Page:Incandescent electric lighting- A practical description of the Edison system.djvu/142

This page has been proofread, but needs to be validated.

131

case, other conditions being the same. The minimum total cost is $400, and the maximum efficiency 3.175 watts per candle.

The curve, Fig. 11, illustrates the case

Lamps 50 cts. each—Life 600 hrs. at 3 Watts per Candle.

Current costs 5 cts. per ㏋. per hour.

Fig. 10.

of very cheap and very good lamps, with moderate cost of current. The minimum total cost is low, $294, while the lamps are run at the high efficiency of 2.38 watts per candle.