The heavens above: a popular handbook of astronomy (1882)
Gillet, J. A. (Joseph Anthony), 1837-1908 · New York, Chicago, Potter, Ainsworth, & Co. · leaf 35
i6 ASTRONOMY. … circle, and 7 of the vernier to coincide with 13 of thecircle. The reading of the circle will then be 6-j7^. 13. Hour Circles. — Great circles perpendicular to thecelestial equator are called hour circles. These circles all pass through the poles ofthe heavens, as shown inFig. 18. E Qii the…
Astronomy
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