Recreations in astronomy : with directions for practical experiments and telescopic work (1879)
Warren, Henry White, 1831-1912 · New York : Harper & Brothers · leaf 52
V light sot in a room is soon from every place; hence light streams iaevery possible direction. If put in the centre of a hollow sphere, every point of the surface will be equally illumined. If put in a sphere oftwice the diameter, the same light will fall on all the larger surface. Thesurfaces o(… … Fig. 7. parent that the light that falls on the first square is spread, at twice thedistance, over the second square, which is four times as large, and at threetimes the distance over nine times the surface. The varying amount oflight received by each planet is also shown in fractions above each…
Astronomy
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