"I should think that, after the log
is once split open, it would stay so. If I split a piece of wood in two
with my knife, the pieces don't try to come together again."

So Rollo began to examine the log, and to look into the cracks, to see
if he could find out what it was that made the parts draw together so
hard as to crush the walnut. Presently, he observed that the log was not
split open from end to end. The crack commenced at one end, and extended
nearly towards the other, but not quite; so that at this other end the
log was solid and whole, just as it always had been. So Rollo perceived
that the two halves being joined and held together firmly here, they
could only be separated at the other end by the wedge springing them
open, and, of course, by their elasticity they tended to spring together
again. Then besides, he saw, by looking into the crack, a great number
of splinters, large and small, which extended obliquely from one side to
the other, and bound the two sides strongly towards each other.

By this time the boy had got the wedge knocked out.

"It is strange," said Rollo, "that such a small wedge will split such a
tough and solid log."

"O, not very strange," said the boy. "You see," he continued, taking up
the wedge, and pointing to the several parts as he explained them, "you
see here at this part, where it enters the wood it is sharp, and the
sides spread out each way, so that, when I drive it in, they force the
wood apart."

"Why don't they have the back of the wedge wider still? and then it
would force the wood open farther; and then you would not have to put in
a wooden wedge afterwards,--so," he added, making a sign with his
fingers. He put the tips of his fingers together, and then separated his
hands, so as to represent a very blunt-shaped wedge.

"Then it would not drive in so easily," answered the boy. "Perhaps I
could not drive it in at all, if it was so blunt."

"They might have the wedge longer then," said Rollo, "and then it would
be just as tapering, and yet it would be a great deal broader at the
back, because the back would be farther off."

"That would make the wedge a great deal too heavy. It would not drive."

"Why, yes, it would," said Rollo.

"No, it would not," said the boy. "It would be just like a shoemaker's
lap-stone; pounding it would hardly move it."

Rollo did not understand what the boy meant by what he said about the
shoemaker's lap-stone; so he paused a moment,