98 THE OCEAN. 
higher elevation. The empty space thus left ia in- 
stantly filled by the surrounding air rushing in, 
pressed by the weight of the atmosphere above: this 
motion communicated to the air, has been supposed 
to constitute a wind blowing in the direction of 
the spot where the heat was generated. It must 
be confessed, however, that the cause thus adduced 
does not seem adequate to produce the effects at- 
tributed to it; though probably some of the cur- 
rents of the air are owing to variations of its tem- 
perature. And as these variations are perpetually 
occurring, dependent on causes which are difficult 
to detect, and as the aerial currents resulting from 
them act and react on each other, variously modi- 
fying their direction, force, and duration, the or- 
dinary winds are irregular and inconstant even to 
a proverb. Some observations, however, recently 
made, have revealed some particulars of a highly- 
interesting character, concerning the winds of the 
termperate zones: one of which is, that they blow 
in a circular direction; that is, the course which 
a storm has taken, if marked out on a map or 
globe, would describe a circle, often of many de- 
grees in diameter. The direction of the gale in 
the circle is not arbitrary, but seems to be inva- 
riably from north to west, south, and east, in the 
northern hemisphere, and in the opposite course 
in the southern. These winds appear to be inti- 
mately connected with magnetism: it is a curious 
fact, that, in the midst of the southern Atlantic, 
where magnetic influence is at the lowest degree 
of intensity, storms are unknown, while the meri- 
