34. A Vessel from which Liquid may be made to flow, on any portion of Water being poured into it.
If into a vessel, provided at the bottom with an open spout, liquid is poured, the spout shall sometimes run from the first, sometimes when the vessel is half filled, and sometimes not until the whole is filled: in fine, when any proposed quantity of liquid has been poured in, the spout shall run until all is exhausted. Let A B (fig. 34), be the vessel, the neck of which is closed: insert the tube C D, air-tight, through the partition, and let it reach to the bottom of the vessel leaving only a passage for the water. Let E F G be a bent siphon the inner leg of which extends nearly to the bottom of the vessel while the other projects without, being fashioned in the shape of a water-spout: the curve of the siphon must be close to the neck of the vessel. In A B make an air-hole, H, near the partition and leading into the body of the vessel. If we intend the spout to run immediately on the entrance of the liquid, we must place the finger on the vent H, and the spout will run, for as the air in the vessel has no wav of retreat, the liquid will rush out through the bent siphon. If we do not close H, the liquid will pass into the body of the vessel, and the spout cannot run until we again close the vent: and then, if we set the vent free, the siphon will exhaust all the liquid.