Nikola Tesla U.S. Patent 645,576 - System of Transmission of Electrical Energy Patent Wrapper Page 10

128 for frymay potential, impracticable with ordinary coils, may be successfully obtai ned! "As the main object of the invention is to produce. a current of extremely high potential, this object will be facilitated by using a primary current of very considerable frequency, but the frequency of the current is, in large measure, arbitrary, for if the potential be sufficiently high and the terminals of the coils be maintained at a pro per elevation where the atmosphere is comparatively rarefied, the intermediate stratum of air will serve as a conductor for the current produced, and the latter will be transmitted through the air with, it may be, even less resistance than through an ordinary copper wire. The apparatus described, it may be observed, is useful as a means for producing currents of very high potential for other purposes than that of the present system, as, for instance, the coils may be used singly for producing extremely high electrical potentials for any purpase, or us ed generally in the same manner as other electrical transformers, for the conversion and transmission of electrical energy. It will be unders to cd that either or both of the coils or transformers and terminals may be movable, as for instance, when carried by vessels floating in the air, or by ships at sea. In the former case the connection of one terminal with the ground might not be permanent, but might be intermittently or inductively established without departing from the spirit of the invention. -6