Nikola Tesla U.S. Patent 645,576 - System of Transmission of Electrical Energy Patent Wrapper Page 53

J J J J J ( ) T } } ( terminal above the ground, and, also, apparently, in a slight measure, with the degree of moisture contained in the air. I have likewise observed, that this region of decidedly noticeable influence continuously enlarges as time goes on, and the discharge is allowed to pass not unlike a conflagration which slowly spreads, this being possibly due to the gradual electrification or ionisation of the air, or to the formation of less insulating gaseous compounds. It is, furthermore, a fact that such discharges. of extreme tensions, approximating those of lightning, manifest a marked tendency to pass upward, away from the ground, which may be due to electro-static repulsion, or possibly, to slight heating and consequent rising of the electrified or ionized air. latter observations make it appear probable, that a discharge of this character, allowed to escape into the atmosphere from a terminal maintained at a great height, will gradually leak through and establish a good conducting path to more elevated and better conducting air strata, a process, which possibly takes place in silent lightning discharges frequently witnessed on hot and sultry days. These It will be apparent to what an extent the conductivity, imparted to the air, is enhanced by the increase of the electromotive force of the impulses when it is stated, that in some instances the area covered by the flame-discharge mentioned, was enlarged more than six-fold by an augmentation of the electrical pressure amounting scarcely to more than fifty per cent. -4This page retyped from microfilm for better readability - Ed.] 171