The theory of Wimshurst's alternating static machine

Abstract

The quantitative theory of Wimshurst's alternating static machine is developed in detail according to the general method previously given by the author for other static machines. The theory predicts that the potential of any element of the machine will reverse at definite intervals and at the same time increase in value. While the exact period of reversal depends on the capacities involved in the machine, the approximate period can be calculated and is found to be the time of one revolution rather than the time of three quarters of a revolution as observed by Wimshurst. An actual machine was constructed and the reversal observed by means of the glow in discharge tubes. It was found that such a machine does reverse every revolution rather than every three quarters of a revolution. The theory given can be extended to other machines of the same type with more than four inductors. The period of reversal of a six-inductor machine is calculated to be approximately the same as that of a four-inductor machine.