body, a "condensing couch" was used. This was a bed or couch with a metal back under its mattress, connected by a wire to the high voltage terminal. Metal handrest electrodes at the sides, which the patient grasped during treatment, served as the "ground" return path and were attached to the bottom of the coil. Thus the couch formed a capacitor, with the patient's body as one electrode. History During the 1800s, experiments in applying electric currents to the human body grew into a Victorian era medical field, part legitimate experimental medicine and part quack medicine, called electrotherapy, in which currents were applied to treat many medical conditions. The discovery of radio waves by Heinrich Hertz in 1886 and subsequent development of radio by Oliver Lodge, Guglielmo Marconi sparked interest in radio frequency currents and circuits for generating them. "High frequency" currents meant any frequency above the audio range, > 20 kHz, and the resonant coils which generated them were generically called "oscillation transformers". During the 1890s doctors began to experiment with applying these high voltage and high frequency currents to the human body (ethical standards in the medical profession were looser then and physicians could experiment on their patients). In 1890 French physician Jacques Arsene d'Arsonval founded the field of high frequency electrotherapy, performing the first experiments applying high frequency currents to the human body. He discovered that currents above 10 kHz do not cause muscle contraction or activate nerves to cause the sensation of electric shock, so that extremely high voltages could be applied to a patient without discomfort. In 1891 in America, engineer Nikola Tesla independently discovered the same thing. Three types of apparatus were used, developed by three pioneers in the field, D'Arsonval, Tesla, and Oudin, and separate bodies of clinical technique grew up around them: D'Arsonval apparatus - D'Arsonval first used a high frequency alternator, but this device could not produce frequencies over 10 kHz. To reach higher frequencies he developed a circuit consisting of a single tuned circuit, made of two Leyden jar capacitors and a small coil of relatively few, 10 to 30 turns of heavy wire, with an induction coil and spark gap to excite oscillations. It resembled a Tesla circuit without the secondary winding. The circuit produced relatively low voltage (perhaps 30 kV), high current electricity, called "D'Arsonval currents". The circuit was "bipolar" with two wires from opposite ends of the