A high-school astronomy: in which the descriptive, physical, and practical are combined .. (1859)
Mattison, Hiram, 1811-1868 · New York, Mason brothers · leaf 236
o a focus, andenters the eye of the observer at C. This telescope has no eye-piece. 530. The focal distance of a concave reflector is equalto half the radius of the sphere formed by the concave 528. What is a comet seeker f Why necessary ? 529. Describe a reflecting telescope. Simplest form ?580.… … Here the curve of the speculum B is that of a circle, whose cen-ter is C; while the focus of the speculum is at D, which is onlyhalf the distance from B to C. 531. Reflecting telescopes are of several kinds—viz.,the Gregorian, the Newtonian, the Cassegranian, theHerschelian, &c. The Gregorian…
Astronomy
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