Elementary natural philosophy : designed for high schools and academies (1881)
Griffin, La Roy F. (La Roy Freese), 1844-1916 · Philadelphia : Sower, Potts & Co. · leaf 206
688. Refraction by the Air. The air constantly increas-es in density from its outer limits to the surface of theearth. Hence the effect upon thelight is the same as though it con-sisted of a series of concentric layersof different media. As the light reach-es each one of these, it is refractedFig.…
Physics
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