No. 7.] HIND — EFFECT OF ARCTIC ICE. if ^ 



thickness of the ice formed during the winter within the 70th 

 parallel of latitude is five feet. Making allowance for land within 

 this limit as before, by including Hudson Bay, Davis Straits, 

 East Greenland Sea, etc., the area of ice thus formed may be 

 estimated to be equal to 4,521,600 geographical miles. One- 

 tenth above water gives the quantity of ice mechanically raised 

 above the level of the sea by the process of freezing, equal to 

 2,260,800 square miles, one foot thick : a close approximation 

 to the first estimate. 



In order to gather some knowledge of the effect likely to be 

 produced upon Ocean currents by the uplifting of so large a body 

 of water in the form of ice above the level of the sea, we may 

 compare it with the Gulf Stream, bearing in mind that a part 

 only of the waters of the Gulf Stream move north-easterly after 

 reaching the 40th degree of longitude. A large portion is directed 

 towards Southern Europe and the northern part of Africa, as 

 shown on Dr. Petermann's charts. 



The " Challenger " found the width, depth and rapidity of the 

 Gulf Stream, where the expedition crossed it, to be as follows : * 



Width - - - 15 nautical miles. 



Depth --- 600 feet. 



Speed - 3 miles an hour. 



This gives a volume of discharge equal to 108 cubic miles per 

 day. Hence, according to the foregoing estimate, the quantity 

 of water required to fill the void created by the rising of the 

 Polar ice above the sea level, would consume the equivalent of 

 the entire discharge of the Gulf Stream for 84 hours, or 3J days. 



The drainage area of the Polar basin is estimated to be 

 4,495,000 square miles, or about the same as that of the 

 Northern Sea area covered during the winter with ice. But 

 practically, land drainage by rivers, glaciers and glacial rivers 

 is reduced to a minimum during the winter season. The preci- 

 pitation takes place in the form of snow, and the land drainage 

 in the Arctic zone may be estimated as not exceeding two inches 

 during the six winter months. As a partial set off against the 

 land drainage, there is the evaporation which takes place from 

 the snow falling on the Polar ice. The precipitation is small 

 within the Polar circle, and the climate of North Greenland is 

 dry, according to Rink, Hayes, Nares, etc. 



* "Challenger" Reports, No. VII. 



