Nikola Tesla U.S. Patent 645,576 - System of Transmission of Electrical Energy Patent Wrapper Page 63

r J t J ) J J J J height and, generally, they should always be, if practicable, at altitudes much greater than those of the highest objects near them, in order to avoid, as much as possible, the loss by leakage. In some cases, when small amounts of energy are required, the high elevation of the terminals, and more particularly of the receiving terminal D' may not be necessary, since, especially when the frequency of the currents is very high, a sufficient amount of energy may be collected at that terminal by electrostatic induction from the upper air strata, which are rendered conducting by the active terminal of the transmitter, or through which the currents from the same are conveyed. with reference to the facts which have been pointed out above, it will be seen that the altitudes required for the transmission of considerable amounts of electrical energy in accordance with this method are such as are easily accessible, and at which terminals can be safely maintained, as by the aid of captive balloons supplied continuously with gas from reservoirs, and held in position securely by steel wires, or by any other means, devices or expedients, such as may be contrived and perfected by ingenious and skilled engineers. From my experiments and observations I conclude that, with electro-motive impulses, not greatly exceeding fifteen or twenty million volts, the energy of many thousands of horse power may be transmitted over vast distances, measured by many hundred, and even thousands of miles, with terminals not more than thirty to thirty-five thousand feet above the level of the sea, and even this comparatively small elevation will be required chiefly for reasons of economy and, if desired, it may be -14This page retyped from microfilm for better readability - Ed.] 181