The elements of dynamic electricity and magnetism

Introduction

This book was written for learners rather than for the learned. Previous to the last decade the demand for electric books was confined chiefly to scientific investigators versed in the higher mathematics, and the authors of such books were electricians of the same class, who recognized the importance of mathematical accuracy in treating electric phenomena. Hence mathematical formulae became a prominent feature of such books. But the various electric industries to which the recent unprecedented electric development has given rise, have given employment to a numerous class of persons to whom mathematical books are almost unintelligible, and yet to whom a scientific knowledge of the various kinds of electric apparatus which they are required to operate, or with which their business is connected, is of the highest importance. There ic also a class of liberally educated persons who desire to extend their knowledge of electric principles, but have not the time or patience to follow the intricacies of mathematical formulae, especially in the abbreviated form usual in the books referred to. A third class are students who intend to become electrical engineers, to whom a thorougli knowledge of elementary, physical, electric principles is important as a preparation for a

ill

IV INTRODUCTION.

more extended mathematical course. To meet the demands of these various classes has been the object of the writer in the preparation of this volume.

As mathematics is simply an abbreviated form of language, mathematical reasoning, where required, has been reduced, so far as possible, to oidinary language, intelligible to unmathematical readers ; thus reducing the amount of mathematical formulae required to a very few simple expressions, not beyond the capacity of persons familiar with arithmetic.

Each chapter is intended to be a complete treatise on the subject to which it relates, and the whole thirteen to embrace all the essential facts pertaining to that form of electricity which manifests itself in currents, as distinct from the form known as static, which has been similarly treated in the author's " Elements of Static Electricity." The publication of the latter book in a separate volume, and the elimination of mathematical formulae from the present book, have left room for a much fuller treatment of the physical principles of electric science in this, its most practical form, than would otherwise be possible in a volume of this size.

This book is not intended as an exposition of the writer's own peculiar views, but of the well established principles of electricity and magnetism, as held by the leading electricians of the world. The writer has collected facts from every available source ; examining carefully the views of various eminent writers on each point, and giving the net result of such examination in his own language ; inspecting the construction and practical operation of electric apparatus and machinery, and consulting practical, electric experts, familiar with such construction and operation.

The chronological order of electric development has been followed, so far as possible, as it is not only in

IN TR OD UC TION. V

accordance with the inductive method, which leads from first principles to full development, but also furnishes a history of electric progress, showing the relations of each important invention to those which preceded and followed it.

On important controverted points the leading views on both sides have been given; and the selections of practical, electric appliances for description have been made with strict reference to the adaptation of each to illustrate some important principle to the best advantage. Clearness of style has been recognized as a first requisite, and conciseness as subordinate to it.

The author takes pleasure in acknowledging his obligations to the following writers : Niaudet, Deschanel, Maxwell, Jenkin, Gordon, Thompson, Ayrton, Faraday, Fontaine, Gore, Hering, Pope, Gladstone & Tribe, Preece & Maier, Maver & Davis, Terry & Finn; also to the U. S. Coast and Geodetic Survey for valuable information, documents, and magnetic maps; and to the following parties for cuts: The E. S. Greeley & Co., The W. J. Johnston & Co., Western Electric Company, James W. Queen & Co., The Electrical Accumulator Company, Thomson Electric Welding Company, The Electrical Supply Company, D. Van Nostrand Company, A. C. Terry, Weston Electric Instrument Company.

To the practical electricians of Chicago he is under the deepest obligations, for the uniform courtesy shown him repeatedly in his search for information, and for permission to inspect and test the practical operation of apparatus; and he would especially mention, in this connection, J. K. Pumpelly, Force Bain, Dr. Louis Bell, George Cutter, the representatives of the Thomson- Houston Electric Company, the Brush Electric Company, the Chicago Edison Company, the Westinghouse Company, the Chicago Arc Light and Power

VI INTRODUCTION.

Company, the Electrical Supply Company, Central Electric Company, the Electrical Accumulator Company, "C & C" Electric Motor Company, the Western Union Telegraph Company, the Chicago Bell Telephone Company, the American Telephone and Telegraph Company.

Philip Atkinson.

Chicago, November i, 1890.