Nikola Tesla Patents
J T 1 J [ J T 1 1 Per 72 5 ? case there will be but one node, at or near the groundplate and, paradoxical as it may seem, the effect will increase with the distance and will be greatest in a region diametrically opposite the transmitter. With oscillations still slower the Earth, strictly speaking, will not resonate, but simply act as a capacity, and the variation of potential will be more or less uniform over its entire surface. -and-absolutely 4P (3) The most essential requirement is, however, that irrespective of frequency, the wave or wave train should continue for a certain interval of time, which I have estimated to be not less than one twelfth or probably 0.08484 of a second, and which is taken in passing to, and returning from, the region diametrically opposite the pole, over the Earth's surface, with a mean velocity of about (471240) kilometers per second. The presence of the stationary waves may be detected in many ways. For instance, a circuit may be connected directly, or inductively, to the ground and to an elevated terminal, and tuned to respond more effectively to the oscillations. Another way is to connect a tuned circuit to the ground at two points lying more or less in a meridian passing through the pole E', P or generally stated, to any two points of a different potential. In Fig. 2 I have shown a device for detecting the presence of the waves, such as I have used in a novel method of magnifying feeble effects, which I have described in my patents Nos. 685,953 and 685,955. It consists of a cylinder D of insulating material which is moved at a uniform rate of speed, by clockwork or other suitable motive power, and is provided with two metal rings F F', upon which bear brushes a and a' con-8This page retyped from microfilm for better readability - Ed.] 543
