222 ELECTRIC LIGHTING. 



chanism need be used to obtain the successive lighting of 

 the candles. When the circuit connections are made simul- 

 taneously through all the candles, one of them will always 

 transmit the current more readily than the rest, and that par- 

 ticular one being lighted by the heat developed, the current 

 will pass almost entirely through the arc, the loss through 

 the other candles being quite insignificant. 



The light given by the Jablochkoff candles is very uni- 

 form, at least so long as the Gramme machines which supply 

 them work regularly. This light may, however, have a more 

 or less white colour, according to the nature of the insula- 

 tor between the carbons. If this insulator is made of kaolin, 

 the light has a somewhat bluish tint; if it is made of plaster 

 of Paris, the colour is rosy and more agreeable. 



The comparative steadiness of the luminous part in the 

 Jablochkoff candles is owing to the carbons being kept always 

 at the same distance from each other, without any motion, 

 and the small derivation of the current due to the. fused 

 insulator which contributes to the steadiness of the light. In 

 consequence of this derivation, the electric current is less 

 weakened than when the carbons are separated by air, and 

 therefore a larger number of lights can be interposed in the 

 same circuit. The flame, too, which accompanies the light 

 appears to enlarge the luminous focus, so that the illumination 

 is better diffused and with less shadow than that given by 

 regulators. Opinions vary as to its intensity; it is generally 

 believed that with equal currents the light of the candle 

 is considerably less intense than that of the regulator. 

 Jablochkoff contends that this is not so, and that in the 

 experiments of comparison from which this conclusion was 

 drawn, the candle was under less favourable conditions than 

 the regulator, which automatically adjusts itself for the best 

 effect. In support of this statement, he mentions the experi- 

 ments made by Fichet, one of the jury at the Exposition, who, 

 in order to remove any doubt in the matter, proceeded as 

 follows: After having measured the illuminating power of a 



