Newcomb, Simon, 1835-1909, Holden, Edward Singleton, 1846-1914, joint author · New York, H. Holt · leaf 86
e rays are thus reflected out laterallythrough an opening in the telescope tube, and are therebrought to a focus, and the image formed at the pointmarked by a heavj white line in Fig. 25, instead of atthe point inside the telescope marked by a dotted line. REFLECTING TELESCOPES. 67 This focal image… … FTG. 26.CASSEGRAINIAN TELESCOPE. The Cassegrainian Telescope.—In this form a second-ary convex mirror is placed in the tube of the telescope 68 ASTRONOMY about three fourths of the way from the large speculumto the focus. The rajs, after being reflected from thelarge speculum, fall on this mirror…
Astronomy
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