CH. II.] THE EOOT. 1^3 



separate sheet of paper, to the sun's rays for an hour, 

 and then put them into a dark cold closet for another 

 houi'. Handle them in succession, and that which 

 feels the warmest will be the most fertile. This is 

 easily explicable from the fact that a fertile soil, that 

 is, one haWng a due proportion of alumina and de- 

 composing matter, is always slower in cooling than 

 one that is deficient in these constituents. 



III. The drainage ivater. — Upon this I shall 

 merely observe, that I have never been able to find 

 that it affords any satisfactory criterion whereby to 

 judge of the fertility of a soil. A red, ocherous 

 deposit from such water shews that the subsoil 

 through which it percolated is an irony gravel or sand. 

 The dark film exhibiting the dove's-neck varying 

 colours, often seen on the surface of drainage water, 

 indicates its having passed through peat, bog, or 

 wood, for that film arises from the vegetable extract 

 it contains. Virgil tells us (Georg. ii. 245) to wash a 

 soil, and that if the water employed becomes con- 

 sequently nauseous and bitter, it indicates a salt soil 

 unsuited to the growth of com. I have never met 

 with such a soil, except where soda was a product of 

 the land, and this is not the case in England. 



IV. Meteorological j^heriomena. — Under this head 

 I have only to remark that, wherever fogs or mists 

 settle, or become apparent in the evening earlier 

 than upon neighbouring soils, it is a certain indica- 



