The Ingenious and Curious Pneumatic Motions of Hero

For the bodies of the air that are left in it at the same time cannot become larger, so as to fill the place of the expelled bodies; for if they were to increase without any other exterior substance being added, it would be probable that this increase would be made by rarefaction. But this is implication by way of evacuation, and because no vacuum is granted, the bodies cannot even increase, nor can one even comprehend with the mind the possibility of such an increase. From this it becomes clear that by means of the bodies of the air, certain vacua are disseminated, which, reached by a certain violence, are forced out of nature to recline into vacua. Whence the air that is enclosed in the vessel submerged in water, even if it comes to be much pressed, that which by reason would give cause to 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 in the depths of the Sea, who even if they have infinite measures or Amphorae upon their shoulders, are not forced by the water to breathe otherwise, even though in their nostrils a small quantity of air is understood. But whence it happens that those who swim in the Sea are not compressed by the infinite weight of the water that they have upon their shoulders and upon 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 depths are not compressed by the water above, for this certainly must be demonstrated in this way. Let it be understood that there is some body equally heavy and equally humid, which has the same form or figure as the superior humidity, the upper surface of which is as that of the compressed, and let us understand this thrown by us into the water, and let it be that the lower surface of this conforms to the upper, or rather is the same as it, and similarly let it be placed equal to the superior humidity. It is very clear that this body submerged in the water will not float above it, nor will it submerge below the surface of the superior humidity, which is learnedly demonstrated by Archimedes Ancient Greek mathematician and physicist in the book of those equally heavy bodies, in which he also proves that the humid immersed in the humid neither swims above the humid nor submerges into it. It is seen, therefore, that bodies subjected to water cannot be compressed by its gravity. Since it can be said, 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 underlying bodies. For as far as the extreme that pertains to the reasons of motion and rest, there is no difference from the said body to the humidity that occupies the same place. But if anyone intends that there is no vacuum, it not being given, and there being none, nor for the water, nor for the air, nor for any other body, light or heat or any other corporeal power could 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, whence it would happen that full vessels would overflow. This we do not see 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 downward, nor are they seen hitting the particles of the water breaking in the upper place. But that by falling into the water and passing through the small par-