sir," replied Rollo; "at least it is Jonas's magnet."

"There you see the marks," continued his father, pointing to the
net-work, "of the old file teeth. Jonas ground them nearly out."

"Are those the marks of the file teeth?" said Rollo. "I thought it was
the magnetism."

"No," said his father, smiling, "those are the traces of the file teeth,
undoubtedly. You may go and ask Jonas how he got his magnet."

So away went Rollo and Nathan in pursuit of Jonas. They found him in the
kitchen, just arranging his wood for the morning fires. They asked him
where he got his magnet, and Jonas replied as follows:--

"Why, the other day, I went into town with your father's watch, to get a
new crystal put in; and when I was at the watchmaker's, I saw a
curious-shaped piece of iron hanging up. I asked the man what it was. He
said it was a magnet, that he kept to touch needles. Then he gave me a
nail, and let me see how the magnet would attract it. He told me, too,
that if I had a knife, and would rub my knife on the magnet, the knife
would attract, too; and so I did rub it, and I found that my knife would
attract the nail, though not very strong. Then I asked him if any piece
of iron would attract, after it was rubbed upon the magnet; and he said
that _iron_ would not, but that any piece of _steel_ would. He told me
that if I would bring a larger piece of steel, when I came after the
watch, he would rub it for me, and then I should have a larger magnet. I
told him I had not any steel. But he said any old file would do, and
that I might grind the sides and edges a little, and make it smooth.

"So, when I came home, I found some old files in the barn. Some were
three-cornered, and some were flat. I thought the flat would be the best
shape, and I asked your father if he would give me one of them. He said
he would; and so I ground the ends square, and the sides smooth, upon
the grindstone. Then, when I went after the watch, the man rubbed it for
me, and it makes a very good magnet."

Then Rollo and Nathan went back, and repeated this story to their
father.

"Very well," said their father; "that was a very good way to get a
magnet. I remember giving Jonas the file; but I did not know what he
wanted it for."

"I think a magnet is a very curious thing," said Rollo. "See how the
nail sticks to it!"

"There are a great many other things curious about it," said his father,
"besides that."

"What?" said Rollo.

"I should want some