SURFACE OF THE GLOBE. 49 



and, among these, the great rivers of America are 

 conspicuous. The course of the Ganges is estimated 

 at 2000 miles, that of the Nile at 2400; but the 

 Orellana is said to run 5000 miles before it reaches 

 the sea. Among the larger rivers of the earth, may 

 also be enumerated the Oby, the Jenissei, the Saint 

 Lawrence, the Amazon, the Plata, the Lena, the 

 Amoor, and the Hoanho of China. The breadth of 

 some of these is no less extraordinary than their 

 length ; the Orellana being sixty miles broad at its 

 exit, and the Plata ninety ; the mass of water which 

 they bring down freshening the ocean to great dis- 

 tances from their aestuaries. 



The sestuaries of rivers vary according to the form 

 of the land which they last quit ; and, in the larger, 

 are regulated by their own actions. It is only in 

 rapid declivities in general, or where they have made 

 more deep sections in the land, that they open by one 

 mouth. When they deposit much sand and mud, 

 they not only form various openings, but these are 

 subject to changes, both in number and position ; cir- 

 cumstances which often render their entrances difficult 

 and dangerous. Thus the Danube opens into the 

 Euxine by seven mouths; while the Wolga termi- 

 nates by not less than seventy. Of changes of this 

 nature, the Nile is an example ; as it is recorded by 

 antient writers to have once entered the Mediterranean 

 by the Canopic branch alone ; whereas it now opens 

 by seven distinct actuaries. 



All rivers do not however terminate in the sea; but 

 many are lost in lakes^ as in the Caspian and the Dead 

 sea, whence no corresponding streams find an exit. 

 Some vanish in marshes or sands, an instance of which 

 has lately been thought to be discovered in New South 



VOJL. !, E 



