The Ingenious and Curious Pneumatic Motions of Hero

is somewhat greater than the first tube, and is equally distant from it. The mouth of this is stopped with the utmost diligence at E. F., so that the air does not enter it; but its lower mouth G. H. is so far from the bottom of the vessel that the water, wishing to exit, can freely flow. These, as I have said, being so accommodated, if through the mouth D. we draw the air that is in the tube C. D., we will also consequently draw the water that is in the vessel, which will all exit for the reason of that part of the tube that advances outside below the foot of the vessel. Because the air that is between the water and the tube C. at I. K. in the tube E. F., drawn by the mouth D., will pull the water with it; the flow of which will not stop due to the part that is outside the vessel. But if the tube E. F. G. H. is not there, the flow of the water will cease, even if its surface is at C., the excess remaining still. But because the air cannot enter under the whole tube E. F. G. H. submerged in the water, for this reason the flow will not stop, and the air having entered into the vessel A. B., as it exits, the water will succeed in its place; because the mouth of the tube that is outside the vessel is always lower than the surface of the moisture that is in it. And these surfaces not being able to render themselves equal, due to the greater gravity of the water, it will happen that all the water will exit out of the vessel. And if we do not want to pull out with the mouth the air contained by the tube C. D. and I. K., we will fill the vessel A. B. with water until, by being infused through the tube C. D., it takes on its flow, and thus all the water that is in the vessel will exit out; and this tube will be called a Spiritual Siphon.

From what has been said, therefore, it is clear that the flow of the tube (it remaining stationary) will be unequal, and the same will happen if the vessel is pierced at the bottom and the water exits from it; because its flow will be unequal, because at the beginning of the effusion it is pressed by greater gravity, which always becoming less, the more the water lowers in the vessel, the flow becomes smaller and weaker. And the greater the excess of the tube is, the faster the flow becomes, and the slower the less it is, as was also said in the past proposition. It is manifest, therefore, from what we have said, that the flow of the water through the tube or pipe is always unequal; whence, proceeding further, it is necessary to demonstrate the flow of the water always being equal through the bent pipe proposed above.