Newcomb, Simon, 1835-1909, Holden, Edward Singleton, 1846-1914, joint author · New York, H. Holt and Company · leaf 86
e thej reach theprincipal focus. The rajs are thus reflected out lateralljthrough an opening in the telescope tube, and are therebrought to a focus, and the image formed at the pointmarked bj a lieavj white line in Fig. 25, instead of atthe point inside the telescope marked bj a dotted line.… … Fig. 25.newtonian telescope. Fig. 26.cassegrainian telescope. The Cassegrainian Telescope.—In this form a second-ary convex mirror is placed in the tube of the telescope 08 ASTRONOMY. about three fourths of the way from the large speculumto the focus. The rays, after being reflected from thelarge…
Astronomy
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