‘Barker's Mill......................159
  - Barlow Lens for Telescopes . . . 409
  - Barlow’s Wheel......................184
  - Bar Magnets, Cylindrical v . . 175
  - Bar Magnets in Sets................175
  - Bar Magnets on Stand...............175
  - Bar Magnets, Various . . . .173-174
  - Bar Magnets, Telephone .... 276
  - Bar of Iron and Copper to show different Conducting Power . . 442
  - PAGE
  - Barographs and Thermographs . 104-105
  - Barometer Tubes...................514
  - Barometer Tubes, fitted with Brass Cap and Stuffing Box . . . .165
  - Barometer Tubes.....................98
  - Barometer Tubing . . . . . . 40
  - Barometer Vernier, Model ... 8
  - Barometers, Aneroid, Carved Wood
  - Frame.............................99
  - Barometers, Fortin’s................96
  - Barometers, Various .... 97-98
  - Baroscope for showing Buoyancy of
  - Air..............................165
  - Baro-Thermograph...................105
  - Bars of Antimony, Bismuth and
  - Nickel...........................175
  - Bars of Bismuth and Antimony . . 302
  - Bars of Brass and Iron for expansion of Solids Experiments .... 438
  - Bars of Soft Iron..................176
  - Bars of Steel, Unmagnetised . .176
  - Bars, Wooden, for Sound Experiments ...........................348
  - Bar Weights, Iron..................141
  - Baseboard Mounting (X-Ray Apparatus) ...........................305
  - Basins, Porcelain...................30
  - Basket Inductances.................295
  - Bass Bows.....................349, 361
  - Batswing Burners....................32
  - Battery Cells for Bunsen’s Batteries 204 Battery Cells, Porous Ware . . . 205
  - Battery Switches, Plug Key . . . 278
  - Battery Terminals..............206-207
  - Battery Wall Telephones .... 275 Batteries (Accumulators) . . .214-2.18
  - Batteries, Bichromate . . . .199
  - Batteries, Daniell’s, Bunsen’s Lec-
  - lanche, etc..................200-202
  - Batteries, Floating................183
  - Batteries complete with Tray and Lifting Arrangements . . . .199
  - Batteries, Groves’.................201
  - Batteries, High Tension . . . .222
  - Batteries of Leyden Jars . . . .188
  - Batteries, Spare parts for . . . 204
  - Beakers, Enamelled Steel ... 30
  - Glass......................29
  - Thick Glass for Cold Solu-
  - Beakers,
  - Beakers,
  - tions
  - Beakers,
  - Zinc
  - 30
  - 30
  - 53
  - Beam Compasses................
  - Beams and Springs, Testing Apparatus for...................131-132
  - Beckmann’s Boiling Point Apparatus 456 Beckmann’s Freezing Point Apparatus ...................... 456-457
  - Magni-
  - 30
  - Beckmann’s Thermometers Beckmann’s Thermometers,
  - fiers for..............
  - Beechwood Pantographs Beeswax.
  - Bell Crank Lever Bell Experiment Bell Jars Bell Pushes “ Bell ” Receivers Bell Set, Electric Bell Wire .
  - Bells, Electric .
  - Bell’s Telephones Bellows, Acoustic Bellows, Foot, for use Bellows, Foot .
  - Bench Drills Bench Grinder .
  - Bench, Polarisation Bench Vices Benches, Optical Bennett’s Gold Leaf Electroscopes Bent Wire Stirrups for Glass Rods etc.
  - Berthelot’s Apparatus for Determin ing the Latent Heat of Steam
  - with Sirens
  - 484
  - 484 56 46 144 342 164 274 276 273
  - 213
  - 273 276
  - 354 360 32 48 48 4°4 5J 367-372 195
  - 187
  - 474
  - PAGE
  - 278
  - II7
  - 347
  - 204
  - 199
  - 365
  - 434
  - 412
  - 15
  - 191
  - Bertin’s Commutator .
  - Bertram’s Inclined Planes Bezold’s Tuning Fork.
  - Bichromate Batteries, Zincs and Carbon Plates for .
  - Bichromate Batteries .
  - Binaural Stethoscopes.
  - Binding Strips for Lantern Slides Binoculars, Prismatic .
  - Binomial Cubes
  - Biot’s Apparatus to Demonstrate that Electricity resides only on the Surface .............................
  - Bi-Prisms, Fresnel’s .
  - Birch’s Tangent Lens Gauge.
  - Bismuth and Antimony Thermopiles
  - 302,
  - Bismuth and Antimony Bars Bismuth, Antimony and Nickel Bars set of three Bars
  - Bismuth Cylinders for Conductivity
  - Experiments......................442
  - Blackboard Chalks...................56
  - Blackboard Compasses . . . 53, 56
  - Blackboard Easels...................56
  - Blackboard Set Squares .... 56
  - Blackboard T Squares .... 56
  - Blackboards.........................56
  - 387. 389 383
  - 480
  - 302
  - 175
  - Black Glass Plates, optically worked 403
  - Trans
  - Bladder Frame and Weights Bladder Glasses Bladders, India Rubber . Blanket Pins .... Blocktype Accumulators .
  - Blocks of Wood (Supports) Blocks, Hardwood and Boxwood Blocks, Wooden, Rectangular . Blowpipe . . ,
  - Blue Radiating Powder Bobbin, high frequency
  - former.............
  - Bobs, Pendulum .
  - Boiler, Steam, Marcet’s Boiling Point Apparatus Boiling Point Apparatus, mann’s
  - Bologna Phials Bolometer, Langley’s Boss Heads
  - Bottles, Glass, Reagent, etc Bottles, Prismatic .
  - Bottles, Specific Gravity Bourdon’s Ring Box Compass for use with G
  - 165
  - 164 164 46 217
  - 34 19-20 21 32 320
  - Beck
  - 303
  - alvano
  - 291
  - 115
  - 455
  - 455
  - 456 441 481
  - 37
  - 33
  - 385
  - 23
  - 166
  - meters..........................229
  - Boxes of Drawing Pins .... 55
  - Boxwood Blocks ..... 19-20
  - Boxwood Cones......................18
  - Boxwood Cylinders..................20
  - Boxwood Prisms.....................19
  - Boxwood Protractors................54
  - Boxwood Pulleys...................126
  - Boxwood Pyramids . . • • • 18
  - Boxwood Rules................2-3, 8
  - Boxwood Scale Thermometers . . 100
  - Boxwood Sliding Callipers ... 6
  - Boxwood Spheres ...................17
  - Boxwood Trough Compass . . .172
  - Boyle’s Law Apparatus . 26, 465-467
  - Boyle’s Law, Marriotte’s Apparatus
  - for proving......................27
  - Boyle’s Law Tubes . .26-27, 465-466
  - Bows, Violin, ’Cello and Bass 349* 361 Boxes for Lantern Slides. . . -435
  - Boxes, Glass......................39°
  - Boxwood Scale Thermometer . . 486
  - Braces, Drilling . . . ... 48
  - Brackets, Cast Iron, for determining Stiffness and Strength of Beams . 131 Brackets, Iron, for Pulley Experiments ............................I26
  - Bramah’s Press Models . . . .157
  - Brass Balls for Statical Electricity Experiments..................... .194
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- - 520 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Brass Balls on Stand for use with
  - Whirling Tables.................154
  - Brass Carriers for Lantern Slides . 435
  - Brass Chain........................193
  - Brass Clamp for holding Lenses . 382
  - Brass Clamps........................38
  - Brass Compass Box . . . 177, 229
  - Brass Cones.........................18
  - Brass Cubes......................16-17
  - Brass Cylinders.....................20
  - Brass Cylinder and Bucket for Archimedes’ Principle .... 22
  - Brass Dividers......................53
  - Brass Holders for Luminous Panes,
  - etc.............................192
  - Brass Pencil Compasses . . . .53
  - Brass Pocket Levels................159
  - Brass Prisms........................19
  - Brass Protectors....................53
  - Brass Pulleys...........124-125
  - Brass Pyramids......................18
  - Brass Rods.........................186
  - Brass Slotted Weights . . . .143
  - Brass Spectroscope Stands . 337, 399
  - Brass Spheres.......................17
  - Brass Spheres for inserting Proof
  - Planes..................... . .189
  - Brass Spheres on Vulcanite Uprights ............................191
  - Brass Stands, for holding Diffraction
  - Gratings........................400
  - Brass Stands for Solar Thermometers ..............................102
  - Brass Terminals....................209
  - Brass Supports for Magnetic Needles 177 Brass Wire Spiral for showing Waves 340 Braun’s Cathode Ray Tubes 332, 335 Braun-Wehnelt’s Vacuum Tubes . 332 Braun’s Tubes, Magnet Spools for . 332 Breaking Stress of Steel Wires Apparatus ....................... . . 132
  - Breast Drill........................48
  - Brequets Metallic Thermometer . 439 Bresina’s Chemical Harmonicons . 357
  - Bridge, Carey-Foster...............253
  - Bridge, Kohlrausch’s Universal . . 256
  - Bridges, Wheatstone . . . 252-253
  - Brushes, Paper.....................193
  - Bucket and Cylinder for Archimedes’
  - Experiment.......................22
  - Bucket and Syphon for Electrical
  - Experiments.....................194
  - Bucknell’s Balance Hydrometer . 24
  - Bulbs, Glass, Weighted .... 447 Bulbs, Glass, for Specific Gravity of
  - Gases............................23
  - Bulbs, Luminous....................332
  - Bulbs, Vacuum......................332
  - Bungs, rubber, squat, tall and shallow
  - pattern.......................43-45
  - Bunsen Burner Tubing . . . .41
  - Bunsen Burners.................33, 167
  - Bunsen’s Apparatus for Determining Expansion of Water on Freezing ...............................458
  - Bunsen’s Absorptiometer . . .5x4
  - Bunsen’s Batteries, Glass Jars for . 205
  - Bunsen’s Cells ....................200
  - Bunsen’s Cells, Zincs and Carbon
  - Plates for......................204
  - Bunsen’s Grease Spot Discs . . . 374
  - Bunsen’s Grease Spot Photometers
  - 366-367
  - Bunsen’s Ice Colorimeter .... 458 Bunsen-Reichert’s Ice Calorimeter . 458 Bunsen’s Syphon Barometers . . 98
  - Bunsen’s Universal Clamp Supports 34
  - Burettes . . . !..............29
  - Burette Clips.......................35
  - Burette Stands.................3i» 35
  - Burner and Oven for Soldering . 50
  - Burners, Bunsen................33, 167
  - Burners, Gas, for Optical Bench Experiments........................374
  - PAGE
  - Burners, Gas, for producing Singing
  - Flames...........................358
  - Burners, Koenig’s Sensitive Flame . 358 Burner with Batswing Jet . . .32
  - Bursting Bottles, Cast-iron . . . 459
  - Butterfly Net, Faraday’s . . .189
  - Buzzer, Electric....................273
  - CABINET of Mechanical Powers 126 Cabinet, Silencing .... 306
  - Cabinets, Tool.......................47
  - Cable Type Accumulators . . .217
  - Cadmium Cells..................... 203
  - Cage, Wire, for Electrical Experiments 195 Cagniard de la Tour’s Simple Sirens 360
  - Calculating Rules.................58-60
  - Callendar’s Mechanical Equivalent of
  - Heat Apparatus...................476
  - Calliper Gauges.......................6
  - Callipers...........................5-6
  - Calorifer, Andrews’.................473
  - Calorimeters, Bunsen’s Ice . . . 458
  - Calorimeters, Joule’s...............303
  - Calorimeters, Various . . . 468-472
  - Calorimeters for Fuel Testing . . 471
  - Calorimeters, Roland Wild . . . 472
  - " Camden ” Measure (for Rain Gauge) 106
  - Camera, Obscura.....................407
  - Camera, Pinhole.....................407
  - Camera Stands.......................417
  - Cameras, Various .... 414-416
  - Cams, Reciprocating and Circular
  - Motion...........................145
  - Canal Ray Tubes . . . 329-331
  - Canary Wood Mercury Trays . . 31
  - Candle Holders......................373
  - Canisters, Cubical Tin .... 478
  - Cannon, Electrical..................19°
  - Canvas Lined Rubber Pressure Tubing .............................. 41
  - Capillary Plates....................159
  - Capillary Tubes, Set of 6 in Frame . 159 Carbon Bisulphide Prisms . . . 385
  - Carbon Blocks for Bunsen’s Batteries 204 Carbon Dioxide, Apparatus for determining the Isothermals of . . 463
  - Carbon Megohms......................249
  - Carbon Plates for Bichromate Batteries ............................204
  - Carbon Rheostats....................255
  - Carbons, Arc Lamp...................267
  - Carbons for Arc Lamps .... 430 Carborundum Detectors .... 298 Cardboard Cylinders for showing
  - Stationary Waves.................340
  - Cardboard Pill Boxes .... 46
  - Cardboard Resonators . . . .351
  - Cardboard Sheets.....................46
  - Cardboard Tube for Heat Experiments .............................477
  - Carey-Foster Bridge.................253
  - Carry’s Ice Machine, Apparatus for demonstrating Principle of . . 458
  - Carry’s Liquefaction Apparatus . . 459
  - Carrier for Slotted Weights . . .143
  - Carriers for Lantern Slides . . . 435
  - Cartesian Divers....................160
  - Cartesian Figures...................160
  - Carved Wood Frame Aneroid Barometers .............................99
  - Case Openers.........................49
  - Case for Sequoia Plane Table . .172
  - Cases for Bar Magnets . . . .173
  - Cases of Mathematical Instruments . 52
  - Cassettes for Intensifying Screens . 310 Cast-iron Bursting Bottles . . . 459
  - Cathetometers.....................12-13
  - Cathode Ray Tubes . . 332, 333, 335
  - Catskin Rubbers.....................186
  - Cello Bows..................349, 361
  - Cells, Battery, Porous Ware. . . 205
  - Cells, Bunsen’s.....................200
  - Cells, Cadmium ...... 203
  - Cells, Daniell’s PAGE 200, 201
  - Cells, Grove’s . 201
  - Cells, Leclanche .... . 202
  - Cells, Lighting Type . . 219
  - Cells, Minotti . 202
  - Cells, “ Nivoc ” Dry . . 221
  - Cells, Smee’s .. 20X
  - Cells, Stoneware, for Bunsen’s Bat-
  - teries . 204
  - Celluloid Protractors . • • 53
  - Celluloid Set Squares . • • 55
  - Centre of Gravity Apparatus 152-153
  - Centrifugal Force Machine • • 155
  - Chain, Brass • • 193
  - Chain of Platinum and Silver . . . 302
  - Chains, Land . . . . . . 172
  - Chalk Holders .... . . 56
  - Chalks, Blackboard . . 56
  - Charging Dynamos . 271
  - Charging Sets for Accumulators . 220 Charles’s Law, Apparatus to prove. 467 Charts for Thermographs. . . .105
  - Charts of the Metric System . . 1
  - Chatterton Compound . . . . .205
  - Chemical Harmonicons . . . . 357
  - Chemicals, Various...................46
  - Cheshire’s Disc.....................341
  - Cheshire’s Wave Motion Apparatus. 341
  - Chimes, Electric....................192
  - Chisels..............................47
  - Chladni Plates......................361
  - Chladni Mirrors.....................361
  - Chladni’s Figures, Set of Apparatus for 362 Chronographic Tuning Fork . . . 346
  - Cinematographs .... 425-426
  - Circles, Rubber, for Foot Bellows . 32
  - Circular Diffraction Gratings . . 400
  - Circular Protractors .... 53-54
  - Circular Spirit Levels . . . .159
  - Circular Verniers, Models of . . 9
  - Circulation of Water Apparatus. . 445 Clamp and Screw for Light Experiments ..............................493
  - Clamp Supports, Bunsen’s ... 34
  - Clamped Deal Drawing Boards . . 54
  - Clamps for Condensers .... 38
  - Clamps for holding Chladni Plates 361 Clamps for holding Lenses . . . 382
  - Clamps, Iron, for supporting Kundt’s
  - Tubes............................356
  - Clamps, Malleable Iron . . . .51
  - Clamps, Retort Stand .... 38
  - Classen’s Apparatus for the Electro-lytical Estimation of Copper . . 304
  - Clement and Desormes Apparatus . 472 Clips, Earth (for Wireless) . . . 299
  - Clips for Burettes...................35
  - Clock Springs.......................176
  - Clocks, Seconds.....................121
  - Co-efficient of Absolute Expansion of Liquids, Weinhold’s .... 448 Co-efficient of Dilation of a Liquid, Apparatus for Determining . . 450
  - Co-efficient of Expansion of Gases
  - Apparatus........................467
  - Co-efficient of Expansion of Air
  - Apparatus........................464
  - Coil Friction Apparatus . . . .147
  - Coil, Induction, for use with Microphones .............................282
  - Coil, Induction, Weinhold’s . . .183
  - Coils for d’Arsonval Galvanometers 223 Coils, Resistance .... 247-248
  - Coils, Tuning or Inductance 294-295^ Cold Water Floats . . . 160, 449
  - Collision Ball Lantern Slide . . . 340
  - Colour Blindness, Tests for . . . 405
  - Colour Discs, Newton’s .... 392 Coloured Wools, Set of ... 405
  - Combination Pliers...................49
  - Combinations of Magnets . . .175
  - Combined Ammeter and Voltmeter. 237 Combined Barograph and Thermograph ...................... . . 105
- p.520 - vue 539/555
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Combined Inclinometer and Sighting
  - Rule..........................170
  - Combined Inclinometer and Compass 170 Combined Screw and Worm Wheel
  - Jack..........................128
  - Combined Volt and Ammeters,
  - Watch Type....................240
  - Communicating Vessels, Glass . . 25
  - Commutators.....................277-278
  - Comparison Gas Burners . . . 374
  - Comparison Magnetometer . . .179
  - Compass Box, Azimuth . . . .178
  - Compass Box for use with Galvanometers ............................229
  - Compass Cards .... 233-235
  - Compass and Inclinometer combined 170 Compass, Trough, Boxwood . . .172
  - Compasses, Beam .....................53
  - Compasses, Blackboard . . . 53, 56
  - Compasses, Magnetic.................177
  - Compasses, Pencil....................53
  - Compasses, Prismatic................170
  - Compasses, Trough...................170
  - Compensated Pendulum, Harrison’s 440 Complementary Prisms .... 388 Compound Bars of Brass and Iron for Expansion of Solids Experiments ..............................438
  - Compound Cylinder of Brass and Wood for showing different Conducting Powers ....................442
  - Compound Horseshoe Magnets . .173
  - Compound Wheels and Axles 114, 127
  - Compression Balances . . 138-139
  - Compression of Springs, Apparatus. 133 Concave Mirror with strip of silver
  - scraped off......................373
  - Concave Mirrors.....................375
  - Concave Reflectors..................363
  - Concussion of Air Apparatus . .341
  - Condenser Clamps.....................38
  - Condenser for use with Induction
  - Coils ...........................281
  - Condenser Panels (for Wireless) . . 292
  - Condensers for Statical Electricity
  - Experiments.............194-195
  - Condensers (for Wireless Sets) 292-293
  - Condensers, Paper...................255
  - Condensers, Sliding.................194
  - Condensing Syringes.................162
  - Conducting Powers of Solids, Apparatus for showing . . . 441-442
  - Conduction and Convection Apparatus ..............................441
  - Conduction of Metals, Apparatus for
  - showing..........................442
  - Conductivity, Apparatus for Experiments in.......................443-444
  - Conductivity of Water, Apparatus to
  - demonstrate ..................
