Presidential Address. 269 



most instructive with reference to its past history. The 

 great internal plateau of the American continent is now dry 

 land; the passage across Central America between the 

 Atlantic and Pacific is blocked ; the Atlantic opens very 

 widely to the north ; the high mass of Greenland towers in 

 its northern part. The effects are that the great equatorial 

 current, running across from Africa and embayed in the 

 Gulf of Mexico, is thrown northward and eastward in the 

 Gulf Stream, acting as a hot-water apparatus to heat up to 

 an exceptional degree the western coast of Europe. On the 

 other hand, the cold Arctic current from the polar seas is 

 thrown to the westward, and runs down from Greenland 

 past the American shore. 1 The pilot chart for June of this 

 year shows vast fields of drift ice on the western side of the 

 Atlantic as far south as the latitude of 40.° So far, therefore, 

 the Glacial age in that part of the Atlantic still extends ; and 

 this at a time when, on the eastern side of the Ocean, the 

 culture of cereals reaches in Norway beyond the Arctic 

 Circle. Let us inquire into some of the details of these 

 phenomena. 



The warm water thrown into the North Atlantic not only 

 increases the temperature of its whole waters, but gives an 

 exceptionally mild climate to Western Eui'ope. Still the 

 countervailing influence of the Arctic currents, and the 

 Greenland ice is sufficient to permit icebergs, which creep 

 down to the mouth of the Strait of Belle Isle, in the latitude 

 in the south of England, to remain unmelted till the snows of 

 succeeding winters fall upon them. Now let us suppose that a 

 subsidence of land in tropical America were to allow the 

 equatorial current to pass through into the Pacific. The effect 

 would at once be to reduce the temperature of Norway and 

 Britain to that of Greenland and Labrador at present, while 

 the latter countries would themselves become colder. The 

 northern ice, drifting down into the Atlantic, would not, as 

 now, be melted rapidly by the warm water which it meets 

 in the Gulf Stream. Much larger quantities of it would 

 remain undissolved in summer, and thus an accumulation of 



1 1 may refer here to the admirable expositions of these effects by 

 the late Dr. Carpenter, in his papers on the results of the explorations 

 of the Challenger. 



