English: Drawing from US patent no. 645576 filed September 2 1897 by inventor Nikola Tesla covering his proposed system for transmitting electric power through the air without wires. Tesla believed that at 30,000 feet altitude there was a stratum of "rarified air" that would conduct electric currents at high voltages. His proposed system was a transmitter (left) consisting of a high voltage resonant transformer (C,A) which increased the voltage produced by an alternating current generator (G) to millions of volts. A wire (B) suspended by a balloon (D) would transfer the current to the atmosphere. At the receiving point (right), a similar balloon borne electrode (D' ) would receive the electricity and a transformer (C', A' ) would reduce the voltage to a convenient potential to be used by consumers (L, M). Tesla never got a chance to test his idea, a high voltage wireless transmitting station, now called the Wardenclyffe Tower in Shoreham, New York which Tesla began in 1901 was left incomplete when investors pulled out in 1904. Although the opinion of modern scientists is that the system would not have worked, Tesla never lost faith, and to the end of his life believed that wireless power was just around the corner.

Alterations to image: cropped out surrounding text, consisting of captions and signatures of Tesla and witnesses, and rotated image slightly CW to compensate for flaw in original scan.