HIGH FREQUENCY AND HIGH POTENTIAL CURRENTS. 347

by whatever process it was separated from other bodies—and thisis the accepted view of its origin—it must have retained a charge,as occurs in all processes of mechanical separation. If it be acharged body insulated in space its capacity should be extremelysmall, less than one-thousandth of a farad. But the upper strataof the air are conducting, and so, perhaps, is the medium in freespace beyond the atmosphere, and these may contain an oppositecharge. Then the capacity might be incomparably greater. Inany case it is of the greatest importance to get an idea of whatquantity of electricity the earth contains. It is difficult to saywhether we shall ever acquire this necessary knowledge, but thereis hope that we may, and that is, by means of electrical resonance.If ever we can ascertain at what period the earth’s charge, whendisturbed, oscillates with respect to an oppositely electrified systemor known circuit, we shall know a fact possibly of the greatestimportance to the welfare of the human race. I propose to seekfor the period by means of an electrical oscillator, or a source ofalternating electric currents. One of the terminals of the sourcewould be connected to earth as, for instance, to the city watermains, the other to an insulated body of large surface. It is pos-sible that the outer conducting air strata, or free space, containan opposite charge and that, together with the earth, they form acondenser of very large capacity. In such case the period ofvibration may be very low and an alternating dynamo machinemight serve for the purpose of the experiment. I would thentransform the current to a potential as high as it would be foundpossible and connect the ends of the high tension secondary to theground and to the insulated body. By varying the frequency of thecurrents and carefully observing the potential of the insulated bodyand watching for the disturbance at various neighboring points ofthe earth’s surface resonance might be detected. Should, as themajority of scientific men in all probability believe, the period beextremely small, then a dynamo machine would not do and aproper electrical oscillator would have to be produced and perhapsit might not be possible to obtain such rapid vibrations. Butwhether this be possible or not, and whether the earth contains acharge or not, and whatever may be its period of vibration, it cer-tainly is possible—for of this we have daily evidence—to pro-duce some electrical disturbance sufficiently powerful to be per-ceptible by suitable instruments at any point of the earth’ssurface.