Here, then, was the true explanation of Arago’s experiment: by the rapid revolution of the plate the momentary effect became continuous. Without using the magnet, a revolving plate became an electrical machine. A revolving globe was found to exhibit electromagnetic action, the circuit being complete in the globe itself without the addition of any wire. It was later found by Faraday that mere motion of the wire of a galvanometer produced an electrodynamic effect upon the needle.[10] Meanwhile, Ampère, “by a combination of mathematical skill and experimental ingenuity, first proved that two electric currents act on one another, and then analyzed this action into the resultant of a system of push-and-pull forces between the elementary parts of these currents.”[11] Örsted having shown that electric currents produced certain effects on magnets without being in actual contact, and Ampère having demonstrated that magnets can in their turn be supplemented by electric currents,—a magnetic needle being deflected not only by a current passing through a wire, but also by another magnet brought into its neighborhood, and two electric currents acting on one another at a distance—the question now arose as to whether or not electrical attraction and repulsion could be reduced to an action at a distance proportional to the inverse square of the distance. As early as 1773, Henry Cavendish (1731-1810)—one of the foremost chemists and experimentalists of his day—answered this question affirmatively by experiment.[12] Coulomb (1736-1806)—inventor of the torsion balance—showed that ponderable matter charged with electricity followed the same formula for attraction and repulsion as gravitating bodies did. Poisson (1781-1840) worked out the difficult mathematics of fluids actuated by repelling forces depending on the inverse square of the distance. Laplace (1749-1827) had very early become convinced that the actions of ponderable substances in which electric currents were flowing could be reduced to an action at a distance proportional to the inverse square of the elements of the electric current. Faraday regarded the electric field as full of lines of electric force, in a state of tension, and naturally repelling each other. To him, as to a number of his contemporaries, the idea of “action at a distance” was repugnant; though such a possibility seemed to be indicated by the action of gravitation—the relation of the forces between two charged bodies to the distance between them being very similar to that of the gravitational forces between two bodies to the distance between them. But Faraday, like the great Descartes long before him, rejected the theory of action at a distance in favor of “action through a medium.”