The Pneumatics of Hero of Alexandria

cup be equal to the mouth H. of the pipe G.H. Having done this, let the wine be poured through the mouth, and through the pipe E.F. into the vessel A.B., such that the air in the body of the closed vessel A.B. will exit through the pipe G.H.; and if the faucet K.L. is open,

A technical diagram of a pneumatic or hydraulic apparatus. It shows a large upper vessel labeled A and B, connected by internal tubes G, F, and E to a lower collection basin or cup R. Various internal components are labeled with letters including V, K, L, H, M, S, X, and N. The cup R is shown being filled from the system above.

the wine that is infused through it will go into the base, and into the cup. But if it is blocked, the vessel A.B. will be pressurized. Now, let us place wine also in the base M.N.X.O. and in the cup P.R., so that it is full, and the base M.N.X.O. is also full up to the mouth of the pipe G.H. This having been done, let the mouth E be closed, so that the wine which is in the vessel A.B. will no longer descend into the base through the faucet K.L., not being able to have air from elsewhere except through the mouth E, which is already plugged. But when the wine is drawn out of the cup, open the mouth E again, and the wine will descend into the base and into that cup K.R. until it is full again, with the air entering the vessel in place of the water. This will happen as many times as the wine is drawn from the cup. However, it will be necessary that the base M.N.X.O. be perforated at Y so that the air which is in the vessel A.B., yielding its place to the wine, enters through the mouth G and exits through the hole Y.

THAT THE PROPOSED CUP (THOUGH ONE

may draw a large quantity of wine or water) SHALL ALWAYS

remain full. Theor. XX.

Let there be the vessel A.B. in which there is water for future use in sufficient quantity, and the channel that exits from it shall be C.D., under which let another vessel G.H. be placed. Next to the channel, let the ruler E.F. be placed, and from the extremity E, suspend the float K inside the vessel G.H., and from the extremity F, suspend a lead weight X by a cord or small chain. Arrange it so that the float swimming in the vessel G.H. closes the mouth of the channel C.D. When drawing water from G.H., the float will lower with it and open the mouth of the channel C.D. When the vessel G.H. is filled again, the mouth of that channel will be plugged.

where the flow of water is impeded. Thus, if the cup is placed in any location whatever, the extreme lip of which is equal to the surface of the water,

A small schematic diagram showing a funnel-like vessel labeled M, L, N connected to a larger cylindrical container G, H, K. A lever system with points E, D, K, B is visible, suggesting a valve mechanism.

it will happen that if anyone draws water from the cup, the water of G.H. will also lower, and with it the float, opening the mouth of the channel, through which, as the water flows, the cup will return to being full. And when the vessel G.H. is filled again, the float, which by its lightness must necessarily stay afloat on the water, will (as we have said) come to close the mouth of the channel. This will happen as many times as the water is drawn from the cup.

A VESSEL INTO WHICH A COIN OF

five drachmas is thrown, and water comes out, and sprinkles the person who puts the coin into the vessel. Theor. XXI.

An illustration of a decorative ornate urn or "spondeio" on a pedestal. The vessel is ornately decorated with handles and classical carvings. A cutaway view reveals an internal mechanism: a horizontal lever O-P balanced on a vertical support N-X, with a flat plate R on one side and a cylindrical piston weight above a cup L on the other side. Labels include A, B, Q, F, H, G, S, M, D, and C.

Let there be the spondeo sacrificial vessel, that is, the Treasury A.B.C.D., the mouth of which, Q, is covered, and inside there is a small vessel F.H. in which there is water, and in it is the box L, from which the channel L.M. exits out of the vessel. Let there then be placed in the vessel the straight ruler N.X., fixed at the bottom, upon which, on a pin, let the other ruler O.P. be placed. This should have at O the platismatio a wide plate or pan, or as we say, the wide shovel R, and it should be parallel to the bottom of the spondeo. At P, there is a cylinder with a cover, and said cylinder enters into the box L so that the water does not exit through the channel L.M., and the cover with the cylinder is as much heavier than the platismatio, or shovel, whichever it be called, as is