Practical electrical engineering, direct currents; a manual for use in industrial and evening schools and for home study

Front matter

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Preface

This book was written for the use of Industrial and Evening schools and also as a home-study text. The basic principles of direct-current electrical engineering are presented, the kejmote being simplicity. The only requisite for a full comprehension of the text is a knowledge of simple arithmetic, for mathematical derivations and proofs are dispensed with. This book is the only one, within the author's knowledge, on this phase of electrical engineering which does not use s)mabols and does not require a knowledge of algebra.

The course gives a correct and definite conception of the principles forming the foundations of electrical engineering. It is laid out according to a specific and logical plan. First, the fimdamental imits of the "practical" system are defined and explained. It is necessary for the student to learn and memorize these units as they will be used continually and will serve as his tools. It is then necessary to become acquainted with the fimdamental laws of electrical engineering. Having mastered these, the student is ready to attack the more diflSicult problems which arise. After the fundamental laws, the properties of electrical and magnetic circuits are discussed. Under this heading (lesson 3) the author has endeavored to present the subject of "Current-Canying Capacity'' in a thorough and novel manner. When this much of the text has been mastered, the student has a sure groundwork. Electrical instruments are next taken up. Instead vi PREFACE

of going into constructional details, the basic principle governing the operation of each type of instrument is shown. The next lessons are devoted to direct-current measurements and to primary and secondary cells, and these are followed by lessons on direct-current generators and motors. Fimdamental laws are always referred to, so that the student increases his knowledge step-by-step and in a logical manner. The appendix contains a complete laboratory course of twenty experiments which will be foimd serviceable in supplementing the text.

The topical form of the text and the use of main headings and sub-heacjings serve to emphasize the important points of the subject. The outlines preceding each lesson will prove of value to the instructor in preparing his lectures, and to the student in summarizing and in reviewing his text assignments.

The electrician who has gained his knowledge of things electrical by actual practice can obtain from this book a real imderstanding of the basic principles of electrical engineering. Having mastered the text, he will know "why" as well as "how." There are a nimiber of men engaged in the electrical industry, many in important executive and non-technical positions, who have had neither the time nor the opportunity to obtain even a general knowledge of electrical science. Such men will find in this book exactly what they have been looking for — the facts presented in simplified but not childish form and in a manner which can be grasped by those who do not possess either a college education or technical training.

H. G. Cism

JANUARY, 1922