The Pneumatics of Hero of Alexandria

one of the holes that is in the neck with a finger, submerging the ball in the water; for since the air shut in that part of the ball whose tube is blocked cannot exit, it will only enter the other part, from which the air can exit through the open tube, and give place to the water. And after said part is filled with hot water, close the air-hole of it in the neck, and lift it from the vessel of hot water; then uncover the other, and placing the ball in the cold water, let it be filled similarly. Then, having blocked the other hole, lift it from the water, and the ball will be full. And wishing to send out the hot water, let the air-hole or tube of that part of the ball in which it is enclosed be opened, so that it will exit through the holes in the bottom part (of said ball), and when we no longer wish it to come out, we will block that tube again. And we will do the same for the part where the cold water is. Wishing to send out both at once, open one air-hole and the other, and close them when we no longer wish them to come out. And it is to be noted that these air-holes can be reduced to a single tube divided into two parts, and in the top of it, one can make a single hole, accommodated in such a manner that by closing and opening these holes at our pleasure, it may seem that everything comes from one and the same hole through said neck, as the following example demonstrates.

OF THE VESSEL CALLED PROCHITA, WHICH

was anciently used in sacred ministries. Theor. VIII.

An ornate vessel with a molded face on the left side. The vessel contains a horizontal internal divider (C, D) perforated with holes. A central tube (E, G, H) runs from the top opening through the divider towards the bottom. The handle system on the right is labeled with letters A, B, E, D, G, H, K to explain its pneumatic function.

Vessels are also manufactured that, filled with wine and water, at times give pure water, at times send out pure wine, and at times water and wine mixed together. Their construction is done in this way. Let the vessel be A. B., in the middle of which is placed the diaframma diaphragm, that is, the cartilage or diameter C. D., and around the body of the vessel, said diameter is bored with thick holes in the manner of a screen or sieve, as we call it. And in the middle of said diameter is the round hole E, through which the bored pipe E. G. H. passes, well-fitted and soldered at E, with the mouth G a little distance from the bottom of said vessel. The other mouth at H is very well soldered to the vessel, and in it is made a small perforation that enters into the mouth of said pipe at H on the ear of the handle, which will be made as the figure shows, and perforated like the pipe. And on the fold of it at K, another perforation or air-hole is made, which, when blocked with a finger, and then the vessel filled with water, it will remain above the diaframma diaphragm or diameter, not being able to descend to the bottom, the air that is in it having no other place from which to exit and yield its place, except for the vent K and H, which, once opened, the water will immediately descend through the sieve to the bottom of the vessel. Wherefore, if we first put wine in the vessel, then close the air-hole K, if we subsequently fill the vessel with water, it will not mix with the wine. But by pouring from the vessel, only the pure water will come out, with the air-hole K remaining closed. Then, closing the perforation H and opening the air-hole K, only the wine will come out through the mouth of the vessel, into which the mouth of the pipe will arrive level with the mouth of the vessel. And with one and the other opened, wine and water will come out. Whence it is clear to us that from said vessel we will pour, at our pleasure, water and wine, and wine only, and pure water, when we want to play a trick on our friends. Which vessel shall be manufactured as the above-written figure shows.