The practical astronomer : comprising illustrations of light and colours, practical descriptions of all kinds of telescopes, the use of the equatorial-transit, circular, and other astronomical instruments, a particular account of the Earl of Rosse's large telescopes, and other topics connected with astronomy (1845)
Dick, Thomas, 1774-1857 · London : Seeley, Burnside, and Seeley · leaf 540
are united by brass rodspassing through the door-cheeks of wainscot at aand a by means of nuts that screw upon theirends, which union allows the dome to be separatedinto two parts when there may be occasion to dis-place it. The wooden plate 66, which appears ina straight line, is a circular broad… … Fig. 92* shows a small door that lies over thesummit of the dome, and may be separatelyopened for zenith observations; the rod of metalwith a ring at the lower end passing through it,serves to open and shut this door, and at the sametime carries upon its upper end a large ball thatfalls back on the…
Astronomy · Astronomical instruments · Telescopes
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