e carpet nail into each end of the strap. The
strap, when it was nailed, passed directly across the clapper or valve.
It was not drawn tight across, but it lay upon the clapper loosely. The
ends were nailed tight, but the middle rested loosely upon the clapper.

"Now," said Jonas, "I can push the clapper up a little way, but I can't
push it far. The strap keeps it from coming up far."

"But why," said Nathan, "do you want it to go up at all?"

"To let the air in," said Jonas. "When I get the leather all nailed on
again, I'll show you the whole operation of it."

"And you can be telling us about it in the mean time," said Rollo.

"Well, then," said Jonas, "when I lift up the upper side of the bellows
by the handle, to blow, the air comes in by the hole. The clapper lifts
up a little way, and lets it in. Then, when I press down the handle
again, it presses the air out through the nose, because it can't go back
through the valve hole."

"Why not?" said Nathan.

"Because," said Jonas, "the valve falls down over the hole, and stops it
up. It is made so as to lift up easily, and then to fall down and cover
the hole exactly, and prevent the air going out the same way it came in.
So, as it cannot get out by the valve, it has all to go out through the
nose. If the nose were stopped up, it could not get out at all."

"And what then?" said Rollo.

"Why, then," replied Jonas, "you could not bring the two sides of the
bellows together again. The air between would keep them apart."

"I should like to try," said Rollo.

"Well," said Jonas; "and there are some other experiments you may
perform with it too."

At length, Jonas said that he had got the leather all nailed on, and
they might try the experiment. He took hold of the nose of the bellows,
and held his thumb near the end of it, ready to stop up the hole.

"Now, Nathan, you may take hold of the handles, and pull them apart as
if you were going to blow."

Nathan did so. He pulled the handles apart, and held them open.

"Now," said Jonas, "I will stop up the nose, and the valve will close
itself; and then you will find that you cannot bring the sides together
again."

So Jonas put his thumb over the hole, and told Nathan to blow.

Nathan pressed hard, and the sides came together again, about as easily
as usual.

"What!" exclaimed Jonas with surprise. He did not know what to make of
the failure of his experiment.

"There must be a leak somewhere," said he. And