HOT. WATER. 



329 



34. 



siplion, as he calls it, has shown how its various modifi- 

 cations may be employed in warming hot walls, as well 

 as in heating glazed houses. The following statement 

 of the principle is given in the Gfardener's Magazine, 

 vol. V. " Any one may prove that hot water will cir- 

 culate in a siphon, by taking a piece of lead pipe, say 

 of half an inch bore, and four or five feet long, bend- 

 ing it like a siphon, but one leg a good deal more bent 

 than the other, in order to give the descending water 

 time and space for giving out its heat ; and then, filling 

 this tube with water, and placing one hand on each end 

 to retain it full, immerse the extremities in a pot of water 

 over a fire, as represented in the annexed 

 diagram. Supposing the water of a uni- 

 form temperature in both legs of the siphon, 

 no circulation would take place; but suppos- 

 ing it to cool sooner in the long leg a than 

 in the short leg 5, then the equilibrium would 

 be destroyed, and the water in the long leg 

 a would descend, and draw up water through 

 the short leg b; and this circulation would 

 continue as long as the water c was main- 

 tained at a temperature above that of the surrounding 

 atmosphere." 



Mr. Kewley's adaptation of the siphon is one of the 

 simplest and most efficient that has been proposed. In 

 Fig. 35, ace, are the two legs of a siphon, through the 

 upper of which the heated water ascends, and by the 

 lower descends. Immediately over the descending bend, 

 a pipe connected with an air-pump is inserted, in order 

 to fill the pipes, or remove the air which collects in the 

 superior limb. Instead of the air-pump, a funnel with 

 air-tight valves is sometimes employed. This mode of 



