Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 125
Fig. 16.—Polar Curve of 230 v. 100 w. gas-filled lamp in conjunction with Semi-indirect 10 in. Opal Bowl and Over Re-flector shown in Fig. 4b (Over Reflectorjust full of light).
Lighting
Internet Archive · University of Toronto Libraries · Public Domain Mark 1.0. Free to use for anything.