Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 196
t the use of anv COtOtU ii or filter brought about aconsiderable falling off in the efficiencyof the light Bource because even he ;of these screening device-; absorbed any-thing from oil to 80 per cent, of the light.This was a very important factor indeedwhen illuminating a large area bugs as that… … FIG. 3.—Showing light and shade in low-relief objects lighted by semi-indirect arc lamps.
Lighting
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