500 



By Charles Holford, Esq. 



cient to heat both, in the early part of the winter ; when a 

 stronger heat is required, a lining is added to the outside of 

 each pit, and the whole covered with boarded shutters, which 

 prevent the escape of heat, and at the same time protect the 

 linings from wet or cold. I found in the coldest nights of the 

 last very severe winter, that a regular temperature of sixty to 

 sixty-five degrees, or higher, if required, could be constantly 

 maintained. If Pits on this construction are used for early 

 forcing, the ventilation can be effected without admitting 

 any cold air, by means of a copper, iron, or leaden pipe, three 

 or four inches diameter, placed obliquely along the front, 

 and connected with short vertical pipes of smaller diameter 

 opening into the pits. The lower end of the large pipe 

 communicates with the open air, by means of a funnel, and 

 the whole being heated by the dung lining, a constant current 

 of fresh warm air is admitted whenever the aperture at the 

 end of the funnel is left open. 



The space in which the plants are plunged may be filled 

 with tan, leaves, or well fermented dung. It is essential that 

 the pits should be sunk in the ground, the better to confine 

 the heat and protect them from cold winds, care being taken 

 that the bottom is well drained. 



I remain, dear Sir, 



with great esteem, truly yours, 



Hampstead, 

 Ifth June, 1823. 



Charles Holford. 



