The Pneumatics of Hero of Alexandria

OF CONCORDANT VESSELS.

The vessels that are called concordant are fixed upon a base, of which, even if one of them is full of wine and the other empty, although their channels are both open, the wine will not exit unless the other vessel is filled (let us say) with water, so that immediately both will spill, one water and the other wine, nor will their flow cease until they are entirely empty. And they are manufactured in this way. Let the Base upon which the vessels will be placed be A. B. C. D., but let the vessels be E. F., and in each of them let the bent pipes be placed; in vessel E. let there be the pipe G. H. K., and in F. let there be L. M. N., so that their exits have curved channels that spill outside the vessels; and let the pipes of these be bent through another pipe in the Base, which is O. P. Q. R., their mouths O. P. being next to the curvatures of the pipes. Then let one of these vessels be filled with wine, which for example is E., but not so much, however, that it is above the curvature of the pipe H., for if the wine does not arrive above it, it will not exit at all; because the pipe cannot have a beginning of flow. But if we put so much water into vessel F. that it rises above the curvature of the pipe M., then the water will begin to flow through the pipes O. P. Q. R. into vessel E., giving a beginning of flow to the wine; and at the same time both vessels will pour, this one wine and that one water, until all the wine and all the water has come out of them.

A technical diagram of two decorative classical-style urns or jugs sitting on a wide rectangular pedestal. The jug on the left is labeled E, with a curved spout labeled G, H, K. The jug on the right is labeled F, with a spout labeled L, M, N. Inside the transparent view of the pedestal (labeled A, B, C, D), a horizontal pipe labeled O, P, Q, R connects the inner drainage points of the two jugs.

OF VESSELS IN WHICH, BY POURING

There are also certain vessels in which, if we pour water with art, we create different sounds according to our taste, which are formed in this way. Let the Base be closed all around A. B. C. D., and above the lid of it let the funnel E. F. be placed, which has the tube as high from the bottom of the vessel as will suffice for the flow of the water; let this be closed very well all around on the lid of the base. Then let the pipe G. H. K. be made in such a way,

A technical diagram showing a rectangular box labeled A, B, C, D acting as a reservoir. On the left side, a funnel labeled E, F is inserted through the top. On the right side, an L-shaped tube labeled G, H, K emerges from the top and bends downward into a small bowl labeled L. Next to the bowl is a decorative tree with a bird perched on a branch, its beak aimed toward the tube's exit to suggest the source of the sound.

accommodated in the part above the vessel, that by blowing into it, it may render a sound; this (with the Base perforated) should be soldered into the lid; but let the mouth of it, K., be bent somewhat so that it is placed in a small vessel of water, as in L. for example. If through the funnel E. F. we put water into the base, the air that is in the base will be forced to exit through the pipe G. H. K., and consequently to create the sound; and if we place the extremity of that pipe in the water, a loud sound like that of a nightingale will come out; and if there is no water there, it will render a simple whistle. The example is this.