"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.