Light, photometry and illumination : a thoroughly rev. ed. of ''Electrical illuminating engineering'' (1912)
Barrows, William Edward, 1878-1960 · New York ; London : McGraw-Hill Book Co. · leaf 238
that point, so that the values of equilux density are simul-taneously the values of light flux density normal to the horizontalplane (floor). Expressed in other words, the illumination alongthe floor at any point is known at once ^/hen one has determinedthe value of light flux density on the… … 7654 3210 12-3456 7Figs. 127 and 128.—Floor illumination for two ceiling heights. been constructed. One could not well wish for a simpler solution.It is especially worthy of note that the square of any diagonalsuch as AD—which is used in calculating the value of the illumi-nation density on each…
Light · Photometry · Electric lighting
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