  - Conductors, Wood covered with Tin
  - foil.......................
  - Cone and Inclined Plane
  - Cones, Boxwood................
  - Cones, Brass..................
  - Cones for producing Circular Spec
  - trum.......................
  - Cones in 4 Sections showing Circle Ellipse, etc. . . • .
  - Conical Conductors..................191
  - Conical Tins, Glazebrooks . . .455
  - Connectors for Coupling .... 297 Connectors for Flexible Wire . . 265
  - Connectors, Various.................209
  - Constant Volume Air Thermometer. 467 Contact Breakers for Induction Coils 281
  - Contact or Press Keys Contrast of Colours Apparatus . Control Switchboards .... Convection in Air, Glazebrook’s Apparatus to show Convection of Heat, Apparatus . Converging System of Lenses Convex Mirrors................
  - 445
  - 191
  - 153
  - 18
  - 18
  - 389
  - 278
  - 405
  - 306
  - 445
  - 445
  - 402
  - 375
  - PAGE
  - Convex Mirrors with strip of Silver
  - scraped off......................373
  - Copper Balls, for Heat Experiments 479
  - Copper Calorimeters . . . 468-469
  - Copper Tube and Pair of Oak Boards for Heat Experiments .... 477 Copper Vessels for use as Steam .
  - Boilers..........................475
  - Copper Voltameters . . . 303-304
  - Copper and Zinc Plates for making
  - simple Cells.....................203
  - Copper Bell Wire .............213
  - Copper Cubes.........................16
  - Copper Cylinders.....................21
  - Copper Sulphate......................46
  - Copper Tube and Oak Boards for Friction Experiments . . . .154
  - Copper Tubing, Flexible .... 32
  - Copper Wire, Bare, Enamelled, Cotton covered or Silk covered . 211 Copper Wires for Conductivity Experiments . 442
  - Cord, Flexible Bell.................213
  - Cord, Rubber........................133
  - Cork and Lead Cubes . . . .22
  - Cork Cubes...........................16
  - Corks and Shives, Ordinary Bark . 34
  - Corks, Rubber, Squat and Tall pattern ......................... 42-45
  - Coulomb’s Magnetic Magazines . .175
  - Coulomb’s Torsion Balance . . . 196
  - Cover for Cutting off Light from Valve
  - Tubes............................305
  - Cover Glass and Spot Binder for
  - Lantern Slides...................434
  - Covers, Perforated, for Resistances . 263 Cradles for supporting Tin Tubes . 479
  - Crane, Jib..................114, 129
  - Critical Temperature Apparatus . 463 Critical Temperature for Sulphur-
  - Dioxide Apparatus................460
  - Croolce’s Radiometers .... 480 Crooke’s Tubes .... 322-324
  - Cross Spirit Levels . . . 159, 170
  - Cross’s Vacuum Scale .... 328
  - Crova’s Discs.......................341
  - Cryophorus, Sulphuric Acid, Wein-
  - hold’s...........................458
  - Cryophorus, Wollaston’s .... 458 Crystal and Valve Receiving Sets . 288
  - Crystal Detectors...................298
  - Crystal Receiving Sets . . 286-288
  - Crystal Stage for Polariscope . . 402
  - Crystals for Detectors .... 298 Crystals, Plates of, for showing Absorption phenomenon .... 399 Crystals,' Plates of, for use with
  - Polariscope......................403
  - Cubes, Cork and Lead .... 22
  - Cubes, Glass, for Refraction Experiments ...........................379
  - Cubes, Hollow........................17
  - Cubes, Metal, Cork, Glass, Marble
  - etc............................16-17
  - Cubes of Iceland Spar . . . .391
  - Cubes, Wood.......................14-15
  - Cubical Expansion of a Solid, Weight Thermometer to determine 447
  - Cubical Organ Pipes.................353
  - Cubical Tin Canisters .... 478 Cup, Aluminium, for Determination
  - of Dew Point.....................453
  - Curved Pipettes.....................451
  - Cuthbertson’s Plate Electrical
  - Machines.........................197
  - Cutting Nippers......................50
  - Cutting Pliers.......................50
  - Cylinder and Bucket for Archimedes’
  - Principle ........................22
  - Cylinders, Measuring . . . . 28, 30
  - Cylinders, Metal.....................21
  - Cylinders, Spouting.................160
  - Cylinders, Wood and Brass ... 20
  - Cylinder, Wire Gauze . . . .195
  - PAGE
  - Cylinders, Cardboard, for showing
  - Stationary Waves....................340
  - Cylinders for Conductivity Experiments ..............................442
  - Cylinders, Metal, for Specific Heat
  - Experiments.........................469
  - Cylindrical Bar Magnets . . . .175
  - Cylindrical Cardboard and Zinc Resonators ...........................351
  - Cylindrical Conductors . . . .191
  - Cylindrical Lenses . . . 381-382
  - Cylindrical Mirrors....................375
  - Cylindrical Vacuum Vessels . . 462
  - Cylindrical Vessel to show Pressure of Atmosphere.......................166
  - D’ARSONVAL Galvanometers ....................... 223-224
  - Damp Detectors.....................104
  - Daniell’s Cells............200, 201
  - Daniell’s Cells, Zincs for . ... 204
  - Daniell’s Hygrometers . . 103, 454
  - Danish Steelyards . . . . . .143
  - Dark Chamber for examining Phosphorescent Substances .... 320
  - Dark Room Lamps....................417
  - “ Dark Space ” Tube .... 323
  - Davy Safety Lamps..................167
  - Dead-beat Moving-coil Ammeters
  - and Voltmeters .................238
  - Dead-beat Moving-Coil Pointer Galvanometer .......................238
  - Deal Drawing Boards .... 54
  - Decomposition of Water Apparatus .............................304
  - Deflection of Beams and Springs, Testing Apparatus for . . 131-132
  - Deflection Magnetometers . . .179
  - Deflection Tubes .................329
  - Delachanal and Mermet’s Spark Tube 400 De La Rive’s Apparatus . 185, 322
  - Delezenne’s Circle.................184
  - Demonstration Lanterns . 421-423
  - Demonstration Models . . . .272
  - Demonstration of Hertz Waves Apparatus .........................300
  - Demonstration Rules..............3
  - Demonstration Set of Instruments for Frictional Electricity Experiments . ................
  - Demonstration Set of Thermometers
  - and Screen....................
  - Demonstration Spherometers Demonstration of Transverse Waves
  - Apparatus....................338
  - Demonstration Wheel Barometer . 97
  - Density of Atmospheric Air, Vessel
  - for determining..............453
  - Density of Water Apparatus . . 449
  - Depth Gauges.....................7
  - Detectors, Crystal..............298
  - Determination of Freezing Point
  - Apparatus....................449
  - Determination of “ G ” Apparatus
  - 114, 119
  - Dew Point Determination, Reg-nault’s Hygrometer for Dew Point Determination, Aluminium Cup for Dewar’s Vacuum Vessels Developing Dishes Dial Resistance Boxes Dialyser, Graham’s Dialysis Papers Dia-magnetic Apparatus “ Diamond ” Leyden Jars Differential Air Thermometers . .481
  - Differential Pulley Blocks . . .125
  - Differential Thermometer, Beckmann’s ..........................484
  - Diffraction Gratings...............400
  - Digester, Papin’s..................455
  - Dilatometers.......................447
  - 198
  - 94
  - 384
  - 453
  - 453 462 418 249 457 457 181-182 188
  - 30
- p.521 - vue 540/555
- - 522 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - 103, 454
  - . 178
  - 30,
  - ter.
  - Dine’s Hygrometers .
  - Dip Circle.................
  - Dip Needles................
  - “ Direct Reading ” Barometers Direct Vision Spectroscopes .
  - Discharge Key, Morse Discharging Pillars and Points
  - Discharges.................
  - Disc Records for Gramophones Discs, Sturgeon’s ....
  - Discs, Bunsen’s Grease Spot.
  - Discs, Cheshire’s ....
  - Discs, Crova’s.............
  - Discs of Soft Sheet Iron Discs, Newton’s Colour .
  - Discs, Vulcanite Discs, Whirling Table Discs, Wooden Dishes, Photographic Displacement Vessels Distribution of Electricity App
  - tus...................
  - Divers, Cartesian .
  - Divided Megohm .
  - Dividers, Brass.
  - Dodecahedron, Hardwood Dolezalek’s Quadrant Electrome Doppler’s Tuning Fork .
  - Dorman’s Wave Slide.
  - Double-barrelled Air Pumps Double Concave Lenses .
  - Double Convex Lenses Double Cone and Inclined Plane Double Connectors ....
  - Double Pole double throw Switches 298 Double Type Variable Condensers . 292 Double Pendulum, Airy’s Double Refracting Prism Double-Walled Vacuum Vessels
  - Dove’s Sirens..............
  - Dove’s Improved Hydrometer Draining Racks ....
  - Drawing Boards, Deal Drawing Instruments .
  - Drawing Pins...............
  - Drenteln’s Apparatus for demonstrating interference of Sound
  - Waves.................
  - Drills...................
  - Drum Armature, Model of Dry Cells, “ Nivoc ” .
  - Dubilier Condensers .
  - Du Bois Magnet .
  - Du Bois Raymond Keys.
  - Du Bois Raymond Coils .
  - Dumas’ Vapour Density Apparatus Dumas’ Vapour Density Bulbs Dust Tube Apparatus, Kundt’s
  - Dutch Metal................
  - Dutrochet’s Endosmometer . Dynamometer and Rope Brake Dynamometers, Spring
  - Dynamos....................
  - Dynamos for Charging Accumulators, or for House Lighting, etc. . Dynamos, Driving Gear for .
  - 178
  - 97
  - 392
  - 280
  - 3°5
  - 188
  - 365
  - 184
  - 374
  - 34i
  - 34i
  - 176
  - 392
  - 187
  - 359
  - 21 418
  - 22
  - 189
  - 160
  - 251
  - 53
  - 20
  - 197
  - 347
  - 340
  - 161 380 38° 153
  - 209
  - 348 385 463 360 . 24
  - . 419
  - • 54 53-55
  - • 55
  - 362
  - 48
  - 272
  - 221
  - 293
  - 181
  - 278
  - 280
  - 452
  - 452
  - 356
  - 46
  - 457
  - 146
  - 155
  - 270
  - 271
  - 270
  - EARTH Clips (for Wireless) . . 299
  - Earth Inductor . . . .184
  - Earth Thermometer.................102
  - Ear, Models of....................364
  - Ear, Trumpets.....................365
  - Easels for Blackboards .... 56
  - Ebert’s Tubes.....................326
  - Ebonite Rod....................205
  - Ebonite Sheet..................205
  - Ebony Bar Parallel Rules ... 54
  - Ebony Cones...........................18
  - Ebony Cubes...........................14
  - Ebony Cylinders.......................20
  - Ebony Spheres.........................17
  - Edser’s Thermal Conductivities of
  - Metal Rods Apparatus . . . 444
  - PAGE
  - Efficiency of Screw Apparatus . .128
  - Eisenlohr’s Wave Machine . . . 340
  - Elasticity of Steam, Apparatus for
  - Measuring........................45°
  - Electric Amalgam . . . . * .187
  - Electric Arc Lamps . . . 266-267
  - Electric Arc Lamps ... 429-430
  - Electric Bells......................273
  - Electric Bell Wire..................213
  - Electric Buzzer ....................273
  - Electric Chimes, Set of . . . . 192
  - Electric Enlarger...................4x9
  - Electric Generators.................271
  - Electric Lamps and Fittings . . 265
  - Electric Motors for Statical Electricity Experiments....................193
  - Electric Motors and Regulators 268-269 Electric Wave Apparatus . . . 3QI
  - Electric Whirls ....................193
  - Electrical Cannon...................190
  - Electrical Circus...................193
  - Electrical Machines . . . 197-198
  - Electrical Pistol...................19°
  - Electrical Radiometers, Puluy’s . 325 Electrical Units, Table of . . -5X7
  - Electrical Wires on Reels . 210-213
  - Electrolytic Interrupters .... 306 Electrolytical Estimation of Copper, Classen’s Apparatus for . . . 304
  - Electro Magnet for Vacuum Tubes . 323 Electro Magnets .... 180-182
  - Electrometer, Dolezalek’s. . . .197
  - Electrometer, Henley’s . . • • 194
  - Electrometer, Pith Ball . . . .194
  - Electrometer, Stewart & Gees . .196
  - Electrophorus.......................187
  - Electro-Plating Apparatus . . . 274
  - Electroscopes...................I95-I9b
  - Elements, Table of..................5T^
  - Ellipsoid of Revolution, Hardwood . 20
  - Emery Cloth..........................46
  - Empty Thermometer Tubes . . . 446
  - Enamelled Steel Beakers ... 3°
  - Endosmometer, Dutrochet’s . . -457
  - Energy of Fly-Wheels Apparatus . 146
  - Engineers’ Rules......................4
  - English Weights and Measures . • 5I5
  - Enlarger, Electric..................4I9
  - Enlargers for Artificial Light . .419
  - Eolipile.......................... 477
  - Equal-weight Wire Figures, Plateau’s 161 Equilateral Prism mounted on Foot. 388
  - Equilateral Prisms..................386
  - Equilibrium Apparatus . . . .153
  - Ether Apparatus, Weinhold’s . . 450
  - Ether Thermoscope...................478
  - Eureka Wire, Bare and Double Silk
  - covered..........................212
  - Evaporation Gauge...................108
  - Exhausting Syringe..................162
  - “ Exide ” Batteries ..... 218 Expansion of Gases Apparatus, on
  - Stand............................158
  - Experimental Fly-Wheels . . .146
  - Extension and Compression of Springs
  - Apparatus........................133
  - Expansion of Gases, Apparatus . . 467
  - Expansion of Air and Gas, Apparatus 464 Expansion of Water, Bunsen’s Apparatus for Determining .... 458 Expansion of Liquids Apparatus 336-447 Expansion of Solids Apparatus 437-441 Eyepieces for Telescopes . . 409-410
  - Eye, Models of.................... 405
  - FACTORY Thermometers. . .485
  - Faber’s Precision Calculating
  - Rules..........................58-59
  - Face Mask...........................309
  - Faraday’s Apparatus for Dia-mag-
  - netic Experiments................182
  - Faraday’s Apparatus for Induced Currents............................184
  - PAGE
  - Faraday’s Butterfly Net . . . .189
  - Faraday’s Ice Pails.................189
  - Faraday’s Law, Apparatus for proving 182 Ferguson’s Pyrometers .... 437
  - Field Cameras ......................415
  - Field Glasses.......................412
  - Field Telescopes....................411
  - Figures, Cartesian..................160
  - Figures, Pith.......................19°
  - Filament Resistances (for Wireless
  - Sets)............................291
  - File and Rasp........................33
  - File Cleaner or Wire Brush ... 47
  - Files, Assortment of six, on card . 47
  - Files, Triangular, Flat and Rat-tail 33
  - Filings, Iron.......................176
  - Filings, Steel......................X76
  - Fire Engine Models..................157
  - Fire Syringe, Pneumatic . . . -477
  - Fitzroy Barometers...................98
  - Fixed Condensers, Dubilier . . . 293
  - Flame Experiments, Wire Gauze, etc.
