A popular handbook and atlas of astronomy, designed as a complete guide to a knowledge of the heavenly bodies and as an aid to those possessing telescopes (1891)
Peck, William, Sir, 1862-1925 · New York, G. P. Putnam's Sons · leaf 173
utthree inches aperture, or a silvered glass reflector with a diameter of about four inches. By means ofsuch an instrument, which may conveniently be used at an open window, striking views can be obtainedof the more interesting celestial objects, as it would reveal the spots in the sun, the… … Fig. 40. the sextant.T, Telescope. I, Index Glass. S, Horizon Glass. D, Dark Glasses. hundred times, depending on the kind of object examined, ASTRONOMICAL INSTRUMENTS. 109 The magnifying power of any telescope depends entirely on the proportion between the focal lengthsof the object-glass and…
Astronomy
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