Nikola Tesla U.S. Patent 645,576 - System of Transmission of Electrical Energy Patent Wrapper Page 55

E T 1 J 1 J T T 3 J T modes of transmission, it is useful to state that all previous efforts made by myself and others for transmitting electrical energy to a distance without the use of metallic conductors, chiefly with the object of actuating sensitive receivers, have been based, insofar as the atmosphere is concerned, upon those qualities which it possesses by virtue of its being an excellent insulator, and all these attempts would have been obviously recognized as ineffective, if not entirely futile, in the presence of a conducting atmosphere or medium. The utilization of any. conducting properties of the air for purposes of transmission of energy has been hitherto out of the question in the absence of apparatus suitable for meeting the many and difficult requirements although it has long been known or surmised that atmospheric strata at great altitudes, say, fifteen or more miles above sea level are, or should be, in a measure conducting; but assuming even that the indispensible means should have been produced, then still a difficulty, which in the present state of the mechanical arts must be considered as insuperable, would remain, namely, that of maintaining terminals at elevations of fifteen miles or more above the level of the sea. Through my discoveries before mentioned, and the production of adequate means, the necessity of maintaining terminals. at such inaccessible altitudes is obviated, and a practical method and system of transmission of energy through the natural media is afforded, essentially different from all those available up to the present time and possessing, moreover, this important -6This page retyped from microfilm for better readability - Ed. 173