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 154
ject at some distance from it.If the object OB was of a pure red colour, therays proceeding from it would form a red imageat Rr ; if the object was of a violet colour, animage of that colour would be formed at Vv,nearer the lens ; and if the object was white orany other combination of the… … This may be illustrated by experiment in thefollowing manner. Take a card or slip of white G 5 130 THE PRACTICAL ASTRONOMER. pasteboard, as ABEF, (fig. 33.) and paint onehalf ABCD red, the other half CF, violet orindigo ; and tying black threads across it, set itnear the flame of a candle G, then…
Astronomy · Astronomical instruments · Telescopes
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