Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 268
r must be chosen which cannot \>-seen. In the case of a flickering lightthe point i balance continuallymoves. The illumination corresponding toeach perforation is ascertained by cali-bration in a photometric laboratory.The lamp is supplied by a portablebattery, and so long as the voltage ismust… … Fig. 2.—View of Supplementary Flare Photometer. tends nearly the whole length of thetube, and this is covered with a stripof thin metal having perforations in theform of letters or numbered and gradu-ated slits. This strip is painted whiteand receives the illumination to bemeasured. Since the…
Lighting
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