INTRODUCTORY 9 



a revolving field external to it not internal to it, as in the type 

 shown. In this case the poles projected radially inwards from a 

 large rotating frame. 



There is also another class of machine which has not been 

 inserted the Alternating-current Commutator Motor. 



As this is still in the developmental stage, its many types 

 could not be so classified as to be easily brought within the scope 

 of Fig. 8. So far as relate to construction, the treatment of 

 stationary and rotating armatures and commutators in this work 

 will apply generally to the Alternating - current Commutator 

 Motor. 



