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 516
he perpendicular tothe horizon, and A the zenith point. If the linesBC and CA represent a pair of compasses withthe legs standing perpendicular to each other, andthe curved lines AB, DE and FG, the quarterof as many circles of different sizes—it is evidentthat although each of these differs from… … C L a E B 492 THE PRACTICAL ASTRONOMER. would all contain exactly 90 degrees each. Bythe application of this principle the comparativemeasure of angles may be extended to an indefi-nite distance. By means of an instrument con-structed in the form of a quadrant of a circle,with its curved edge…
Astronomy · Astronomical instruments · Telescopes
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