30 NATURAL HISTORY 



water by rivers, as it loses by evaporation. Tht 

 windings in the channels of rivers uniformly have 

 corresponding angles on their opposite banks ; and as, 

 mountains and hills, which may be considered as the 

 banks of the vallies by which they are separated, 

 have also, sinuosities with corresponding angles, this 

 circumstance seems to demonstrate, that the vallies 

 have gradually been formed by currents of the ocean, 

 in the same manner as the channels of rivers have 

 been produced. 



The waters which run upon the surface, compose 

 perhaps not one half of the quantity that is produced 

 by vapour. In almost all the vallies and low grounds 

 at a certain depth, water is uniformly to be found ; 

 hut in high grounds, it is impossible to extract water 

 from the bowels of the earth. There are extensive 

 countries where no wells can be obtained. In the 

 east, and especially in Arabia, Egypt and Persia, 

 wells and springs are seldom to be met with. To 

 supply their place the inhabitants have been obliged 

 to make large reservoirs to collect the rain water. In 

 plain countries, furnished with large rivers, it is al- 

 most impossible to break the surface of the earth 

 without "finding water. 



The greatest part of the water so liberally diffused 

 through low grounds, comes from the neighbouring hills 

 and eminences. During great rains, or the sudden 

 inciting of snow, part, of the water runs upon the sur- 

 face, but most of it penetrates the earth arid rocks by 

 small chinks and fissures. It emerges indeed as soon 

 ?s it can find an opening ; but it often creeps along un- 

 til it can find a bottom of clay, or hard earth and there 

 forms subterraneous lakes, brooks, and perh;:ps rivers, 

 whose channels arc ccn.-i"ned to eternal oblivion. 



