A text-book of general astronomy : for colleges and scientific schools (1888)
Young, Charles A. (Charles Augustus), 1834-1908 · Boston ; London : Ginn & Company · leaf 71
er, at an elevation h above A. The line OH is truly horizontal, while the tangent line, OB, corresponds to the line drawn from the eye to the visible horizon. The angle HOB is the dip. This is obviously equal to the angle OCB at the centre of the earth, if we regard the earth as spherical, as we… … FlG. 33. — Dip of the Horizon. cos A = R + h This formula is exact, but inconvenient, because it gives the small angleA by means of its cosine. Since, however, 1 —cos A = 2sin2.^ A, we easilyobtain the followiinr:— sin i A: V, h 2 (R + h) DIP OF THE HORIZON. 59 This gives the true depression of the…
Astronomy
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