Sett. I. Agriculture and Vegetation. 41 



plough, is not the chief means of increafing 

 the vegetable matter, as T#// aflerts, appears 

 plainly from thefe two fads ; that even the 

 lighter!: foil is the better of fallowing ; and 

 that when fallow ground is laid up in 

 ridges, more benefit is received than when it 

 is left quite flat. 



BUT this nutritious influence of the air 

 is yet more obfervable in thofe earthen dikes 

 or walls made of the foil taken from the 

 furface, and thrown up to inclofe the meep- 

 folds. Thefe dikes are expofed to the in- 

 fluence of the air, which pafTes through 

 and through them for many months. The 

 foil thus expoied is rendered prodigioufly 

 fruitful, fo that it is eafily diftinguimable 

 by the quantity and deep green colour of 

 the grain, from the internal parts of the 

 fold, which have been well manured by 

 the urine and dung of the fheep. It is 

 likewife remarked by farmers, that the 

 earth of the dike lafts for three or four 



years 



