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 195
Fig. 103.—Macbeths calculator. the line. Hold the two disks, and bring the runner to 5 on theheight scale. Under the runner on the outer scale read 542. Todetermine the position of the decimal point with both disks set, … Fig. 104.—Macbeths calculator. refer back to zero angle, from which we note that the equivalentcandle-power at 0° 20 is 1.35. The decimal point may then bereadily determined by I jh^ or 1.35/25, which equals 0.05 roughly,indicating that the previous reading should be .0540. ILLUMINATION…
Light · Photometry · Electric lighting
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