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 165
sum of their valuesby 20 we obtain the approximate value of the mean sphericalcandle-power. If the hemispherical candle-power is disired,consider only the areas corresponding to that hemisphere anddivide the sum of the values of the 10 lines by 10. The use of the Rousseau diagram for showing the… … Fig. 86.—The Rousseau diagram applied to curves of Fig. 83. distribution curves as indicated by a, h, c and d, respectively, ofFig. 83. It will be seen that the four areas determined by thecurves a, h, c and d are equal. Since these areas representgraphically to scale the value of the light flux we…
Light · Photometry · Electric lighting
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