OCEANIC CIRCULATION. 219 



sluggish equatorial current. Moreover, if we remember 

 how shoals commonly take their origin, we may con- 

 sider that the very existence of the Bahama Bank is 

 probably due to the former encounter of the two im- 

 portant branches of the equatorial current the part 

 which had circled the Gulf of Mexico and the part 

 which had travelled outside the West Indies. Thus, 

 the northerly course finally taken by the Gulf Stream 

 implies that the latter portion had prevailed over the 

 former, and therefore that it is the most considerable 

 portion. I must mention, however, that the Edinburgh 

 Reviewer holds the part which enters the Caribbean Sea 

 to be the larger. 



Be this as it may, the Gulf Stream proper has ac- 

 quired, during its circuit, characteristics perfectly 

 distinct from those which it had had when entering the 

 Caribbean Sea, or from those possessed by the remain- 

 ing portion when approaching the Bahamas. In the 

 first place, having traversed a much longer course under 

 the same intense tropical heat, the Gulf Stream has 

 become much warmer than the outer stream. In the 

 second place (probably from having traversed the outlets 

 of the Mississippi, and so carrying with it the finely- 

 divided matter brought down by that river), the Gulf 

 Stream has acquired a peculiar blue colour, somewhat 

 resembling that recognised in most of the Swiss lakes. 1 



1 This explanation of the colour of the Gulf Stream seems the best 

 that has hitherto been offered. The Edinburgh Reviewer thus states the 

 matter : ' The remarkable blueness which distinguishes the water of the 

 Gulf Stream from the oceanic water through which it flows may be due 

 to its retaining in suspension the finest of the sedimentary particles 



