Lamp Tests

—M. André Larnaude, as the result of a series of tests, estimates that the life of an incandescent lamp inereases much more rapidly than its efficiency decreases, also that lamps run so as to absorb. 25 watts per candle, last for ae hours 3.0 3.5 oe “se és Le. et 700 <5 4.0 t “ o “e « 4900 “ Very different figures are given by Siemens and Halske of Berlin, whose experiments tend to show the following to be the duration of 16 candle power ləmps: 1.5 watts per candle, last for 45 hours PLE F‘ a ù “66 29g + 2 3.0 5 “A u ad.& ae t t6 “ ae e 4000 450 ae « 3.5 sé té é ee se 1000 sé After a lamp has burned 500 or 600 hours it is more economical to replace it with a new one if the price of current is that usually charged by central stations A lamp will give only 60 to 70 per cent of its rated power during the later half of its life.