Six lectures on light : delivered in America in 1872-1878 (1886)
Tyndall, John, 1820-1893 · New York : D. Appleton · leaf 41
rge opening (L, fig. 2),from which the lens has been removed, and which isclosed at present by a sheet of tin-foil. Pricking bymeans of a common sewing-needle a small aperture inthe tin-foil, an inverted image of the carbon-pointsstarts forth upon the screen. A dozen apertures willgive a dozen… … Eemoving the tin-foil altogether, the screen becomesuniformly illuminated. Hence the light upon thescreen may be regarded as the overlapping of innumer-able images of the carbon-points. In like manner thelight upon every white wall on a cloudless day may beregarded as produced by the superposition…
Light
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