Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 149
illu-mination betAveen two adjacent sur-faces. Tlius one may take (I) a, 136 THE ILLUMINATING ENGINEER. reading of the illunii nation on thebrighter portion, and (2) a corre-sponding reading for the darker portion,and then subtract (2) from (1), andexpress as a percentage ratio withregard to (1).… … Fig. 20.—Distribution curve of hare lamp andsame lamp with various Holophane reflectors. Figs. 21 and 22 are interesting asillustrating in a practical way theeffect of an extension of the area ofthe hght source in subduing shadows.A lamp was arranged 8 ft. above theground and near a stanchion,…
Lighting
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