Nikola Tesla U.S. Patent 645,576 - System of Transmission of Electrical Energy Patent Wrapper Page 61

C C ( J ( J 1 T transmitting terminal. The primary and secondary circuits in the transmitting apparatus being carefully synchronized, an electromotive force from two to four million volts, and more, was obtainable at the terminals of the secondary coil A, the discharge passing freely through the attenuated air stratum maintained at the above barometric pressures, and it was easy, under these conditions, to transmit with fair economy considerable amounts of energy, such as are of industrial moment, to the receiving apparatus for supplying, from the secondary coil C', lamps L or kindred devices. The results were particularly satisfactory when the primary coil or system A' with its secondary C' was carefully adjusted, so as to vibrate in synchronism with the transmitting coil or system A, C. I have, however, found no difficulty in producing, with apparatus of substantially the same design and construction, electro-motive forces exceeding three or four times those before mentioned, and have ascertained that, by their means, current impulses can be transmitted through much denser air strata. By the use of these, I have also found it practicable to transmit notable amounts of energy, through air strata not in direct contact with the transmitting and receiving terminals, but remote from them, the action of the impulses, in rendering conducting air of a density, at which it normally behaves as an insulator, extending, as before remarked, to a considerable distance. The high electro-motive force obtained at the terminals. of coil or conductor A was, as will be seen, in the preceding instance, not so much due to a large ratio of transformation, as to -12This page retyped from microfilm for better readability - Ed.] 179