CHAP. VIL] ELECTRIC MOTORS. 653 



the magnetised bars when the current communicates to the latter 

 their magnetising force. It is plain, then, that if the current passes 

 successively and alternately through each pair of coils a reciprocating 

 motion of the cylinders and their rods will be the result, and conse- 

 quently an alternate circular motion of the beam. By means of a 

 crank and an excentric this motion is transformed into a continuous 

 circular motion of the driving shaft of the engine and its fly- 

 wheel. 



It remains to be seen how the current from the battery is intro- 

 duced successively into the turns of each coil. For this purpose an 

 excentric is attached to the driving shaft of the engine, which moves 



FIG. 425. Bourbouze's electro-motor. 



an ivory bar aob, covered in part of its length by a metal band 

 along a slider. 



The wire from the positive pole of the battery communicates 

 through p with the two electro-magnets, and each of the latter with 

 one of the ends of the inside of the slider, which in the centre o 

 communicates on the other hand with the negative pole of the 

 batter}^. Suppose the bar aob to occupy the position indicated by 

 the figure. 1 The current then takes the path pecaon, for the 



1 A mistake has been made in the drawing with regard to the position of the 

 lider. The wire a should touch the metal plate, while b rests on the ivory. 



