Elements of astronomy ... with explanatory notes, and questions for examination (1855)
Brocklesby, John, 1811-1889 · New York, Farmer, Brace & co. · leaf 113
ecliptic is likewise observed, we have the means ofsolving this problem. It is a law in optics, that the ap-parent magnitude of a body is inversely proportioned toits distance;1 that is if at a certain distance it appears ofa certain size, when ten times nearer it will appear tentimes larger, and… … from the eye at C. At the distanoe CB1 the body A is seen under theangle DCL1 which is 10°. Ten degrees is at this distance its apparentdiameter. At the distance CB which is twice CB1 the apparent diameterof A is LCD, the half of DCL1 or an angle of five degrees. Thus the lawis proved. : —. -^ _…
Astronomy
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