ill probably be _severe_. The philosophy of this,
according to my present apprehension of it, is, that these storms present
an _extended easterly front_--_settle very near the earth_--and _have a
rapid progress_--thus accumulating the atmosphere somewhat, in advance of
them.

2d. _As to its fall before storms without previous rise._--This is always
very regular before the second class of storms, or polar belts of showers
and storms. It is very fairly exemplified in the table from Reid, on page
329. The barometer, so far as I have opportunity to observe, does not rise
from a stationary position on the approach of this class of storms. At the
commencement of heated, summer, dry terms, my barometer has most
frequently ranged at about 30.30, and gradually, but slowly, fallen below
30 inches before the belt of showers arrived, and the term closed. The
fourth rule of Dalton (Meteorology, page 183) indicates a similar law in
England. It is as follows:

"In summer, after a long continuance of fair weather, with the
barometer high, it generally falls gradually, and for one, two, or
more days, before there is much appearance of rain. If the fall be
sudden and great for the season, it will probably be followed by
thunder."

3d. _It falls frequently and considerably without rain._--This is owing to
the fact that _all_ regular, periodic efforts at condensation do not
result in rain. The second, third, and fourth classes of storms described,
may not (as we have said) _be sufficiently active to precipitate_,
although the _series of phenomena_ (including the fall of the barometer)
may be, in other respects, perfect. Such an instance may be found in
Reid's table, on page 329, and on the 11th of the month. But the fall in
such cases is not as great, unless the wind be violent.

4th. _It rises during considerable gales._--But these are of the kind so
often alluded to--viz., the N. W., in the northern hemisphere, and the S.
W., in the southern; and the _philosophy_ of it has been explained, and is
observable.

With these explanations, the reader will be able to understand, and
practically apply, the barometric changes, in connection with the other
phenomena, in forming an opinion of the weather.

_The thermometer_ is also an auxiliary. It _rises_, during the winter half
of the year, in the _advance portion of the storm_, and falls when it
passes off again; and the reverse is true, as we have seen, when its ra