The geography of the heavens, and class-book of astronomy: (1858)
Burritt, Elijah H. (Elijah Hinsdale), 1794-1838, Mattison, Hiram, 1811-1868 · New York, Mason brothers · leaf 317
placed in the focus, and theobject-glass directed toward any desired object. 691. The object-glass of a telescope is usually protected, whennot in use, by a brass cap that shuts over the end of the instru-ment ; and the eye-pieces, of which there are several, of differ- 689. Galilean telescope ?… … ent magnifying powers,are so fixed as to screwinto a small movable tubein the lower end of theinstrument, so as to adjustthem respectively, to thefocus, and to the eyes ofdifferent observers. Suchtelescopes usually repre-sent objects in an invert-ed position. The adjoining cut represents…
Constellations · Stars
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