The geography of the heavens : and class-book of astronomy : accompanied by a celestial atlas (1860)
Burritt, Elijah H. (Elijah Hinsdale), 1794-1838, Mattison, Hiram, 1811-1868 · New York : Mason Brothers · leaf 319
ed to the lower end of the large one—it maybe kept in view by the clockwork for any desirable length of time. A telescope thus fur-nished with right ascension and declination circles is called an Equatorial, or is said tobe equatorially mounted, because it sweeps east and west in the heavens… … 692. How refractors mounted, and why? When equatorial, and why?object-glasses made ? What a lem ? A Barlow lens? 693. How TELESCOPES REFRACTORS AND REFLECTORS. 317 towards each other, or with a thin double concave glass betweenthem. They are thus double, or triple ; but when thus con-structed, the…
Constellations · Stars
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