  - for..............................167
  - Flannel Rubbers.....................186
  - Flask and Tube for Determining Boiling Point of Thermometer . 455 Flask for Examining Absorption
  - Bands in Liquids.................399
  - Flask for Liquefying Gases . . . 463
  - Flasks, Glass........................29
  - Flasks, Measuring . . •. . . . 28
  - Flasks to show that Air has Weight 164
  - Flat File and Rasp...................33
  - Flat Files...........................33
  - Flat Spirals for illustrating Induced
  - Currents.........................I82
  - Fletcher’s Trolley Apparatus . .122
  - Fleuss’ Patent Geryk Vacuum Pumps
  - 162-163
  - Flexible Bell Cord..................213
  - Flexible Metallic Steel Tubing . . 32
  - Flexible Wire, Connectors for . . 265
  - Floating Batteries..................183
  - Float, Cold Water...................449
  - Floats, Cold Water..................160
  - Flow of Water Apparatus . . . 156
  - Fluid Friction Apparatus . . .148
  - Fluid Pressure Apparatus . . .158
  - Fluorescent Liquids in Sets . . . 320
  - Fluorescent Screens (Barium Platino
  - Cyanide)........................310
  - Fluorescent Screens (White Salt) . 310 Fluorescent Vacuum Tubes . 315-3*6
  - Fluoroscopes........................3IQ
  - Fly-Wheels, Experimental . . .146
  - Focus Tubes, X-Ray..................3°7
  - Focuslite Outfits for Lanterns . . 427
  - Focuslite Slide Lantern .... 424
  - Folding Lenses......................4°8
  - Folding Plate and Film Camera . 414 Foot Bellows, for use with Sirens . 360
  - Foot Bellows.........................32
  - Foot Bellows, Rubber Circles for . 32
  - Foot Bellows, String Net for . . 32
  - Foot Pump..........................161
  - Forbes’ Thermal Conductivity Apparatus ...............................443
  - Force Pump Models...................157
  - Forks, Tuning . . . . 344_347
  - Formation of Vapour in a Vacuum, Apparatus to show . . • • 451
  - Fortin’s Standard Barometers . . 96
  - Foucault’s Pendulum.................154
  - Fountain of Fire Apparatus . . 379
  - Fountains of Glass, Hero’s . . .158
  - Fountain in Vacuo Apparatus . .165
  - Fox-tail Rubbers....................187
  - Framed Set Squares...................55
  - Franklin’s Fulminating Panes . .192
  - Freezing Apparatus..................463
  - Frick’s Parallelogram of Forces
  - Apparatus........................X5°
  - Friction Apparatus . . 117-118, 148
  - Frictional Electricity Apparatus 186-187
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Frictional Electricity Experiments, Demonstration Set . . . .198
  - Friction Tubes..................321
  - Freezing Point Determination Apparatus ..........................449
  - Freezing Point Apparatus, Beckmann’s '......................456_457
  - Freezing Water, Apparatus for . . 458
  - Frequency of Tuning Forks Appar-
  - Fresnel’s Bi-Prism.................389
  - Fresnel’s Bi-Prism.................387
  - Fresnel’s Mirrors..................3^9
  - Fresnel’s Rhombs...................388
  - Fry’s Apparatus for Determining Co-efficient of Linear Expansion . 439 Fry’s Spring Balance Monochores. . 342
  - Fuel Testing, Calorimeters for . .471
  - Fulcrum and Lever..................152
  - Fuller Blocktype Accumulators . .217
  - Fulminating Panes.................192
  - Funnels, Glass....................31
  - Fusible Wire for Cut-outs . . . 213
  - GALILEAN Telescope, Model of 385 Galton’s Whistles .... 363 Galvanometer, Dead-beat, Moving-
  - Coil ...........................238
  - Galvanometer Dials . . . 233-235
  - Galvanometer Lamps and Scales 226-227 Galvanometer Mirrors .... 224
  - Galvanometer Scales................227
  - Galvanometer Shunts . . . .230
  - Galvanometers, Astatic . . . .231
  - Galvanometers Astatic .... 480 Galvanometers, d’Arsonval . 223-224
  - Galvanometers, Lecture . . . . 232
  - Galvanometers, Reflecting . . . 225
  - Galvanometers, Tangent . 228-230
  - Galvanometers......................302
  - Galvanoscopes......................232
  - Gas Burner and Oven for Soldering. 50 Gas Burner with Batswing Jet . . 32
  - Gas Burners for Optical Bench Experiments .........................374
  - Gas Burners for producing Singing
  - Flames..........................35$
  - Gas, Expansion of, Apparatus . . 464
  - Gas Jars....................... . 33
  - Gas Pliers . . . . , ( . . 49
  - Gaugain’s Tangent Galvanometer . 230 Gauges, Calliper ...... 6
  - Gauges, Depth........................7
  - Gauges for Lenses..................383
  - Gauges, Evaporation................108
  - Gauges for Rain . . . 95, 106-107
  - Gauges, Hole and Cylinder ... 7
  - Gauges, Micrometer Screw ... 7
  - Gauges, Syphon for Air Pump Work 164
  - Gauges, Wire.........................7
  - Gauze, Iron Wire....................39
  - Gauze, Iron Wire for Flame Experiments .............................167
  - “ G ” Determination Apparatus 114, 119 Gear Wheels, Trains of . . . .148
  - Gee Resistance Board .... 247 Gehrke & Reichenheim’s Anode Ray
  - Tubes.................... . . . 334
  - Generators and Jets, Acetylene . 432
  - German Tinder......................477
  - Geissler’s Vacuum Tubes. . 311-319
  - Gem Spanner.........................49
  - Generators, Electric...............271
  - Geometric Tripod Stands. ... 34
  - Geometrical Figures, Set of 12 . . 46
  - Geometrical Instruments in Case . 53
  - George’s New Balancing Machine . 155 Geryk Vacuum Pumps . . 162-163
  - Gilding and Plating Apparatus. . 274 Gill’s Chart of the Metric System . 1
  - Gilt Watch Aneroids . . . .104
  - Glaisher’s Rain Gauge .... 107 Glass Ball, Rotating (Electrical Circus) 193
  - PAGE
  - Glass Ball, Rotating for Air Pump
  - Work...........................165
  - Glass Beakers.....................29
  - Glass Beakers, thick, for Cold Solutions, etc..........................3°
  - Glass Boxes.......................39°
  - Glass Breaking Squares . . . .166
  - Glass Bulbs for Specific Gravity of
  - Gases..........................23
  - Glass Bulbs, Weighted .... 447
  - Glass Calorimeters................469
  - Glass Communicating Vessels . . 25
  - Glass Cubes for Refraction Experiments .............................379
  - Glass Cubes.......................16
  - Glass Flask for Liquefying Gases . 463
  - Glass Flasks to show that Air has
  - Weight.........................164
  - Glass Flasks......................29
  - Glass Funnels.....................31
  - Glass Globes for use with Whirling
  - Tables. . . . :.............154
  - Glass “ H ” Tubes for Cadmium Cells 203 Glass Immersion Jars for Hydrometers . 23
  - Glass Jars for Bunsen’s Batteries . 205 Glass Jars for Grove’s Cells . . . 204
  - Glass Jars, Resonance . . . .. 349
  - Glass Jars for Smee’s Cells . . .201
  - Glass Jugs, Graduated . . . .418
  - Glass, Lead.......................309
  - Glass Measures, Conical and Cup
  - form...........................28
  - Glass Measuring Cylinders ... 28
  - Glass Measuring Flasks . . . .28
  - Glass Models of Pumps, Fire Engines, etc.........................157
  - Glass Plates, Black, Optically worked 403 Glass Prisms, Various . . 386-389
  - Glass Receivers for Guinea and
  - Feather Apparatus..............165
  - Glass Receivers for Torricellian Experiments .........................164
  - Glass Reservoirs for Mercury 27, 31, 465
  - Glass Rod.............................40
  - Glass Scales...........................4
  - Glass Slabs for Refraction Experiments .............................379
  - Glass Steam Traps . . . . -473
  - Glass Syphons, for Liquefied Sulphurous Acid, etc..................460
  - Glass Syphons, with Suction Tube
  - and Bulb.......................161
  - Glass Table Tops..................34
  - Glass Three-limbed Tubes ... 25
  - Glass Tube to show Circulation of
  - Water..........................445
  - Glass Tube filled with Filings . .176
  - Glass Tube with five Branches . .159
  - Glass Tubes, for Boyle's Law Apparatus ......................... 465-466
  - Glass Tubes for Frictional Electricity
  - Experiments....................186
  - Glass Tubes, plain, for Boyle’s Law
  - Apparatus......................27
  - Glass U Tubes for Relative Density
  - Experiments....................25
  - Glass Tubing......................40
  - Glass Vessel for Determining the Density of Atmospheric Air . .453
  - Glass Vessels for Displacement Experiments ..........................22
  - Glass Vessel with five Capillary
  - Tubes..........................159
  - Glasses, Coloured, Set of seven . . 392
  - Glasses for showing Newton’s Rings 391
  - Glasses, Reading..................408
  - Glasses, Steel Coloured, to show Absorption ..........................385
  - Glazebrook’s Apparatus, for Experiments on the Eye and Vision . 405 Glazebrook’s Apparatus for Determining Co-efficient of Linear Expansion .............................441
  - PAGE
  - Glazebrook’s Apparatus to show
  - Convection in Air...............445
  - Glazebrook’s Apparatus, for Experiments in Mechanics . . . .123
  - Glazebrook’s Parallelogram of Forces
  - Apparatus.......................150
  - Glazebrook’s Conical Tins . 166, 455
  - Glazebrook’s Density of Water Apparatus .........................449
  - Glazebrook & Shaw’s Apparatus for Demonstrating Law of Magnetic
  - Force...........................179
  - Glazebrook & Shaw’s Calorimeter . 470 Glazebrook’s Thermal Conductivity
  - Apparatus.......................443
  - Globes, Glass, for use with Whirling
  - Tables..........................154
  - Globular Vacuum Vessels . . . 462
  - Gloves, Lead Rubber .... 309
  - Glycerine...........................46
  - Goetze’s Vacuum Tubes .... 337
  - Gold Leaf...........................46
  - Gold Leaf Electroscopes . . 195-196
  - Goldstein’s Tubes .................329
  - Goniometers, Wollaston’s Reflection. 407
  - Goniometers.........................51
  - Governors for use with Whirling
  - Tables..........................154
  - Graduated Glass Jugs . . . .418
  - Graduated Measuring Cylinders . 28
  - Graduated Sliding Callipers ... 6
  - Graduated Tubes for Archimedes’
  - Principle .......................22
  - Graham’s. Dialyser.................457
  - Gramme’s Ring, Model of 272
  - Gramme’s Ring Armature, Model of 272
  - Gramophones........................365
  - Gramophone Records.................365
  - Grass Minimum Thermometer . . 102
  - Gratings, Transmission Diffraction . 400 Gravesande’s Ball and Ring . . 438
  - Gravesande’s Parallelogram of Forces
  - Apparatus.......................150
  - " Gravity ” Type Ammeters and
  - Voltmeters......................236
  - Grease Spot Discs, Bunsen’s. . . 374
  - Grease Spot Photometers, Bunsen’s
  - 366-367
  - Grimlich’s Mercury Arc Lamps . . 400
  - Grinder, Bench.....................48
  - Grooved Planes, V-shaped . . .113
  - Ground Glass Screens for Optical
  - Bench Experiments . . -373-374
  - Groves’ Batteries .................201
  - Groves’ Batteries, Terminals for. . 207
  - Groves’ Cells......................201
  - Groves’ Cells, Glass Jars for . . 204
  - Groves’ Cells, Zincs for .... 204 Gud Leaks (for Wireless) . . . 293
  - Guinea and Feather Apparatus . .165
  - Gunpowder Cup......................189
  - Gunthur’s Apparatus for Determining the Latent Heat of Steam . 474 Gunther’s Apparatus for Determining Co-efficient of Linear Expansion 440 Gutta-Percha Cubes . . . 16
  - Gutta-Percha Rods..................186
  - Gyroscopes ........................152
  - H AMMER Type Contact Breakers 281 Hammerl’s Apparatus for producing Currents...................272
  - Hammers............................48
  - Hammers for striking Tuning Forks. 349
  - Hammers, Water....................166
  - Hand-Driving Gear.................270
  - Handles, Metal, for Fluorescent
  - Screens.........................310
  - Hand Saws..........................51
  - Hand Vices.........................51
  - Handwheel for Centrifugal Force
  - Machine.........................155
  - Hanging Carrier for Slotted Weights 143
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Hard and Soft Spheres . . . . 17
  - Hardwood Blocks................19-20
  - Hardwood Cylinders............20
  - Hardwood Cubes................15
  - Hardwood Spheres..............17
  - Hare’s Apparatus for Determination of Relative Densities of Liquids 24-25 Harmonicons, Chemical .... 357 Harrison’s Compensated Pendulum 440
  - Head of Hair.......................190
  - Head Telephone Receivers for Wireless Sets................. . . 290
  - Heat Experiments, Various Apparatus for..........................477
  - Heaters for Steam..................475
  - Heliostats.........................406
  - Helmholtz’ Siren...................360
  - Helmholtz’ Spherical Resonators . 351 Helmholtz’ Synthesis of Sound Apparatus ...........................347
  - Helmholtz’ Vibration Microscope . 347 Henley’s Quadrant Electrometers . 194 Henley’s Universal Discharger . .188
  - Hero’s Fountains of Glass . . .158
  - Hero’s Steam Engine .... 477 Hero’s Steam Engine . . . .166
  - Hertz’ Tubes....................326
  - Hertz’ Waves Demonstration Apparatus .............................300
  - Hibbert’s d’Arsonval Galvanometer 224 Hibbert’s Magnetic Balance . . -175
  - Hibbert’s Potentiometer .... 256 Hick’s Ballistic Balance . . . .123
  - High Frequency Transformer . . 291
  - High Frequency Transformer Bobbin...............................291
  - High Temperature Thermometers . 483 High Tension Batteries . . . . 222
  - Hittorf’s Tube.....................326
  - Hofmann’s Vapour Density Apparatus .............................452
  - Hog’s Bristles...............46, 346
  - Holders, Brass, for Luminous Panes 192
  - Holders for Candles.............373
  - Holders for Chalk..............56
  - Holders for Lamps...............265
  - Holders for Lenses . . . 374, 383
  - Holders for Vacuum Tubes . . . 193
  - Holders for Valve Tubes . . . 305
  - Holder, Tuning Inductance . . . 295
  - Holders, Valve.....................295
  - Hole and Cylinder Gauges ... 7
  - Hollow Brass Prisms.............19
  - Hollow Cubic Decimetre Cubes . . 17
  - Hollow Glass Prisms............390
  - Hollow Lenses..................382
  - Hollow Prisms on Brass Stand with
  - Metal Basin......................389
  - Hollow Prism for Spectroscope . . 395
  - Hollow Tin Cubes...............17
  - Holmgren’s Set of Coloured Wools . 405 Hope’s Apparatus to show Temperature of Water .... 447, 449
  - Hopkins’ Forked Tubes for Demonstrating the Interference of Sound
  - Waves............................362
  - Holtz’ Vacuum Tubes .... 334 Honeycomb Type Inductance Coil . 294
  - Horizontal Adapters................295
  - Horizontal Galvanometer . . .231
  - Horseshoe Magnets..................173
  - Hot Water Circulation Model . . 445
  - Howard's Rain Gauge .... 107
  - Humming Top Sirens ................359
  - “ H ” Tubes for Cadmium Cells . . 203
  - Hydraulic Ram Model . . . .158
  - Hydraulic Press for Compressing
  - Moulds...........................460
