Light, photometry and illumination : a thoroughly revedof ''Electrical illuminating engineering'' . onditions and learn how approximately the infinitedimension relationship may apply in practice. For this purposethe writer has chosen the 100-watt tungsten unit equipped withthe intensive type of high efficiency reflector. This type ofreflector is so designed that when used with the proper lamp andthe units are properly placed approximately uniform illuminationon the working plane will be obtained. PRINCIPLES OF INTERIOR ILLUMINATION 267 The distribution of light in a vertical plane through the
Light, photometry and illumination : a thoroughly revedof ''Electrical illuminating engineering'' . onditions and learn how approximately the infinitedimension relationship may apply in practice. For this purposethe writer has chosen the 100-watt tungsten unit equipped withthe intensive type of high efficiency reflector. This type ofreflector is so designed that when used with the proper lamp andthe units are properly placed approximately uniform illuminationon the working plane will be obtained. PRINCIPLES OF INTERIOR ILLUMINATION 267 The distribution of light in a vertical plane through the axisof this type of lighting equipment is shown in Fig. 158. Thispolar curve shows only the intensity of the light in differentdirections in a vertical plane and gives no clue as to the resultingillumination. The illumination due to one lamp placed 12 the reference plane is indicated by curve I^ of Fig. two lamps are placed 15 ft. apart and 12 ft. above the planethe illumination along a line beneath the two lamps will beapproximately uniform as indicated by curve I^ of Fig. 654321012345678Feet from Midway between Sources. Fig. 160.—Illumination due to one and two 250-watt Tungsten lampsequipped with intensive, extensive and focusing types of reflectors. With a distance of 15 ft. between lamps, 12 ft. is the minimumheight of suspension which will secure approximately uniformillumination. The two lamps can be placed at greater heightswith the same spacing without impairing the uniformity ofillumination, although the intensity of illumination will be investigate the effect of the height of suspension of lampsabove the plane illuminated the writer has assumed a room75 by 75 ft. in size and lighted by the equipment just lamps are placed, according to common practice, at thecenters of equal areas each 15 ft. square in this case, as shownin Fig. 161. The reflection from walls and ceiling is neglected, 268 LIGHT, PHOTOMETRY AND ILLUMINATIO
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectlight, bookyear1912
