the Distribution of Heat over the Globe. 105 



equal to all the heat which falls on the southern hemisphere 

 within fully 420 miles of the equator, supposing the sun to be 

 vertical over the whole area. But even supposing that the 

 actual difference is only one-half this amount, still it is nearly 

 equal to all the heat which is received by the entire area of 

 the Atlantic Ocean from the tropics to the arctic regions, a 

 quantity quite sufficient to account for the lower mean tempera- 

 ture of the southern hemisphere. 



Without Ocean-currents the Globe would not be habitable. — All 

 these foregoing considerations show to what an extent the cli- ^ 

 matic condition of our globe is due to the thermal influences of 

 ocean-currents. 



As regards the northern hemisphere, we have two immense 

 oceans, the Pacific and the Atlantic, extending from the equator 

 to near the north pole, or perhaps to the pole altogether. Be- 

 tween these two oceans lie two great continents, the eastern and 

 the western. Owing to the earth's spherical form, by far too 

 much heat is received at the equator and by far too little at high 

 latitudes to make the earth a suitable habitation for sentient 

 beings. The function of these two great oceans is to remove 

 the heat from the equator and carry it to temperate and polar 

 regions. Aerial currents could not do this. They might remove 

 the heat from the equator, but they could not, as we have already 

 seen, carry it to the temperate and polar regions ; for the greater 

 portion of the heat which aerial currents remove from the equa- 

 tor is dissipated into stellar space : the ocean can alone convey 

 the heat to distant shores. But aerial currents have a most im- 

 portant function; for of what avail would it be, though ocean- 

 currents should carry heat to high latitudes, if there were no 

 means of spreading the heat thus conveyed over the land ? The 

 function of aerial currents is to do this. Upon this twofold ar- 

 rangement depends the thermal condition of the globe. Exclude 

 the waters of the Pacific and the Atlantic from temperate and 

 polar regions and place them at the equator, and nothing now 

 existing on the globe could live in high latitudes. 



Were these two great oceans placed beside each other on one 

 side of the globe, and the two great continents placed beside each 

 other on the other side, the northern hemisphere would not then 

 be suitable for the present order of things : the land on the 

 central and on the eastern side of the united continent would be 

 by far too cold. 



7 he foregoing conclusions not ajfectedby the imperfection of the 

 data. — It will hardly do to object to the general results at which 

 we have arrived in reference to the influence of ocean- currents 

 on the climatic condition of the globe on the ground of any im- 

 perfection in the data employed. It is perfectly true that con- 



