64 



the heaped blocks of granite, change their direc- 

 tion, and carry sometimes more sometimes less 

 water towards one or the other bank. The 

 causes of these changes may be very remote 

 from the cataracts ; for in the rivers that spread 

 life over the surface of the globe, as in the ar- 

 teries by which it is diffused through organized 

 bodies, all the movements are propagated to 

 great distances. Oscillations, that at first seem 

 partial, react on the whole liquid mass contained 

 in the trunk, and in it's numerous ramifica- 

 tions. 



I am not ignorant, that some writers, on com- 

 paring the actual state of the rapids of Sy^ne, 

 the separate steps of which have scarcely a fall 

 of six inches*, with the pompous descriptions of 

 the ancients, have been eager to recognize in 

 the bed of the Nile the effects of those erosions, 

 of that action of running waters, by which geo- 

 logists long believed, that they explained with 

 success the formation of vallies, and the chaos 

 of rents in the Cordilleras. The inspection of 

 these places little favors this opinion. We will 

 not deny the action of rivers and runningwaters, 

 when they furrow friable ground, covered with 

 secondary formations. But the granitic rocks 



* The chellal between Philoe and Syene has ten steps, 

 forming together 5 or 7 feet in height, according as the wa- 

 ters of the Nile are high or low. The length of the cataract 

 is 500 toises. 



