OF THE SPIRITUALS

BY HERON.

ON DRAWING WATER BY WAY OF A

bent Tube, or Pipe. First Theorem.

An engraving illustrates Heron's first theorem on siphons. It depicts an ornate, footed vessel labeled 'A' and 'B', partially filled with liquid. A decorative relief of a face is on the side of the vessel. A bent tube (siphon) is inserted, with its inner leg submerged to point 'C' and its outer leg extending downwards. Points on the diagram are labeled with letters: 'D' at the top bend, 'E' at the bottom of the outer leg, 'F' and 'G' indicating the water surface level, 'H' where the inner leg meets the surface, 'I' an opening on the bend, and 'K' an opening on the outer leg.

Let there be water in a vessel A. B., the surface of which is F. G.; and in this, let the bent pipe C. D. E. be inserted with one leg, and let the leg C. H. be in the water, which should be filled with water up to H., level with the surface F. G., and the part H. D. I. shall be full of air. I say that if we make a hole at I., and through it draw the air out with our mouth, the moisture, that is, the water, will follow; because, as has been said above, it is clear that the place of the whole cannot be a vacuum. And to this it must be added that if the hole I., through which we have drawn the air, is in line with the surface F. G., the pipe will not spill, but the water will remain up to that limit, so that the part C. D. I. will remain full, even if, contrary to the order of nature, it remains suspended on high like a balanced scale, the water standing elevated on high from H. to D. and suspended downwards from D. to I. But if the hole in the top of the pipe is in a straight line as at K., the pipe will spill, and the water will run out; because the part D. K., being heavier than the part D. H., will prevail and pull it, and it will flow out of that channel until the surface of the water, which will lower in the vessel as the channel keeps flowing, has reached the level of the hole K., and there it will no longer flow—