"That is just the thing. Isn't it wonderful what a friend common clay has been to us since we have been on this island!"
"I think we ought to erect a monument to Monsieur Clay?"
"It would be a fitting thing to do, because at the end we are all bound to go back to him."
"I believe you said, Professor, that we should have to grind up the coke and then mix it up and make plates out of it?"
"Yes; we can use either carbon or copper for the negative plates."
"What are the other plates?"
"The positive. That is what I wanted the zinc for, which we made several weeks ago."
"Why should we have positive and negative plates in a battery?"
"Everything must have an opposite. If there is an up there must be a down; there would be no darkness without light; no heat without cold; no strength without weakness, and no joy without sorrow. Like all these things, the electric current flows from one to the other."
"But in electricity the current flows only one way, does it not?"