A high-school astronomy: in which the descriptive, physical, and practical are combined .. (1853)
Mattison, Hiram, 1811-1868 · New York, F. J. Huntingdon [etc.] · leaf 236
lector is so called from M.Cassegrain, its inventor. It resembles the Gregorian,except that the speculum placed in the focus of the re-flector is convex, instead of concave. 534. The Herschelian Reflector differs from all others,in having no small reflector whatever; the light beingreflected back… … Here the concave speculum is seen to be inclined a little to the lower side of thetube, so that the parallel rays A are reflected back to the observer at B, at the side ofthe instrument, where the eye-piece is placed. 535. The first telescope constructed upon this plan wasthat by Sir William…
Astronomy
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