Philosophy of Storms. 123 
ratures, it follows that a pound of steam being condensed into 
1198 pounds of water at 32° would heat it up 1°. And as the 
specific caloric of air is only 0.267, if a pound of vapor should 
be condensed into 1198 pounds of air, it would heat that air 
nearly 4°, or which is the same thing, it would heat 119 pounds 
of air 4°, or 100 pounds 48°, and in all these cases it would ex- 
pand the air about 8000 times the bulk of water generated ; that 
is, 8000 cubic feet for every cubic foot of water formed out of 
the condensed vapor. And as it requires between 1300 and 1400 
cubic feet of vapor, at the ordinary temperature of the atmos- 
phere, to make one cubic foot of water—if this quantity be sub- 
tracted from 8000, it will leave upwards of 6600 cubic feet of 
actual expansion of the air in the cloud for every cubic foot of 
water generated there by condensed vapor. 
This great expansion of the air in the forming cloud will cause 
the air to spread outwards in all directions above, causing the ba- 
rometer to rise on the outside of the cloud shove the mean, and 
to fall below the mean under the middle of the cloud as much 
as it is known to do in the midst of great storms. | 
For example, if the dew point should be very high, say 78°, 
then the quantity of vapor in the air would be about one fiftieth 
of its whole weight, and if the up-moving column should rise 
high enough to condense one half its vapor into cloud, it would 
heat the air containing it 45°, and the air so heated would be 
#;ths larger than it would be if it was not so heated. And if 
We assume a case within the bounds of nature, and suppose the 
cloud and the column under the cloud to occupy three fourths of 
the whole weight of the atmosphere, or in other words, if we 
suppose the top of the cloud sosnathoahtialit where the barom- 
eter would stand at 74 inches, and the mean temperature of the 
whole column 40° warmer than the surrounding air, then would 
the barometer fall under the cloud at the surface of the earth 
z';°;ths of 22.5, or a little more than two inches. 
Though the air may be driven up by the ascending column 
much higher than the point assumed in the last article, the cloud 
will cease to form at greater heights, because the dew point at 
these great elevations, falls by a further ascent as rapidly as the 
temperature—and at greater elevations, it will even fall more 
expitin If for instance the air should rise from where the ba- 
rometer stands at six inches to where it stands at three inches, 
