87

ASTRONOMICAL OBJECT GLASSES.

Clear aperture.., 2^-in. 3-in. 3i-in- 4-in. 4i-in. 5-in. 6-in.

Focal length ... 36-in. 48-in. 48-in. 60-in. 72-in. 80-in. 100-in.

In Brass Cells... £2 IS®- £5 £8 £12 IOS. £iS £26 £45

The above foci are those usually employed by us; but object-glasses of particular foci or diameter can be made to order at slightly higher prices.

HOftNEftTHORNTH WAITE

Fig- 36.

Horne & Thornthwaite’s Student’s Astronomical Refracting Telescope. Page 16. Fig. 3.

This Telescope, although so low in price, is well made in all its parts, and quite equal in its definition to those formerly sold at a much higher cost.

The body of the Telescope is of polished brass, with pillar and claw stand ; rackwork adjustment to eye-piece; achromatic object glass, of our own manufacture, 2’85 in clear aperture, and 3 feet focus ; one astronomical eye-piece with sun cap, and one day eye-piece, and finder; The whole enclosed in a polished pine wood case, with lock and key.

This instrument will, on a fine clear day, show the time by a church clock twelve miles distant, and clearly define the moon arid belts of Jupiter, the rings of Saturn, and many of the double stars; and the object glass will bear a magnifying power of 200 diameters.

The eye-pieces supplied with this Telescope, at the above price, are a terrestrial or day power of 40, and a celestial, for observing the stars, &c., of 60 ; but a celestial of any other power may be substituted for that of 60 without extra cost. ^10, or without the finder, ;£8 8s.

Mahogany Tripod Garden Stand for the above, 5 feet high, firm, steady and portable, £1 us. 6d.

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