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 318
293 focal distance of the small mirror L n 1.5—or 1|inch—its breadth g h 0.6—or ^ of an inch ; thebreadth of the hole in the great mirror UV, 0.5—or half an inch—the distance between the smallmirror and the next eye-glass LR, 14.2; the dis-tance between the two eye-glasses SR, 2.4; thefocal… … Taking this telescope as a standard, the followingtable of the dimensions and magnifying powers ofGregorian reflecting telescopes, as constructed byMr. Short, has been computed. Focal distance of thegreat mirror. Breadth of the greatmirror. Focus of the smallspeculum. i Breadth of the hole inthe…
Astronomy · Astronomical instruments · Telescopes
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