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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 36

An illustration from Light, photometry and illumination : a thoroughly rev. ed. of ''Electrical illuminating engineering'', 1912, leaf 36 — the substitutionmethod. For this purpose a tungsten lamp with a frosted bulband operating a little above normal voltage proves very satis- COLOR VALUES OF ILLUMINANTS 21 factory. It may be placed near the colored slits and a strip offlashed opal glass will serve to diffuse and equalize the… … Fig. 9.—Vertical section of colorimeter. observer sees a divided field, one-half of which is illuminated bya mixture of the three primary colors, and the other side by thelight to be investigated. The rotating lenses are at A and aredriven by a small motor. Focusing lenses are shown at F and /.The…

Light · Photometry · Electric lighting

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