THE BANISHMENT OF NIGHT 



doing this it was necessary that contact be made be- 

 tween two carbon points, whether they lie parallel or 

 point to point, and the necessary slight separation for 

 producing the light effected later. To accomplish this 

 Jablochkoff joined the tips of the carbons of his candle 

 with a thin strip of carbon, which quickly burned away 

 when the current was turned on, leaving the necessary 

 space between the points for the arc. 



There was one difficulty with the "candle" that 

 seemed insurmountable for a time the wasting of the 

 two carbons was unequal, as in any arc light, the points 

 thus gradually drawing apart until the passage of the 

 current was no longer possible. To overcome this the 

 rapidly wasting positive carbon was made double the 

 thickness of its mate; but while this answered fairly 

 well the thinner negative carbon gradually became 

 heated by the increased resistance, and burned up too 

 rapidly. The difficulty was finally overcome by the 

 simple expedient of alternating the flow of the current, 

 so that each carbon was alternately a positive and a 

 negative pole. As the magneto-electric machines then in 

 use produced alternating currents it was only necessary 

 to use such machines for generating the current to 

 produce an equal destruction of both carbons. 



The simplicity and excellence of the light of these 

 " candles" brought them at once into general popularity, 

 not only in the large cities of Europe, but in many out- 

 of-the-way places. Greece, Portugal, and other obscure 

 European countries adopted them, and even Brazil, 

 La Plata, and Mexico installed many plants. But 

 stranger still, they were soon used for illuminating the 



VOL. VL 15 [ 225 ] 



