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 121
ject. In fig. 23,GF is a concave mirror, whose focus of parallelrays is at E. If an object OB be placed a littlewithin this focus, as at A, a large image IM willbe seen behind the mirror, somewhat curved anderect, which will be seen by an eye looking directlyinto the front of the mirror. Here the… … and the mirror. If the mirror be one inch focaldistance , and the object be placed eight-tenths ofan inch from its surface, the image would be fivetimes as large as the object in length and breadth,and consequently twenty-five times larger in sur-face. In this way small objects may be magnifiedby…
Astronomy · Astronomical instruments · Telescopes
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