An elementary book on electricity and magnetism and their applications . -quently lamp manu-facturers often givethe mean horizontalcandle power and thereduction factor, whichwhen multiplied bythe mean horizontalcandle power gives themean spherical candlepower. Thus, in thecurve A (shown infigure 327) the spheri-cal reduction factorwould be andconsequently themean spherical candle power is , or 510. Since for street lighting it is the distribution of light in thelower hemisphere which is important, the manufacturers oftenstate the mean hemispherical candle power and in discussingef
An elementary book on electricity and magnetism and their applications . -quently lamp manu-facturers often givethe mean horizontalcandle power and thereduction factor, whichwhen multiplied bythe mean horizontalcandle power gives themean spherical candlepower. Thus, in thecurve A (shown infigure 327) the spheri-cal reduction factorwould be andconsequently themean spherical candle power is , or 510. Since for street lighting it is the distribution of light in thelower hemisphere which is important, the manufacturers oftenstate the mean hemispherical candle power and in discussingefficiency state the watts per mean hemispherical candlepower. For example, a certain 300-watt luminous or magnetitearc lamp, when tested, shows the distribution curves whichare given in figure 328. In curve .4 the mean spherical candlepower is 763 and the mean hemispherical candle power is711, while in curve B the mean spherical candle power is 607and the mean hemispherical candle power is 1035. This showsan efficiency of watts per mean hemispherical candle Fig. 327. — Distribution of light. Curve Awithout shade, curve B with shade. ELECTRIC LIGHTING 465
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmagnetism, bookyear19
