The elements of theoretical and descriptive astronomy, for the use of colleges and academies (1901)
White, Charles J. (Charles Joyce), 1839-1917 · New York, J. Wiley & sons; · leaf 47
. [See Note A, page 2G8J 42 SEXTANT. THE SEXTANT. 40. The sextant is an instrument by which the angular dis*tance between two visible objects may be measured. It is usedchiefly by navigators; but its portability gives it great valuewherever celestial observations are required. The angles forthe… … ■oh Fig. 14. of a sector of a circle, the arc of which comprises 60°. A movablearm, CD, called the index-bar, revolves about the centre of thesector. This bar carries at one extremity a vernier, D. At theother extremity of the index-bar, and revolving with it, is placeda silvered mirror, C, the…
Astronomy
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