The heavens above: a popular handbook of astronomy (1882)
Gillet, J. A. (Joseph Anthony), 1837-1908 · New York, Chicago, Potter, Ainsworth, & Co. · leaf 38
ope is mounted on/ MM two axes, — one par- allel with the axis ofthe earth, and theother at right anglesto this, and thereforeparallel with the planeof the earths equator.The former is calledthe polar axis, andthe latter the declina-tion axis. Each axiscarries a graduatedcircle. These circlesare… … 20 ASTRONOMY. the line of sight will describe a diurnal circle ; so that, whenthe tube is once directed to a star, it can be made to fol-low the star by simply turning the telescope on its polar axis. In the ca.se of large instruments of this class, the polaraxis is usually turned by clock-work at…
Astronomy
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