26 Quarterly German Magazine. 



short time, so that the opening follows almost immediately 

 on the closing. If we have two coils of wire, of which the 

 one is united to the chain, and therefore a permanent current 

 flows through it, while the other is united to the multipUca- 

 tor, no part of the current from the chain can go through 

 the second roll, and the needle of the multiplicator therefore 

 does not deviate. As soon as the current in the first coil is 

 interrupted and then again closed, we see a sudden motion 

 in the needle of the multiplicator. As both coils stand near 

 each other, the first coil influences the second, and indeed in 

 such a manner, that every time the current rises in the first 

 coil, another is excited in the second, which takes an oppo- 

 site direction; but when the current in the first coil disap- 

 pears, then a current rises in the second coil, which flows in 

 the same direction. The currents which show themselves in 

 the second coil, are called induced magnetism or magnetic in- 

 duction. They only last as long as the act of closing and 

 opening in the first coil. In consequence of this short dura- 

 tion they are especially suited to stimulate the muscles and 

 nerves. Indeed, if we let an, induced current go through a 

 muscle, we can see, each time, that the current in the first 

 coil is closed or interrupted, that a sudden contraction, a so- 

 called convulsive motion of the muscles takes place. But if 

 we insert one of Wagner's hammers in the circuit of the 

 chain near the first coil, so that the current is continuall)' 

 closed and interrupted, the single induced currents follow each 

 other very quickly, and the muscle falls into a continual con- 

 vulsive state, 



Induced currents can also be produced by the magnet. 

 If we bring a magnet quickly near a coil, a momentary cur- 

 rent is produced in one direction; but when we remove the 



(148) 



I 



