54S 



THE PRACTICAL GARDENER. 



be laid out with some shar^of taste, and so be an additional 

 ornament, at once pleasing and useful. 



The following will explain the principle upon which it acts : 

 A is a boiler, to which the cast-iron pipe B is joined, and 

 which is four inches in diameter ; the uppermost of which B 

 proceeds horizontally from the top of the boiler A, towards 







D 







? = 



A 



the opposite side, or end of the house, where it is joined to 

 the reservoir at D, or it may make a turn at an elbow, as at E; 

 this depends upon the size of the house. If large, the reser- 

 voir D, containing a large body of heated water, gives an 

 increase of heat at the coldest end of the house, and renders 

 the temperature there equal almost to that at the end next the 

 boiler. C is a returning-pipe from the bottom of the reservoir 

 D to the bottom of the boiler A. The boiler is set in brick- 

 work, in the usual manner. As soon as the fire is lighted, 

 and the water begins to heat at the bottom of the boiler, the 

 particles of warm water, being lighter than those that are cold, 

 ascend to the surface of the boiler, and gradually flow hori- 

 zontally along the pipe B to the reservoir D ; and the cold 

 water in the reservoir, being heavier than that which is warm, 

 gradually flows along the pipe C to the bottom of the boiler. 

 As long as any heat remains in the brick-work round the 

 boiler, this circulation is kept up. It is found in practice, 

 that it is essentially necessary to have two pipes employed, 

 one from the top and one from the bottom of the boiler, con- 

 nected at the end, either by a reservoir, as at D, or by an 

 elbow-pipe, as at E, to keep up this circulation. The boiler 

 is furnished with a wooden cover, and the reservoir with an 

 iron one : the former is preferred, as the water in the boiler 

 will always be rather warmer than that in the reservoir; the 

 wooden cover being a better non-conductor of heat than t)ie 



