344 PHYSIOGRAPHY. [chap. 



transported from the pole to the equator to come into con- 

 tact with the surface of the earth in the latter region. The 

 immediate effect upon the bodies at that surface would be the 

 same as if they were transported, through still air, at the rate 

 of i,ooo miles an hour to the east. That is to say, they 

 would seem to be subjected to a frightful hurricane from 

 the east ; just as the traveller in a railway carriage, passing 

 through perfectly still air, at the rate of sixty miles an hour, 

 feels a gale of wind blowing from the direction in which he 

 is travelling. 



However, the polar air, in passing south, would soon 

 become influenced by the motion of the regions over which 

 it passes. It would thereby be deflected towards the east, 

 and this deflection would constantly increase, until it reached 

 the maximum at the equator. During its passage from high 

 to low latitudes, the velocity of the eastward movement im- 

 pressed upon the current would have been constantly increas- 

 ing. But common experience shows that a body cannot 

 accommodate itself, in a moment, to any great change of 

 motion. If a carriage suddenly starts, or increases its velocity, 

 the passenger is likely to be thrown in an opposite direction 

 to that of the movement. The air, in like manner, lags 

 behind in passing from high to low latitudes ; and there- 

 fore while? the earth rotates from west to east, the air, as it 

 passes south, acquires a relative motion from east to west. 

 Thus the current which started from the north pole would 

 acquire, during its course, a relative motion to the west ; 

 and, by combining the two motions — that from the north, 

 with that from the east — the wind thus produced would seem 

 to come from the north-east ; in other words, it would appear 

 as a north-easterly, and not as a due north, wind.^ 



^ It may be well to remark that winds receive their names from the 

 qnzrtcrs/rom which they blow. Ocean currents, however, are generally 



