156 the Principles of Part III. 



that they might meet with much fat earth 

 below the furface, very fit for their pur- 

 pofe, and that there mould always be a 

 proportion of abforbent or calcarious earth 

 in thefe walls. He fays, that there is al- 

 ways leaft nitre on the fouth fide of the 

 wall. He orders, that all vegetables mould 

 be pulled from the walls, as they confume 

 the nitre j that no cattle mould be allowed 

 to come near them, as they are fond of it -, 

 and that they mould be covered with 

 ftraw, to hinder the rains from warning 

 off the nitre : what ought then to hinder 

 our farmers from making fuch walls of 

 fat earth, dung, efpecially that of pigeons, 

 ftraw, which will take a time before it 

 rots, and a fmall proportion of lime, marl, 

 or fhells ? Moft of thefe materials will be 

 found every where. In two years they 

 would become a very rich manure. They 

 would operate inftantly j whereas, it takes 

 two years before many of our manures 

 have a fenfible effecl: on the foil. Although 

 heavy rains warn off the nitre, yet a gentle 



moifture 



