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 247
case. To calculate the normal candle-power of anelement dl at B, a summationwould be made of the luminousintensities in the direction of Pof elementary areas of the stripdl. As the summation would becarried over only the arc HBC,the computed normal candle-power, lo, would be less thanwhen… … Fia. 135.—Sections of tube illumi-nating point P. than 6 Fig. 134, will be somewhat less than /<, cos d. The tube is not, however, a solid radiating body, but giveslight by the luminosity of a gas, hence consideration on this latterbasis will lead to more correct conclusions. Experiment…
Light · Photometry · Electric lighting
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