THE ATLANTIC OCEAN. 205 



We must, then, excuse in our author his somewhat desul- 

 tory view of a phenomenon, of which no single or simple 

 explanation can rightly be given. It is certain, from the 

 permanent characters of the Gulf-stream, that he is correct 

 in treating of it as part of a great circuit of waters in 

 the Atlantic, determined and directed by natural causes of 

 constant operation. One main influence we may presume to 

 be, the tendency of the polar and equatorial waters to ex- 

 change and equalise their temperature by currents flowing at 

 different depths through the ocean ; a condition certain to 

 exist, and well illustrated by the phenomena of those constant 

 or periodical winds, which fulfill a similar object, by main- 

 taining the needful balance of temperature in the great 

 atmospheric sea around us. Nor is this reference to the 

 trade winds one of analogy only. We cannot doubt that 

 they are concerned in keeping up the flow of those vast 

 equatorial currents which, traversing the Atlantic from the 

 African coasts, are pressed into the Caribbean Sea and 

 Mexican Gulf on their southern side ; and sweeping round 

 this great basin and its islands, are mainly discharged through 

 that narrow passage between Cuba and Florida, where the 

 name of the Gulf-stream is first attached to the current. All 

 its characteristics may best be explained under this general 

 view. If a mass of waters be constantly thrown into the 

 Gulf, a mass of waters must as constantly find exit from it. 

 If the exit be narrow, the force of the stream will be propor- 

 tionally augmented, by the unceasing pressure from behind ; 

 rendering it powerful aud persistent enough to cleave the 

 waters of the ocean ; making a return path for itself to the 

 more northern parts of the eastern hemisphere, and carrying 

 thither the warmth derived from the eternal summer of the 

 equatorial seas. 



We can have little doubt that this outline conveys the true 

 theory of the Gulf-stream ; associating it broadly with those 



