Excerpt from Direct-Current Machinery: A Text-Book on the Theory and Performance of Generators and Motors Although but few graduates in electrical engineering ever have occasion to design a generator or a motor, the majority of them, at some time in their careers, will be called upon to operate or test such machines, or to pass upon their suitability for a particular service. The greater part of this book is therefore devoted to the performance, application, and testing of the various types of direct-current generators and motors. The graphical method, given in Chapters VI and VII, for determining the performance characteristics of generators and motors, was developed by the author several years ago, with the assistance of Mr. H. R. West. This method, although in its simple form only approximate, brings out in a readily understood manner, the dependence of the performance of the machine upon the nature of its electric and magnetic circuits. In the chapter on Commutation the attempt has been made to treat this subject in an understandable, and yet rigorous, manner. The nature of the effects produced by the various factors involved. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.