“Yes, that’s right.”
“The wires go out from the cave and fence in a circle of level ground a hundred yards in diameter; they make twelve independent fences, ten feet apart—that is to say, twelve circles within circles—and their ends come into the cave again.”
“Right; go on.”
“The fences are fastened to heavy oaken posts only three feet apart, and these posts are sunk five feet in the ground.”
“That is good and strong.”
“Yes. The wires have no ground-connection outside of the cave. They go out from the positive brush of the dynamo; there is a ground-connection through the negative brush; the other ends of the wire return to the cave, and each is grounded independently.”
“No, no, that won’t do!”
“Why?”
“It’s too expensive—uses up force for nothing. You don’t want any ground-connection except the one through the negative brush. The other end of every wire must be brought back into the cave and fastened independently, and without any ground-connection. Now, then, observe the economy of it. A cavalry charge hurls itself against the fence; you are using no power, you are spending no money, for there is only one ground-connection till those horses come against the wire; the moment they touch it they form a connection with the negative brush through the ground , and drop dead. Don’t you see?—you are using no energy until it is needed; your lightning is there, and ready, like the load in a gun; but it isn’t costing you a cent till you touch it off. Oh, yes, the single ground-connection—”