ADDRESS. 25 



The ocean is a great equaliser of extremes of temperature. It does 

 ithis by its great capacity for heat and by its cooling and heating power 

 ■when passing from the solid into the liquid and gaseous states, and the 

 reverse. It also acts by its mobility, its currents serving to convey heat 

 to great distances or to cool the air by the movement of cold icy waters. 

 The land, on the other hand, cools or warms rapidly, and can transmit its 

 influence to a distance only by the winds, and tbe influence so transmitted 

 is rather in the nature of a disturbing than of an equalising cause. It 

 follows that any change in the distribution of land and water must affect 

 climate, more especially if it changes the character or course of the ocean 

 currents.' 



At the present time the North Atlantic presents some very peculiar 

 and in some respects exceptional features, which are 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 the 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 otber hand, the cold Arctic 

 current from the polar seas is thrown to the westward, and runs down 

 from Greenland past the American shore. ^ 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 the whole of its water, but gives an exceptionally mild 

 •climate to Western Europe. 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 

 •of the south of England, to remain unmelted till the snows of a succeed- 

 ing winter fall upon them. Now let us suppose that a subsidence of land 

 m tropical America were to allow the equatorial current to pass through 

 into the Pacific. The efiect 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 



Von WcBickofE has very strongly put these principles in a review of CroU's 

 Jecent book, Climate and Cosmology; American Journal of Science, March 1886. 



* I 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. 



