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 240
e vertical distance of the point belowthe ceiling. At all points along a side wall at a distance below the ceilingequal to the normal distance of this wall from the center of thelighting source the vertical component of the flux density is equalto the equilux sphere value, being equal obviously to… … Figs. 130 and 131.—Wall illumination. correspondingly less. For example, with a distance of 3 radiibetween the wall and the source (Fig. 131) the normal illumina-tion on the wall is equal to the equilux values at a distance of3 radii below the ceiling; at 1 radius it is three times as great asthe…
Light · Photometry · Electric lighting
Internet Archive · Boston Public Library · Public Domain Mark 1.0. Free to use for anything.
