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 226
ust be placed furtherapart. Under these conditions the polar curve must be made up of acombination of those shown in Figs. 112 and 113, i.e., each lampmust uniformly illuminate a section of the area beneath itselffrom which the illumination may then assume a constant declinereaching zero value…
Light · Photometry · Electric lighting
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