132 Account of a new Frame with rising Lights. 



introduced wherever an apparatus for that purpose has been 

 fitted up, and it will be seen that either one or more pits, as 

 may be desired, can be worked at one time with the steam. 

 I am, Sir, 



Your very humble servant, 



John Nairn. 



Postscript. 



A Frame intended to answer some of the same purposes 

 as the one I have described, was, a few years ago, construc- 

 ted by Mr. Edward Weeks, of the King's Road, Chelsea ; 

 it is therefore incumbent upon me to state, in what essen- 

 tial particulars mine differs from his. To the inside of Mr. 

 Weeks's Frame was fitted a wooden box, about nine inches 

 deep, to contain the mould, and plants, which was suspen- 

 ded over the dung : this, by means of a rack and pinion, 

 was to be elevated and depressed, as occasion required, the 

 lights remaining stationary. The inconvenience of such a 

 plan must be obvious, when we consider the weight of the 

 material to be moved, to say nothing of the impossibility of 

 applying any other mode of heating than that of dung. In 

 my Frame, the dung, mould, and plants, are placed in the 

 usual way, and the lights are the only parts moved. Mr. 

 Weeks's plan was applicable to a Frame with dung heat 

 only, mine answers equally well for a Pit, and therefore, may 

 be used with tan, steam, or fire heat, as well as with dung. 



