166 



truth, and with short periods and large 

 self-induction, two machines in series 

 might easily be run to work with 

 stability. He had only been able to indi- 

 cate the use of such diagrams as he 

 recommended. A very slight addition to 

 the diagrams enabled the effect of hys- 

 teresis to be taken into account. Hyster- 

 esis was the work absorbed in the magnet- 

 ized masses in the field, upon change 

 taking place in the degree or direction of 

 magnetization. This was now a recog- 

 nized fact, and well-known measurements 

 of the effect had been made by Dr. 

 Ewing and others. On the subject of 

 transformers, he might mention a system 

 of transformation which might be 

 usefully employed in many practical 

 ways. Suppose that an alternate- current 

 machine (Fig. 35) played into a con- 

 ductor possessing, besides resistance, 

 various causes of self-induction. And 

 suppose that at two points A, B, of the 

 circuit were coupled the poles of a con- 

 denser. Then in general it would be 

 found that : (1) The relative values of 



