io6 ELECTRIC LIGHTING. 



Each of the currents produced by this kind of machine is 

 able to light four Jablochkoff candles, and consequently each 

 system of machines maintains 16 electric candles. There 

 are, it is true, two candles lighted at once in each lamp in 

 the Place de r Opera, but there is only one in the lamps of the 

 Avenue de r Opera and in those of the Place du- Theatre 

 Fran$ais. 



Experiment has shown that about i horse-power of motive 

 force must be reckoned for the maintenance of each of these 

 candles, which, however, last little more than one hour and 

 a half. But to this subject we shall presently return. 



In Fig. 34 the machine is shown with one half in section, 

 the other half in elevation. It will be seen that the electro- 

 magnetic system is covered up by a cast-iron frame at the 

 two ends, and by a casing of wood on the curved part. 



Gramme has recently constructed a new form of these 

 machines, in which the thickness of the wire in the induced 

 -coils, their grouping, and their connection with each other, 

 have been so adjusted as to supply the maximum effect with 

 the Jablochkoff candles, while using the least possible motive 

 force. With a horse-power of 4 a machine of small size was 

 capable of lighting eight candles. 



This machine is moreover able to supply at pleasure 

 8, 6, or 4 lights. In the former case it absorbs a horse- 

 power of 4!; in the second, 2 '8 horse-power; in the third, 

 2-1 horse-power. These lights are equal to 25 gas-jets, and 

 the Jablochkoff candles which supply them have carbons 

 3 millimetres in diameter. RapiefFs machine, mentioned on 

 page 81, is a machine of this kind. 



At the establishment of the Societe general d' electridte 

 there is also a form of Gramme machine, giving lights equal 

 to from 70 to 84 gas-jets, with carbons 6 to 8 millimetres in 

 diameter. Thanks to these different forms of the machine, 

 lights may now be obtained giving illuminations equal, ac- 

 cording to the requirements, to 25, 52, 70, and 84 unshaded 

 gas-jets, and these illuminations are diminished by only 



