A FUNNY HORSESHOE.
"What a funny horseshoe!" said Charlie, "It has no holes for the nails!"
I looked up and saw that he had taken up a small "horseshoe magnet."
"Why that isn"t a horseshoe," I said. "It"s a magnet."
"Magnet! What"s that?"
Charlie turned it over in his hands, and pulled the bar a little. The bar slipped so that it hung only by a corner.
"Never mind," I said, as he looked up with a scared expression. "It isn"t broken. Put the bar back."
Charlie put it back, and it sprung into place with a sharp click.
"That"s funny!" he cried again. "What made it jump so? And what makes it stick? It doesn"t feel sticky."
"We call it magnetism," I said. "Now, take hold of the bar, and see if you can pull it straight off."
"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?"
"These," he said, pointing to a pile of things on one side of the box.
"And these things it doesn"t pull."
"Let us see what you have in this pile," I said, looking at the first little heap; "keys?"
"Trunk keys," said Charlie. "It doesn"t pull door keys. I tried ever so many."
"Try this key," said I, taking one from my pocket. "This is a trunk key.
See if the magnet pulls it."
"No-o," said Charlie, thoughtfully, "it doesn"t; but it pulled all the rest of the trunk keys I could find."
"Try this key to my office door."
Charlie tried it, and to his great amazement the key stuck fast to the magnet.
"Surely," said I, "it pulls some door keys, and fails to pull some trunk keys."
Charlie was more puzzled than ever. He looked at the keys, thought a moment, then picked up my trunk key, and said: "This key is bra.s.s; the rest are iron."
"That"s so," I said.
"And all these door keys that the magnet didn"t pull," he continued, "are bra.s.s, too. Perhaps it can"t pull bra.s.s things."
"Suppose you try. But first see if there are any bra.s.s things that the magnet pulled."
Charlie looked them over. Then we tried the casters of my chair, and all the other bra.s.s things we could find, none of which the magnet would pull.
"There"s no use in trying any longer," said Charlie. "It won"t pull bra.s.s."
"Then, there"s another matter settled," I said. "The magnet does not pull bra.s.s. Is there any thing else it does not pull?"
"Wood," said Charlie. "I tried lots of pieces."
"Any thing else?"
"Stones," said Charlie, eagerly.
"What are these?" I asked, holding up a couple of heavy stones he had put among the things the magnet pulled.
"I guess I put those there by mistake," said Charlie, testing with, the magnet a number of stones in the other pile.
"Try them," I said.
"O!" he said, as the magnet lifted them; "I forgot. It does lift some stones."
"Well, what else have you in that pile of things the magnet did not pull?"
"Gla.s.s, leather, lead, bone, cloth, tin, zinc, corn, and a lot of things."
"Very well. Now let us see what the magnet does pull."
"Iron keys," said Charlie, "and nails."
"Here"s a nail in this other pile."
"That"s a bra.s.s nail. The magnet pulls only iron nails."