Elementary astronomy; a beginner's text-book (1899)
Holden, Edward Singleton, 1846-1914 · New York, H. Holt and company · leaf 167
RONOMY. becomes fatigued with the extreme attention required for astronomi-cal observing. The photographic plate is not subject to fatigue. Ithas certain disadvantages that need not be discussed here, and theplate will never supersede the eye. On the other hand, it hasalready been of immense… … Fig. 90.—The Sextant.The radius of its divided circle is usually from 6 to 10 inches. used by navigators at sea. It was invented by Sm Isaac Newton,and quite independently by Thomas Godfrey, a sea-captain ofPhiladelphia. The figure shows its general appearance. Its pur-pose is to measure the…
Astronomy
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