The Pneumatics

force. If, therefore, anyone blowing in, and applying his hand to the mouth itself, should immediately block the siphon with a finger, the compressed air will remain in the sphere at all times. But if anyone opens it, the injected air will again break out with a great noise and sound; because, as we have proposed, it is expelled by the expansion of the pre-existing air, produced with a certain impetus. Again, if anyone wishes to draw out the air which is in the sphere by mouth through the siphon, it will follow in great quantity, although no other substance enters into the sphere, just as was said before regarding the egg. Wherefore, it is clearly shown from this that a great accumulation of vacuum has been produced in the sphere. For the bodies of air which are left behind at that time cannot become larger, so as to fill the place of the expelled bodies. For if they were increased when no substance from without reached them, it would be probable that the increase occurred through rarefaction. This, however, is an implication involving evacuation. But they say that no vacuum exists. Therefore, the bodies will not be increased; for neither