Rollo was confident that it could not possibly make any difference whether a wooden wedge was used first or last. The boy was sure that it did, though he could not tell why. Finally, they determined to try it; so the boy struck his axe into the end of the next log, and then attempted to drive in his wooden wedge. But he did not succeed at all. The wedge would not stay. Rollo told him that he did not strike hard enough. Then he struck harder, but it did no good. The wedge dropped out the moment he let go of it, and on taking it up, they found that the edge of it was bruised and battered; so that even Rollo gave up all hopes of making it enter.
“Ah!” said the boy, taking up the wedge, and looking at it, “now I know what the reason is. It is the edge.”
“Where?” said Rollo. “Let me see.”
“Why, when there is no crack,” said the boy, “you see the edge of the wedge comes against the solid wood, and when I drive, it only bruises and batters it; but the iron is hard, and goes in. But then, when a crack is made, the wedge can go in easily; for the edge does not touch; then only the sides rub against the wood.”
“How?” said Rollo. “I don’t understand.”
“I’ll show you in a minute,” said the boy. So he took the iron wedge, and went to work driving it into the log. It soon began to make a crack, which ran along the log, and opened wider and wider. When, at length, it was pretty wide, he put the wooden wedge in, and he showed Rollo that the edge of the wedge did not now have to force its way, but went easily into the crack, and only the sides came in contact with the two parts of the log which it was separating.
“That’s curious,” said Rollo.
“Yes,” said the boy.
“I wish I had a little beetle and wedge,” said Rollo. “I have got a hammer. That would do for a beetle, if I only had a wedge.”