The Pneumatics of Hero of Alexandria

clay, or of brass, and on the potter’s wheel, which we commonly call boccalari potters/jug-makers. The example is A. B., in the lower part of which thick and minute perforations are bored; but in the upper part, the mouth is made, and on each side, handles to support it, and in it a small tube C. D. And when one wishes to use it, let him submerge it in water, so that it will enter through the perforations, and the air, forced out, will exit through the tube C. D. If we close the mouth of it at C with our thumb while pulling the ball from the water, it will not come out at all, because the air cannot enter through any place, since the opening C, which is closed with the finger, is shut; but if we wish to scatter the water, lift the finger from the mouth C, and immediately the water will come out, with the air succeeding in its place. The flow will stop if we again close the mouth C with our finger, until, by lifting it again, we open a path for the air. Nor will there be any difference between the tube C. D. and a bent pipe; rather, this one will prove more convenient than the other, as the mouth can be closed with the finger with such ease.

THAT THE CONCAVE BALL CAN BE FILLED

with hot and cold water, one separated from the other, and sent out, now one, now the other; and both together.

Theorem VII.

A spherical vessel on a base, shown in cross-section with an internal vertical divider (C, D). A complex neck at the top (E, F) splits into two tubes that enter each side of the divided sphere. The tubes join at a single opening at the top (G).

With the aforementioned method, the ball is filled with hot and cold water, or water and wine, separated from one another, and made to exit now one, now the other; and both together at our will in this way. The ball having been manufactured in two parts, let the diaframma diaphragm be placed; that is, a thin cartilage, closed in one of them, and soldered to this half-part all around. Then let one half of the ball be soldered to the other. The ball will be A. B., and the cartilage C. D., which divides one part of the ball from the other; and this ball, in the manner of a sieve, is bored in the bottom. And in the top, a neck E. F. is made, bored with two tubes, one of which goes into one part of the ball, the other into the other, and they join together at G. And when we wish to fill half the ball with hot water, we will block...