Nikola Tesla U.S. Patent 649,621 - Apparatus for Transmission of Electrical Energy Patent Wrapper Page 10

} T work to be performed, by the condition of the atmosphere, and also by the character of the surrounding country. Thus, if there be high mountains in the vicinity, the terminals should be at a greater height and, generally, they should always be at an altitude much greater than that of the highest objects near them. Since, by the means described, practically any potential that is desired may be produced, the currents through the air strata may be very small, thus reducing the loss in the air. The apparatus at the receiving station responds P-m to the currents propagated from the transmitter in a manner which will be well understood from the foregoing description. The primary circuit of the receiver, that is, the is thin wire coil A excited by the currents propagated by conduction through the intervening natural medium from the transmitter and these currents induce in the secondary coil C other currents which are utilized for operating the devices included in the circuit thereof. Pobviously the receiving coils, transformers, or other apparatus may be moveable, as, for instance, when they are carried by a vessel floating in the air or by a ship at sea. In the former case the connection of one terminal of the receiving apparatus to the ground might not be permanent, but might be intermittently or inductively established without departing from the spirit of my invention. 5 207