26 
THE PHYSICAL GEOGRAPHY OF THE SEA. 
philosophers. Modern investig-ations and examinations are begin- 
ning to throw some hght upon the subject, though all is not yet 
clear. 
. 4. Early writers maintained that the Mississippi River was the 
'father of the Gulf Stream. Its floods, they said, produce it ; for 
its velocity, it was held, could be computed by the rate of the cur- 
rent of the river. 
5. 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 one thousandth part of that 
which escapes from it through the Gulf Stream. 
6. Moreover, the water of the Gulf Stream is salt — of the Mis- 
sissippi, fresh ; and those philosophers 4) 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 
below — neither of which is probable — would become a fresh-water 
basin. 
7. The above quoted argument of Captain Livingston, however, 
was held to be conclusive ; and upon the remains of the hypoth- 
esis which he had so completely overturned, he set up another, 
which, in turn, has 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." 
8. But the opinion that came to be the most generally received 
and deep-rooted in the mind of seafaring people was the one re- 
peated by Dr. Franklin, and which held that the Gulf Stream is 
the escaping of the waters that have been fo7'ced into the Carib- 
bean Sea by the trade-winds, and that it is the pressure of those 
winds upon the water which forces up into that sea a head, as it 
were, for this stream. 
9. We know of instances in which waters have been accumu- 
lated on one side of a lake, or in one end of a canal, at the ex- 
pense of the other. But they are rare, sudden, and partial, and 
for the most part confined to sheets of shoal water where the rip- 
ples are proportionably great. As far as they go, the pressure of 
the trade-winds may assist to give the Gulf Stream its initial ve- 
locity, but is it of itself adequate to such an effect ? To my mind, 
