CHAP, vm.] THE GULF-STREAM. 397 



The North Atlantic and Arctic seas form together 

 a cul de sac closed to the northward, for there is 

 practically no passage for a body of water through 

 Behring's Strait. While, therefore, a large portion 

 of the water, finding no free outlet towards the 

 north-east, turns southward at the A9ores, the re- 

 mainder, instead of thinning off, has rather a ten- 

 dency to accumulate against the coasts bounding 

 the northern portions of the trough. We accordingly 

 find that it has a depth off the west coast of Iceland 

 of at least 4,800 feet, with an unknown lateral 

 extension. Dr. Carpenter, discussing this opinion, 

 says : " It is to me physically inconceivable that 

 this surface film of lighter (because warmer) water 

 should collect itself together again — eyen supposing 

 it still to retain any excess of temperature — and 

 should burrow downwards into the ' trough,' dis- 

 placing colder and heavier water, to a depth much 

 greater than that which it possesses at the point of 

 its greatest 'glory' — its passage through the Florida 

 Narrows. The upholders of this hypothesis have to 

 explain how such a re-collection and dipping-down 

 of the Gulf-stream water is to be accounted for on 

 physical principles." ^ I believe that as a rule, 

 experimental imitations on a small scale are of little 

 use in the illustration of natural phenomena ; a very 

 simple experiment will, however, show that such a 

 process is possible. If we put a tablespoonful of 

 cochineal into a can of hot water, so as to give it 

 a red tint, and then run it through a piece of india- 

 rubber tube with a considerable impulse along the 

 surface of a quantity of cold water in a bath, we see 



' Dr. Carpenter's Address to Geographical Society, op. cit. 



