The elements of natural philosophy : copiously illustrated by familiar experiments and containing descriptions of instruments, with directions for using : designed for the use of schools and academies (1856)
Sprague, A. W. (Alfred White), 1821-1891 · Boston : Phillips, Sampson & Company · leaf 333
may be learned, and their injurious results therebyguarded against. In a word, this instrument enables our visionto explore fields of beauty and variety before undiscovered,but replete with interest, as bearing upon our physical well-being and happiness. 312. The Telescope^ is an instrument for… … arrangement of the more common form of this telescope, knownas the Gregorian Telescope. In a large open tube is fixed ahighly polished metallic concave speculum,! ni m, havinga circular aperture in its centre. The rays, r r\ entering found in Bohemia, consists almost entirely of tlie skeletons of…
Physics
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