CAUSE OF THE GULF STREAM. 53 



sea, that the line of demarcation may be traced by 

 the eye. Its influences on the currents of the sea, 

 and on the climates and the navigation of the world, 

 are so great and important, that we think a some- 

 what particular account of it cannot fail to interest 

 the reader. 



The waters of the Gulf Stream are salter than 

 those of the sea; which fact accounts for its deeper 

 blue colour, it being well known that salt has the 

 effect of intensifying the blue of deep water. 



The cause of the Gulf Stream has long been a 

 subject of conjecture and dispute among philosophers. 

 Some have maintained that the Mississippi river 

 caused it; but this theory is upset by the fact that 

 the stream is salt salter even than the sea while 

 the river is fresh. Besides, the volume of water 

 emptied into the Gulf of Mexico by that river is 

 not equal to the three thousandth part of that which 

 issues from it in the form of the Gulf Stream. 



Scientific men are still disagreed on this point. 

 They all, indeed, seem to hold the opinion that 

 difference of temperature has to do with the origina- 

 tion of the stream ; but while some, such as Captain 

 Maury, hold that this is the chief cause, others, 

 such as Professor Thompson, believe the trade- winds 

 to be the most important agent in the matter. We 

 venture to incline to the opinion that not only the 

 Gulf Stream, but all the constant currents of the sea 

 are due chiefly to difference of temperature and salt- 

 ness. These conditions alter the specific gravity of 



