114 Scientific Intelligence. 
of 800—-15=53°33 candles, and the total power required (inelud- 
ing on etc.), would be 3,200+-53'33=60, about sixty foot- 
pounds per minute per candle. 
In the vicinity of Boston, power is furnished, per horse — 
at the rate of $180 per year of 313 days of ten hours each, or 
180 
MEya =0°0575. (53 cents) per hour. If only one- 
33,000 
fourth of this power could be utilized as light iipee candles 
the rate of 
ay be the equivalent of one horse power, and would cost 
0575-550=$0.0001046, about one-tenth of a mill per hour per 
als, being about one-tenth the cost of gas light 
t us fora moment take another view of he matter. The 
get 495,000—4—=123,750 Nea, or as light, mae 5 
hour candle 2 from one pound of coal, through the agency of 
steam engine and the magneto-electric machine 
With the psmcieene ivt i battery I have heck able to pees. 
30,00 
130,000 foot-pounds of electricity from one pound of coal= ENT. 60 
=144-4=to about 144 candle lights. 
_ There is a0 another point of view worthy our attention. 
Common gas will yield about ten thousand cubic feet of 
gas per ton. This, at three hour candle lights per cubic foot, 
would Lae (3X10, 000)--2,000=15 hour candle-lights per poun nd 
of ae bout twenty-five cubic feet of illuminating gas weigh 
on 60 Hence one pound of gas, after it is made from the 
bial will yield a light equal to that of a candle for Pigs tei 
hours. One pound of pure carbon, wholly burned to carbon 
acid se yields 14,500 units of heat, equal to 772% 14,500= 
o 
total energy of one pound of pure carbon ¢ oaverted into light, 
it 
15X365 x24 x60 TFS or one year and five months. 
"Thus it will appear that by our ordinary methods of gas light- 
Sud sos ges much less ee one —- cent of the oes stored — 
