Light, photometry and illumination : a thoroughly revedof ''Electrical illuminating engineering'' . 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^. Fig. 17
Light, photometry and illumination : a thoroughly revedof ''Electrical illuminating engineering'' . 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^. Fig. 178.—Distribution of illumination (lamps staggered). order that the light source may be removed as far as possiblefrom the center of the field of vision when the eye reaches thepoint toward which the maximum candle-power is directed. Many types of illumination curve could be given and thecorresponding distribution curves shown to be open to it to say that it can be established by a mathematicalline of reasoning, which space limitations do not permit to be PRINCIPLES OF STREET ILLUMINATION 297 here given in detail, that the curve which best meets the condi-tions imposed is such as shown in Fig. 178. This curve isformed by two circle quadrants combined as shown. The cor-responding distribution curve shows a low maximum whichoccurs at a slightly smaller angle than that subtended by halfthe separation of the units. It is also as well adaptable topractical realization as any curve obtainable. We have, therefore, obtained the ideal illumination curvefrom which the d
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectlight, bookyear1912
