Light, photometry and illumination : a thoroughly revedof ''Electrical illuminating engineering'' . f light distributions which willgive uniform illumination from a line of light units along a lineextending immediately under those units. Other considerationsthan the obtaining of uniformity must therefore serve to enableus to select the most desirable distribution curve. Two such considerations are of especial importance and maytherefore be applied with especial propriety. First, we shouldseek such a distribution as will be best suited for actual, practical 296 LIGHT, PHOTOMETRY AND ILLUMINATIO
Light, photometry and illumination : a thoroughly revedof ''Electrical illuminating engineering'' . f light distributions which willgive uniform illumination from a line of light units along a lineextending immediately under those units. Other considerationsthan the obtaining of uniformity must therefore serve to enableus to select the most desirable distribution curve. Two such considerations are of especial importance and maytherefore be applied with especial propriety. First, we shouldseek such a distribution as will be best suited for actual, practical 296 LIGHT, PHOTOMETRY AND ILLUMINATION attainment. This consideration is of the more importancebecause, as we shall find, even when maximum weight is giventhis consideration, our derived curve will present considerablethough by no means insurmountable difficulties of practicalrealization. Second, the illumination at any point should bederived from a source as near as possible in order to avoid bothexcessively long shadows, and the glare effect which results fromthe high candle-power made necessary by illumination at greatdistances. Fig. 177.—Distribution of illumination (lamps staggered). Fig. 177 shows a sine wave type of illumination curve. Thisdistribution curve has a relatively low maximum and is as welladaptable to practical realization as any curve obtainable. Ithas, however, one defect. The maximum value occurs at anangle considerably greater than that subtended by half the sepa-ration of the units. To obtain minimum glare effect, the angleof maximum candle-power should be as small as possible in ^ f^ t^ t^
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectlight, bookyear1912
