"First," said Jonas, "you, Rollo, may take hold of the nose of the bellows with your hand, in such a way as to put your thumb over the end of it, to stop it up, and then let Nathan try to blow." Rollo did so, and Nathan tried to blow. He found that he could open the bellows very easily; but when he attempted to press the sides together again, he could not. He crowded the handle belonging to the upper side down, as hard as he could, but it would not move. "What makes it do so?" said Nathan. "The air inside," said Jonas. "We have stopped up all the places, where it could get out. The valve stops itself. Rollo stops the nose with his thumb, and I have nailed the leather down close, about all the sides. And so the air can't get out, and that keeps you from bringing the sides together again." Nathan tried again with all his strength. The sides came together very slowly. "They're coming," said he. "Yes," said Jonas. "They come a little, just as fast as the air can leak out through the little leaks all around." "I thought you stopped all the leaks," said Nathan. "Yes," replied Jonas, "I stopped all the real leaks, but still I can't make it perfectly tight. Some air can escape between the leather and the nails all around, and just as fast as it can get out, so fast you can press the sides together, and no faster." Here Nathan tried again with all his strength; but he could only bring the sides together very slowly. "Now comes the second experiment," said Jonas. "While Nathan is trying to press the two handles together, you, Rollo, may run your finger into the hole, and push up the valve a little." Rollo did so. He pushed up the valve a little with his finger, and that allowed the air to escape through the opening. The consequence was, that the bellows collapsed at once under the pressure which Nathan was exerting upon them. "There," said Jonas, "you see that when the air is kept in, you cannot bring the sides together; but when I let the air out, then they come together easily." "Yes," said Nathan; "do it again, Rollo." So they performed the experiment again. Nathan pulled the handles apart wide, while Rollo kept his thumb over the nose, to keep the air from issuing through. Then Nathan tried to press them together; but he could not, until Rollo put his finger under, and pushed up the valve a little, and then they came together again very easily. "The air is a real thing, I verily believe," said Nathan. "Yes," said Rollo, "I know it is. And now for the third experiment, Jonas." "The third experiment," said Jonas, "is this. Turn the bellows bottom upwards, and try to blow." Nathan did so. He found that he could work the bellows easily--too easily, in fact; but they did not blow. "Hold your hand opposite the nose, and see if any wind comes," said Jonas. They did so; there was no wind, or rather scarcely any.