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 170
l line. The first arc is drawnfrom -f 10° to — 10° with the radius equal to the mean horizontalintensity. The Fluxolite Paper.—The fluxolite diagram devised by-Mr. Wohlauer offers a convenient means of determining theluminous flux and spherical candle-power. The value of theflux is obtained by… … 0° 15° 30 Fig. 90.—Wohlauers fluxolite paper. It can be shown geometrically that the altitude and hence thearea of a zone is proportional to the sine of the angle, measuredfrom the vertical axis, which bisects the zone. Hence if theimaginary spherical area be divided into n numbers of equi-angular…
Light · Photometry · Electric lighting
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