The Pneumatics of Hero of Alexandria

OF THE DIVERSITY OF THE VOICES

of various birds. Theor. XV.

Even if all voices are created with pipes, the sounds nevertheless differ because of their lengths, thicknesses, thinnesses, and shortnesses. Or when some of them are immersed in water, they render such various and different voices and songs of various birds. These are made either above fountains or in caverns, or whichever place is most convenient, provided that there is a flow or course of water there; arranged in order as many birds as is convenient. But those are arranged such that a Nottola, or Owl as it is called, is placed opposite them, so that when it turns its face toward the birds by itself, they stop their song, and turning its back to them, they resume it. They are manufactured in this way: Let a small water channel be arranged that always runs, and let this be A., under which is placed the vessel B. C. D. E., in which is placed the pneumatic tube or the bent pipe F. G. Then let the funnel-shaped vessel H. be placed above the large vessel B. C. D. E., whose tail remains as high from the bottom as we think will suffice for the flow of the water. This should have many pipes that pass into the body of the large vessel, very well sealed around the lid of

A detailed woodcut illustration of a mechanical pneumatic and hydraulic apparatus. On the left, a large rectangular vessel (labeled B, C, D, E) is filled with water. A funnel (H) is positioned at the top. Two smaller bird-like figures (L, M) are connected to the vessel by pipes. On the right, a mechanism features a vertical rod (X) on a base (MM). A sleeve (O) around the rod is connected to a series of pulleys (Y) and counterweights (Z), which are in turn linked to a bucket (V) inside the main water system. Atop the rotating rod sits an owl figurine (R, S, P). The diagram illustrates how water movement automates bird sounds and the movement of the owl.

it, as I said in the aforementioned, and as for example in L. M., so that while the vessel B. C. D. E. fills with water, the forced air will come out through the pipes L. M., imitating the song of the birds. And let each pipe be accommodated in the feet and body of the birds in such a way that it sends a screech through their mouths, and when the vessel B. C. D. E. is full, because it will empty through the pneumatic tube or bent pipe, they will cease to sing.

BUT so that the Owl turns immediately toward the birds in this way, as was said above: Let a rod or straight stilus be placed, and excellently worked around on a base MM., which rests on a pivot, and let it be stilus X., around which let the perforated pipe O. P. be placed, but not entirely hollow. And let this stilus have a thin point, upon which the pipe turns expeditiously, at the top of which let a conveniently small ball R. S. be placed, upon which an Owl, well-soldered to it, rests. Let there then be a small chain, which is wrapped around the

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aforementioned pipe with the ends in opposite directions one from the other, and let them be T. Y. V. Q. At the end T. Y. let the weight Z. be suspended above the pulley or wheel Y., and let the end V. Q., placed on another pulley, suspend the concave vessel which we call a bucket; which stays under the pneumatic tube or bent pipe, so that while the vessel B. C. D. E. empties, the water will descend into the bucket, which, descending due to the weight, the chain will turn the pipe O. P. and will make the breast of the Owl turn toward the birds, and it will watch them while they cease to sing; but the vessel B. C. D. E. emptying into the bucket and it emptying through the pneumatic tube, which must be placed in it, once the vessel is empty, the weight Z. will descend, and the pipe P. O. turning, the Owl will turn back, and all at once the vessel B. C. D. E. will return to fill with air, and the birds will resume their song: until, emptying, the Owl will return to turn again, and they will cease to sing.

BY THE SAME REASON, TRUMPETS

are made to sound. Theor. XVI.

Similarly, trumpets are made to sound by the aforementioned reasons; for when the funnel is placed in the well-sealed vessel, the tail of which is placed a little distance from the bottom, sealing the funnel with the lid with extreme diligence, after having placed the mouth of the trumpet, of which the lingula tongue/reed and the dodoneo bell/trumpet-end are perforated with the lid of the vessel and well-soldered around: so that the breath of the air, in exiting, cannot go through any other place than through the dodoneo and the lingula, it happens that in pouring water into the vessel, which we call a funnel, the air shut up in the large vessel, forced by the water, through the lingula forces the Trumpet to sound.

IN OPENING THE DOORS OF TEMPLES,

it is done in this way, that one or more trumpets sound.

Theorema XVII.

Let the vessel A. B. C. D. be placed behind the doors, in which there is water, and in it an inverted vessel F., that is, with the mouth toward the water and the bottom toward the sky, in which, a hole being made, the trumpet is accommodated, which has the dodoneo in the mouth with the lingula, and on the level of the channel of the Trumpet, a ruler L. M. is accommodated, fixed in the inverted suffocating vessel, and tied to the channel of the Trumpet; let a hole Z. be made at the extremity, as large as the work can suffice, inside which let the ruler N. X. be placed, which through L. M. sustains the suffocator F. as far from the water as suffices; and let N. X. move in the middle on the pivot O., and at the extremity X. let a rope or chain be tied, which through the pulley P. is carried to the back parts of the doors in the middle, where they join.