From the Preface. Since nearly all of the phenomena met with in electrical engineering in connection with the relations between electricity and magnetism are involved in the action of electromagnets, it is readily recognized that a careful study of this branch of design is necessary in order to predetermine any specific action. With the rapid development of remote electrical control, and kindred electro-mechanical devices wherein the electromagnet is the basis of the system, the want of accurate data regarding the design of electromagnets has long been felt. With a view to expanding the knowledge regarding the action of solenoids and electromagnets, the author made numerous tests covering a long period, by means of which data he has deduced laws, some of which have been published in the form of articles which appeared in the technical journals. In this volume the author has endeavored to describe the evolution of the solenoid and various other types of electromagnets in as perfectly connected a manner as possible. In view of the meager data hitherto obtainable it is believed that this book will be welcomed, not only by the electrical profession in general, but by the manufacturer of electrical apparatus as well....
