INTRODUCTION. 95 
rapidity through the confined limits of the Strait of 
Florida, and pours a vast volume of tepid water into 
the cold bosom of the Atlantic. Here, unrestrained, 
it of course widens its bounds and slackens its speed, 
though such is its impetus that it may be distinctly 
perceived even as far as the Great Bank of New- 
foundland. Nor is its strength then spent; for 
many curious facts seem to warrant us in con- 
cluding, that even to the coasts of Scotland and 
Ireland, and down. the shores of Western Europe, 
this mighty marine river continues to roll its won- 
derful waters. The temperature of this current is 
much higher than that of the surrounding water, and 
this is so uniformly the case that an entrance into 
it is immediately marked by a sudden rise of the 
thermometer. Another unfailing token of its pre- 
sence is the Gulf-weed (Sargassum vulgare), which 
floats in large fields, or more frequently in long 
yellow strings in the direction of the wind, upon 
its surface. The cause of this vast and important 
current seems to be the daily rotation of the earth. 
If we turn a glass of water quickly upon its axis, we 
shall perceive that the glass itself revolves, but that 
the particles of water remain nearly stationary, owing 
to the slightness of their cohesion to'the glass. To 
a very minute insect attached to the vessel, it would 
seem that the water was rushing round in an op- 
posite direction while the glass remained stationary. 
Now the earth is whirled round with great rapidity 
from west to east, and the greatest amount of this 
rapidity is of course at the equatorial regions, being 
the part most remote from the axis: but the par- 
c 
