Jones, H. Spencer (Harold Spencer), 1890- · London E. Arnold & co. · leaf 335
he Zollner type of photometer, the star under observation. 290 GENERAL ASTRONOMY is compared with the image of an artificial star whose brightnesscan be varied at will until equality between the two images isobtained. An arm is attached to the telescope tube at rightangles to its axis (Fig. 87) and… … Fig. 87.—The ZoUner Photometer. simulate stars of different magnitudes. The divergence of therays is increased by a double concave lens, m, and they thenfall upon a Nicol prism, k, which polarizes the light, i.e. permitsonly the vibrations in one definite plane to pass through. Onemergence from the…
Astronomy
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