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PHYSICAL GEOGRAPHY. 



a thousand feet above the level of the sea. The springs of the Missouri and the Columbia 

 are in the Rocky Mountains ; and it is generally the case, that those parts of a country from 

 which large rivers flow in contrary directions, are the most elevated sites in their respec- 

 tive districts, consisting either of mountain-chains, plateaus, or high table-lands. There 

 is one remarkable exception to this in European Russia, where the Volga rises in a plain 

 only a few hundred feet above the level of the sea, and no hills separate its waters from 

 those which run into the Baltic. The great majority of the first-class rivers commence 

 from chains of mountains, because springs are there most abundant, perpetually fed by 

 the melting of the snows and glaciers. They have almost invariably an easterly direction, 

 the westward-bound streams being few in number, and of very subordinate rank. Of 

 rivers flowing east, we have grand examples in the St. Lawrenc'e, Orinoco, Amazon, 

 Danube, Ganges, Amour, Yang-tse-Kiang, and Hoang Ho. The chief western streams 

 are the Columbia, Tagus, Graronne, Loire, and Neva, which are of far inferior rank to the 

 former. The rivers running south, as the Mississippi, La Plata, Rhone, Volga, and 

 Indus, are more important, as well as those which proceed to the north, as the Rhine, 

 Vistula, Nile, Irtish, Lena and Yenisei. The easterly direction of the great rivers of 

 America is obviously due to the position of the Andes, which run north and south, on 

 the western side of the continent, while the chain of mountains which traverses Europe 

 and Asia, from west to east, cause the great number of rivers which flow north and south. 

 In our own island, the chief course of the streams is to the east. This is the case with 

 the Tay, Forth, Tweed, Tyne, Humber, and Thames, the Clyde and Severn being the 

 most remarkable exceptions to this direction. The whole extent of country from which 

 a river receives its supply of water, by brooks and rivulets, is termed its basin, because 

 a region generally bounded by a rim of high lands, beyond which the waters are drained 

 off into another channel. The basin of a superior river includes those of all its tributary 

 streams. It is sometimes the case, however, that the basins of rivers are not divided by 

 any elevations, but pass into each other, a connection subsisting between their waters. 

 This is the case with the hydrographical regions of the Amazon and Orinoco, the 

 Cassiaquaire, a branch of the latter, joining the Rio Negro, an affluent of the former. 

 The vague rumours that were at first afloat respecting this singular circumstance, were 

 treated, by most geographers with discredit, till Humboldt ascertained its reality, by 

 proceeding from the Rio Negro to the Orinoco, along the natural canal of the 

 Cassiaquaire. 



Rivers have a thousand points of similarity, and of discordance. Some exhibit an 

 unbroken sheet of water through their whole course, while others are diversified by 

 numerous islands. This peculiarly characterises the vast streams of the American 

 continent, and contributes greatly to their scenical effect, of which our illustration gives 

 us an example, selected from the beautiful Susquehanna, the largest Atlantic river of the 

 United States. The St. Lawrence, soon after issuing from the Lake Ontario, presents 

 the most remarkable instance to be found of islands occurring in a river channel. It is 

 here called the Lake of the Thousand Islands. The vast number implied in this name 

 was considered a vague exaggeration, till the commissioners employed in fixing the 

 boundary with the United States actually counted them, and found that they amounted 

 to 1692. They are of every imaginable size, shape, and appearance ; some barely visible, 

 others covering fifteen acres; but in general their broken outline presents the most 

 picturesque combinations of wood and rock. The navigator in steering through them 

 sees an ever-changing scene, which reminds an elegant writer of the Happy Islands in 

 the Vision of Mirza. Sometimes he is enclosed in a narrow channel ; then he discovers 

 before him twelve openings, like so many noble rivers ; and soon after a spacious lake 

 seems to surround him on every side. River-islands are due to original surface 



