THE PERPETUAL SNOW-LINE. 



581 



The limit of eternal snows, or perpetual snow-line, which at the 

 Pole sinks to the very level 'of ocean, rises higher and higher as it 

 approaches the lower latitudes, and attains its maximum elevation 

 towards the Equinoctial Line. It follows, that in the countries bor- 

 dering on the Arctic Circle, mountains of very moderate altitude show 

 themselves all through the year in a shroud of radiant snow ; while, 

 under the Tropics, if we would meet with masses of eternal ice, we 

 must mount to a height of 13,500 feet and more. The limit of the per- 

 manent snows is, however, affected by a variety of local circumstances, 

 such as the neighbourhood of great seas or forests. The subjoined 

 table, therefore, which shows the height of the curve of congelation in 

 different latitudes, is founded upon the known law of the decrease of 

 heat by elevation, and must be regarded rather as approximatively 

 correct than strictly accurate. 



TABLE OF SNOW-LINE. 



That the foregoing table needs considerable modification in par- 

 ticular localities is evident from the following facts : In the Scan- 

 dinavian Alps, lat. 65 north, the snow-line occurs at an elevation of 

 5200 feet, instead of 2722 ; in the Alps of Savoy, lat. 45 north, it 



* 51 30' north latitude, the parallel of London. 



