Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 151
lty A\dth artificial hglitingin practice is to reproduce the bestdirect daylight conditions with themeans at our disposal. Artificial directsystems should, in order to comparefavourably Avith direct dayhght, comply 138 THE ILLUMINATING ENGINEER. approximately witli the following con-ditions :— (a)… … Fig. 23.—Showing shadow-tester illuminated by direct light. (6) Distribute over the lower hemi-sphere 80 per cent of tlie light. (c) Diffuse into the upper hemi-sphere 20 per cent of the light. (d) Give fairly uniform illumina-tion over the working planes. (/) Give a horizontal illumination,and…
Lighting
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
