2142. Fowler's method of circulating hot water in his thermosiphon consists in employing the power of the descending fluid in the leg of a common siphon, to draw up hot fluids in the opposite leg, 'for the purpose of causing hot fluids to flow from boiler to boiler, or from vessel to vessel, through connecting tubes of various lengths and forms. How this is done will be readily understood by reference to the diagram shown in fig. 635. Supposing the water of an uniform temperature in both legs of the siphon (a b), no circulation would take place; but supposing it to cool sooner in the long leg (a) than in the short leg (b), then the equilibrium would be destroyed, and the water in the long leg (a) would descend, and draw up hot water through the short leg (b); and this circulation would continue as long as the water at c was maintained at a temperature above that of the surrounding atmosphere.' Any engineer will easily see how this principle may be applied to the circulation of hot water in horizontal tubes; and this application has been made in a very perfect manner by Mr. Kewley.