Newcomb, Simon, 1835-1909, Holden, Edward Singleton, 1846-1914, joint author · New York, H. Holt and Company · leaf 85
object. In reflecting telescopes (reflectors) theobjective is a mirror of speculum metal or silvered glassground to the shape of a paraboloid. The figure showsthe action of such a mirroi on a bundle of parallel rajs,which, after impinging on it, are brought bj reflection toone focus F. The image… … Fig. 24.—concave mirrok forming an image. have to be placed to the right of the point F, and theobservers head would thus interfere with the incidentlight. Various devices have been proposed to remedj thisinconvenience, of which we will describe the two mostcommon. The Newtonian Telescope.—In this…
Astronomy
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