PREFACE. 



The literature of electrical engineering has become so vast and ex- 

 tensive that it is impossible for any man to keep pace with all that 

 is written on electrical subjects. He who produces a new book that 

 adds to the swelling tide of new publications, may justly be asked for 

 his credentials. My justification for writing this tract will be found 

 in the fact that, though almost all branches of applied electricity have 

 enlisted the industry of authors, the induction motor has received 

 comparatively little attention from competent engineers. The few 

 whose experience and knowledge would entitle them to speak with 

 authority on this subject are deterred from publishing by commercial 

 reasons. 



I have made the induction motor the subject of early and special 

 studies, and a comparison of my treatment of its theory with the 

 purely analytical theories will show how far I have succeeded in sim- 

 plifying and elucidating so complex a subject. The graphical treat- 

 ment of abstruse natural phenomena is constantly gaining ground, 

 and I quote with satisfaction the words of so great a mathematician 

 as Prof. George Howard Darwin, Fellow of Trinity College, Cam- 

 bridge, who says on p. 509 of the second volume of Lord Kelvin 

 and Prof. Tail's Treatise on Natural Philosophy that "the simplicity 

 with which complicated mechanical interactions may be thus traced 

 out geometrically to their results appears truly remarkable." 



All through this little book I have endeavored to let inductive 

 method check at every step the mathematical or graphical deduction 

 of the results. A wide experience with mono- and polyphase alter- 

 nating current induction motors, gained at the Oerlikon Engineering 

 Works, Switzerland, has enabled me to do so. Thus the careful 

 reader who is willing to profit by the experience of others, will find 

 many valuable hints and results which he can turn to account in his 



