The Pneumatics of Hero of Alexandria

to that square as if it were a flap: afterwards, let a hole be made in the middle of it; then let a square, which we shall call C. D., be made on one side of the first, with a pipe divided into five parts, of which two are cut in the middle, as the example below shows. After this is done, let another large square be made, like the first, and similarly another square marked within it, as was done in the first. But let as much of the margin be cut away in this one as the other square is hollow beyond the flap; so that when assembled together, the height of this one enters into the hollow of the other, and the margin of the first into the lower part of this one. Joined together, let the two parts of the cut pipe that are missing in the first square be placed there; but let these be joined to the second, and let an iron wire be placed in the hole of the pipe, riveted at each end, so that F. cannot come out. And let the first square be marked A.B.C.D. The second F.G.H.E. and the pipe C. D. attached to the first, and E. F. to the second, which opens and closes like a hinge; from which it receives the air and closes the exit hole of it, for which I have provided the present figure, easy to be understood by any mediocre talent.

TO SACRIFICE AS MANY ANIMALS AS WE

wish by the power of a lit fire. Theor. XI.

Animals are made to sacrifice in this way. Let the Base upon which they rest, A. B. C. D., be excellently closed all around; above the

A woodcut illustration of a mechanical altar. On a large rectangular base labeled A, B, C, D, L, N, sits an ornate pedestal featuring a central figure blowing wind. On top of the pedestal, a fire burns on a small altar (G). To the left, a woman stands holding a round object (mirror or bowl). To the right, a bearded man in a long robe pours liquid from a jug into a bowl on a small stand. The base is shown with internal mechanical components and tubes labeled with letters and numbers (K, M, O, G, 3, L, N).

which you place an altar, similarly closed all around together with the Base, holed at G. But let tubes pass through the Base, as many as there are Animals, which are H. L. N. O., a little distance from the bottom; in L. N. let these be perforated, and let the arms of the animals be perforated, which have in their hands either a vase or whatever thing is to be sacrificed. After this, let water be placed in the base through some hole, such as at M., which shall then immediately be plugged. Then, light a fire above the altar E. F. so that the air in that closed altar will be immediately forced by the vapor of it to descend into the base through the tube P. and drive out the water, which, having no other exit, must needs come out through the tubes N. O. H. L., pushed by the force of the vapor through the vases or whatever thing the Animals have in their hands, and thus sacrifice. And the sacrifice will last as long as the fire stays lit on the altar; which, once extinguished, the sacrifice will cease. Whence it will happen that they will sacrifice as many times as the fire is lit. But it is necessary that the tube through which the heat must pass be thick in the middle; because it is necessary that the vapor be great, so that it has greater force to drive out the moisture, so that it may operate more greatly.

OF VESSELS WHICH, IF THEY ARE NOT FULL,

do not pour; but when full, all the moisture that is inside them escapes. Theor. XII.

Let the uncovered vessel be A. B. C. D., through the bottom of which is placed the diabete spiritale pneumatic siphon E. F. G. H. or the bent or curved pipe I. K. L. Let the vessel A. B. C. D. then be full of water, so that for the reasons alleged above, all the water will go away until the vessel remains empty, provided that the canna pipe or tubo Spiritale pneumatic tube is only as far from the bottom as suffices for the flow of the water.

Two woodcut diagrams showing hydraulic vessels. The left diagram shows a cross-section of a footed bowl (A, B, C, D) with a central tube (G, I) that functions as a siphon. The right diagram shows a wider, ornate basin with handles, containing a curved siphon tube labeled K, L, I.