in Fluids. 329 



cific gravity is again diminished. But this Heat they 

 never can regain in the polar regions; for innumerable ex- 

 periments have proved, beyond all possibility of doubt, 

 that there is no principle of Heat in the interior parts of 

 the globe ^ which, by exhaling through the bottom of the 

 ocean, could communicate Heat to the v/ater which rests 

 upon it. 



It has been found that the temperature of the earth at 

 great depths under the surface is different in different lati- 

 tudes, and there is no doubt but this is also the case 

 with respect to the temperature at the bottom of the sea, 

 in as far as it is not influenced by the currents which 

 flow over it ; and this proves to a demonstration that the 

 Heat which we find to exist, without any sensible change 

 during summer and winter, at great depths, is owing to 

 .the action of the sun, and not to central fires ^ as some 

 have too hastily concluded. 



But if the water of the ocean, which, on being de- 

 prived of a great part of its Heat by cold winds, de- 

 scends to the bottom of the sea, cannot be warmed where 

 it descends, as its specific gravity is greater than that of 

 water at the same depth in warmer latitudes, it will im- 

 mediately begin to spread on the bottom of the sea, and to 

 flow towards the equator, and this must necessarily pro- 

 duce a current at the surface in an opposite direction ; 

 and there are the most indubitable proofs of the exist- 

 ence of both these currents. 



The proof of the existence of one of them would in- 

 deed have been quite sufficient to have proved the exist- 

 ence of both, for one of them could not possibly exist 

 without the other; but there are several direct proofs of 

 the existence of each of them. 



What has been called the Gulf Stream in the Atlantic 