  - Hydrogen Singing Flame Apparatus 358 Hydrometer Immersion Jars. . . 23
  - Hydrometer Trial Jars . . . 23
  - Hydrometers, Accumulator . . .218
  - Hydrometers, Nicholson’s . . 23-24
  - Hydrometers, Simple form ... 23
  - PAGE
  - Hydrometers, Specific Gravity . . 23
  - Hydrostatic Presses..............156
  - Hygrometers, Various . . . .103 Hygrometers, Various . . 453, 454
  - ICE Calorimeter, Bunsen’s . . 458
  - Ice Calorimeter, Lavoisier’s and
  - Laplace’s......................469
  - Iceland Spar......................391
  - Iceland Spar Cubes................391
  - Iceland Spar and Glass Prism . . 385
  - Iceland Spar Rhombs...............391
  - Ice Machine, Carry’s, Apparatus for Demonstrating Principle of . . 458
  - Ice Pails, Faraday’s..............189
  - Ice, Properties of, Apparatus for
  - Demonstrating..................460
  - Icosahedron, Hardwood .... 20
  - Ignition Batteries................214
  - Uluminants for Lanterns, Methylated
  - Spirit and Paraffin............431
  - Uluminants for Lanterns 427-428, 431 Immersion Jars for Hydrometers . 23
  - Incandescent Lamps with sliding Pillar and Tripod Foot . . . 373
  - Incandescent Lamps................265
  - Inclined Plane and Double Cone . 153 Inclined Plane and Friction Apparatus ................................117
  - Inclined Plane Apparatus . . .111
  - Inclined Planes .... 116-117
  - Inclinometer and Compass Combined 170 Inclinometer and Sighting Rule
  - Combined.......................170
  - Inclinometers...............113, 170
  - Incubator Thermometers . . . 485
  - India-rubber Bands................46
  - India-rubber Bladders.............164
  - India-rubber Bungs, Squat, Tall and Shallow Pattern . . . . 43-45
  - India-rubber Corks, Squat and Tall
  - Pattern...................42-45
  - India-rubber Prepared Tape . .205
  - India-rubber Sheets for Insulating
  - Purposes .........................192
  - India-rubber Solution .... 205 India-rubber Tubing for Wave Motions ...............................340
  - India-rubber Tubing...............41
  - Indicators, Speed .....................7
  - Indigo Prisms........................385
  - Induced Currents Apparatus 182-184 Inductance Holder, Tuning . . . 295
  - Inductances or Tuning Coils (for Wireless Sets) .... 294-295
  - Induction Apparatus to Demonstrate that the + and — are equal in
  - quantity..........................191
  - Induction Coil for use with Microphones .............................282
  - Induction Coil, Weinhold's . . .183
  - Induction Coils, Condensers for . 281 Induction Coils, Contact Breakers for 281 Induction Coils, Various . . 280-281
  - Inductively Coupled Tuning Inductance ..............................294
  - Inertia Apparatus....................130
  - Ingenhousz’s Apparatus for Conductivity Experiments..................442
  - Injector Lime Lights.................431
  - Ink for Lantern Slides .... 434 Instrument Wires .... 210-213
  - Insulated Stands for Spectrum Analysis Tubes........................337
  - Insulating Stands ...................192
  - Insulating Stools....................192
  - Insulators, Aerial...................299
  - Intensifying Screens.................310
  - Interference Wave Slide, Woodward’s 340 Interrupters, Electrolytic . . . 306
  - Intervalve Transformer .... 291
  - Iron Bar Weights.....................141
  - Iron Brackets for Pulley Experiments 126
  - PAGE
  - Iron Clamps for supporting Kundt’s
  - Tubes, etc.....................356
  - Iron and Copper Bar to show different Conducting Power . . . . . 442
  - Iron and Copper Wire to show difference in Conducting Power . . 442
  - Iron Cradles for supporting Tin Tubes 479
  - Iron Cubes........................16
  - Iron Cylinders....................21
  - Iron Discs........................176
  - Iron Filings......................176
  - Iron Kilo. Weights................343
  - Iron Mercury Vessels..............31
  - Iron Retort Stands................37
  - Iron Ring for Magnetism Experiments 182
  - Iron Ring Weights ....................141
  - Iron Sliders for Sliding Friction
  - Apparatus......................118
  - Iron Table Tops...................34
  - Iron U. Tubes . . . . . . .180
  - Iron Weights ................... 140^-141
  - Iron Wire Gauze...................39
  - Iron Wire Gauze for Flame j Experiments .............................167
  - Iron Vices for holding Glass Tubes,
  - etc............................356
  - Iron Wires for Conductivity Experiments .............................442
  - Irregular-shaped Figures . . . .114
  - Isothermals of Carbon Dioxide, Apparatus for Determining . . . 463
  - JAMIESON’S Sensitive Paper for
  - Experiments in Conduction, etc. 444 Japanese Fibre Mercury Trays . . 31
  - Japanned Tin Measures .... 28
  - Jars, Bell..........................30
  - Jars, Gas...........................33
  - Jars, Glass, for Resonance Experiments ...........................349
  - Jars, Glass, for Bunsen’s Batteries . 205 Jars, Glass, for Groves’ Cells . . 204
  - Jars, Glass, for Smee’s Cells. . . 201
  - Jars, Immersion, for Hydrometers . 23
  - Jars, Leyden, Various .... 188 Jars, Trial, for Hydrometers . . 23
  - Jet, Auto-Magnetic.................306
  - Jets, Acetylene....................432
  - Jib Cranes................114, 129
  - Jolly’s Air-Bulb Tubes .... 466
  - Jolly’s Air-Bulb Tubes..............26
  - Jolly’s Paraffin Wax Photometers . 367 Joly’s Specific Gravity Balances . 25
  - Joly’s Steam Calorimeter. . . . 470
  - Joule’s Calorimeter................303
  - Jugs, Graduated Glass . . . .418
  - Jumping Spiral, Roget’s . . . .185
  - Kaleidoscopes .... 407
  - Kaleidophone, Melde’s Universal ........................348
  - Kater’s Reversible Pendulums . .149
  - Kemp’s Discharge Key . . . .279
  - Kilo Weights, Iron, for Monochords . 343
  - Kilo Weights..............140-141
  - Kinnersley’s Thermometer . . .189
  - Knife-Edges (Iron Brackets, etc.) . 131
  - Knife Switch......................298
  - Knitting Needles, mounted on Metal
  - Foot ..........................373
  - Knitting Needles............46, 176
  - Koenig’s Graduated Universal Resonators .......................351
  - Koenig’s Manometric Flame Apparatus ...........................354
  - Koenig’s Organ Pipe .... 354 Koenig’s Sensitive Flame Burner . 358 Kohlrausch’s Universal Bridge . . 256
  - Kundt’s Apparatus for Determining the Velocity of Sound .... 356 Kundt’s Dust Tube Apparatus . . 356
  - Kundt’s Tube for Demonstrating Interference of Sound Waves . . 3.62
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  - 373 400
  - 325, 327
  - PAGE
  - LABORATORY Gramophones . 365 Laboratory Note-Books and
  - Squared Paper.................60
  - Laboratory Potentiometer . . . 254
  - Laboratory Stands................39
  - Laboratory Tools . . . . . 47-51
  - Lamp Holders.....................265
  - Lamp for Lanterns, Methylated
  - Spirit........................431
  - Lamp Outfits for Lanterns . . . 428
  - Lamp Resistance.....................251
  - Lamp Resistance, Woodhouse . . 250
  - Lamp, Tesla.........................327
  - Lamps, Arc.................429-430
  - Lamps, Dark Room....................417
  - Lamps and Scales for Galvanometers
  - 226-227
  - Lamps, Davy’s.......................167
  - Lamps, Electric Arc . . . 266-267
  - Lamps (Electric) and Fittings . . 265
  - Lamps, Incandescent, with Sliding Pillar and Tripod Foot Lamps, Mercury Vapour .
  - Lamps, Phosphorescent .
  - Lamps, Spirit ................" ^32
  - Land Chains.........................172
  - Landsberger’s Apparatus for Determination of Molecular Weights . 457 Langley’s Bolometer . . . 303, 481
  - Lanterns, Demonstration . 421-423
  - Lantern Slide Binding Outfits . . 434
  - Lantern Slide Boxes .
  - Lantern Slide Carriers Lantern Slide, Collision Ball.
  - Lantern Slide Masks .
  - Lantern Slide Making Apparatus Lantern Slide Materials .
  - Lantern Slide Printing Frames Lantern Slide Painting Outfits Lantern Slides showing Diagram of
  - Solar Spectrum .............399
  - Lantern Slides, " Wireless Telegraphy ”...........................299
  - Lantern Slides.............488-513
  - Lanterns, Focuslite Slide . . . 424
  - Lanterns, Outfits for .... 427
  - Lanterns, Projection................420
  - Larynx, Models of...................364
  - Latent and Specific Heat, Apparatus f°r . . . . . . . 473-474
  - Latent Heat of Steam, Apparatus for
  - 473-474
  - Latent Heat of Fusion and Vaporisation Apparatus . . . 468-470
  - • 435
  - • 435
  - • 340
  - • 434
  - • 433 434-435
  - 434 434
  - 132
  - 136
  - 132
  - 132
  - 255
  - 469
  - H3
  - Lathe Bed Rigidity Apparatus Lathe Bed Testing Apparatus
  - Laths, Metal......................
  - Laths, Wooden..................21,
  - Latimer-Clarke’s Potentiometer . Lavoiser’s and Laplace’s Ice Calorimeter ............................
  - Law of Moments Apparatus .
  - Law of Moments of Forces Apparatus n Law of Work, Apparatus for proving 14' Lead Balls for making Simple Pendulums ..................
  - Lead Cubes ....
  - Lead Cylinders
  - Lead Glass...............
  - Lead Glass Spectacles Lead Rubber Aprons .
  - Lead Rubber Gloves .
  - Lead Rubber Sheet
  - Lead Sheet...............
  - Lead Sheet for X-Ray Work
  - Lead Shot ...............
  - Leaks, Grid ....
  - Leaning Towers ...
  - Lecture Apparatus to show Rotation of a Current
  - Lecturers’ Lenses, in sets Leclanche Cells.
  - Leclanche Cells, Zincs for Lecturers’ Chalks .
  - PAGE
  - Lecture Galvanometers .... 232 Lees and Chorlton’s Conductivity
  - Apparatus......................444
  - Lees’ Photometer..................367
  - Lehfeldt’s Vapour Pressure Apparatus ..............................452
  - Leidenfrost’s Apparatus for showing the Spheroidal State .... 460 Lenard’s Tubes for Experiments on
  - Cathode Rays...................333
  - Lens Holders...............374, 383
  - Lens Measures . . . . . . . 383
  - Lens, Sondhauss...................359
  - Lenses, Cylindrical, and Sphero-
  - Cylindrical ............... 381-382
  - Lenses, Double Convex and Double
  - Concave........................380
  - Lenses, Folding...................408
  - Lenses, Highly Convergent for Polari-
  - scope...................401, 402
  - Lenses, Hollow....................382.
  - Lenses, Lecturers’, in sets . . . 382
  - Lenses (Magnifiers)................408
  - Lenses, Plano-Convex and Plano-
  - Concave ........................381
  - Lenses, Prismatic..................381
  - Lenses, Reading....................408
  - Lenses, Spectacle..................380
  - Lenses, Spectacle, Assorted, in Sets . 382
  - Leslie Canisters...................478
  - Leslie’s Differential Air Thermometer 481 Level of Water Apparatus . . .159
  - Levelling Tables...................159
  - Lever Apparatus................110,142
  - Lever and Wedge-shaped Fulcrum
  - 142, 152
  - Lever, Optical.......................9
  - Lever Switches . . . . 282-, 298
  - Levers, Moments, etc., Apparatus for
  - Experiments on..................144
  - Levers, Optical....................383
  - Levers for Suspension . . . .142
  - Lewis Thompson Calorimeter . .471
  - Leyden Jar Batteries . . . .188
  - Leyden Jars........................188
  - Lift Pump Models...................157
  - Lighting Type Cells................219
  - Lightning Arresters................299
  - Lightning House....................190
  - Lime Lights........................431
  - Linear Expansion, Table of . . . 516
  - Linen Measuring Tapes, Wind-up
  - and Spring........................5
  - Linen Provers......................408
  - Liquefaction Apparatus .... 459 Liquefied Sulphureous Acid . . . 460
  - Liquid Oxygen and Liquid Air . . 462
  - Liquid Shunt Resistance .... 335 Lissajou’s Figures Apparatus . . 348
  - Lodestone mounted in Frame . .173
  - Lodestones.........................173
  - Logarithm Paper.....................60
  - Longitudinal Wave Apparatus 338-339
  - Loud Speakers......................296
  - Loud Speaking Receivers . . . 296
  - Low Frequency Amplifiers . . . 297
  - Low-Resistance Mercury Bichromate
  - Battery.........................199
  - Lucy’s Metrangle (Surveying Instrument) .............................171
  - Luminous Paint, Balmain’s . . . 320
  - Luminous Panes.....................190
  - Luminous Tubes.....................192
  - Low Temperature Thermometers 463, 483 Luminous Cascade Apparatus . -379
  - Lummer-Brodhun Photometer . . 367
  - Luminous Bulb, Thompson’s . . 332
  - Lycopodium Powder . . . 356, 361
  - MABOR Limes........................431
  - Mach’s Organ Pipe . . . 354
  - Mach’s Wave Machine .... 339 Machines, Wave, Various . 339-340
  - 173
  - PAGE
  - Magazine Plate Camera .
  - Magdeburg Hemispheres “ Magnavox ” Power Amplifiers.
  - “ Magnavox ” Junior Loud Speaker “ Magnavox ” Senior Loud Speaker Magnet, Du Bois .....
  - Magnet Spools for Braun’s Tubes Magnetic Balance, Hibbert’s Magnetic Force, Glazebrook & Shaw’s Apparatus for Demonstrating Magnetic Magazines, Coulomb’s Magnetic Needles ....
  - Magneto Dynamos...............
  - Magnetometer, Searle's Vibration Magnetometers, various .
  - Magnetoscopes..............
  - Magnets, Bar...............
  - Magnets, Bar, on Stand Magnets, Electro ....
  - Magnets fixed to Glass Slides Magnets, Horseshoe Magnets, Robison’s Ball-ended Magnets, Telephone, Bar Magnifiers for Beckmann Thermo
  - meters......................
  - Magnifiers....................
  - Malleable Iron Rings.............
  - Manganin Wire, Bare and Double Silk
  - covered ....................
  - Manometers....................
  - Manometric Apparatus, Koenig’s Manometric Flame Apparatus . Manometric Flame Mirrors .
  - Marble Chips..................
  - Marble Cubes..................
  - Marcet’s Steam Boiler Marconi Double Head Telephone
  - Receivers...................
  - Marconi Unit System Receiving Ap
  - paratus ....................
  - Marconi Valves for Reception .
  - Marine Glasses................
  - Mariners’ Compass.............
  - Marriotte’s Apparatus for proving
  - Boyle’s Law..................27, 465
  - Mask, Face.......................309
  - Mason’s Wet and Dry Bulb Hygrometers....................... I03, 454
  - Mathematical Instruments in Sets . 52
  - Mathematical Stencil . . . .57
  - Maximum Thermometers ' . . 95, 100
  - Maximum Density of Water Apparatus ............................
  - Maximum Density of Water Apparatus for use with Projection Lantern .........................
  - Maximum Thermometers Maxwell’s Needles for Torsion of Wires Experiments .
  - McFarlan Moore’s Apparatus Measures for Laboratory and Photographic Work.....................
  - Measures, Glass, Conical and Cup Form ....
  - Measures, Japanned tin Measures for Lenses .
  - Measures for Rain Measuring Cylinders .
  - Measuring Flasks .
  - Measuring Tapes . .
  - Mechanical Equivalent of Heat Ap
  - paratus .................
  - Mechanical Powers, Cabinet of Mechanical Powers, Sets of .
