Samuel D. Cohen

“ The terminals of this coil are connected to the large spark gap, which, when the apparatus was excited, was filled with a spark two feet long. The high tension condenser is inclosed within the cabinet. The large coil is used as kick-coil for increasing the voltage. With this device Dr. Tesla was able to obtain a potential of one million volts, which is quite extraordinary with such small apparatus.
Dr. Tesla can rightfully claim priority in employing conical coils for high frequency work, as Fig. 3 shows the first conical coil ever employed for such work, as early as 1892. ”

“ This great scholar and philosopher has not devoted his time to electrical devices alone, but recently turned his attention to a new form of prime-mover, which will develop more power than any other motor or engine, and he has stated that it is within the limits of practicability to develop 20 horse-power for each pound of engine weight. The Tesla turbine is shown in Fig. ”

“ The steam does not exert pressure against the rotor blades sidewise as in other types, but shoots thru between the blades edgewise. The velocity of the moving steam jet and the peculiar frictional effect resulting is sufficient to rotate the turbine spindle and blades at high speed and with unprecedented torsion or turning effort in foot-pounds. ”

“ This one had a field energized by currents of different phase relation (i.e. while one current was at zero amplitude the other would be at maximum, etc.) , producing a rotating field in which conductors were employed, and in this way the high frequency current was obtained. This type of machine was subsequently developed by Goldschmidt and is now known under that name, altho Tesla described this principle in a patent dated 1889.
Fig. 2. An Early “Tesla” High Frequency Oscillator Developing 2 Sq. Ft. ”