Elements of astronomy: accompanied with numerous illustrations, a colored representation of the solar, stellar, and nebular spectra, and celestial charts of the northern and the southern hemisphere (1875)
Lockyer, Norman, Sir, 1836-1920 · New York, D. Appleton and company · leaf 238
r plane. One side concave, the other plane. Fig. 91.—DifferentKinds of Lenses. 418. Refraction by Convex Lenses.—A prism refracts aray of light as shown in Fig. 89 ; hence, two prisms ar-ranged as in Fig. 92 would cause two parallel beams com-ing from differ-ent points at aand b, to con-verge at…
Astronomy
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