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 295
ght of8 ft. 6 in. from the floor and the reference plane at which illu- Paper read before the Chicago Section of the Illuminating Engineering Society, Feb.,1912. 280 LIGHT, PHOTOMETRY AND ILLUMINATION mination measurements were made with a Sharp-Millar photom-eter was 30 in. from the floor.… … 0.20 0.30 0.40 0.50 O.CO 0.70 Coefficient of Reflection of WallsFig. 169.—Relative illuminating efficiencies for various types of reflectors,with medium colored (40 per cent, coefficient) ceiling. Small or mediumsized rooms with the distributed unit type of installation; Two interiors were used.…
Light · Photometry · Electric lighting
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