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 240
r-ranging the prisms as shown in Fig. 92, with their bases together, weplace thempoint to point, itis evident thatthe rays fallingupon them willno longer con-verge ; they willin fact separate,or diverge. Wemay suppose a lens formed of an infinite number of prisms,joined together in this way. Such a… … FlG -Bi-concave Lens, causing Parallel Eatsto diverge. principle on which we see. 422. In order that we may see, what is essential ?Explain the principle of the common magnifying-glass. 423. Explain the actionof a bi-concave lens. 424. What kind of an image would we naturally expect a 234…
Astronomy
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