influenced by the Distribution of Land and Water. 191 



sphere. If the presence of dry land in high latitudes is favour- 

 able to a cold climate, this condition appears to be more com- 

 pletely manifested in the northern than in the southern hemi- 

 sphere ; and if the presence of a certain amount of dry land 

 within the tropics is favourable to a high temperature, that con- 

 dition is almost equally well fulfilled at both sides of the 

 equator. 



Let us conceive all the land north of the equator to be sub- 

 merged, and its place to be supplied, first, by a mass of land in 

 the north tropical zone, exactly similar in area and configuration 

 to that touching it in the southern zone. Let the arctic regions 

 of North America, Nova Zembla, and Greenland be replaced by 

 an island similar to Victoria Land, and let a few scattered 

 islands replace the greater part of Asia, Europe, and North 

 America ; we shall then have a globe with a considerable belt of 

 equatoi-ial land, while the polar and temperate regions will be 

 occupied chiefly by water. We should thus have a state of 

 things approximating much more to the conditions required for 

 a high terrestrial temperature than the present distribution of 

 land and water. Yet the distribution here supposed for both 

 hemispheres would be precisely what at present exists in the 

 colder of the two ; and we should thus have the paradox of 

 warming the entire globe by modelling its warmer hemisphere 

 after its colder. Unless the influence of Victoria Land as a re- 

 frigerator of the southern hemisphere should be greater than that 

 of the immense masses of land in the northern parts of the new 

 and old continents, this paradox would seem inexplicable on 

 the theory under consideration. But it can be in some measure 

 explained, if the agency of oceanic currents in storing up and 

 transporting the heat acquired from sunshine be fully admitted. 

 In the actual state of the earth's surface, the form of the basin 

 of the South Atlantic Ocean, combined with other physical 

 conditions, seems to determine the transfer of a great volume of 

 heated water from the southern intertropical regions to the 

 northern hemisphere, which, passing subsequently through the 

 Caribbean Sea and Gulf of Mexico, acquires a still higher tem- 

 perature, and ultimately confers its warmth on regions in high 

 northern latitudes. From the direction of the currents of the 

 Pacific, as laid down on some of Maury's charts, it is probable 

 that a similar transfer northwards, of heated southern intertro- 

 pical water, is eflected in that great ocean as well as in the 

 Atlantic. The general result is, that the southern hemisphere 

 is not only deprived of a certain amount of the solar heat 

 absorbed by its waters, but that the temperature of the northern 

 hemisphere is augmented to a corresponding amount. But 

 although the paradox alluded to may be thus explained, this 