  - Mechanics of Fluids Apparatus Mechanics, “ Nivoc ” Interchangeable Apparatus for Experiments in
  - 109-115
  - Megohms, Carbon . . . . . .249
  - Megohm, Divided .................251
  - Melde’s Apparatus for showing Stationary Wayes . . . . . .341
  - Melde’s Universal Kaleidophone . 348 Memoranda, Physical Laboratory 515-517
  - 414 165 297 296 296 181 332 l75
  - 179 175 177 270
  - 174
  - 179- 180
  - 180 -174
  - 175
  - 180- 182 I75 *73 173 276
  - 484 408 37
  - 213 159 354
  - 358
  - 359 46 16
  - 455
  - 290
  - 283 290 412 177
  - 449
  - 449
  - 486
  - 138
  - 328
  - 418
  - 28
  - 28
  - 383
  - 106 28, 30 28 5
  - 476
  - 126
  - 127 156
- p.525 - vue 544/555
- - 526 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Mercurial Barometer...............98
  - Mercury Bichromate Battery . .199
  - Mercury Metal.....................46
  - Mercury Reservoirs, Glass 27, 31, 465 Mercury Shower Apparatus . . .166
  - Mercury Spectral Lamp .... 400
  - Mercury Trays.....................31
  - Mercury Troughs, Porcelain . . .31
  - Mercury Vapour Lamps .... 400
  - Mercury Vessels, Iron.............31
  - Metal Clamp and Screw for Light Experiments . . . . . . . 403
  - Metal Cubes....................16-17
  - Metal Cylinders...................21
  - Metal Cylinders for Conductivity
  - Experiments.....................442
  - Metal Cylinders for Specific Heat
  - Experiments.....................469
  - Metal Handles for Fluorescent
  - Screens.........................310
  - Metal Laths.......................132
  - Metal Lens Holders . . . . . 383
  - Metal Objects, Regular and Irregular
  - shape...........................22
  - Metal Screen and Iris Diaphragm . 374
  - Metal Spheres, Solid..............18
  - Metallic Steel Tubing .... 32
  - Metallic Thermometer, Brequet’s . 439 Metallurgical Chisels . . . . . 47
  - Metallurgical Shears..............50
  - Meteorological Instruments, “ Science
  - School ” Set....................95
  - Methylated Spirit.................46
  - Metrangle, Lucy’s (Surveying Instrument) ..........................171
  - Metre Rules....................2-3, 8
  - Metric Protractors................54
  - Metric System, Charts of ... 1
  - Metric Weights and Measures . -515
  - Metronomes..........................121
  - .Mica Wheel Tube....................324
  - Micrometer Screw Gauges ... 7
  - Microphones.........................282
  - Microscope, Helmholtz Vibration . 347
  - Microscope, Model of................384
  - Microscope, “Nivoc”..................93
  - Microscopes, Vernier . . . . 10-12
  - Milk-glass Scale Thermometers . . 483
  - Mill, Barker’s......................159
  - Milli-Ammeters......................239
  - Milli-Voltmeters....................239
  - Miners’ Lamps.......................167
  - Minimum Thermometers . . 101, 487
  - Mining Apparatus....................167
  - Minotti Cells.......................202
  - Mirror on Brass Stand .... 377 Mirror Glass, Strips of ... 376
  - Mirror Scales for measuring the slope of the Elastic Curve . . . .131
  - Mirrors, Angular....................376
  - Mirrors, Chladni....................361
  - Mirrors, Concave....................375
  - Mirrors, Concave and Convex, with strip of silver scraped off . . . 373
  - Mirrors, Convex.....................375
  - Mirrors, Cylindrical................375
  - Mirrors, Fresnel’s..................289
  - Mirrors and Large Lens, etc. . -377
  - Mirrors for Tuning Forks . . . 346
  - Mirrors, Manometric Flame . . . 359
  - Mirrors, Parallel...................376
  - Mirrors, Plane Glass................376
  - Mirrors for Reflecting Galvanometers 224 Mixed Gases, Voltameter for . . . 304
  - Model Air Thermometer . . . 467
  - Model of an Arch....................132
  - Model of Astronomical Telescope . 385
  - Model Barometer......................98
  - Model Cranes........................129
  - Model of Drum Armature . . . 272
  - Model Dynamos.......................270
  - Model of Galilean Telescope . . 385
  - Model of Gramme Ring .' . . . 272
  - Model of Gramme’s Ring Armature 272
  - PAGE
  - Model of Hydraulic Ram . . .158
  - Model of Microscope..............384
  - Model of Nicol’s Prism .... 388
  - Model of Roman Steelyard . . .143
  - Model of Sheer Legs..............130
  - Model of Siemen’s Armature . . 272
  - Model of Single Needle Telegraph . 279 Model Speaking Trumpet . . . 364
  - Model Spectroscope...............395
  - Model of Steam Engine . . . .166
  - Model of Terrestrial Telescope . . 384
  - Model Thermometer.................446
  - Model Verniers....................8
  - Models of Bramah’s Press . . . 157
  - Models of Circular Verniers . . 9
  - Models of Ear.....................364
  - Models of Eye.....................405
  - Models and Figures, Set of 16, in
  - box.............................14
  - Models of Fire Engines . . . .157
  - Models of Larynx..................364
  - Models of Pumps...................157
  - Models of Screw and Nut . . 22, 126
  - Models of a Set of Water Wheels . 15
  - Modulus of Rigidity Apparatus . 136 Modulus of Torsion in Rods, Apparatus ...............................153
  - Modulus of Wires Apparatus 134-135 Mohr’s Burette Clips .... 35
  - Mohr’s Burettes...................29
  - Molecular Weights, Apparatus for
  - Determining.....................457
  - " Moment of a Force " Apparatus . 142 Moments Apparatus . . no, 143-144
  - Moments of Forces Apparatus . .111
  - Moments and Levers Apparatus . 142 Money’s Apparatus for Determining Co-efficient of Linear Expansion . 440
  - Monochords....................342, 343
  - Monochord Slotted Weights . . . 343
  - Morse Keys....................278, 298
  - Morse Sounders .... 279, 298
  - Morse Telegraphs, Pair of . . .279
  - Morse Writing Apparatus . . .279
  - Moulds for showing the Regelation
  - of Ice...........................460
  - Mousson’s Apparatus for Demonstrating Properties of Ice . . . 460
  - Motor with Colour Discs . . . 268
  - Motor Parts for Easy Construction . 268 Motor with Vacuum Tube Rotator . 3x9 Motors, Electric .... 268-269
  - Motors, Electric, for Statical Electricity Experiments . . . .193
  - Mounting, Baseboard (X-Ray Apparatus) ............................305
  - Movable Pulley Block . . . .114
  - Movable Joint Clamps .... 38
  - Moving-Coil Ammeters and Voltmeters ...........................238
  - Moving Coil Galvanometers . . 224
  - Moving Coil Pointer Galvanometer 238 Moving Coil Type Ammeters and
  - Voltmeters.......................237
  - “ M.V.T.” Electroscope .... 195 Muller’s Reflection Apparatus . .378
  - Muller’s Trough for the Refraction of Liquids........................378
  - Nail Puller.........................49
  - Needles, Dip.................178
  - Needles, Knitting .... 46, 176 Needles, Knitting, mounted on Metal
  - Foot.............................373
  - Needles, Magnetic..................177
  - Needles (Maxwell’s) for Torsion of
  - Wires Experiment.................138
  - Needles, Sewing . . . . . .176
  - Net, Faraday’s......................189
  - Nets, String, for Foot Bellows . . 32
  - Newton’s Colour Discs .... 392 Newton Rings, Apparatus for showing ...............................391
  - PAGE
  - Nicholson’s Hydrometers . . 23-24
  - Nickel, Bismuth and Nickel Bars, Set
  - of three Bars.....................175
  - Nickel-Chrome Wire...................212
  - Nickel Silver Wire (German Silver),
  - Bare and Double Silk covered. . 212
  - Nicol’s Prism, Model of ... 388
  - Nicol Prism Polariser . . . .401
  - Nicol’s Prisms ......................388
  - Nicol’s Specific Gravity Tubes . . 23
  - Nippers, Cutting......................50
  - “ Nivoc ” Ammeters and Voltmeters (“ Gravity ” Type) ..... 236 “ Nivoc ” Ammeters and Voltmeters
  - (Moving Coil Type)................237
  - “ Nivoc ” Bunsen Burners 33
  - “Nivoc” Chemistry Stencils . -517
  - “ Nivoc ” Combined Ammeter and
  - Voltmeter • • 23 7
  - ‘ Nivoc ’ ’ Condenser . • 195
  - ‘ Nivoc ' Dial Resistance Box . . 249
  - ‘ Nivoc ’ ’ Dip Circle . . 178
  - ‘ Nivoc ’ ’ Dry Cells . . 221
  - ‘ Nivoc ’' Foot Bellows . • • 32
  - ‘ Nivoc ” Galvanometer Lamp and
  - Scale . . 226
  - “ Nivoc ” High Tension Batteries . 222 " Nivoc ” Interchangeable Apparatus for Experiments in Mechanics 109-115 “ Nivoc ” Laboratory Clamp . . 38
  - “ Nivoc ” Laboratory Note-Books . 60
  - " Nivoc ” Lens Holders .... 374 “ Nivoc ” Lens Holders .... 383
  - “ Nivoc ” Microscope...............93
  - “Nivoc” Optical Bench. . .. . 370
  - “ Nivoc ” Patent Mathematical
  - Stencil..........................57
  - “ Nivoc ” Potentiometer . . . .256
  - "Nivoc” Squared Paper. ... 60
  - “ Nivoc ” Telescope...............410
  - " Nivoc ” Tangent Galvanometers . 228 “Nivoc” Theodolite . . . ... 168
  - “Nivoc” Vacuum Foot Pumps . . 161
  - Nodal Rings, Steel Rod and Disc for
  - showing.........................350
  - Noerrenberg’s Polariscope . 401-402
  - Normal Thermometer . . . .485
  - Normal Thermometer, Anschutz . 485 Normal Weston Cadmium Cells . . 203
  - Note-Books, “ Nivoc ” . . . .60
  - AK Boards and Copper Tube for Heat Experiments. . . -477
  - Oersted’s Apparatus..............185
  - Oersted’s Piezometer.............463
  - Oil for use with Geryk Pumps . .163
  - Oiled Silk................ . . 46
  - Olive Oil.........................46
  - Opaque Screen for Radiant Heat
  - Experiments.....................478
  - Opisometers........................9
  - Optical Benches .... 367-372
  - Optical Bench Experiments, Apparatus for . 373
  - Optical Instruments, Miscellaneous . 407 Optical Lanterns .... 422-423
  - Optical Lever ...... 9, 383
  - Organ Pipes ....'. 352-354
  - Orrery, for Statical Electricity Experiments ......................189
  - Orrery...........................436
  - Oscillating Prism . . . . . .389
  - Oscilloscope Tubes...............308
  - Ovens, Tin, for Warming and Drying
  - Rubbers, etc...................187
  - Owen’s College Pattern Magnetoscope 180 Oxygen, Liquid...................462
  - AINTING Outfits for Lantern Slides ........ 434
  - Pair of Flat Spirals . . . . ,182
  - Paint, Luminous . . . . . . 320
- p.526 - vue 545/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1. 527
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Panes, Fulminating...............192
  - Panes, Luminous..................190
  - Pantographs......................56
  - Paper Brushes........................193
  - Paper Condensers ....................255
  - Paper, Pole-finding..............218
  - Paper, Jamieson’s Sensitive for Lectures on Heat...................... 444
  - Paper Scale Thermometers . . . 483
  - Paper Scales......................4, 8
  - Paper, Squared...................60
  - ' Paper Wheels for Sound Experiments ..............................364
  - Papers, Dialysis.....................457
  - Papin’s Digester.....................455
  - Para Rubber Strip................205
  - Parabolic Reflectors.............363
  - Paraffin Wax Photometers, Jolly’s . 367
  - Paraffin Wax..........................46
  - Paraffin Wax Cubes....................16
  - Parallel Bench Vices..................51 .
  - Parallel Mirrors.....................376
  - Parallel Rules, Ebony Bar ... 54
  - Parallelogram, Ampere’s . . .183
  - Parallelogram of Forces Apparatus
  - 109-m, 150-151
  - Pascal’s Pressure of Liquids Apparatus ...............................160
  - Peltier’s Apparatus..................303
  - “ Peandar ” Self-Recording Rain
  - Gauge.............................106
  - Pendulum, Airy’s Double . . . 348
  - Pencil Compasses......................53
  - Pendant Frame Aneroid Barometers 99 Pendulum, Foucault’s . . . .154
  - Pendulums, Various...................149
  - Pendulum Bobs........................115
  - Pentane-filled Thermometers . . 463
  - Percussion Apparatus . . . .123
  - Perforated Covers for Resistances . 263 Perry’s Experimental Fly-Wheels . 146 Pfaundler’s Apparatus for showing
  - Lissajou’s Figures................348
  - Phenomenon of Critical Temperature
  - Apparatus.........................463
  - Phosphor-Bronze Strip . . . .224
  - Photographic Apparatus .417-419
  - Photographic Dishes..................418
  - Photometers, Various . . . 366-367
  - Phosphorescent Lamps, Puley’s . . 325
  - Phosphorescent Substances . . . 320
  - Phosphorescent Vacuum Tubes 317, 318 Photographic Dry Plates, X-Ray . 310 Physical Balance for Mechanics’ Experiments ........................112
  - Physical Laboratory Memoranda 515-517 Picket Flags for Ranging Poles . .172
  - Pickets or Ranging Poles . . .172
  - Piezometers..........................463
  - Pile of Glass Plates.................403
  - Pill Boxes, Cardboard .... 46
  - Pillars and Points, Discharging . 305
  - Pincers............................. 49
  - Pin-hole Camera......................407
  - Pin-hole Gas Burners for Producing
  - Singing Flames....................358
  - Pins .................................46
  - Pipe Wrench Pliers....................49
  - Pipes, Organ.................... 352-354
  - Pipettes, Various.....................29
  - Pistol, Electrical...................190
  - Pith Ball Apparatus . . . 190, 193
  - Pith Ball Electrometers . . . .194
  - Pith Balls...........................190
  - Pith Figures ........................190
  - Pith Figure Plates . . . . .190
  - Plane Glass Mirrors..................376
  - Plane Tables.........................172
  - Planes, Inclined . . . . 116-117
  - Planes, V-shaped, Grooved . . .1x3
  - Planks for Bending...................132
  - Planimeter............................56
  - Plano-Concave and Plano-Convex Lenses..............................381
  - PAGE
  - Platinum Vessel for Silver Volta-
  - meter ..............................304
  - Platinum and Silver Chains . . . 302
  - Plateau’s Equal-weight Wire Figures 161
  - Plates, Adhesion......................130
  - Plates, Air-Pump .... 162-163
  - Plates, Capillary.....................159
  - Plates, Chladni.......................361
  - Plates of Crystal for showing Absorption Phenomena .... 399 Plates of Crystals for use with Polari-
  - scope ..............................403
  - Plates, Glass, Optically Worked . 403
  - Plates, Pith Figure....................190
  - Plates of Tourmaline...................403
  - Plates, X-Ray..........................310
  - Plates of Zinc and Copper for Making
  - Simple Cells........................203
  - Plating and Gilding Outfit . . .274
  - Plating Outfits........................274
  - Platinoid Wire, Bare and Double
  - Silk covered........................213
  - Platinum Plates for Grove’s Cells . 201
  - Pliers, Various................49-5°
  - Plug and Tapping Keys Combined . 278
  - Plug Adaptors..........................265
  - Plug Key Battery Switches . . . 277
  - Plug Key Commutators . . . .277
  - Plug Switches..................-.277
  - Plumb Bobs.............................152
  - Plumb Lines............................152
  - Pneumatic Fire Syringe . . . -477
  - Pneumatic Troughs.......................32
  - Pocket Direct Vision Spectroscopes 392
  - Pocket Rules.............................4
  - Pocket Spirit Levels...................159
  - Pocket Watch Type Voltmeters and
  - Ammeters............................240
  - Pohl’s Commutators.....................277
  - Pointer Galvanometer, Dead-beat,
  - Moving-coil.........................238
  - “ Pointolite ” Lamp Outfit for Lanterns ........................ ... 428
  - Polariscopes...................401 -403
  - Polarisation Bench . . . . . 404
  - Polariscopes, Lenses for . . 401-402
  - Polarised Light Apparatus . . .401
  - Polariser, Nicol Prism . . . .401
  - Pole-finding Paper.....................218
  - Polygon of Forces Apparatus . . .150
  - Polyprism..............................388
  - Porcelain Dishes for Photographic
  - Work................................418
  - Porcelain Basins . . . . . .30
  - Porcelain Fixing Troughs . . .418
  - Porcelain Mercury Troughs . . .31
  - Porous Ware Battery Cells . . . 205
  - Portable Batteries . . . 215-216
  - Portable Cinematograph Projector . 426
  - Portable Geryk Pump . . . .162
  - Portable Standard Instruments (Milli-Ammeters, Ammeters, Milli-Voltmeters, Voltmeters) .' . . 239
  - Portable Testing Sets, for Resistance
  - or Insulation.......................246
  - Post Office Resistance Boxes . . 244
  - Potash High Vacuum Tube . . -324
  - Potassium Bichromate .... 46
  - Potentiometer and Wheatstone Bridge. ......... 254
  - Potentiometers, various . . .255-256
  - Powder, Radiating . ... . 320
  - Powell’s Wave Machine .... 340
  - Power Amplifiers.......................297
  - Poynting’s Combined Tapping and
  - Plug Keys................... . 278
  - Poynting’s Galvanometer Lamp and
  - Scale ..............................226
  - Precision Calculating Rules, Faber’s 58-59
  - Press Keys.............................278
  - Presses, Hydrostatic...................156
  - Pressure of Air Apparatus . . .165
  - Pressure of Atmosphere Cylinder . 166
  - Pressure of Fluids Apparatus . .158
  - PAGE
  - Pressure of Gas in all directions,
  - Apparatus........................158
  - Pressure of Liquids Apparatus . .160
  - Pressure Tubing......................41
  - Pressure Tubing for Air-Pump Work
  - 162, 163
  - Pressure of Water Apparatus . .161
  - Printing Frames.....................419
  - Printing Frames for Lantern Slides 434
  - Prism Photometers...................367
  - Prism Tables........................374
  - Prismatic Compass...................170
  - Prisms, Boxwood and Brass. . . 19
  - Prisms, Carbon Bisulphide . . .385
  - Prisms, Double Refracting . . .385
  - Prisms, Glass, Various . . 386-389
  - Prisms, Hollow on Brass Stand with
  - Metal Basin .....................389
  - Prisms, Hollow, for use with Spectroscope ..............................395
  - Prisms, Hollow Glass .... 390
  - Prisms, Indigo......................385
  - Prisms, Oscillating.................389
  - Prisms, Quartz......................389
  - Prisms, Silbermann’s................389
  - Prismatic Binoculars . :. . . .412
  - Prismatic Bottles...................385
  - Prismatic Lenses....................381
  - Prismatic Troughs...................390
  - Press, Hydraulic, for Compressing
  - Moulds...........................460
  - Pressure Co-efficient of a Gas, Apparatus for Measuring .... 464 Pressure of Water Vapour, Apparatus
  - for Measuring....................450
  - Projection Lanterns.................420
  - Projector, Cinematograph . . . 426
  - Projectoscope.......................424
  - Proof Planes........................187
  - Propagation of Light Apparatus . 366 Propagation of Sound Apparatus 341, 342 Properties of Ice, Apparatus for Demonstrating . . . . . . 460
  - Properties of Vapours Apparatus 450-452 Protective Appliances (for X-Ray
  - Work)............................309
  - Protractor for Dividing Circles . . 54
  - Protractors, Brass and Celluloid . 53
  - Protractors, Boxwood .... 54
  - Puley’s Electrical Radiometer . .325
  - Puley’s Phosphorescent Lamps . . 325
  - Puley’s Tubes...............325, 326
  - Pulley Block Apparatus . . . -115
  - Pulley Blocks..................114,125
  - Pulley Brackets....................126
  - Pulley Frames......................126
  - Pulleys, Aluminium and Brass
  - 115, 124-125
  - Pulleys, Boxwood....................126
  - Pulleys, Teakwood . . . . .125
  - Pullinger’s Apparatus for Determining Co-efficient Expansion. . . 439
  - Pumps, Air......................161-162
  - Pumps, Foot ... . . . . . 161
  - Pumps, Geryk Vacuum . . 162-163
  - Pumps, Models of....................157
  - Puncture of Glass Apparatus . .193
  - Pyramids, Boxwood and Brass . . 18
  - Pyrometers, Ferguson’s .... 437
  - Pyramid, Wire.......................366
  - Pyramid, Wire, for Experiments on Radiation..........................-478
  - UADRANT Electrometer, Dol-
  - V, ezalek’s........................197
  - Quadrant Electrometers, Henley’s . 194
  - Quadrant Electrometer, Stewart &
  - Gee’s........................ 196
  - Quartz Prisms......................389
  - Quincke’s Lecture Apparatus, . . . 355
  - Quincke’s Tube.....................362
- p.527 - vue 546/555
- - 528 F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - Rackwork
  - Slides . . .
