134
the lamp itself. Identical lamps operated under different conditions of cost of current must be burned at different efficiencies to make the cost of operation a
Lamps 25 cts. each—Life 1200 hrs. at 3 Watts per Candle.
Current costs 5 cts. per ㏋. per hour.
Fig. 13.
minimum for the production of a given amount of light. In order to determine the maximum efficiency of lamps, therefore, we must know the quality of the lamps referred to some standard, the cost of the lamps to the consumer, and
