ic6 



ILLUSTRATIONS OF THE 



getable mould, fpread out over the furface of 

 the earth. This coat, as it condfts of loofe ma- 

 terials, is eaiily wafhed away by the rains, and 



IS 



ally carried d 



by 



he fea. This efFedl is viiible td 



rivers into 

 :very one; 



th 



earth is 



oved not only in the form of 



f 



fand and gravel, but its finer particles fufpend- 

 ed in the waters, tinge thofe of fome rivers con- 

 tinually, and thofe of all occafionally, that isj 

 when they are 



flooded or fwoll 



h rains. 



The quantity of earth thus carried down, varies 

 according to circumftances ; it has been compu- 

 ted, in fome inllances, that the water of a ri- 

 ver in a flood, contains earthy matter fufpended 

 in it, amounting to more than the two bun- 

 dred and fiftieth part of its own bulk *. The 



foil, therefore. 



is 



continually diminifhed, its 



parts being tranfported from higher to lower 

 levels, and finally delivered into the fea. But 

 it is a fad, that the foil, notwithftanding, re- 

 mains the fame in quantity, or at leall nearly 

 the fame, and muft have done fo, ever fince the 

 earth was the receptacle of animal or vegetable 

 life. The foil, therefore, is augmented from 

 other caufes, jull as much, at an average, as it 

 is diminiflied by that now mentioned -, and this 



augmentation evidently can proceed from no- 

 thing 



* See Lehman, Traites de Phyf. &c. torn. iii. p. 3S9' 



Note. 



i 



