PREFACE 



HAVING been for some years engaged in lecturing to advanced 

 students on the subject of alternating currents, the author has 

 endeavoured to present, in as simple a manner as possible, a 

 subject which, though intensely interesting in its purely 

 physical aspect, is often expounded by mathematicians who, 

 while revelling in the mathematical gymnastics afforded by its 

 problems, so bewilder their less mathematical readers by the 

 adoption of unnecessarily ponderous methods that the majority 

 give up in disgust a subject which would otherwise exercise 

 great fascination for them. That such should ever happen is 

 lamentable in the extreme, since it retards the progress of the 

 practical application of alternating currents. 



The author has employed the method of vector algebra 

 wherever possible to solve the various problems, as he has found 

 that it is quite easy for a student knowing only the elements of 

 algebra and trigonometry to obtain a good working knowledge of 

 the method in a very short time, and become enabled to attack 

 problems which are otherwise beyond his comprehension. 



The application of vector algebra to alternating-current 

 problems should appeal to everybody. It is a tool peculiarly 

 adapted to the subject, and combines simplicity with all the 

 advantages of a powerful method. 



No one will dispute the use of a treatise on the subject in 

 which the chief aim of the writer is to eliminate mathematical 

 difficulties and give prominence to the physics of the subject. 

 Since the author has engaged in practice as a consulting 

 engineer he has found that the want of a simple though com' 

 prehensive treatise is often a deterrent to practical engineers 

 acquiring a requisite knowledge of the subject. 



