“You understand the law of the _attraction of_ gravitation”—I nodded assent—“but you know nothing of the _repulsion_ of gravitation.” Indeed I did not. I had never heard of such a thing.
He continued: “All polar attractions are accompanied by repulsions. This you see in magnetism and in electricity, and it is equally true in gravitation. The force with which bodies fall toward each other consists merely of the _difference_ between the attractive and the repulsive force. Ordinarily the attractive force takes hold of the _near_ ends of the molecules of ether contained in solid or fluid bodies, and the repulsive force affects only the further ends of the same molecules, so that by reason of the difference in the distances over which these two forces operate the attractive force always over-powers repulsion. But we have discovered a way by which the action of these forces is reversed, so that the work of repulsion is performed on the near end of the molecules and attraction on the _further_ end, and then attraction being the weaker of the two, the body, as a whole, is repelled. We imitate in fact the action that takes place when the attraction between two electrified bodies turns to repulsion. Repulsion also takes place between the sun and the tails of comets. The comet’s tail is attracted toward the nucleus of the comet and at the same time repelled from the sun. We have not been able to make bodies discriminating like that in their attractions.
“But,” said I, “it must take as much power to make this change as the changed condition yields after it is made and I cannot see where you get the power; you cannot make something out of nothing.”
“Very true,” said he, “but the resistance to the change is in reality—very small, and it is accomplished, even by neuro-magnetism in a wonderfully simple manner. The proportion of force required to do it is no greater than that required to move the slide valve in the steam chest of one of your steam engines, by which the enormous force of the steam is alternately shifted to first one end and then the other of the cylinder. We can generate the force required for this, in our own tissues and it accumulates in electric organs possessed by us similar to those of your electric eels. I will show you.”