171 



to mention the reasons which had led 

 him to avoid the use of iron. He thought 

 that makers of dynamos would agree that 

 almost all the ills that the dynamo was 

 heir to were due to the presence of the 

 iron in the armature. Its use in direct- 

 current machines might be said to be a 

 Fig. 37 



necessary evil, as, although attempts had 

 been made to do without it, all successful 

 types of such machines required it for 

 structural purposes. Iron in armatures 

 when worked at a high magnetic density, 

 and with rapid reversals or variations of 

 magnetisms, became heated, and wasted 

 a good deal of power. In alternators 

 this objection applied with very much 



