Much that might properly be made a part of the preface has been embodied in the book, in order to avoid repetition, and to also bring certain matter to the attention of those readers who consider a preface to be merely an opportunity for the author of a book to express opinions very often quite foreign to the title, and so unconcernedly skip it with hardly more than a passing glance.

The author wishes to extend his sincere thanks to Mr. H. W. Young, Editor of Popular Electricity; to Mr. John Firth, to Colonel George P. Scriven, and to the Scientific American, for their kindness in supplying photographs for some of the illustrations, and to his friend, Mr. Safford Adams, who has kindly read the proofs and made many valuable suggestions.

ALFRED P. MORGAN. May, 1915.

TO

NIKOLA TESLA

WHOSE GENIUS HAS HARNESSED ELECTRICITY TO THE DAILY WORK OF MAN AND WHOSE INVENTIONS ARE THE BASIS OF ALL MODERN WIRELESS TRANSMISSION, THIS BOOK IS DEDICATED.

Contents

LIST OF ILLUSTRATIONS

[Fig. 1.—Throw a stone into a pool of water and little waves will radiate from the spot where the stone struck.]