8 75-78. THE GULF STREAM. 91 



75. Captain Livingston overturned this hypothesis by showing 

 Objection to the ^^^* ^ho volume of Water which the Mississippi 

 iresh-water theory, j^iygr empties into the Gulf of Mexico is not ee^ual 

 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 theory (§ 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. The above quoted argument of Captain Livingston, however, 

 Lhongston'shypoth- ^^^ ^^^^ ^^ ^® couclusivc ; and upon the remains 

 ^^'^- of the hypothesis which he had so completely overr 

 turned, 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. But the opinion that came to be most generally received 

 Franklin's theory, and dccp-rootcd In the mind of seafaring people was 



the one repeated by Dr. Franklin, and which held that the Gulf 

 Stream is the escaping of the waters that have been /orcec? 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 a head, 

 as it were, for this stream. 



78. We know of instances in which waters have been accu- 

 objections to it. mulated 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 they of themselves adequate to such an effect? Examina- 

 tion shows that they are not. With the view of ascertaining the 

 average number of days during the year that the N.E. trade- 

 winds of the Atlantic operate upon the currents between 25° N". 

 and the equator, log-books containing no less than 380,284^ ob- 

 servations on the force and direction of the wind in that ocean 

 were examined. The data thus afforded were carefully compared 

 and discussed. The results show that within those latitudes, and 



* Nautical Monographs, Washington Obsen^atory, No. 1. 



