348 POPULAR LECTURES AND ADDRESSES. 



shores, and then it would go on getting thicker 

 and thicker, till it would make an Arctic ice-cap 

 like the Antarctic ice-cap. But the Arctic Ocean 

 is not wholly enclosed by land. In the present 

 condition of the Arctic Ocean there is an enormous 

 abstraction of ice, by the Gulf Stream flowing in 

 here (Fig. 5), and shooting away past Norway, and 

 even carrying trees through the region of the North 

 Pole. You may depend upon it that under the 

 surface the ice is being simply washed away, and 

 so kept down to 20, 30, or 60 inches in thickness. 

 As I have said, Captain Markham's expedition 

 found it only 64 inches thick within 399 miles of 

 the North Pole, and we have no reason to believe 

 that it is anything thicker, or very much thicker, 

 at the very Pole. The free circulation through the 

 Arctic basin, of water under the ice, is certainly 

 what keeps down the thickness of the Arctic 

 floating ice just now. 



Suppose the circulation were stopped by a bar- 

 rier running across from Norway by Iceland to 

 Greenland, the result would be that the circulation 

 of the water from the rest of the ocean into the 



