20 On the Action of the Barometer in a Hurricane, ete. 
give strong grounds for concluding that the condition of low 
barometer, which often exists at the time of the passage of a 
whirlwind or tornado, is not caused by these meteors; does not 
the low barometer appear to be due to some other cause, and to 
be only a contingent, and not, as storm theorists have assumed, 
stratum consists of a constant occurrence and progression of ey- 
clones from the equator in various degrees of activity; he de- 
fines a cyclone to be a moving disk or stratum of rotating atmo- 
sphere, which sometimes manifests itself by light and feeble, and 
sometimes by strong and violent, winds; the more inert and pas- 
sive cyclones, he says, constantly occupy in their transit the 
rtion of the earth’s surface, and move in orbits corres- 
ponding to the more active cyclones traced on his storm charts; 
and that the effect on the barometer of any cyclone is propor- 
tionate to the general activity of the rotation considere 
whole. In another place he describes the effect as depressing 
the barometer, and says that the intensity of the depression rap- 
idly increases as the axial area of the whirlwind approaches; 
that this axial area is the point of greatest depression, and that 
the latter is obviously due to the centrifugal force of the revoly- 
ing motion in the body of the storm. 
Now bearing these views of Mr. Redfield in mind, let us con- 
sider them in connection with the fall of the barometer repre- 
sented in the diagram above. The fall, which commenced at 
upwards of 4000 miles, supposing that it moved uniformly with 
the velocity with which it was known to move over 300 miles 
of the track, viz., 60 miles per hour; but suppose that its aver- 
age velocity was 30 miles per hour, this would make the distance 
of the axial area upwards of 2000 miles, a distance so great, that 
Mr. Redfield would allow, that it would be preposterous to sup- 
pose that the fall of the barometer on the morning of the 27th 
could be caused by the advance of a storm whose axial area at 
that time was at that distance. 
eae, 
