Lessons in astronomy including uranography. A brief intoductory course without mathematics (1896)
Young, Charles A. (Charles Augustus), 1834-1908 · Boston, London, Ginn and company · leaf 332
THE SEXTANT. 319 observer can determine both the right ascension and declinationof any object which is visible when it crosses the meridian. 420. The Sextant. — All the instruments so far mentioned,except the chronometer, require firmly fixed supports, and are,therefore, useless at sea. The sextant… … Fig. 92. —The Sextant. by pointing first on one and afterwards on the other, but bysighting them both simultaneously and in apparent coincidence.This observation can be accurately made even if he has nostable footing, but is swinging about on the deck of a vessel.Fig. 92 represents the instrument.…
Astronomy
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