32 



ing hothouses. His system is an adaptation of long 

 known scientific facts to a useful purpose ; and its 

 success, like that of Mr. Rendle's system, depends 

 upon the constant circulation of a heated fluid, rising 

 as it is heated, and sinking down as it cools to be 

 heated again. The difference is, that Mr. Murray's 

 fluid is the atmospheric air of the house, and Mr. 

 Rendle's is water. The great merit of using air is, 

 that it does not require an expensive tank or arrange- 

 ment of pipes. 



In the above sketch of a lean-to house, b is the 

 drain or underground flue, conducting the cooled air 

 to the heating stove, d ; e is the warm air chamber ; 

 f, a woollen cloth or blanket fastened over the orifice 

 admitting the warmed air into the house. This 

 blanket is kept moist by means of skeins of worsted, 

 having one of their ends dipping in water, and the 



