Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 170
Fig. 2.—By the use of the specialcondensor, C, placed muchnearer to the filament of thelamp, L, and the sphericalmirror, M. behind it, a muchlarger proportion of the totalflux is usefully employed. denser isis placedside and this means as much as 75 degrees of thelight-flux were intercepted. The…
Lighting
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