  - Racks for X-Ray Tubes Radiating Powder, Blue Radiators, Steam . Radiometers, Acoustic Radiation of Heat Apparatus
  - PAGE
  - Astronomical
  - 4i3 309 320 479
  - 363
  - 478-479
  - Radiometers, Crooke’s .... 480 Radiometers, Puley's Electrical . 325 Rafferty Wave Length Spectroscope 395
  - Railway Tube....................323
  - Rain Gauges .... 95, 106-107
  - Ranging Poles .
  - Rat-tail Files Reading Glasses Reading Telescopes Reagents for Spectrum Analysis Receivers for Torricellian Experi ments ....
  - Receivers, Glass, for Guinea and Feather Apparatus .... Receivers, Telephone Records for Gramophones Rectangular Glass Slabs for Refrac tion Experiments .... Rectangular Glass Jars for Grove’s
  - Cells..................
  - Rectangular Wooden Blocks Rectifiers (Accumulator Charging Sets)
  - Rectangular Tubes for Examining Absorption Bands in Liquids Rectilinear Propagation of Light
  - Apparatus.................
  - Red Wax, Soft ....
  - Reels of Unspun Silk Reflection Apparatus, Muller’s Reflection and Refraction of Light Apparatus ....
  - Reflection and Refraction
  - 172
  - 33
  - 408
  - 12
  - 399
  - 164
  - 165 276
  - 365
  - 379
  - 204
  - 21
  - 220
  - 399
  - 366 514 231 378
  - 378-379
  - Troughs
  - 377-378
  - Reflection Goniometers, Wollaston’s 407 Reflection of Heat Apparatus 478-479
  - Reflectors, Various.................363
  - Reflecting Galvanometers . . . 225
  - Reflex Cameras......................415
  - Refractive Index of Water, Apparatus to show.....................378
  - Regelation of Ice, Moulds for showing 460 Regnault’s Apparatus for Determination of the Absolute Expansion of a Liquid . . . . . . . 448
  - Regnault’s Boiling Point Apparatus ............................455
  - • 470
  - • 103
  - 453-454
  - 463
  - Regnault’s Calorimeter Regnault’s Hygrometers Regnault’s Hygrometers Regnault’s Piezometer Regular and Irregular-shaped Metal
  - Objects.........................22
  - Regulators for Electric Motors . . 269
  - Relation of Forces Apparatus . .129
  - Relative Densities of Liquids Apparatus ................. . . . 24-25
  - Relay and Electric Bell Apparatus . 273
  - Repeating Spectrometer Reservoirs for Mercury Resistance Board Resistance Boxes Resistance Boxes, Dial Resistance Coils Resistance Frames Resistance Lamp, Pattern
  - Resistance Units Resistance Wires Resistances .
  - 398
  - 27. 3U 465 • • 247
  - 241-247 • 249
  - 247-248
  - • • • • 257 Woodhouse ”
  - . 250
  - • • • • 257
  - 210-213 251
  - Resistances, Adjustable, (Slate Types)
  - 258-261
  - Resistances, Adjustable (Tubular
  - Types).........................262-263
  - Resistances, Adjustable (Ventilated
  - Patterns)..........................264
  - Resistances, Anode....................293
  - PAGE
  - Resistances, Filament (for Wireless
  - Sets)............................291
  - Resonance Apparatus . . 349, 350
  - Resonance Glass Jars . . . -349
  - Resonators.........................351
  - Retort Rings........................37
  - Retort Stand Clamps . . . -38
  - Retort Stands....................36-37
  - Reversible Pendulums . . . .149
  - Rheostat, Filament (for Wireless
  - Sets)............................291
  - Rheostats, Carbon..................255
  - Rhombs of Iceland Spar . . .391
  - Rhombs, Fresnel’s..................388
  - Right-angled Prisms................386
  - Rigidity Apparatus . . . 136-137
  - Rijke’s Sounding Tube .... 358
  - Ring Weights, Iron.................141
  - Ring and Ball, for use with Whirling
  - Tables...........................154
  - Ring, Soft Iron, for Magnetism Experiments .........................182
  - “ Ring ” Telephone Receivers . . 276
  - Rings for Retort Stands . . . . 37
  - Rings to Illustrate Spheroidal Form
  - of the Earth.....................154
  - Rintoul’s Spring Dynamometer . . 155
  - Rintoul’s Tube and Flask . . . 446
  - Rising Table........................39
  - Ritchie’s Apparatus for Absorption of Heat Experiments .... 480 Robinson’s Anemometers . . .108
  - Robison’s Ball-ended Magnets . .173
  - Rocking Bar, Trevelyan’s . . . 440
  - Rod and Disc- or Showing Nodal
  - Rings............................350
  - Rod, Ebonite.......................205
  - Rod, Glass .........................40
  - Rod-Testing Apparatus . . . .131
  - Rods, for Conductivity Experiments 442 Rods for Ranging Poles . . .172
  - Rods, half Glass and half Brass . .186
  - Rods, half Vulcanite, half Brass . 186
  - Rods of Brass......................186
  - Rods of Gutta-Percha . . . .186
  - Rods of Sealing Wax . . . .186
  - Rods of Shellac....................186
  - Rods of Sulphur....................186
  - Rods of Vulcanite..................186
  - Rods, Steel and Wooden for Sound
  - Experiments......................348
  - Roget’s Jumping Spiral . . . .185
  - Roland Wild Calorimeters . . . 472
  - Roll of Tinfoil on Glass Tube . .189
  - Roll of Tinfoil on Mahogany Table . 189 Roman Steelyard .... 113, 143
  - Roof Trusses.......................130
  - Rope Brake and Dynamometer . .146
  - Rotary Rectifiers (Accumulator
  - Charging Sets)...................220
  - Rotating Apparatus for Vacuum
  - Tubes............................319
  - Rotating Glass Ball (Electrical Circus) ..............................193
  - Rotating Glass Ball for Air-Pump
  - Work.............................165
  - Rotation of a Current Apparatus . 185 Rotation of a Magnet Apparatus . 185
  - Rubber Bands........................46
  - Rubber Bungs, Squat, Tall and Shallow Pattern .... 43-45
  - Rubber Circles for Foot Bellows . 32
  - Rubber Cord........................133
  - Rubber Corks, Squat and Tall Pattern ........................... 42-45
  - Rubber Sheets for Insulating Purposes . . •....................192
  - Rubber Sheeting, Thin . . . .165
  - Rubber Strip, Pure Para. . . . 205
  - Rubber Tubing for Pressure . . 41
  - Rubber Tubing.......................41
  - Rubbers, Catskin, Flannel and Silk 186
  - Rubbers, Foxtail...................187
  - Ruby Globes........................417
  - PAGE
  - Ruhmkorff’s Commutators . . . 277
  - Ruhmkorff’s Induction Coils . . 280
  - Rules, Boxwood.................2-3, 8
  - Rules, Calculating .... 58-60
  - Rules, Parallel, Ebony Bar . . . 54
  - Rules, Sighting......................170
  - Rules, Steel...........................4
  - Rumford’s Photometer .... 366
  - Rupert’s Drops.......................441
  - “ R ” Valves for Amplifiers . . . 297
  - SAFETY Lamps, Davy's . . .167
  - Salammoniac.................46
  - Sand Paper............................46
  - Sand, Silver..........................46
  - Sanderson Cameras....................416
  - Savart’s Toothed Wheels . . . 359
  - Saws.............................51
  - Scale and Vernier for Young’s Modulus Apparatus......................134
  - Scale Pans for Dynamometers . . 155
  - Scales and Lamps for Galvanometers
  - 226-227
  - Scales, Galvanometer .... 227
  - Scales, Glass..........................4
  - Scales, Paper.................. 4, 8
  - Schuster & Lees’ Calorimeters . . 468
  - Schuster & Lees’ Pendulum . . 149
  - Schuster & Lees’ Potentiometer . 254 Science Lantern Apparatus for Conduction of Metals Experiments . 442 Science Lantern Apparatus to explain Phenomena of Water when
  - Freezing...........................449
  - Science Lantern Voltameter . . . 304
  - Screens, for Heat Experiments . . 479
  - Screens, Fluorescent.................310
  - Screens, Ground Glass, for Optical Bench Experiments . . 373-374
  - Screens, Intensifying................310
  - Screen, Metal, and Iris Diaphragm . 374
  - Screens, Opaque, for Radiant Heat
  - Experiments . 478
  - Screens, Stevenson's..................94
  - Screens, Wire Gauze, Mounted . . 374
  - Screw and Nut, Wooden Model of 22,126
  - Screw Clips for Burettes 35
  - Screw Drivers....................49
  - Screw and Worm Wheel Jack '. .128
  - Screw Efficiency and Friction Apparatus .......................112, 128
  - Screw Gauges, Micrometer ... 7
  - Screw Jacks...................115, 128
  - Screw, Wooden, in Bracket, with
  - Sliding Rod........................127
  - Screws and Nuts................22, 126
  - Sealing Wax Rods.....................186
  - Searle’s Mechanical Equivalent of
  - Heat Apparatus.....................476
  - Searle’s Rigidity Apparatus . 136-137
  - Searle’s Thermal Conductivity Apparatus ...........................443
  - Searle’s Vibration Magnetometer . 174
  - Seconds Clocks.......................121
  - Self-Recording Rain Gauges . . 106
  - Semicircular Glass Slabs for Refraction Experiments . . . -379
  - Semicircular Protractors . . . .53
  - Sensitive Flame Burners, Koenig’s . 358 Sensitive Paper for Conductivity
  - Experiments........................444
  - Sequoia Plane Table..................172
  - Series Resistance Boxes and Bridges 245
  - Series Spark Gap.....................305
  - Set of Apparatus for Illustrating Induced Currents . ; . . . .182
  - Set of 3 Bars, Antimony, Bismuth
  - and Nickel.........................175
  - Set of 7 Coloured Glasses . . . 392
  - Set of Coloured Wools, Holmgren's . 405 Set of Dia-magnetic Apparatus . 181 Set of Electric Chimes . . . . 192
  - Set of Leslie’s Canisters .... 478
- p.528 - vue 547/555
- - F. E. BECKER & CO., NIVOC HOUSE, HATTON WALL, LONDON, E.C.1, 529
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Set of Mathematical Instruments . 52
  - Set of Metal Cylinders for Conductivity Experiments.................442
  - Set of Metal Cylinders for Specific
  - Heat Experiments.................469
  - Set of 16 Models and Figures . . 14
  - Set of Reagents for Spectrum
  - Analysis.........................399
  - Set of Six Rods for Conductivity
  - Experiments......................442
  - Set Squares..........................55
  - Set Squares for Blackboards . . 56
  - Set of Standard Meteorological Instruments ............ . -95
  - Set of Thermometers with Screen . 94
  - Sets of Bar Magnets.................175
  - Sets of Boxwood Cylinders ... 20
  - Sets of Bunsen’s Cells .... 200 Sets of Daniell’s Cells .... 200 Sets of Fluorescent Liquids . . . 320
  - Sets of Hardwood and Boxwood
  - Blocks.........................19-20
  - Sets of Lecturers’ Lenses . . . 382
  - Sets of Mechanical Powers . . .127
  - Sets of Metal Cubes .... 16-17
  - Sets of Phosphorescent Substances . 320 Sets of Regular and Irregular-shaped
  - Metal Objects.....................22
  - Sets of Spheres......................17
  - Sets of Wooden Bars for Sound Experiments .........................348
  - Sets of Wooden Cubes . . . 14-15
  - Sewing Needles......................176
  - Sextant ............................169
  - Shadow and Stencil Tubes . . . 323
  - Shakespear’s Apparatus for Demonstrating Boyle’s Law .... 467 Shakespear’s Constant Volume Air
  - Thermometer......................467
  - Shears, Metallurgical................50
  - Sheer Legs, Model of................130
  - Sheet Ebonite.......................205
  - Sheet Iron Discs....................176
  - Sheet Lead .........................309
  - Sheet, Lead Rubber..................309
  - Sheets of Rubber for Insulating
  - Purposes ........................192
  - Shellac .............................46
  - Shellac Rods........................186
  - Shives...............................34
  - Shunt for Galvanometers. . . . 230
  - Siemen’s Armature, Model of . .272
  - Sieve for use with Iron Filings . .176
  - Sighting Rule and Inclinometer
  - Combined.........................170
  - Sighting Rules......................170
  - Silbermann’s Prism..................389
  - Silencing Cabinet...................306
  - Silica Weight Thermometers. . . 447
  - Silk-covered Flexible Bell Cord . .213
  - Silk, Oiled..........................46
  - Silk Rubbers........................186
  - Silver Leaf .........................46
  - Silver Sand..........................46
  - Silver-plated Copper Calorimeters . 468 Silver and Platinum Chains . . . 302
  - Silver Voltameters..................304
  - Simple Pendulums....................149
  - Singing Flame Apparatus . . . 358
  - Single Needle Telegraph Model . . 279
  - Single Pole Double Throw Switches. 298 Sinkers for Measuring Density of a
  - Liquid............................23
  - Sine and Tangent Galvanometers . 229
  - Siren, Dove’s.......................360
  - Siren Discs.........................359
  - Siren, Helmholtz....................360
  - Sirens, Cagniard de la Tour’s . . 360
  - Sirens, Humming Top . _. ... 359
  - Six’s Self-Registering Maximum and Minimum Thermometer . . .101
  - Slabs, Glass, for Refraction Experiments .............................379
  - Slab Pattern Inductance Coils . . 295
  - PAGE
  - Slate Type Adjustable Resistances 258-261
  - Slide Lantern, Focuslite .... 424
  - Slide Rules.......................58-60
  - Slides, Astronomical (Rackwork Motion) ...............................413
  - Slides, Lantern, “ Wireless Telegraphy ” ............................299
  - Slides, Wave........................340
  - Sliding Callipers, Graduated ... 6
  - Sliding Condensers..................194
  - Sliding Friction Apparatus 115, 118, 148-
  - Sliding Inductance..................294
  - Sliding Weights for Tuning Forks . 346 Slotted Weights, Brass . . . .143
  - Slotted Weights, Iron...............140
  - Slotted Weights, Monochord. . . 343
  - Small Mirrors for Tuning Forks . 346
  - Smee’s Cells........................201
  - Smoke Condensation Apparatus 193-194 “ Snowdon ” Rain Gauges . . 95, 106
  - Soft Iron Bars......................176
  - Soft Iron Ring for Magnetism Experiments ...........................182
  - Soft Red Wax........................5x4
  - Soft Sheet Iron Discs...............176
  - Soft Soda Glass Tubing .... 40
  - Solar Radiation Thermometers . . 102
  - Solder, Wire, for making Electrical
  - Connections.......................205
  - Soldering Irons......................50
  - Soldering Outfit.....................50
  - Solenoids...........................183
  - Solid Spheres, Wood and Metal . 17-18
  - Sondhauss’ Lens.....................359
  - Sound Analysis Apparatus . . . 355
  - Sound Apparatus .... 338-354
  - Sound Propagation Apparatus 341, 342 Sound Synthesis Apparatus . . . 347
  - Sounding Tube, Rijke’s .... 358
  - Spanners..................... . .49
  - Spare Parts for Batteries . . . 204
  - Spark Gap, Various..................305
  - Speaking Receivers, Loud . . . 296
  - Speaking Trumpets, Model . . . 364
  - Specific and Latent Heat, Apparatus
  - for. • 473-474
  - Specific Gravity Balances, Joly’s . 25
  - Specific Gravity Bottles .... 23
  - Specific Gravity Bulbs .... 23
  - Specific Gravity Hydrometers . . 23
  - Specific Gravity Tubes . . . 23-24
  - Specific Gravities, Table of . . .516
  - Specific Heats for Air, Clement & Desormes’ Apparatus .... 472 Specific Heats of Solids and Liquids
