PREFACE TO FIRST EDITION 



This book is intended mainly for the use of students following 

 courses in Electrical Engineering, and for this reason emphasis is 

 laid on fundamentals and principles of general application, while 

 but little attention is paid to the needs of the practical designer, 

 who may be trusted to devise his own time-saving methods of 

 calculation, provided always that he has a thorough understand- 

 ing of the essentials governing all electrical design. 



The writer is a firm believer in the advantage of having a 

 concrete mental conception of the hidden actions which produce 

 visible or measurable results, and in studying the electromotive 

 forces developed in the windings of electric generators, he con- 

 sistently represents the effects as being due to the cutting by the 

 conductors of imaginary magnetic lines. 



No attempt has been made to deal adequately with the me- 

 chanical principles involved in the design of electrical machinery. 

 Thus as a reference book for the designer, this text is admittedly 

 incomplete. It is incomplete also as a means of giving the stu- 

 dent what he is supposed to get from a course in electrical design, 

 for the simple reason that no art can be mastered by the mere 

 reading of a book. In this as in every other study, all that is 

 worth having the student must himself acquire by giving his 

 mind to the business on hand and taking pains. The book cannot 

 do more than serve as a reference text or the basis for a course 

 of lectures; and for every hour of book study, four to six hours 

 should be spent in the actual working out of practical designs. 



The writer has ventured to express some views regarding the 

 qualifications of the successful designer in an introductory chap- 

 ter where he believes they are less likely to remain permanently 

 buried than if embodied in a preface of unconventional length. 

 At the same time he does not claim that the procedure here 

 adopted is such as will meet the requirements of the professional 

 designer; but in criticising the book, it is important to bear in 

 mind that its main object is to illustrate the logical application 

 of known fundamental principles, and so help the reader to 

 realize the practical value of theoretical knowledge. It is not to 



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