10

On Water-Conducting Machines

Therefore, it often happens that air, trapped by the unnatural compression of two bodies, becomes condensed and resides in those empty places.

As soon as this compressing force relaxes, the air immediately returns to its former state and size. This can be seen in bent horns and compressed dried sponges. When the force ceases, they instantly expand as they were before, seeking their original state and space.

A similar effect follows when air particles are stretched against their nature and then released. They immediately flow back together due to their innate character, so that a vacuum does not extend further than is proper.

For this vacuum (or rather, the flight from it) accelerates the movement of bodies so they meet more quickly, unless something else stands in the way.

We experience this daily. If someone moves a light vessel with a narrow opening to their mouth and draws in the air with all their might, the flesh of the lips is pulled in. The lips stick to the vessel against their nature so that the vacuum and empty space are filled. This prevents the vacuum from growing too large.

This can be clearly demonstrated by the medical egg original: "ovo Medico," a specialized glass vessel used for distributing perfumes and by our common cupping glasses original: "cucurbitulis," glass vessels used in medicine to create suction on the skin during bloodletting.

To understand this better, have a hollow sphere made of strong copper plate. Its size should hold about two measures, or one and a half. It must be well-sealed and soldered on all sides.

Pierce this spherical vessel at the top and insert a tube vertically. Do not let it reach the bottom, but

leave enough space for water to flow. This small tube should stick out from the top by about three finger-breadths. It must be sealed tightly to the hole of the sphere, as can be seen in the attached figure (fig. 3). A diagram likely showing a copper sphere with a central pipe, used to demonstrate pneumatic pressure.

According to the opinion of some, no vacuum exists in that sphere. If this were true, it would follow that no more air or water could be sent into it, since it was already full. They believe the vessel would burst rather than admit anything else.

However, this is false. If you take the tube mentioned above and blow into it with as much force as possible, you will add a large amount of air to what was already trapped inside.

From this, we infer that the trapped air contained certain tiny empty spaces. As we said, these were compressed and condensed so much that the vessel could admit even more air.

Or, if you wish to prove the opposite, suck some of the air out. Since no other air is let in to take its place, empty spaces must remain within the sphere. Thus, the vacuum is increased and stretched by that suction.

From all these things, it is clear that there are some tiny empty spaces dispersed throughout the air. Because of these spaces, air can be condensed, thinned, or expanded.

Furthermore, if we absolutely denied these tiny spaces, neither air, nor water, nor other bodies could ever be penetrated by light, heat, cold, or similar things.

How, I ask, could the rays of the sun pass through water to the bottom of a vessel if it lacked all such passages and tiny spaces? They would perhaps be...