Warren, Samuel Edward, 1831-1909. [from old catalog] · New York, J. Wiley & sons · leaf 22
considered. For, by way of a simple example of simui.taneous illumination from several points, let a sphere be exposedto the light from a finite luminous straight line. Each point ofsuch a line would be the vertex of a separate tangent cone ofrays, whose circle of contact with the sphere would be…
Shades and shadows
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