56 



IMPROVEMENTS IN THE CULTURE OF VEGETABLES. 



Evidently be- 

 neficial to ve- 

 getation. 



Does rot the 



air assist the 

 action of the 

 water, as in 

 irrigation? 



Objects of in- 

 quiry. 



hundred and fifty pounds per hour on the surface of a sta- 

 tute aere: whilst on the ground uninokeii, though the glass 

 stood repeatedly for two hours at a 'mie, there was not the 

 least cloud upon it; which p^rpvfid, that no moisture then 

 arose from the earth. 



The evaporation from tee ploughed land was found to de- 

 crease rapidly after the tiril and second day, and ceased 

 after five or six days, depending on the wind and sun. 

 These experiments w* re carried on' for many months. 

 After July the evaporation decreased, which proves that 

 though the heat of the atmosphere be equal, the air is not 

 so dense. The evaporation, after the most abundant rains, 

 was not advanced beyond what the earth afforded on being 

 fresh turned up. The rapid growth of my potatoes corres- 

 ponded perfectly with the previous experiments; and their 

 growth in dry weather visibly exceeded that of other crops 

 where the earth was not stirred- The component parts of 

 the matter evaporated remain yet to be ascertained; the 

 beneficial effects arising from it to vegetation cannot be 

 doubted or denied, but whether they proceed from one 

 or more causes, is a question of much curiosity and im- 

 portance. 



May not a similar process here take place, as when water 

 is exposed to the action of the air in irrigation ? Is it too 

 much to suppose some natural operation to take place in 

 the earth, which may decompose the oxigen contained in 

 air from the hidrogen, during the absence of the sun, 

 which on the sun's reappearance may be again given out in 

 a state highly propitious to vegetation ? Oxigen is found 

 to contain carbon ; and may not the growing plants imbibe 

 it from the air, and may we not thereby account for its form- 

 ing a constituent part of all vegetables? 



The investigation of these objects presents a wide field 

 for inquiry, and may lead to very important discoveries. 

 From more or less oxigen contained in the earth, may not 

 its proportions account for the fertility of one soil above 

 another ? May not the advantages supposed to be derived 

 from loosening the soil, proceed from its being thus ren- 

 dered in a fit state to imbibe the air? Fallows soon be- 

 come so hard upon the surface, as to be capable neither of 



absorption. 



