Siphon

(si'fun,) or SYPHON. (Gr.] (Phys.) In its simplest form is merely a tube open at both ends, and bent at an angle of about 45° C. near its centre. If such a tube be filled with water, its two ends closed and inverted, so that one end is in a basin of water, and so that the surface of water in the basin is at a higher level than the end of the tube outside, which may be called the longer limb, the water will rise in the shorter limb, pa the bend, and fall down the longer limb, so as to empty the basin, or, at all events, bring the surface of the water in it to the same level as that of the end of the longer limb. The action of the S. is that of a longer column of liquid outweighing a shorter one. The column is maintained entire or continuous by the equal pre ure of the air on both open ends of the tube. These pre ures being equal and opposite, will not interfere with the motion. The latter is brought about by a force equal to the weight of a column of water, whose height is equal to the difference between the vertical distance from the surface of water in the basin to the top of the S., and the distance from the open outer opening to the top of the S. For it is clear, 1st, that the effort of the water in the shorter end, as far as the surface of the liquid in the basin, is neutralized by the pre ure of the water in the basin; and, 2d, that the column of wat erin the shorter limb is counteracted by that in an equal length of the longer one. By means of a S. it is impo ible to raise water more than 32 feet, because if a tube of such dimensions be filled with and inserted into water, then the top of the arch is more than that distance above the surface of the water, the atmosphere will no longer be able to support either column, and they will separate at the top. [s. 829]