NEW CONCEPTIONS IN SCIENCE 



simple in the extreme. Here is a row of ordinary 

 electric batteries, such as are used with the tele- 

 phone, the telegraph, or an electric fan. When 

 they are joined together they make what is called 

 a circuit. Through this a current flows. 



But if the wire joining the two poles of the bat- 

 tery be cut the current stops. It will not jump 

 even a very small gap. The air acts as a resistance, 

 and the current is too weak to break it down. A 

 high "tension" is needed. 



To obtain this, the current is made to pass 

 through a transformer. The effect of this is just 

 as if a stream of water flowing through, say, a 

 three-inch nozzle with a force of one hundred 

 pounds were converted into a thin stream say a 

 quarter of an inch in diameter rushing out with 

 a force of one thousand two hundred pounds. The 

 quantity of water that goes through the nozzle is 

 in each case the same. Electricity appears to 

 act in a similar way. A high-tension current will 

 jump a wide gap. Tesla has contrived currents 

 of such high voltage that they will leap across a 

 gap of five or six feet. A spark or a flash is the 

 result. 



No such long sparks are needed here. In the 

 Marconi instruments the current is made to cross 

 a gap of but a fraction of an inch. It leaps be- 

 tween two polished brass balls rather larger than 



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