Young, Charles A. (Charles Augustus), 1834-1908, Young, Anne Sewell, b. 1871., ed · Boston, New York [etc.] Ginn and Company · leaf 443
atedin half-degrees which are numbered as whole degrees, and socan measure any angle not much exceeding 120°. The index §552] THE SEXTANT. 423 arm, or alidade/ MN in the figure, is pivoted at the centreof the arc, and carries a vernier, which slides along thelimb and can be fixed at any point by a… … Fig. 156. —The Sextant. two inches by one and one-half in size, is fastened securelyto the index-arm, so as to move with it, keeping always per-pendicular to the plane of the limb. At H, the horizon-glass about an inch wide and about the same height as theindex-glass, is secured to the frame of the…
Astronomy · Constellations
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