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 145
HT, PHOTOMETRY AND ILLUMINATION diaphragms, D and D\ which are used to vary the intensity andeffect equality of illumination upon screen B. The adjustmentof these diaphragms indicates the result of the photometricsettings. The comparison lamp, C, is a flat-flame gasoline lamp.The instrument is… … Fig. 68.—The Lumeter. it is desired to study the illumination. This plate can be rotatedthroughout a vertical plane about the photometric axis. B isa Lummer-Brodhun cube through which the lower surface of thetest-plate, A, is viewed. Through the prisms, B, may be viewedalso the translucent plate G,…
Light · Photometry · Electric lighting
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