Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 169
Fig. 32.—The old and the- new. Old arm fitting (\) and cluster fitting (b) for vacuum lamps. Type of semi-indirect unit (o) for gas-filled lamps. … Fig. 35.-New holophane reflector-refractor for gas-filled lamps and polar curve.
Lighting
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