II THE PROBLEMS OF THE DEEP SEA 65 



eastern pool communicates by a shallow passage, 

 not a sixth of its greatest depth, with the western 

 pool, so the western pool is separated from the 

 Atlantic by a ridge which runs between Capes 

 Trafalgar and Spartel, on which there is hardly 

 1,000 feet of water. All the water of the Mediter- 

 ranean which lies deeper than about 150 fathoms, 

 therefore, is shut off from that of the Atlantic, 

 and there is no communication between the cold 

 layer of the Atlantic (below 1,000 fathoms) and 

 the Mediterranean. Under these circumstances, 

 what is the temperature of the Mediterranean? 

 Everywhere below 600 feet it is about 55 Fahr. ; 

 and consequently, at its greatest depths, it is some 

 20 warmer than the corresponding depths of the 

 Atlantic. 



It seems extremely difficult to account for this 

 difference in any other way, than by adopting 

 the views so strongly and ably advocated by Dr. 

 Carpenter, that, in the existing distribution of 

 land and water, such a circulation of the water of 

 the ocean does actually occur, as theoretically must 

 occur, in the universal ocean, with which we 

 started. 



It is quite another question, however, whether 

 this theoretic circulation, true cause as it may be, 

 is competent to give rise to such movements of 

 sea-water, in mass, as those currents, which have 

 commonly been regarded as northern extensions of 

 the Gulf-stream. I shall not venture to touch 



VOL. VIII F 



