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 149
ctionis shown in Fig. 71, has a test-plate, A, upon which the light tobe studied falls and which is also a portion of the photometricdevice, B. The comparison lamp, C, illuminates a piece ofbristol board, D, which may be inclined at any desired angle.Through slits in the surface. A, portions of the… … Fig. 72.—Trotters universal photometer. The Trotter universal photometer^ is shown in Fig. 72. Thecomparison source is an incandescent lamp the distance fromwhich to the mirror M can be varied as indicated in the figure.The rays from this lamp are reflected by the mirror onto awhite diffusing…
Light · Photometry · Electric lighting
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