THE GULF STREAM. 
39 
but there is another which tends to produce the same effect ; and 
because it is a physical agent, it should not, in a treatise of this 
kind, be overlooked, be its action never so slight. I allude now to 
the effects (upon the drift matter of the stream) produced by the 
diurnal rotation of the earth. 
43. Take, for illustration, a rail-road that runs north and south. 
It is well known to engineers, that when the cars are going north 
on fsuch a road, their tendency is to run off on the east side ; but 
when the train is going south, their tendency is to run off on the 
west side of the track — i. e., always on the right-hand side. 
Whether the road be one mile or one hundred miles in length, the 
effect of diurnal rotation is the same, and the tendency to run off, 
as you cross a given parallel at a stated rate of speed, is the same, 
whether the road be long or short, .the tendency to fly the track 
being in proportion to the speed of the trains, and not at all in 
proportion to the length of the road. 
44. Now, vis inerti(E and velocity being taken into the account, 
the tendency to obey the force of this diurnal rotation, and to trend 
to the right, is proportionably as great in the case of a patch of 
sea-weed as it drifts along the Gulf Stream, as it is in the case 
of the train of cars as they speed to the north, along the iron track 
of the Hudson River railway, or the Great Western railway of 
England. 
The rails restrain the cars and prevent them from flying off; 
but there are no rails to restrain the sea-weed, and nothing to pre- 
vent the drift-matter of the Gulf Stream from going off in obedi- 
ence to this force. The slightest impulse tending to turn aside 
bodies moving freely in water is immediately felt and implicitly 
obeyed. 
45. It is in consequence of this diurnal rotation that drift-wood 
coming down the Mississippi is so very apt to be cast upon the 
west or right bank. This is the reverse of what obtains upon the 
Gulf Stream, for it flows to the north ; it therefore sloughs off to 
the east. 
The effect of diurnal rotation upon the winds and upon the cur- 
rents of the sea is admitted by all — the trade-winds derive their 
easting from it — it must, therefore, extend to all the matter which 
these currents bear with them, to the largest iceberg as well as 
to the merest sprig of grass that floats upon the waters, or the 
