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 117
meters was made by Whitman. Its construction is illus-trated in Fig, 46. The disk BD, constructed as shown at the left,revolves around its axis A. When in the position shown at theright it presents to the eye of the observer at 0 a surface illumin-ated by /j. When B has revolved from in front of… … Fig. 46.—The Whitman flicker photometer. surfaces are presented to the eye in rapidly alternating succession,and a balance is obtained by varying the intensity on one surfaceor the other as in the case of the ordinary type of photometerhead. The Simmance-Abady flicker photometer consists…
Light · Photometry · Electric lighting
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