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  • Thornthwaite, W. H. - Hints on reflecting and refracting telescopes and their accessories
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  • p.93 - vue 95/100
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  • TABLE DES MATIÈRES
  • TABLE DES ILLUSTRATIONS
  • RECHERCHE DANS LE DOCUMENT
  • TEXTE OCÉRISÉ
  • Première image
  • PAGE DE TITRE
    • Preface to the third edition (p.R2)
    • Contents (p.R3)
    • Introduction (p.5)
    • The various forms of telescopes. Their construction and advantages (p.7)
    • Refracting telescopes (p.11)
      • The perspective and opera-glasses (p.11)
      • The ordinary refracting telescope (p.12)
      • Stands for refracting telescopes (p.16)
      • Reflecting telescopes (p.19)
        • Direct vision reflectors. The gregorian telescope (p.19)
        • The cassegrainian telescope (p.20)
      • Stands for direct vision reflectors (p.21)
        • Indirect-vision reflectors. Nasmyth's modification of the cassegrainian telescope (p.21)
        • The herschelian telescope (p.22)
        • The newtonian telescope (p.23)
        • Adjustments of a newtonian telescope (p.24)
    • Stands for indirect-vision reflectors (p.31)
      • The alt-azimuth stand (p.31)
      • Equatorial stands (p.36)
      • Horne and thornthwaite's portable equatorial (p.36)
      • Berthon's patent equatorials (p.37)
    • Equatorial adjustments (p.41)
      • To place the Polar Axis in the Méridian (p.41)
      • To correct the Declination Vernier (p.41)
      • To adjust the Polar Axis to the Latitude of Observation (p.43)
      • To test the accuracy in position of the Telescope (p.43)
        • To set the Right Ascension Vernier (p.45)
        • To find a Celestial Object by means of the Declination and Hour Circles (p.46)
        • To convert Mean into Sideral Time (p.47)
        • Table of Refractions (Bessel) (p.48)
        • To adjust the “Finder” (p.48)
    • To silver and polish glass specula (p.49)
      • Apparatus (p.49)
      • To support the Mirror in the Silvering Vessel (p.50)
      • To clean the mirror (p.51)
      • To immerse the mirror (p.51)
      • To prepare the Silvered surface for polishing (p.52)
      • To polish the Silvered surface (p.53)
      • To separete the Mirror from the Wooden Support (p.54)
      • Martin's process of silvering (p.54)
      • Dr. Henry Draper's formula for silvering (p.56)
      • The sugar of milk process for silvering (p.56)
      • General, hints on silvering (p.57)
    • Accessories to the telescope (p.58)
      • Eye-pieces (p.59)
      • Solar eye pieces (p.59)
      • Barlow's lens (p.59)
      • The micrometer (p.60)
      • The double image micrometer (p.61)
      • Berthon's dynamometer (p.61)
      • The astronomical spectroscope (p.62)
      • Horne & thornthwaite's miniature universal spectroscope (p.65)
    • Observatories (p.66)
      • To construct an observatory on the Romsey model (p.67)
      • References to illustrations (p.71)
      • Horne & thornthwaite's astronomical clock (p.72)
      • Hints on observation (p.74)
    • Defining and separating tests (p.78)
    • Light tests (p.79)
    • Catalogue of reflecting and retracting telescops and their accessories (p.81)
      • Achromatic perspective glasses (p.81)
      • Achromatic opera glasses (p.81)
      • Achromatic field glasses (p.81)
      • Achromatic telescopes (p.83)
      • Horne and thornthwaite's binocular telescopes (p.83)
      • Refracting telescopes for astronomical purposes (p.84)
      • Astronomical object glasses (p.87)
      • Astronomical reflecting telescopes (p.89)
      • Silvered-glass specula (p.93)
      • Silvered-glass diagonal mirrors (p.93)
      • The “romsey” observatory (p.93)
      • Silvering and polishing specula (p.94)
      • Apparatus for silvering (p.94)
        • Silvering vessels (p.94)
        • Glass measures (p.94)
        • Chemicals (p.94)
      • Set of silvering apparatus (p.94)
      • Astronomical eye pieces (p.95)
        • Huyghenian construction (p.95)
        • Ramsden's construction (p.95)
        • Aplanatic construction (p.95)
        • Kellner's construction (p.95)
      • Solar eye pieces (p.95)
      • Micrometers (p.95)
      • Astronomical spectroscopes (p.96)
      • Trabsit instruments (p.96)
      • Works on astronomy (p.96)
  • Dernière image
  • Première image
  • PAGE DE TITRE
    • The german equatorial stand (p.17)
    • The victoria equatorial (p.18)
    • The alt-azimuth stand (p.32)
    • Horne and Thornthwaite's equatorial reflector (p.34)
    • Horne and Thornthwaite's portable equatorial reflector (p.35)
    • The berthon equatorial (p.38)
    • The berton equatorial (p.39)
    • The victoria equatorial telescope (p.85)
    • Berthon patent equatorial stand (p.90)
    • The alt-azimuth stand (p.92)
    • Binoclar microscope (p.97)
  • Dernière image
93

Newtonian Reflecting Telescope on Alt-azimuth Stand, as described at page 33, fitted with a Silvered Glass Speculum. Fig. 19.

inch Speculum, 6\ or 5-feet focus

°4 »

10 „

i2i »

33

3>

33

£ s. d. 23 o o 32 o o 44 o o 68 o o

If with Horne & Thornthwaite’s improved vertical and horizontal motions and ventilated tube, with superior finish to metal work, Fig. 38, 25 per cent, extra.

SILVERED-GLASS SPECULA {unmounted), Newtonian, Cassegrainian, Gregorian, or Herschelian.

PERFORMANCE GUARANTEED.

£ s. d.

3 inch diametei , 2 feet focus ... 3 10 0

4 33 3 3 3 4 0 0

5 99 4 33 4 10 0

6 M 5 33 5 17 6

64 33 64 ») ••• 6 5 a

84 >3 64 33 • • • 13 0 0

10 3 3 7 33 ... ... ... - 25 0 0

124 3 3 8 33 ' * * ... 38 10 0

14 *3 8 >3 * * * ••• 'â–  55 0 d

16 >3 10 33 . ... ••• 75 0 0.

18 „ 12 33 100 0 a

20 9* 12 33 . "* ... ... 130 0 0.

22 )> l$ 13 ... 165 0 0

24 33. 18 33 200 0 Q

26 M 18 33 ... 250 0 O,

30 33 24 „ ... 300 0 O'

36 3? 30 7- . 400 0 O

48 33 36 33 . 700 0 O

SILVERED-GLASS DIAGONAL MIRRORS {unmounted).

PERFORMANCE GUARANTEED.

I inch in the minor axis, or narrowest diameter of the ellipse

1 4 >! » !V •" !>

2 >, ,)

2^ ») >1 )! )>

3 ” n â–  . M • • ir-

35 j, j) jj

4 ’5 3 3 15

THE “ ROMSEY '* OBSERVATORY.

Page 60.

For 5-feet Telescopes ... ... ...

i> 6 ,, » â–  â–  • â–  • â– 

„ 7

» 8 »» »>

£ s. d.' 100

1 10 o 200

2 IO O'

3 3 ° 440

5 5 °

15 O' o

20 O O

28 O O 35 0 0




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