THE DRIFT OF THE SEA. 247 



535. Plate IX., therefore, is only introduced to give general 

 ideas ; nevertheless, it is very instructive. See how the influx of 

 cold water into the South Atlantic appears to divide the warm 

 water, and squeeze it out at the sides, along the coasts of South 

 Africa and Brazil. So, too, in the North Indian Ocean, the cold 

 water again compeUing the warm to escape along the land at the 

 sides, as well as occasionally in the middle. 



536. In the North Atlantic and North Pacific, on the contrary, 

 the warm water appears to divide the cold, and to squeeze it out 

 along the land at the sides. The impression made by the cold 

 current from Baffin's Bay upon the Gulf Stream is strikingly beau- 

 tiful. 



537. Why is it that these polar and equatorial waters should 

 appear now to divide and now to be divided ? The Gulf Stream 

 has revealed to us a fact in which the answer is involved. We 

 learn from that stream that cold and warm sea waters are, in a 

 measure (§ 53), like oil and vinegar ; that is, there is among the 

 particles of sea water at a high temperature, and among the par- 

 ticles of sea water at a low temperature, a peculiar molecular ar- 

 rangement that is antagonistic to the free mixing up of cold and 

 hot together. At any rate, that salt waters of different tempera- 

 tures do not readily intermingle at sea is obvious. 



538. Does not this same repugnance exist, at least in degree, be- 

 tween these bodies of cold and warm water of the plate ? And if 

 so, does net the phenomenon we are considering resolve itself into 

 a question of masses ? The volume of w^arm water in the North 

 Atlantic is greater than the volume of cold water that meets and 

 opposes it ; consequently, the warm thrusts the cold aside, divid- 

 ing and compelling it to go round. The same thing is repeated 

 in the North Pacific, whereas the converse obtains in the South 

 Atlantic. Here the great polar flow, after having been divided 

 by the American Continent, enters the Atlantic, and filling up 

 nearly the whole of the immense space between South America 

 and Africa, seems to press the warm waters of the tropics aside, 

 compelling them to drift along the coast on either hand. 



539. Another feature of the sea expressed by this plate is a 

 sort of reflection or recast of the shore-line in the temperature of 

 the water. This feature is most striking in the North Pacific and 

 Indian Ocean. The remarkable intrusion of the cool into the vol- 



