24 I'lIYSICAL GEOGRArnr OF THE SEA, AND ITS METEOROLOGr. 



course, and in tlicir effect they are as endless, riiilosopliy points* 

 to them as the chief cause of the Gulf Stream and of all the con- 

 stant currents of the soa. 



74. Early ivritcrs. — Early writers, however, maintained that 

 the Mississippi lUver was the father of the Gulf Stream. Its 

 floods, they said, produce it : for the velocity of this river in the 

 sea (§ 70) might, it was held, be computed by the rate of the 

 current of the river on the land. 



75. Objection to tJie fresh-ioater theory. — Captain Livingston 

 overturned this hypothesis by showing that the volume of water 

 which the Mississippi River empties into the Gulf of Mexico is 

 not equal to the three thousandth part of that which escapes 

 from it through the Gulf Stream. Moreover, the water of the 

 Gulf Stream is salt — that of the Mississippi, fresh; and the 

 advocates of this fresh-water theorj^ (§ 74) forgot that just as 

 much salt as escapes from the Gulf of Mexico through this 

 stream, must enter the Gulf through some other channel from 

 the main ocean ; for, if it did not, the Gulf of Mexico, in process 

 of time, unless it had a salt bed at the bottom, or was fed with 

 salt springs from below — neither of which is probable — would 

 become a fresh- water basin. 



76. Livingston'' s liypotliesis. — The above-quoted argument of 

 Captain Livingston, however, was held to be conclusive ; and 

 upon the remains of the hypothesis which he had so completely 

 overturned, he set up another, which, in turn, has also been 

 upset. In it he ascribed the velocity of the Gulf Stream as 

 depending "on the motion of the sun in the ecliptic, and the 

 influence he has on the waters of the Atlantic." 



77. Franldins them-y. — But the o]->inion that came to be most 

 generally received and deep-rooted in tlie mind of seafiring 

 people was the one repeated by Dr. Franklin, and which held 

 that the Gulf Stream is the escaping of the waters that have been 

 forced into the Caribbean Sea by the trade-winds, and that it is 

 the pressure of those winds upon the water which drives up into 

 that sea-head, as it were, for this stream. 



78. Objections to it. — ^Ve know of instances in which the waters 

 have been accumulated on one side of a lake, or in one end of a 

 canal, at the expense of the other. The pressure of the trade- 

 winds may assist to give the Gulf Stream its initial velocity, but 

 are the}' of themselves sufficient to send such a stream of water all 

 the way across the ocean, projecting by a single im^Dress a volume 



