Nikola Tesla U.S. Patent 645,576 - System of Transmission of Electrical Energy Patent Wrapper Page 18

136 tain such rapid vibrations. But whether this be possible or not, and whether the earth contains a charge or not, and whatever may be its pericd of vibration, it certainly is possible for of this we have daily evidenceto produce some electrical disturbance sufficiently powerful to be perceptible by suitable instruments at any point of the earth's surFig.21 face. Assume that a source of alternating currents, s, be connected, as in Fig. 21, with one of its terminals to earth (convenient to the water mains), and with the other to a body of large surface, P. When the electric oscillation is set up, there will be a movement of electricity in and out of P, and alternating currents will pass through the earth, converging to or diverging from the point C, where the ground connection is made. In this manner neighboring points. on the earth's surface within a certain radius will be disturbed. But the disturbance will diminish with the distance, and the distance at which the effect will still be perceptible will depend on the quantity of electricity set in motion. Since the body P is insulated, in order to displace a considerable quantity the potential of the source must be excessive, since there would be limitations as to the surface of P. The conditions might be adjusted so that the gen4