  - Apparatus..............468-470
  - Specimens of Amber..................186
  - Spectacle Lenses....................380
  - Spectacle Lenses, Assorted, in
  - Sets..............................382
  - Spectacles, Lead Glass .... 309
  - Spectral Lamps......................400
  - Spectrometers . . . • . . 396-398
  - Spectroscope Stands . . . 337, 399
  - Spectroscopes, Direct Vision . . . 392
  - Spectroscopes, Various . . 393-395
  - Spectrum Analysis Apparatus . . 399
  - Spectrum Analysis Tubes . 336-337
  - Spectrum Analysis Tubes, Insulated
  - Stands for........................337
  - Speed Indicators......................7
  - Spheres, Brass, for inserting Proof
  - Planes............................189
  - Spheres, Brass, on Vulcanite Uprights ..............................191
  - Spheres, Solid, Wood and Metal. 17-18 Spherical Conductors . . . .191
  - Spherical Resonators, Helmholtz’ . 351 Sphero-Cylindrical Lenses . . .381
  - Spheroidal State, Leidenfrost’s Apparatus for showing .... 460
  - Spherometers...................9, 384
  - Spiral, Jumping, Roget’s . . .185
  - Spiral Spring Holders for Lamps . 265 1
  - PAGE
  - Spiral Springs......................133
  - Spirals, Flat, for illustrating Reduced Currents...................182
  - Spirit Lamps.........................32
  - Spirit Levels..................... 159
  - Spirit Levels, Cross................170
  - Sponges..............................56
  - Spouting Cylinders..................160
  - Sprengel’s Specific Gravity Tubes . 23
  - Spring Balance Monochords . . . 342
  - Spring Balances .... 139-140
  - Spring Balances, Joly’s Specific
  - Gravity...........................25
  - “ Springclip ” Terminals . . . 209
  - Spring Dynamometer, Rintoul’s. . 155
  - Spring Magnetometer . . . .180
  - Spring Measuring Tapes .... 5
  - Springs, Clock .....................176
  - Springs, Extension and Compression Apparatus...................133
  - Springs, Spiral.....................133
  - Springs, Steel, for Engineering
  - Classes..........................133
  - Springs, Watch......................176
  - Squared Paper........................60
  - Standard Barometers, Fortin’s . . 96
  - Standard Cadmium Cells . . . 203
  - Standard Dip Circle.................178
  - Standard Hygrometers . . 103, 454
  - Standard Meteorological Instruments,
  - “ Science School ” Set .... 95
  - Standard Post Office Boxes . . . 244
  - Standard Resistance Coils . . . 248
  - Standard Solar Radiation Thermometers ..........................102
  - Stands for Braun’s Tubes . . . 332
  - Stands for Burettes . . . . 31, 35
  - Stands for Cameras..................417
  - Stands for Diffraction Gratings . . 400
  - Stands for holding Iron and Copper
  - Balls............................479
  - Stands for Lecture Table Work . 39
  - Stands for Retorts .... 36-37
  - Stands for Solar Thermometers . 102 Stands for Spectroscopes . 337, 399
  - Stands for Spectrum Analysis
  - Tubes............................337
  - Stands for Tuning Forks . . . 346
  - Stands for Vacuum Tubes 193, 319, 320
  - Stands, Insulating..................192
  - Stands, Tripod . . . . . .34
  - Stands, X-Ray Tube..................309
  - Staples, Steel, for Indoor Wiring . 282 Statical Electricity Apparatus 189-190,
  - 193-194
  - Steam Boiler, Marcet’s . . . -455
  - Steam Calorimeter, Joly’s . . . 470
  - Steam Engine (Eolipile) . . . -477
  - Steam Engine, Hero’s . . . .166
  - Steam Engine, Sectional Working
  - Model......................... .166
  - Steam Heaters.......................475
  - Steam Piston, Wollaston’s . . .166
  - Steam Radiators.....................479
  - Steam Traps.........................473
  - Steel Bar, Unmagnetised . . .176
  - Steel Calliper Gauges .... 6
  - Steel Callipers.....................5-6
  - Steel Clock Springs.................176
  - Steel Coloured Glasses to show Absorption ................... . . 385
  - Steel Filings.......................176
  - Steel Knitting Needles . . . .176
  - Steel Measuring Tapes, Wind-up and
  - Spring.............................5
  - Steel Rod and Disc for showing
  - Nodal Rings......................350
  - Steel Rods for Sound Experiments . 348
  - Steel Rules...........................4
  - Steel Sewing Needles................176
  - Steel Springs for Engineering Classes 133 Steel Staples for Indoor Wiring. . 282 Steel Tubing, Flexible Metallic . . 32
  - Steel Watch Springs.................176
  - LL
- p.529 - vue 548/555
- - 530 F. E. BECKER & CO., NIVOC HOUSE, HATTOIM WALL, LONDON, E.C.1.
  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Steel Wires Breaking Stress Apparatus ...............................i32
  - Steelyards..........................143
  - Stencils, Mathematical . . . .57
  - Stencils, “ Nivoc ” Chemistry . .517
  - Stevenson’s Thermometer Screen . 94
  - Stereoscopes, Hand..................407
  - Stereoscopic Slides.................407
  - “ Sterling ” Loud Speakers . . . 296
  - Stethoscopes........................364
  - Stewart & Gee’s Dip Needles . .178
  - Stewart & Gee’s Magnetometers . 179 Stewart & Gee’s Potentiometer . . 254
  - Stewart & Gee’s Quadrant Electrometer ..............................196
  - Stewart & Gee’s Reflecting Galvanometers .............................225
  - Stirrups, Bent Wire, for Glass Rods,
  - etc...............................187
  - Stocks’ Lamp for Lanterns . . . 431
  - Stoneware Battery Cells .... 204
  - Stools, Insulating..................192
  - Stop-Watches........................121
  - String Nets for Foot Bellows . . 32
  - String Telephones...................276
  - Strips of Mirror Glass . . . .376
  - Strips of Pure Para Rubber . . . 205
  - Students’ Bichromate Battery Elements ..............................199
  - Students’ Optical Bench . 367-368
  - Students’ Set of Mathematical Instruments............................52
  - Sturgeon’s Disc.....................184
  - Sulphur Rods........................186
  - Sulphuric Acid Cryophorus, Wein-
  - hold’s............................458
  - Sulphur-Dioxide, Critical Temperature Apparatus......................460
  - Sulphurous Acid, Liquefied . . . 460
  - Sun Dials...........................107
  - Sunshine Recorders . . . . .108
  - Support with two Tubes for use with
  - Whirling Tables...................154
  - Supports (Blocks of Wood) ... 34
  - Supports, Bunsen’s Universal . . 34
  - Supports for Fitting on to Retort
  - Stands.............................37
  - Supports for Vacuum Tubes. 319, 320 Supports for Vacuum Vessels . . 462
  - Supports, Brass, for Magnetic Needles 177 Surface of a Sphere Apparatus . . 18
  - Surveying Instrument (Lucy’s Met-
  - rangle)...........................171
  - Suspension Levers...................142
  - “ Switchboard ” Type Ammeters and
  - Voltmeters........................240
  - Switchboards (X-Ray) .... 306 Switches, Lever .... 282, 298
  - Switches, Plug......................277
  - Switches, Double Pole .... 298
  - Switches, Single Pole...............298
  - Symon’s Rain Gauge..................107
  - Synthesis of Sound Apparatus, Helmholtz’ .............................347
  - Syphon Barometer, Standard . . 97
  - Syphon Barometers, Bunsen’s . . 98
  - Syphon Gauges, for Air-Pumps . .164
  - Syphons, Glass, for Liquefied Sulphurous Acid........................460
  - Syphons, Glass, with Suction Tube
  - and Bulb..........................161
  - Syringe Hydrometer..................218
  - Syringe, Pneumatic, for Heat Experiments ..........................477
  - Syringes, Exhausting and Condensing.................................162
  - TABLE Spectroscopes . . 393-395
  - Table Supports for fitting on to Retort Stands . . . -37
  - Table Telephones....................276
  - Table Tops...........................34
  - Table of Electrical Units...........517
  - PAGE
  - Table of Elements..................516
  - Table of Weights and Measures . 515
  - Tables, Levelling..................159
  - Tables, Plane......................172
  - Tables, Rising......................39
  - Tables of Specific Gravities . . .516
  - Tables, Whirling . . . '. 153-154
  - Tangent Galvanometers . . 228-230
  - Tantalus Cup.......................166
  - Tape................................46
  - Tape, India-rubber.................205
  - Tapes, Measuring, Linen and Steel . 5
  - Tapping and Plug Keys Combined . 278
  - Tate’s Air-Pumps...................162
  - Teakwood Pulleys...................125
  - Telegraph Alphabet Cards . . . 279
  - Telegraph Instruments .... 279 Tele-Microscopical Apparatus . . 385
  - Telephone Bar Magnets .... 276 Telephone for use with Kohlrausch
  - Bridges.........................256
  - Telephone Parts to show Construction .............................276
  - Telephone Receivers................276
  - Telephone Receivers for Wireless
  - Sets............................290
  - Telephone Transformer .... 291
  - Telephones . . ... . . 275-276
  - Telephones, String, for Demonstration Purposes.....................276
  - Telescope for use with Spectroscopes 393 Telescopes, Various . . . 409-411
  - Telescopes, Models of . . . 384-385
  - Telescopes, Reading.................12
  - Telescopic Tripod Stands for Cameras .............................417
  - Temperature of Water, Hope’s Apparatus to show...................449
  - Terminals, Various . . . 206-209
  - Terrestrial and Astronomical Telescopes ...................409, 4x1
  - Terrestrial Telescope, Model of . . 384
  - Terrestrial Radiation Thermometers 102
  - Tesla Lamp.........................327
  - Tesla Tubes........................327
  - Tesla’s High Frequency Apparatus
  - 300-301
  - Test Tubes..........................33
  - Testing Apparatus, including Deflection of Beams and Springs, etc.
  - 131-132
  - Testing Sets for Resistance or Insulation .........................246
  - Tests for Colour Blindness . . . 405
  - Theodolite.........................168
  - Thompson’s Luminous Bulb . . . 332
  - Thompson’s Wave Machine . . -339
  - Thorium Pastilles..................431
  - Thermal Conductivity Apparatus 443-444 Thermal Radiation Apparatus . . 479
  - Thermionic Valves for Wireless Sets 290 Thermo-Electricity, Apparatus . . 302
  - Thermo-Electricity Apparatus . . 303
  - Thermograph and Barograph Combined . . .................105
  - Thermographs and Barographs 104-105 Thermometer, Kinnersley’s . . .189
  - Thermometer Screen, Stevenson's . 94
  - Thermometer Tubes, Empty. . . 446
  - Thermometer Tubing..................40
  - Thermometers and Screen, Demonstration Set.......................94
  - Thermometers, Air, Constant Volume ..............................467
  - Thermometers, Air, Model . . . 467
  - Thermometers, Anschutz-;. . . . 485
  - Thermometers, Beckmann’s . . . 484
  - Thermometers, Boxwood Scale 100, 486 Thermometers, Brequet’s Metallic . 439 Thermometers for Chemical Works,
  - etc. ...........................485
  - Thermometers, Differential . . .481
  - Thermometers, Earth . . . .102
  - Thermometers, High Temperature . 483
  - PAGE
  - Thermometers, Incubator . . . 485
  - Thermometers, Low Temperature 463, 483 Thermometers, Maximum and Minimum “ Science School ” Set . . 95
  - Thermometers, Maximum and Minimum Combined .... iox, 487 Thermometers, Maximum . 100, 486
  - Thermometers, Milk-glass Scale . . 483
  - Thermometers, Minimum . . 101, 487
  - Thermometers, Model, for Heat Experiments .................446, 467
  - Thermometers, Normal .... 485 Thermometers, Paper Scale . . . 483
  - Thermometers, Solar Radiation . .102
  - Thermometers, Ungraduated . . 446
  - Thermometers, Weight .... 446
  - Thermopiles......................302
  - Thermopiles of Bismuth and Antimony .............................302
  - Thermopiles of Bismuth and Antimony .............................480
  - Thermoscope, Ether...............478
  - Thin Rubber Sheeting . . . . 165
  - Thomson’s Astatic Galvanometer . 225
  - Thread...........................46
  - Three-limbed Tubes for Hare's Apparatus ...........................25
  - Tin Foil.........................46
  - Tinder, German...................477
  - Tinfoil on Glass Tube............189
  - Tinfoil on Mahogany Table . .189
  - Tin Cubes........................16
  - Tin Cylinders....................21
  - Tin Fusible Wire for Cut-outs . .213
  - Tins, Glazebrook’s Conical . . . 455
  - Tin Cylinders, for Conductivity Experiments ........................442
  - Tin Ovens for Drying Rubbers, Glass Tubes, etc. . . . . . . .187
  - Tin Vessel for Experiments oxx
  - Radiation.....................478
  - Tin Vessels, for Heat Experiments . 468 Tin Vessels for Displacement Experiments .........................22
  - Tin Vessels with Vulcanite Handles for Electrical Experiments . .194
  - Tins, Glazebrook’s................166
  - Tongs, Tourmaline................403
  - Tool Cabinets....................47
  - Tools for Laboratory Use . . 47-51
  - Toothed Wheels, Savart’s . . . 359
  - Torricellian Receivers . . . .164
  - Torsion Apparatus.................137
  - Torsion Balance, Coulomb's . . 196
  - Torsion of Wire Apparatus . 137-138
  - Torsion in Rods Apparatus . 135, 137
  - Tourmaline, Plates of .... 403
  - Tourmaline Tongs.................403
  - Towers, Leaning .................152
  - Tracing Wheels .... . . 9
  - Trains of Gear Wheels . . . .148
  - Transformers (for Wireless Sets) . 291 Transmission Diffraction Gratings . 400 Transverse Waves Apparatus . . 338
  - Trays, Mercury...................31
  - Trevelyan’s Rocking Bar . . 362, 440
  - Trial Jars for Hydrometers . . 23
  - Triangular Files...................33
  - Triangular Glass Slabs for Refraction
  - Experiments....................379
  - Triangular Tables for Levelling . 159
  - “ Trilby ” Limes..................431
  - Tripod Stands, Geometric ... 34
  - Tripod Stands for Cameras . . .417
  - Tripods.......................... 39
  - Trolley Vibration Apparatus. . .122
  - Troughs, Reflection and Refraction
  - 377-378
  - Trough for Refraction of Liquids,
  - Muller’s.......................378
  - Trough Compasses . . . 170, 172
  - Troughs, Pneumatic.................32
  - Troughs, Porcelain, Mercury . . 31
  - Troughs, Prismatic................390
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Troughs, Washing Photographic . 418
  - Trough, Wave.......................338
  - Trough, Zinc.......................338
  - T Squares..........................54
  - T Squares for Blackboards . . .56
  - Truck for Inclined Plane. . . .117
  - Trumpets, Ear......................364
  - Trumpets, Speaking.................364
  - Tube and Flask for Boiling Point
  - Experiments.....................45
  - Tube and Flask, Rintoul’s . . . 446
  - Tube and Oak Boards for Heat Experiments ......................477
  - Tube and Oak Boards for Friction
  - Experiments.............
