Purdue Investigators "Take" 2 Million Volts, and Live!

LAFAYETTE, Ind., June 9 — Two million volts of flashing, crackling, burning electricity pass through a man — and he lives to try it again!

This voltage is a thousand times that used for execution in the electric chair, but C. C. Fisher, of Sheridan, and W. P. Hallstein, Indianapolis, repeatedly take such a charge as one of the experiments with the Tesla coil, work which they have been conducting as a thesis for graduation from the school of electrical engineering at Purdue University.

The investigators say that allowing this voltage to pass through the body produces only a slight tingling sensation, less than the penny arcade shocking machine, and leaves no ill effects. Yet there is power enough in the charge of electricity which they take to ignite a stick of wood or to break a half-inch plate of glass when placed in the five-foot electric spark which is discharged into the air from the large coil.

The apparatus consists of a condenser, transformer, and two large inductance coils, so arranged that they “step up” the power of an ordinary 110-volt electric light circuit to the extremely high potential of two million volts. When the “juice” is turned on, vine-like sparks shoot out of a metal ball placed atop the large eight-foot coil which gives the voltage its final boost to the two million mark. The top part of the coil is enveloped by a purple glow, or corona, developed by the extremely high voltage.

When one of the experimenters reaches with a metal rod into the vicinity of the discharge, the sparks flash to the rod, apparently pass through his body, and shoot out his toes. Every nail in his shoes will shoot sparks. At the same time, an electric light bulb held in his hand or even in his mouth will glow. The glowing is caused by the field of high voltage emanating from the coil existing around the man.

To the physicist there is no mystery about how a man can live after two million volts are applied to his body. The secret is that the electricity does not pass through his body at all! It travels on the surface of his skin. The Tesla coil produces electricity which vibrates back and forth at a very high frequency, about 400,000 changes in direction in a second, or a frequency of 200 kilocycles. And at high frequencies, electricity travels only on or near the surface of its conductor; if it is on a wire, only the outer shell of the wire will carry the current; and in a man, only his skin is getting any of the current.

But two million volts even on the surface of the skin might prove most annoying, if not fatal, if it were not for the fact that one’s nerves do not respond to frequencies as high as 200 kilocycles. For example, radio waves, which are just a little higher in rate of vibration than these electric waves, are not noticed at all.

The Tesla coil has a wide variety of uses for scientific purposes, and finds practical application in tests of insulators at extra high voltages, and in electric furnaces for developing extremely high temperatures.

The two million volt spark, which will burn a hole through a piece of plate glass, will do the same for a man’s hand if he allows the spark to become concentrated on a point. When they let the spark jump from the coil to the brass rod in their hands, Fisher and Hallstein are always careful to hold the rod in both hands, to keep the electricity distributed over as large a surface as possible. If they were to hold it with one hand, the more concentrated power would cause trembling; and if they tried to hold the rod with two fingers, they would be very likely to get burned.