Nikola Tesla U.S. Patent 645,576 - System of Transmission of Electrical Energy Patent Wrapper Page 32

150 become the high tension coils, the easier it is to obtain the great electromotive force and the more freely the currents pass through the air, as I have demonstrated a few years ago. In the transmission of signals, for instance, I shall by all means use currents of great frequency, produced by peculiar devices which I have perfected, but as such currents are not suitable for the operation of motors, in a plant for industrial exploitation very likely a comparatively low frequency will be adopted. In conclusion, as to the tuning of the transmitter and receiver touched upon by the Examiner, I would say that this is only desirable in so far as it secures the most practical and most economical result. For instance, if the transmitting and receiving coil were each made longer than the quarter of the wave-length of the electrical disturbance in the wire, then the points of highest potential would not fall at the inner ends of the coils, terminals and transmitting air stratum, as required, but nodal points would form, as the case may be, somewhere in the middle of the coils, and then, even with a small fraction of the working pressure the insulating layers in the region of the maximum pressure in the coils would be unable to withstand and would break down, as happens in most cases with high tension induction coils worked with condenser discharges. The adjustment of the coils, however, is not only desirable for this reason, but also because the currents pass with (8) This page retyped from microfilm for better readability - Ed.]