Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 84
Fig. 8.—Middle Holing. … Fig. 9.—Bottom Holing. Typical Positions assumed by the Miner at work. 74 THE ILLUMINATING ENGINEER (march, 1920) by Trotter Illumination, page 173.)Given equal candlepower, up to fivecandlepower, are the yellow rays of thecandle or oil lamp more restful to theeyes than the hard white electriclight…
Lighting
Internet Archive · University of Toronto Libraries · Public Domain Mark 1.0. Free to use for anything.
