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 140
ndescent lamp is found very satisfactory as astandard; it should, however, be calibrated before and after eachtest. PORTABLE PHOTOMETERS 125 The Weber photometer is now made in a more portable formand with some modifications as shown in Fig. 59. The screenis fixed relative to the photometric… … FiG. 59.—Portable form of Weber photometer. along the photometric axis. This photometer is designed toemploy the Hefner lamp as a standard. The result indicatedby the position of the standard lamp when a balance is obtained,is in terms of a unit of illumination intensity. The range isincreased by…
Light · Photometry · Electric lighting
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