Lessons in astronomy including uranography. A brief intoductory course without mathematics (1896)
Young, Charles A. (Charles Augustus), 1834-1908 · Boston, London, Ginn and company · leaf 327
ofwhich can be moved witha fine screw with a grad-uated head, so that thedistance between the two wires? can be varied atpleasure, and then readoff by looking at themicrometer head. Fig. 87represents such an instru-ment attached to a telescope: the spider threads are in thebox BB, and are viewed… … Fig. 87. — The Filar Position Micrometer. §416] THE ASTRONOMICAL CLOCK, ETC. 815 Ys, which are firmly set upon some sort of framework or onthe top of solid piers, and so placed that the axis will be ex-actly east and west and precisely level. When the telescopeis turned on its axis, the mid-dle…
Astronomy
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