84 



that with a revolving field the greatest 

 force will be exerted upon the armature 

 whilst this is at rest, and that the power 

 will decrease as the armature begins to 

 revolve and gather speed, just as in an 

 ordinary direct-current motor. When 

 the speed of the armature coincides with 

 that of the resultant field, no torque is 

 produced, whilst at starting, the torque 

 is a maximum. According to the load 

 put upon the motor, the armature will 

 therefore automatically assume that speed 

 which corresponds to the load, and in 

 this respect the condition of working is 

 comparable to that of a continuous-cur- 

 rent motor. The current through the 

 armature coils C produces a field, 0/» 

 which is also revolving, and in sweep- 

 ing past the wires in the fixed coils A A, 

 B B, creates therein an electromotive 

 force which is always opposing the flow of 

 current, as will easily be seen from the 

 diagram. It will also be observed that 

 the wave of counter electromotive force 

 in the fixed coils, thus produced, coin- 

 cides with the current wave therein, and 



