The Pneumatics of Hero of Alexandria

contraction of those bodies that are implicated in the voids within it. But in this, the contraction happens because Nature is here violated by the violent introduction of the spirito spirit/breath. If, therefore, we blow through that mouth and immediately stop the hole with our finger, the compressed air will remain inside the Sphere. But if we open that mouth, the air introduced into it will burst out again and escape with great noise and shouting, because, as we have proposed, it is driven out by the dilation of the pre-existing air, made with a certain impetuosity. Again, if someone wishes to draw out the air that is in the proposed Sphere with their mouth through the tube, they will draw out a great quantity of it, nor will any other substance succeed into the Sphere, as was said above concerning the physician. From which it is clearly demonstrated that in the void of the Sphere, a great gathering had been made; for the bodies of air that are left there at the same time cannot become larger, so that they fill the place of the expelled bodies. For if they were to increase without any other exterior substance being added, it would be likely that this growth would happen by rarefaction. But this is implication by way of evacuation, and because no void is conceded, the bodies cannot even increase, such that not even with the mind can one comprehend the possibility of adding another increase. From this it becomes clear that by means of the bodies of air, certain voids are disseminated, which, when approached by a certain violence, are forced against nature to recline into the voids. Hence, the Air that is closed in the Vessel immersed in water, even if it comes to be much pressed, that which by reason should violate it is not sufficient in this place, because naturally water in itself has neither gravity nor vehement compression, as we see happening to those who dive into the depths of the Sea, who, even if they have infinite metrete jars/amphorae or amphorae upon their shoulders, are not otherwise forced by the water to breathe, even though a small quantity of air is understood to be in their nostrils. But whence it comes that those who swim in the Sea are not compressed by the infinite weight of the water that they have above their shoulders and above their waist is certainly worthy of consideration. Some say this happens because water is equally heavy according to itself; but these do not say for what reason those who swim in the deep are not compressed by the superior water. This must certainly be demonstrated in this way. Let it be understood that there is some body equally heavy and equally humid, that has the same form or figure as the superior humidity, the surface of which is as if compressed, and let us understand this thrown by us into the water, and let it be that the lower surface of it conforms to the upper, or rather is as it is itself, and similarly let it be placed equal to the superior humidity. It is very clear that this body immersed in the water will not float upon it, nor will it immerse itself under the surface of the superior humidity, which is learnedly demonstrated by Archimede Archimedes in the Book of those bodies equally heavy, in which he also proves that the humidity immersed in humidity neither floats above the humidity nor immerses itself into it. It is seen, therefore, that bodies subjected to water cannot be compressed by its gravity. Being, as one can say, how can that body be compressed to which it is not granted to descend into the lower place? And for this reason, the humidity,

where the body was, will not be able to compress the bodies beneath it. For, as far as the extreme that pertains to the reasons of motion and of rest, there is no difference from the said body to the humidity that occupies the same place. But if someone understands that there is no void, and that it is not given, and not being, then neither for water, nor for air, nor for any other body could light, or heat, or any other corporeal power pass. For how would the rays of the Sun pass through the water to the bottom of the vessel? If the water did not have porosity, these rays, there is no doubt, would break the water with violence, from which it would happen that full vessels would overflow. We do not see this happen, and for this reason, if they broke the water with their violence, certainly some of them would break in the upper part; others would fall downwards: one does not see them breaking in the upper place when striking the particles of the water. But that in falling into the water, and passing through the small particles, they go to the bottom of the vessel, makes us clearly understand that there are voids in the water. One sees, besides this, wine poured into water going through it according to the effusion; which would not happen if there were no voids in the water. And the lights are carried one through the other, for if we light more lamps, they will illustrate everything more greatly in the same way, passing and penetrating one through the other reciprocally. But for copper, and for iron, and for all other bodies, such penetration happens in the exact way that happens in the torpedine electric ray (fish), a marine fish. But because we have demonstrated that gathered void is against nature, and through the light vessel opposed to the mouth, and through the physician, and it seems to us that there are many demonstrations of the nature of the Void explained by us, we have thought to have said enough about this, since we have demonstrated it through sensible demonstrations. Let it therefore be universally permitted to say that every body is composed of light and small bodies, in which, or among which, there are small voids disseminated in particles; and that we abuse ourselves when we say that nothing of void is to be found, if it is not violated by any violence; but that every thing is full, either of air, or of water, or of some other substance, and as much of one of these is missing, so much there is of the other that fills the place. We say again that no void is naturally gathered or amassed if it is not violated by any violence, and again that no void is found at all except outside of nature. And since we have explained these, it is time now to give principle to describe the Theoremi theorems that are made by means of the battles of the aforementioned Elements, for by means of these are found various and marvelous Motions, which, first considered as Elements, we will reason of the inflected Siphoni siphons, they being most useful for many Cose Spiritali spiritual/pneumatic things.