Auxiliary poles for direct-current machines

This paper discusses the design and testing of auxiliary pole machines, from the standpoint of conceptions developed by the author during a rather extensive practical study of the subject. It was at a time when there was very little theoretical information to be had, and when as a consequence, the result of tests often seemed to be confused and even misleading. The paper is therefore, primarily intended for those who are interested in the practical design and testing of such machines, and if the results are of assistance to any such persons, it will be a source for gratification.