[Fig. 152.—The curved lines represent the radius of the government high-power wireless stations and show the zones over which direct communication may be had with ships.]

[Fig. 153.—The aerial system of a transatlantic station.]

[Fig. 154.—Fong Yee, a Chinese amateur wireless operator.]

[Fig. 155.—Tesla world power plant.]

[Fig. 156.—Twenty-five-foot sparks from a Tesla transformer.]

CHAPTER I. INTRODUCTORY: WIRELESS TRANSMISSION AND RECEPTION. THE ETHER. ELECTRICAL OSCILLATIONS. ELECTROMAGNETIC WAVES.

Wireless telegraphy, that marvelous art which has made possible the instantaneous transmission of intelligence between widely distant parts having no apparent physical connection save that of the earth, air, and water, is one of those wonders of science which appeal to the average mind as either incomprehensible or only explainable through the use of highly technical language. Contrary to this general opinion, however, the whole theory and practice of the wireless transmission of messages is capable of the simplest explanation.

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

Throw a stone into a pool of water. A disturbance is immediately created, and little waves will radiate from the spot where the stone struck the water, gradually spreading out into enlarging circles until they reach the shores or die away. By throwing several stones in succession with varying intervals between them it would be possible to so arrange a set of signals that they would convey a meaning to one who is initiated, standing on the opposite side of the pool. The little waves are the vehicle which transmits the intelligence, and the water the medium in which the waves travel.