"I can't. It sticks fast."
"Pull harder."
Charlie braced himself for a strong pull. Suddenly the bar came off, and he went tumbling backward.
"What did you say makes it hold so hard?" said he, getting up.
"Magnetism," said I again.
"But what is magnetism?"
"I couldn't tell you if I tried; but I think you could learn a great deal about it with that magnet. You will find a lot of things in that box that may help you."
Saying this, I left him to pursue his studies as best he could. When I came back, I found him more puzzled than when I left him.
"That's the queerest thing I ever saw," he said. "Some things just jump at it as though they were alive; some things it pulls; and some things it doesn't pull a bit."
"That's a very long lesson you have learned," I said. "What does it pull?"