RIVERS. 



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the tide flows out of the river, it pours forth its unshackled current with greater fury, 

 and meeting at right angles with the ocean current that runs from Cape St. Eoque along 

 the north-east coast of Brazil, the shock of these two bodies raises their waters into an 

 embankment, upwards of a hundred feet in height. The roar of the clashing waves is 

 heard for miles around, and the fishermen and mariners fly in terror from the scene till 

 the strife is over, speedily to be renewed. 



In treating of the magnitude of rivers, some writers refer to the elevation of the range 

 of mountains from which they descend ; and it is obviously true, that the greater the height 

 of the mountains, the more extensive are their snows and glaciers, and the larger the 

 supply of water furnished by springs and torrents. But the magnitude of a stream is more 

 especially regulated by the extent of country which forms the declivities of its basin, 

 though there is no invariable proportion here, for a small basin in a humid region will 

 yield a greater quantity of water than one much more considerable in a different situation. 

 High mountains, a humid climate, and a wide superficial drainage, are the three physical 

 circumstances which lead to the accumulation of vast bodies of water, the magnitude of 

 which will be proportionate to the degree in which these causes are in combined operation. 

 Upon the surface of the New World, we have these causes acting with greater intensity 

 than upon that of the Old, which explains the superior character of the streams of the 

 western continent. The following table exhibits the extent of the hydrographical regions 

 of the principal rivers of the globe, with the proportionate size of their basins : 



Elvers, according to their termination, may be grouped in two grand classes, the conti 

 nental and the oceanic. The continental are those which have no communication at all 

 with the ocean, but discharge their waters into completely insulated lakes, or lose them 

 selves in sands and swamps. Thus the Volga, Kour, Terek, and Ural, terminate in the 

 Caspian ; the Amou, or Jihoon (ancient Oxus), the Sir, or Sihoon (ancient Jaxartes), flow 

 to Lake Aral ; and the Jordan finishes its course in the Dead Sea. On the lofty table 

 lands of Mexico, Bolivia, and Central Asia, there are respectively the Rio Grande, 

 Desaguadero, and Yarkand, which are entirely confined to those elevated regions, termi- 



