34 



IRON MOVED NEAR MAGNETS. 



of revolutions of the coils inclosing the soft iron 

 bar B. 



Two flexible wires pressing against the arbors 

 serve to break the circuit for an instant, and to 

 change the direction of the alternate currents 

 to a uniform circuit by their adaptations for this 

 purpose. 



Fig. 8. 



The rapidly ebbing and returning electrical 

 surges through the conducting wires, terminated 

 by handles at H, serve to give a rapid succession 

 of electric, shocks when held in the hands. 



By the instrumentality of these revolving coils 

 and magnets, several thousand changes of direction 

 of electric surges are produced per minute, when 

 numerous magnets are multiplied in the great ma- 

 chines now employed for producing electric light. 

 It is practically found that the most powerful elec- 

 tric excitation is produced by using electro-magnets, 

 formed of bars of soft iron, with electric currents 

 circulating around them through spiral coils of 



