Nikola Tesla Patents
al a distance, and thereby bringing the latter into action. This method is the oldest and best known, and has been brought particularly into prominance in recent years through the investigations of Heinrich Hertz. "Another method consists in passing a current through a circuit, preferably one enclosing a very large area, inducing thereby in a similar circuit situated at a distance, another current, and affecting by the same, in any convenient way, a receiving device. "Still another way, which has also been known for many years, in to pass, in any suitable manner, a current through a portion of the ground, as by connecting to two points of the same, preferably at a considerable distance. from each other, the two terminals of a generator, and to energize by a part of the current diffused through the earth, a distant circuit which is similarly arranged and grounded at two points widely apart and which is made to act upon a sensitive receiver. "These various methods have their limitations, one especially, which is common to all, being that the receiving circuit or instrument must be maintained in a definite position with respect to the transmitting apparatus, which often imposes great disadvantages upon the use of the apparatus. Fin In several applications filed by me and patents granted to me, have disclosed other methods of accomplishing results of this nature which may be briefly described as follows: In one system the potential of a point or region of the earth is varied by imparting to it intermittent or -2443
