THE GULF STREAM AXD DEEP SEA CURRENTS. 1C9 



three or four thousand miles the exj>eriment is not a compara- 

 tive one. The ice and the heated iron almost touch ono 

 another, whereas in the ocean there are thousands of miles of 

 water of a medium temperature. If the trough were a milo 

 long, by the same depth and height, it -would afford a better 

 comparison, and, of course, it is easy to conjecture that the two 

 temperatures would never meet to form a current. 



This polar current Dr. Carpenter says is so strong, that in many 

 places it has rounded the stones at the bottom of the sea, as in a 

 channel between the Faroe Islands and Shetland. But it only 

 requires one to reflect how much force is necessary to roll 

 stones over one another in order to round them, to be convinced 

 that this explanation of their form is not the correct one. Be- 

 sides, at another place he says the motion is only a creeping 

 one. 



Dr. Wyville Thomson, one of Dr. Carpenter's colleagues in 

 Deep Sea Explorations, says in his late book on the Depths of 

 the Sea, that he differs from him in his theory of oceanic 

 circulation, and does not think that the facts he has given 

 warrant him in arriving at the conclusions he draws from them. 



Moreover, it is not a matter of necessity that there should be 

 such an oceanic circulation. It is enough for the purpose of 

 keeping the water pure, and preventing stagnation, that there is 

 a continuous reciprocal or chemical atomic action between the, 

 upper and lower strata of water, throughout the whole body of 

 it. This we believe to be the true producer of the oceanic 

 circulation, for its action is not confined to the ocean, but per- 

 vades the whole system of our planet. For instance, water 

 percolates to the interior of the earth, and by its chemical 

 action, dissolves minerals and produces gases which find tlieir 



