Discussion on “sphere gap discharge voltages at high frequencies” (Clark and Ryan), Detroit, Mich., June 24, 1914. (continued from January proceedings, page 124)

Harris J. Ryan (by letter): Replying to Mr. Fortescue´s questions: The high-frequency driving voltage of the arc was multiplied about one hundred times by resonance. The impressed voltage of the arc having an irregular wave form was consumed in the first few turns of the outer helices. Thus in a given case the potential to neutral of the sixth turn from either arc terminal would, on test, be found at low (almost zero) alternating potential. On either side of this turn the potential would be found to rise regularly. By theory, under these circumstances, it is difficult to understand how the high-potential wave form can have departed appreciably from that of the true sine wave. The cyclograph traced a quadrature combination of current and potential waves. The result was a true elipse with no evidence of the presence of harmonics. In regard to the use of isolated spheres made necessary in the method devised to eliminate harmonics in the high frequency high voltage: The case is not one of actual isolation, as assumed by Mr. Fortescue. The arc was supplied with current from two 600-volt direct-current generators connected in series with their neutral grounded. Furthermore, the oscillating circuit would fail utterly to operate unless both sides of the circuit were nicely balanced, developing substantially equal voltages.