334 POPULAR LECTURES AND ADDRESSES. 



consideration whatever regarding the possibilities of 

 thickness of Antarctic ice, I think we may say that 

 if it is 500 or 600 or 2,000 feet thick at one time, it 

 may be at another time more or less, and if so we 

 should have corresponding changes of level all over 

 the world. We have had such perfectly feasible 

 cases put before us by Taylor, Heath, and others 

 as to the thickness of ice at either Pole, and in 

 respect to the level of the sea. 



Before taking up the question of how thick the 

 ice may be at either Pole, think a little of the 

 shape of the earth and ocean around the North 

 Pole. There is the North Pole (see Fig. 5, giving 

 an outline chart). Here is Greenland and Iceland. 

 You enter into the Arctic Ocean west of Iceland ; 

 then you come on to Spitzbergen, and further 

 north to Nova Zembla, or again away to the east. 

 This (the Arctic) ocean is merely a landlocked sea. 

 The Behring Strait is only fifty miles wide and fifty 

 fathoms deep, so that you may look upon the 

 Arctic Ocean as practically stopped here. America 

 is an island separated from the north-cast of Asia 

 by Behring Strait ; and Europe, Asia, and Africa 



