494 Notices of Communications, fyc. 



are covered at that time with about two or three inches of 

 light mould only ; //. are dung linings ; g. g. walls to keep 

 up the earth all round the pit ; h. h. drains to keep the dung 

 dry ; L shews a hill prepared for receiving the plants, and the 

 line k. marks the height of the earth when the bed is com- 

 pletely moulded up for the season. A pit on this plan may 

 be constructed much cheaper than on M'Phail's, and the 

 temperature in it will be found to be more equal. The 

 expense may be materially reduced by omitting the walls g.g. 

 in which case the earth must be cut in a slanting direction 

 from the pit, making the trench wider at the top than the 

 bottom, which will have a beneficial effect in always keeping 

 the dung close packed against the wall of the pit. 



