practice. Many induction motors have been designed on the prin- 

 ciples laid down in this little treatise, and in no case has the theory 

 failed to answer the questions suggested by observation. 



The writing of this book has been mainly a labor of love. Those 

 who know of the troubles, cares and labor involved in writing a 

 book and bringing it through the press, not to mention the sacrifice 

 of personal experience by publication, will doubtless be able to appre- 

 ciate this thoroughly. 



I wish to thank the editors of the ELECTRICAL WORLD AND ENGINEER 

 for the pains they have taken with the publication of this book, and I 

 must specially thank Mr. W. D. Weaver for the encouragement he 

 has always given to me. To Mr. T. R. Taltavall, Associate Editor 

 of ELECTRICAL WORLD AND ENGINEER, who has taken endless pains 

 with the proofs of this book, I feel very much indebted. 



The substance of this volume was delivered in January, 1900 in 

 the form of lectures at the University of Wisconsin, Madison, Wis., 

 and I wish to thank Prof. John Butler Johnson, Dean of the Col- 

 lege of Mechanics and Engineering, for the invitation as non-resi- 

 dent lecturer which he extended to me. To him and to Prof. D. C. 

 Jackson I am greatly indebted for the hospitality conferred upon the 

 stranger within their gates. 



