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 174
g themidzone values upon the line OK or upon another line 24° 3above the horizontal, and transposing to the horizontal as above.The simplicity of this method is manifest. The only apparatusnecessary is a pencil and piece of paper and the only calculationis simple addition of the nine or eighteen… … 0^ 5 15 25^ 35 45 55 Fig. 92.—Modification of Wohlauers method. It is obvious that this method may be applied to any distri-bution curve plotted upon polar coordinate paper. In this casea series of vertical lines together with the radial line, Fig. 93,laid on a quadrant of transparent celluloid,…
Light · Photometry · Electric lighting
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