[ 281 ] 



XXXII. An Account of some Improvements in the Construc- 

 tion of Hot Beds. By Thomas Andrew Knight, Esq. 

 F.R.S. $c. President 



Read July 3, 1827. 



I submit an account of a small addition which I have made 

 to the machinery of a common Hot-bed, from the use of 

 which, I believe, that every gardener who has occasion to 

 raise cucumbers, and other plants, in winter, or very early in 

 the spring, will be able to derive very considerable advan- 

 tages. At these periods of the year, it is not easy to give the 

 plants a sufficiently high temperature, with proper change of 

 air, however well the bed may have been constructed, and with 

 whatever care the material which composes it may have been 

 prepared; and the sudden changes of temperature, which 

 often occur in the climate of England, will frequently sub- 

 ject the roots of the plants to be injured by excess of heat, 

 and the mould, when lying upon horsedung, to be what is 

 called by the gardener burned, that is, I believe, so much 

 impregnated with ammonia, that the roots of the plants can- 

 not retain life in it. Another defect of the common hot-bed 

 is, that whilst its interior part is excessively hot, so little heat 

 ascends through the mould, that a covering of glass alone 

 does not afford sufficient protection to any tender plant in 

 very cold weather, during the night. 



By means of the machinery which I shall proceed to de- 

 vol. vii. O o 



