BOOK ONE

ANOTHER DEMONSTRATION THAT THE VACUUM

cannot exist in nature.

GENERALLY all the machines called pneumatic pneumatic: machines operated by the movement or pressure of air are made insofar as nature cannot suffer any vacuum original: "vuide", and I will give another demonstration of this. Let there be a vessel marked A. B. C. D., well-closed and soldered on all sides, in which there will be a pipe, E. F., of which one of the ends, F., shall approach the bottom without touching it, so that there is a distance to allow passage between the said end F. and the bottom of the vessel. There will also be a vent-hole vent-hole: "fouspiral," a small opening or "breather" used to regulate pressure or allow air to escape marked G., which must be plugged. Then, pour water into the said vessel through the pipe E. F.; it is certain that some quantity of water will enter therein. For the air will press together (as has been shown) and a compression of air will occur in the said vessel, such that nothing more can enter; but if one opens the vent-hole, then the air that was in the place of the water will exit, and as one fills the said vessel with water, the air will exit through the vent-hole.

A woodcut diagram within the text block shows a rectangular vessel labeled A. A vertical tube labeled E descends into it, with the bottom end labeled F positioned near the floor of the vessel. At the top left, a small vent or funnel-like opening is labeled G.

THEOREM III.

THERE ARE FIVE different means to raise water higher than its level, and for each means there are several different machines: The first is for lack of a vacuum original: "vacuité"; the second, by its own means likely referring to capillary action or the internal properties of the fluid; the third, by the help of fire; the fourth, by air; and the fifth, by variously composed machines driven by the force of men or horses. I will demonstrate an example of each means and will begin with that which causes water to rise for lack of a vacuum. Let there be, then, a vessel full of water marked A, in which there is a siphon siphon: "sifon," a tube used to move liquid over an edge to a lower level using gravity and atmospheric pressure marked B.C., one of the legs of which shall be in the vessel and the other outside. Then one must have a pipe marked D, made in such a way that it can be fitted into the end C of the siphon; afterwards, one must plug the end of the said pipe and fill it with water, then fit it very tightly inside or outside the end of the siphon C. Then open the bottom end, and as the water exits the said pipe, it draws that which is in the vessel along the siphon, because a vacuum original: "vacuité" cannot be created in the said pipe. Once the said water has begun its course, one may remove the pipe D, and the water will continue its course until it reaches the level of the end C, and then it will cease. Thus one can see by this example that if the water rises upward through the siphon, it is in order to descend lower than its level; for if the outside end were cut at E, it would not flow at all. Thus, by the help of pipe D, the water rises for lack of a vacuum, because the weight weight: "pesanteur," here referring to the gravity acting on the water column in the external leg in the leg of the siphon is heavier than that in the inner leg. As for the length of pipe D, it must be a little longer. And if the siphon [is measured] from the surface of the water to the mark E, [the pipe should be] as wide as the said siphon, or a little more.

A woodcut diagram illustrating the mechanics of a siphon. A rectangular tank labeled A is shown with a curved siphon tube (B-C) drawing water out and over the edge. An additional priming tube labeled D is shown attached to the external leg of the siphon to initiate the flow. Points E and C are marked on the external apparatus to demonstrate the principles of hydraulic pressure and flow.