Nikola Tesla Patents
542 ? electrical oscillations in the system E' C E, being communicated to the ground, cause corresponding vibrations to be propagated to distant parts of the globe, whence they are reflected and, by interference with the outgoing vibrations, produce stationary waves, the crests and hollows of which lie in parallel circles, relatively to which the ground plate E' may be considered to be the pole. Stated otherwise, the terrestrial conductor is thrown into resonance with the oscillations impressed upon it just like a wire, More than this, a number of facts ascertaianed by me clearly shows that the movement of electricity through it follows certain laws with nearly mathematical rigor. For the present it will be sufficient to state, that the planet behaves like a perfectly smooth or polished conductor of inappreciable resistance, with capacity and self induction uniformly distributed along the axis of symmetry of wave propagation and transmitting slow electrical oscillations without sensible distortion and attenuation. O.K. Besides the above, three requirements seem to be essential to the establishment of the resonating condition: (1) The Earth's diameter passing through the pole should be an odd multiple of the quarter wave length, that is, of the ratio between the velocity of light and four times the frequency of the currents. (2) It is necessary to employ oscillations, in which the rate of radiation of energy into space in the form of hertzian or electromagnetic waves is very small. To give an idea I would say, that the frequency should be smaller than twenty thousand per second, though shorter waves might be practicable. The lowest frequency would appear to be six per second, in which -7This page retyped from microfilm for better readability - Ed.]
