An almost infinite variety of controlled destructive effects is made available to the surgeon by modulation of high frequency oscillating currents. The character of the effect produced is not determined by the frequency of the oscillations, but appears to depend entirely on the character of the oscillatory wave trains utilized. When a surgeon desires to destroy tissue en masse by heating, a train of damped oscillations is customarily used; but to obtain cutting effects, a train of undamped waves is used, although tissue can also be readily heated by undamped waves. A damped wave is one with an oscillating potential which tends to return to zero, as shown in figure 1b; an undamped wave is one with an oscillating potential which remains constant, as shown in figure 1a. The fundamental arrangements for production of high frequency damped oscillations (condenser-gap-inductance) and undamped oscillations (e. g., triode tube), which are