  - Tube, Glass, with five branches
  - Tube Rack..................
  - Tube Stands (X-Ray).
  - Tubes, Anode Ray
  - Tubes, Aron’s..............
  - Tubes, Barometer
  - 154 159 3°9 309 334 334 98, 514
  - Tubes, Barometer, with Cap and
  - . . 165
  - 465-466 . 26-27
  - 329-331 159
  - Stuffing Box Tubes, Boyle’s Law .
  - Tubes, Boyle’s Law .
  - Tubes, Canal Ray Tubes, Capillary, in Frame Tubes, Cardboard, for Heat Experiments ...............................477
  - Tubes, Cathode Ray . . . 332-335
  - Tubes, Crooke’s .... 322-324
  - Tubes for Demonstrating Interference of Sound Waves, Various . 362
  - Tubes, Ebert’s.......................326
  - Tubes, Empty Thermometer . . 446
  - Tubes, Glass, for Cadmium Cells . 203 Tubes, Glass, for Frictional Electricity Experiments..................186
  - Tubes, Glass, filled with Filings. . 176 Tubes, Glass, for Boyle’s Law Apparatus ........................... 465-466
  - Tubes, Glass Three-limbed ... 25
  - Tubes, Goldstein’s...................329
  - Tubes, Graduated, for Archimedes’
  - Principle .........................22
  - Tubes, Hertz’........................326
  - Tubes, Hittorf’s.....................326
  - Tubes, Holtz'........................334
  - Tubes, Jolly’s Air Bulb . . .26, 466
  - Tubes, Lenard's......................333
  - Tubes, Luminous......................192
  - Tubes, McFarlan Moore’s . . . 328
  - Tubes, Oscilloscope..................308
  - Tubes, Plain, for Boyle’s Law Apparatus ..........................27
  - Tubes, Puley's..................325, 326
  - Tubes, Rectangular, for Examining Absorption Bands in Liquids . . 399
  - Tubes, Quincke’s.....................362
  - Tubes, Specific Gravity . . . 23-24
  - Tubes, Spectrum Analysis . 336-337
  - Tubes, Tesla.........................327
  - Tubes, Test...........................33
  - Tubes to Show Circulation of Water 445 Tubes, U, for Relative Density Experiments ............................25
  - Tubes, U-form, Iron..................180
  - Tubes, Vacuum 311-319, 321-324, 326-
  - ~ ^ , 328’ 333-337
  - lubes, Valve.........................308
  - Tubes, Vapour Tension . . .2 7, 465
  - Tubes, X-Ray ..... 307, 308
  - Tubing, Barometer and Thermometer, etc........................40
  - Tubing, Bunsen Burner . . . .41
  - Tubing, Flexible Metallic. ... 32
  - Tubing, Pressure, for Air-Pump
  - Work.........................162, 163
  - Tubing, Rubber . . . . . .41
  - Tubing, Soft Soda Glass .... 40
  - Tubing, Rubber Pressure. . . .41
  - Tubular Compression Balances . .138
  - Tubular Type Adjustable Resistances
  - 262-263
  - PAGE
  - Tuning Coils (for Wireless) . 294-295
  - Tuning Forks, Apparatus for comparing Frequency . . . 345, 348
  - Tuning Forks................ 344~347
  - Tuning Forks, Chronographic . . 346
  - Tuning Forks for measuring Small
  - Intervals of Time...............346
  - Tuning Forks on Resonance Boxes
  - 344-346
  - Tuning Inductance Holder . . . 295
  - Tumscrews.......................49
  - Turpentine......................46
  - Tyndall’s Apparatus for Demonstrating that Vibrating Segments and Nodes of a Bell are similar to
  - those of a Disc..............350
  - Tyndall’s Apparatus for Showing that Bodies have different Specific
  - Heats........................469
  - Tyndall’s Percussion Apparatus. . 123
  - Tyndall’s Propagation of Sound Apparatus . . . . . . 341, 342
  - UNJ3RADUATED Thermometers ............................446
  - Unit Jar........................188
  - Universal Clamp Supports ... 34
  - Universal Condenser, Dubilier . . 293
  - Universal Discharger, Henley’s . .188
  - Universal Resonators, Koenig’s . . 351
  - Universal Shunt for Galvanometers. 230
  - Universal Tuner (for Wireless) . . 294
  - Unmagnetised Steel Bar . . , .176
  - Unspun Silk.....................231
  - Upright Pillar for holding Lenses . 382
  - U Tubes for Relative Density Experiments ........................25
  - U Tubes, Iron...................180
  - VACUUM Bulbs, Thompson’s , 332 Vacuum Contact Breaker,
  - McFarlan Moore’s................328
  - Vacuum Foot Pumps.................161
  - Vacuum Pumps, Geryk . . 162-163
  - Vacuum Scale, Cross’s .... 328 Vacuum Tube Holders and Stands
  - 192-193, 319, 320
  - Vacuum Tube Supports and Rotating Apparatus .... 3x9, 320
  - Vacuum Tubes 311-319, 321-324, 326-
  - 328, 332-367
  - Vacuum Tubes for Spectrum Analysis
  - 336-337
  - Vacuum Tubes Apparatus . 193, 319
  - Vacuum Vessels, Dewar’s . . . 462
  - Vacuum Vessels, Double-walled . . 463
  - Vacuum Vessels for Liquid Air . 462
  - Vacuum Vibrator.....................328
  - Valve Holders.......................295
  - Valve Receiving Sets ..... 289
  - Valve Tube Holders..................305
  - Valves for Wireless Sets .... 290 Vapour Density Apparatus, Various 452 Vapour Density Bulbs, Dumas . . 452
  - Vapour in a Vacuum, Apparatus to
  - show Formation of................451
  - Vapour Lamps, Mercury .... 400 Vapour Pressure, Apparatus for Experiments on....................450-451
  - Vapour Tension Tubes .... 27
  - Vapour Tension Tubes .... 465 Variable Condensers . . . . . 292
  - Vaseline.............................46
  - Velocity of Sound Apparatus, Kundt’s 356 Ventilated Pattern Adjustable Resistances ..........................264
  - Ventilation Apparatus (Mining) 167, 445 Vernier Microscopes . . . . 10-12
  - Verniers, Circular, Models of 9
  - Verniers, Models of...................8
  - Vertical Adapters ..................295
  - PAGE
  - Vessel of Tinplate to show Pressure
  - of Atmosphere....................166
  - Vessels, Displacement .... 22
  - Vessels for Mercury, Iron . . .31
  - Vessels for Use as Steam Boilers . . 475
  - Vessels, Glass, for Determining the Density of Atmospheric Air . .453
  - Vessels, Glass, Communicating . . 25
  - Vessels, Glass, with five Capillary
  - Tubes............................159
  - Vessels, Tin, for Experiments on
  - Radiation........................478
  - Vessels, Tin, for Heat Experiments 468 Vessels, Tin, with Vulcanite Handles 194 Vessels, Vacuum, Dewar’s . . . 462
  - Vibration Apparatus, Fletcher’s . 122 Vibration Magnetometer, Searle’s . 174 Vibration Magnetometers, Stewart &
  - Gee’s ...........................179
  - Vibration Microscope, Helmholtz’ . 347
  - Vibrator, Vacuum....................328
  - Vices, Iron, for holding Glass Tubes. 356
  - Vices, Various.......................51
  - Victor Meyer’s Vapour Density Apparatus ...........................452
  - Violin Bows...................349, 361
  - Vitreous Enamelled Resistance Units 257 Volt and Ammeters Combined, Watch
  - type.............................240
  - Voltameters, Various . . . 303-304
  - Volta’s Electroscope................196
  - Volta's Pile.......................203
  - Voltaic Electricity Apparatus . .185
  - Voltaic Electricity Apparatus (Bichromate Batteries, etc.) . . . 199
  - Voltmeter and Ammeter Combined . 237
  - Voltmeters......................236-240
  - Volume and Temperature of Gas
  - Apparatus........................467
  - Vulcanite Discs.....................187
  - Vulcanite Rods......................186
  - V-shaped Grooved Planes . . .1x3
  - WALL Cranes.........................129
  - Wall Telephones. . . .275
  - Washing Troughs.....................418
  - Watches, Stop.......................121
  - Watch Form Aneroids . . . .104
  - Watch Form Calculating Rule . . 60
  - Watch Form Voltmeters and Ammeters ............................240
  - Watch Springs, Steel................176
  - “ Watch ” Telephone Receivers . 276 Water, Apparatus for Freezing . . 458
  - Water Decomposition Apparatus . 304
  - Water Hammers.......................166
  - Water Level Apparatus . . . .159
  - Water Pressure Apparatus . . .161
  - Water Vapour, Apparatus for Measuring Pressure of..................450
  - Water Wheels, Models of 158
  - Watson’s Copper Calorimeter . . 469
  - Watson’s Spring Balance Monochord 342 Wave Apparatus .... 338-341
  - Wave Length Spectroscope . . . 395
  - Wave Motion Spiral..................340
  - Wave Slides, Various................340
  - Wave Trough.........................338
  - Wax, Soft Red.......................514
  - Wax, Soft Red, Paraffin and Bees’ . 46
  - Weather Vanes.......................107
  - Wedge and Divided Block of Hard
  - Wood............................116
  - Wedge Apparatus . . . . . .113
  - Wehnelt’s Vacuum Tubes . . . 335
  - Weighted Glass Bulbs .... 447 Weights and Measures, Table of. . 515 Weights for Tuning Forks . . . 346
  - Weights, Iron ..... 140-141
  - Weights, Iron Kilo..................343
  - Weights, Monochord Slotted . . 343
  - Weights, Slotted, Brass .... 143 Weight Thermometers .... 446
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  - W. & J. GEORGE (LONDON), Ltd., PROPRIETORS.
  - PAGE
  - Weinhold's Apparatus for Determining the Co-efficient of Absolute
  - Expansion of Liquids .... 448 Weinhold’s Ether Apparatus . . 450
  - Weinhold’s Induction Coil . . . 183
  - Weinhold’s Longitudinal Wave Machine ...........................339
  - Weinhold’s Sulphuric Acid Crophorus 458 Wells’ Apparatus for Wire Testing . 134 Weston Differential Pulley Blocks . 125 West’s Graduated Tube for Archi-
  - medes’ Experiment................22
  - Wet and Dry Bulb Hygrometers 103, 454 Wheatstone Bridges . . . 252-253
  - Wheel and Axle . . . 113, 114, 127
  - Wheel Barometer.....................97
  - Wheel of Life......................407
  - Wheel Pattern Mercurial Barometers 98
  - Wheels, Barlow’s...................184
  - Wheels, Paper, for Sound Experiments 364 Whirling Tables and Accessories . 153-154 Whirling Table Siren Discs . . . 359
  - Whirls, Electric...................193
  - Wiedmann’s Apparatus, to illustrate the Phenomena of Geysers . . 477
  - William Thompson Calorimeter . .471
  - Wilson Self-registering Rain Gauge . 106 Wimshurst Machines . . . 197-198
  - Wind-up Measuring Tapes ... 5
  - Wind Vanes.........................107
  - Wire, Aerial.......................299
  - Wire Brush or File Cleaner ... 47
  - Wire Cage for Electrical Experiments 195
  - Wire, Copper.....................211
  - Wire, Electric Bell................213
  - Wire, Eureka.......................212
  - Wire Figures, Plateau’s . . . .161
  - Wire for Cut-outs, Pure Refined Tin 213
  - Wire Gauges..........................7
  - Wire Gauze..........................39
  - Wire Gauze Cylinder................195
  - Wire Gauze for Flame Experiments 167
  - PAGE
  - Wire Gauze Screens, Mounted . '. 374 Wire, Iron and Copper, to show Difference in Conducting Power . 442
  - Wire, Manganin..................213
  - Wire, Nickel-Chrome . . . . .212
  - Wire, Nickel Silver.............212
  - Wire, Platinoid.................213
  - Wire, Pure Refined Tin . . . . 213
  - Wire Pyramid.......................366
  - Wire Pyramid for Experiments on
  - Radiation.......................478
  - Wire Solder........................205
  - Wire Spiral for showing Waves . . 340
  - Wire Stirrups for Glass Rods, etc. . 187 Wire Testing Apparatus, Wells’. . 134 Wires, Breaking Stress Apparatus . 132 Wires, Copper, for Conductivity
  - Experiments.....................442
  - Wires, Iron, for Conductivity Experiments ......................442
  - Wires for Young’s Modulus of Wires
  - Apparatus.......................134
  - Wireless Receiving Sets . . 286-289
  - Wireless Telegraphy and Telephony
  - Apparatus...................283-301
  - ‘ ‘ Wireless Telegraphy ’ ’ Lantern Slides 299 " W. J.” Burette Stands .... 35
  - Wollaston’s Atmospheric Engine . 477 Wollaston’s Cryophorus .... 458 Wollaston’s Reflection Goniometers. 407 Wollaston’s Steam Piston . . .166
  - Wooden Bars for Sound Experiments 348 Wooden Blocks, Rectangular . . 21
  - Wooden Blocks (Supports) ... 34
  - Wooden Cases for Bar Magnets. . 173
  - Wooden Cubes.....................14-15
  - Wooden Cylinders....................20
  - Wooden Discs........................21
  - Wooden Laths . ^..............21, 132
  - Wooden Lens Holders . . . -383
  - Wooden Mercury Trays . . . .31
  - Wooden Model of Nicol’s Prism . 388
  - PAGE
  - Wooden Models of Screw and Nut 22, 126 Wooden Moulds for showing the
  - Regelation of Ice...............460
  - Wooden Rods for Sound Experiments 348 Wooden Screw in Bracket with Sliding Rod...........................127
  - Wooden Spheres.....................17
  - Wooden Stands for Braun’s Tubes . 332 Wooden Supports for Vacuum Vessels 462 Woodhouse Lamp Resistance . . 250
  - Wood Stands for Solar Thermometers 102 Woodward’s Interference Wave Slide 340
  - Works Thermometers................485
  - Worm and Wheel....................128
  - Worm Wheel and Screw Jack, Combined ....................... . .128
  - Wright’s Wave Slides .... 340
  - X-RAY Apparatus . . 305-310
  - X-Ray Plates...............310
  - X-Ray Tubes...................307-308
  - YACHT ” Pattern Barometers 99 Young’s Modulus of Wires
  - Apparatus..............134-135
  - ZINC and Copper Plates for
  - making Simple Cells . . . 203
  - Zinc Beakers.....................30
  - Zinc Cubes....................... . 16
  - Zinc Cylinders...................21
  - Zinc Figures to illustrate Centre of
  - Gravity........................152
  - Zincs for Bichromate Batteries . . 199
  - Zincs for Leclanche Cells, Daniell's
  - Cells, etc.....................204
  - Zinc Resonators..................351
  - Zinc Steam Heaters...............475
  - Zinc Trough, Round...............338
  - Zoetrope.........................407
  - Zonophone Disc Records . . . 365
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