Mc Graw-Hill Book Co. Ine PUBLISHERS OF BOOKS FOR Electrical World Engineering News-Record Electric Railway Journal ▾ ELECTRICAL MEASUREMENTS IN THEORY AND APPLICATION FORMERLY PUBLISHED UNDER THE TITLE OF BY ARTHUR WHITMORE SMITH, PH.D. SECOND EDITION MCGRAW-HILL BOOK COMPANY, INC. COPYRIGHT, 1914, 1924, BY THE PRINTED IN THE UNITED STATES OF AMERICA THE MAPLE PRESS COMPANY, YORK, PA. 281609 SEP 15 1924 TNE SM47 3 6969331 PREFACE This book is a revision and enlargement of the Principles of Electrical Measurements, and is written for those who have passed one year of college physics and desire further knowledge regarding electrical and magnetic matters. It can be used as a guide in laboratory work, but it is more than a laboratory manual. The principles involved are amply treated, and the reader is led to reason out the relations between the various quantities rather than to memorize a formula. The student is urged to learn the facts from his own observations, and direct information is often replaced by a suggestion as to how the knowledge can be obtained. The time has certainly come when the electron theory of electrical phenomena should be presented to all students of physics and electrical engineering. Regarding the electron tubes used in radio communication, for instance, there is no doubt that the stream of electrons through the tube continues as an electron current through the connecting wires. This point of view has been taken throughout the book and electrical currents are considered as the flow of electrons along the circuit. This is in accordance with the ideas of modern Physics, and it adds a concreteness to the subject that is especially helpful in the class room. The book is arranged on the progressive system. The simpler and more fundamental parts of the subject are taken up in the first chapters, and in the first part of each chapter, while the more difficult measurements and the methods involving more extended knowledge are reserved until the student has attained greater proficiency. For example, Chapter I shows how to measure current, resistance, electromotive force, and power, by ammeter and voltmeter methods. For an elementary course in Electrical Measurements nothing could be better than this series of simple experiments, well understood. They bring out the fundamental relations with a minimum of apparatus to confuse the mind; and they are not out of place at the beginning of a more extended course that contemplates using the entire book. |