Johnson's natural philosophy and key to philosophical charts : illustrated with 500 cuts; being reduced photographic copies of all the diagrams contained in the author's philosophical series of indestructible school charts ; for the use of schools and families (1878)
es, termed the eye-piece. The manner in which the component parts are arranged, togetherwith the nature of the auxiliary pieces, determines the particular kindof telescope. ^80. Figure 22. — The refracting astronomical tele-scope.—This instrument consists essentially of two convex lenses,the one,… … placed at a distance from the image, T, equal to its principal focal dis-tance. The pencils of light from this image are refracted and con-verged to the eye, so as to form a visual angle many times larger thanit would be if the object were viewed with the naked eye; and, conse-quently, the object…
Physics · Astronomy
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