t continuing into the evening of the day
before the belt of condensation arrives.

3. Belt of condensation, with or without rain or showers, with the
easterly wind blowing axially, if the condensation is heavy and the belt
wide; westerly if the condensation is feeble or the belt narrow--the
clouds moving about E. N. E.

4. Cooler air, light N. W. in summer, heavy N. W. in autumn, winter, and
spring.

And, the next period--

5. Still warm weather or light airs.

6. Southerly wind, fresh.

7. Belt of condensation.

8. Cool northerly wind.

And so on, successively, unless broken in upon by some other class.

Sometimes these periods are exceedingly regular, at other times the other
classes prevail. I have much reason to believe that this is the _normal,
periodic_ provision for condensation of our portion of the northern
hemisphere, and probably of every other where rain falls regularly in the
summer season, and that the other classes are exceptions, as the
hurricanes are exceptions to the normal condition of the weather every
where. Perhaps in some seasons, during the northern transit, the
exceptions may equal the rule, but I do not now remember such a season. In
other years nearly all the storms are of this character. Thus, Dr.
Hildreth (in Silliman's Journal for 1827), speaking of the year 1826, in a
note to his register of that year, says: "There have been, this year, an
unusual number of winds from N. or N. W. Nearly every rain the past summer
has been followed with winds from the northward, when, in many previous
summers, the wind continued to the southward after rain." The immediate
occurrence of northerly wind after the passage of the belt of
condensation, is a peculiar feature of this class of storms.

As this also will be new, and is of great practical interest, I shall be
pardoned for referring to other evidence. Bermuda is in latitude 32 deg.
north. In the summer season they are within the range of the Calms of
Cancer, as Lieutenant Maury terms them, and not subject to storms. From
November to May, inclusive, they have successions of revolving wind.
Colonel Reid gave them much attention, and studied them barometrically:
that is, he studied the changes of the wind during the successive periodic
depressions. He found them revolving like ours, and hence inferred the
truth of the gyratory theory in relation to all winds. But it is perfectly
evident the same polar belts which pass over us reach them during