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 331
s instrument (Art. 81), it is necessary also to have thenadir point as a zero ; i.e., the circle-reading which correspondsto the vertical position of the telescope. This point is foundby pointing the telescope down towards a basin of mercury 318 APPENDIX. [§419 beneath it, and setting it so that… … Fin. oi.— A Meridian Circle. (north) horizontal point and the polar point is the latitude ofthe observatory. Obviously the instrument can also be used as a simple tran-sit instrument in connection with a clock, so that (Art, 99) the §419] THE SEXTANT. 319 observer can determine both the right…
Astronomy
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