Science for beginners . he open flame jet, or fish tail burner,usually burns about 5 cu. ft. of gas per hour. If gas costs$ per 1000 cu. ft. the cost per hour for gas is about 5mills for an open flame jet. When gas is burned in a Welsbach mantle it is generallyconsumed at the rate of from 3% to 5 cu. ft. per hour. Thecost for gas, is, therefore, from 3% to 5 mills per hour. Electricity is sold by the watt-hour or kilowatt-hour is equal to 1000 watt-hours. The ordinary NATURAL AND ARTIFICIAL LIGHTING 63 house meter reads off directly the number of kilowatt-hours ofcurrent
Science for beginners . he open flame jet, or fish tail burner,usually burns about 5 cu. ft. of gas per hour. If gas costs$ per 1000 cu. ft. the cost per hour for gas is about 5mills for an open flame jet. When gas is burned in a Welsbach mantle it is generallyconsumed at the rate of from 3% to 5 cu. ft. per hour. Thecost for gas, is, therefore, from 3% to 5 mills per hour. Electricity is sold by the watt-hour or kilowatt-hour is equal to 1000 watt-hours. The ordinary NATURAL AND ARTIFICIAL LIGHTING 63 house meter reads off directly the number of kilowatt-hours ofcurrent used. This watt hour-meter, or watt-meter, asit is usually but erroneously called, is really little more thana very small and easy running motor (Fig. 54). A verysmall portion of the current passing through this meter runsthe motor which, in turn, operates a chain of gear wheelswhich turn the hands before the dials (Fig. 54). The usualcost of electric current for lighting purposes is from 8 to15 cents per Fig. 54.—A watt-hour meter The common carbon filament lamps are made in severalsizes; the sizes most commonly used are the 50-watt lampand the 100-watt lamp. If electricity sells for 10 cents perkilowatt-hour, the current for the 50-watt lamp costs 5 millsper hour; the current for the 100-watt lamp costs 10 mills, or1 cent per hour. The tungsten filament lamp is also made in several sizes;the sizes most commonly used for resident lighting are the25-watt lamp, the 40-watt lamp, and the 60-watt lamp. There-fore, at 10 cents per kilowatt-hour for current, these lamps 64 THE PRODUCTION AND USE OF LIGHT cost about 2y2 mills, 4 mills, and 6 mills, respectively, perhour. Exercise 24.—Reading the Common House Kilowatt-hour Meter Study carefully the dial of a watt-hour meter and see how itdiffers from the dial of the gas meter, Figs. 22, 23, 24 and that the number of cubic feet indicated above each dial onthe gas meter shows the amount of gas used while th
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscience, bookyear1921
