NEW HUSBANDRY EXEMPLIFIED. 7 



their land recovering its fertility to any thing 

 but dung and manure; and thole late authors, 

 who mean to decry the New Hufoandry, do 

 not appear to comprehend the true practice of , 

 it, nor the principles upon which it is found- 

 ed ; as we (hall have occafion to (hew, and to 

 prove that its principles are founded in na- 

 ture. 



The operations of nature are not the ob- 

 jes of our fenfes ; they are too abftrufe and 

 fuhtle to be difcovered by us : for which rea- 

 fon, we know not certainly what is the vege- 

 table food, or that matter which intimately 

 joins, and unites with, the fubftance of 

 plants, and whereby they are enlarged and 

 nourished. Several learned and ingenious 

 men have endeavoured to difcover this, but 

 hitherto without fuccefs; and they differ 

 much in opinion. So that, if this were ne- 

 ceflary to be known, it does not appear that 

 farmers, or any cultivators of land, could 

 attain to any certain principles of vegetation : 

 and, what is ftill of further importance, 

 we are not certain whether the knowledge of 

 the food of plants would enable us to derive 

 any practical advantages from it. 



It appears from experiments, that the leaves 

 of plants imbibe air and moifture ; .tnd with 

 thefe, other kinds of matter ; but the prin- 

 cipal fource of the vegetable food is univer- 

 {ally allowed to be derived from the earth, 

 whence plants receive their nourifliment 



B 4 chiefly 



