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greater force than in direct- current ma- 

 chines, for in the latter the reversals 

 of magnetism were comparatively slow. 

 Thus the first result arrived at, in quite 

 recent practice, was that the magnetic 

 density that could be used in iron cored 

 alternators must only be about one-half 

 that employed in direct current arma- 

 tures. This alone meant a considerable 

 increase in the size of armatures, 

 without any gain in output or efficiency. 

 Although the loss per cubic inch was 

 reduced by decreasing the magnetic den- 

 sity, the armature had to be made larger 

 to compensate for it, and the total loss 

 was actually increased, not reduced. Iron 

 was used to reduce the magnetic resist- 

 ance, to afford mechanical support, and 

 to introduce self-induction into the cir- 

 cuit. The latter, an evil in itself, was 

 said to be a modern necessity, caused by 

 the convenience of working alternators 

 in parallel. If iron was indispensable 

 for this purpose, which he was not 

 prepared to admit, it could readily be 

 inserted in some part of the circuit where 



