98 



warm the atmosphere of the plants ; the upper level 

 of the platform on which the plants stand is nearly 

 on a level with the external surface (e, e,). The pots 

 of plants are set on the sand, so that when moisture 

 is added either to it or to the plants, it causes a fine 

 gentle steam to arise through the whole of the pit, 

 which can be regulated at pleasure, by adding more 

 or less fire, according to the season or other circum- 

 stances. The temperature kept during the spring 

 and summer season is from eighty to a hundred 

 degrees through the day, and as low as from sixty- 

 five to sixty degrees during the night ; in the autumn 

 and winter it is as low as fifty-five or fifty degrees. 

 (Hort. Soc. Trans, v.) 



Fire heat and Fermenting materials. — A pine pit 

 erected in the garden of W. Forman, Esq., is heated 

 by a flue in a chamber below the tan. The tan (a.) 



is supported by oak joints resting on the side walls, 

 and on a middle wall of open brickwork (b). The 



