822 EEPOET — 1893. 



to a current from the opposite direction to bring him Lis necessary store of wood 

 from the Siberian forests. 



We can only hope that Nansen will find the currents as favourable to his needs, 

 and that so much bravery may be supported by good luck. 



By no means the least important physical feature of the Polar Basin is its 

 gigantic 



EIVEK SYSTEMS. 



The rivers which flow into the Arctic Ocean are some of them amongst th& 

 greatest in the world. 



Some idea of the relative sizes of the drainage areas of a few of the best known 

 rivers maj' be learnt from the following table, in which the Thames, with a 

 drainage area of 6,000 square miles, is the unit: — 



Perhaps a more scientific classification of rivers would be to call those with a 

 drainage area (between 2,560,000 aud) over 1,280,000 square miles rivers of the 

 first magnitude, a category which contains the Amazon alone. There are ten rivers 

 of the second magnitude, with drainage areas between 1,280,000 and 640,000 square 

 miles (Ob, Congo, Mississippi, La Plata, Yenisei, Nile, Lena, Niger, Amur, 

 Yangtse). There are twelve rivers of the third magnitude, with drainage areas be- 

 tween 640,000 and 320,000 square miles (Mackenzie, Volga, Murray, Zambesi,. 

 Saskatchewan, Ganges, St. Lawrence, Orange, Orinoco, Hoang Ho, Indus, and 

 Bvamapiitra). There are more than a dozen rivers of the fourth magnitude, with 

 drainage areas between 320,000 and 160,000 square miles, but none of them empties- 

 itself into the Arctic Ocean. They include the Danube, Euphrates, and several 

 of the African and South American rivers. Of the numerous rivers which are 

 of the fifth magnitude, with drainage areas between 160,000 and 80,000 square 

 miles, the Pechora belongs to the Polar Basin. The number of rivers of lesser 

 magnitude is legion, and it is only necessary to quote one of each as an example. 



6lh magnitude (80,000 to 40,000), Rhine. 

 7th „ (40,000 to 20,000), Rhone. 



8th „ (20,000 to 10,000), Garonne. 



9th „ (10,000 to 5,000), Thames. 



There is nothing that makes a greater impression upon the Arctic traveller than 

 the enormous width of the rivers. The Pecliora is only a river of the fifth magni- 

 tude, but it is more than a mile wide for several hundred miles of its course. The 

 Yenisei is more than three miles wide for at least a thousand miles, and a mile- 

 wide for nearly another thousand. Wbymper describes the Yukon as varying- 

 from one to four miles in width for three or four himdred miles of its length. The 

 Mackenzie is described as averaging a mile in width for more than a thousand 

 miles, with occasional expansions for long distances to twice that size. 



The drainage area does not measure the size of the Arctic rivers at all 

 adequately. Though the rainfall of many of them is comparatively small, the size 

 of the rivers is relatively very large, owing to the sudden melting of the winter's 

 accumulation of snow, which causes an annual flood of great magnitude, like the 

 rising of the Nile. Even on the Amur in Eastern Siberia, and on the Yukon in 

 Alaska, the annual flood is important enough, but on the rivers which flow north 

 into the Polar Sea the damming up of the mouths by the accumulations of ice 

 produces an annual deluge, frequently extending over thousands of square miles, 

 a catastrophe the etfects of which have been much underrated and never 

 adequately described. 



J.i we assume that the unknown regions are principally sea, then the Polar 



