To the great body of our seamen, whether in her Majesty's or the
mercantile service, the subject can present none other than the most
interesting features. The laws that govern the transmission of large
bodies of air from one part of the oceanic surface to another, either in
a state of rapid rotation or presenting a more or less rectilineal
direction, must at all times form an important matter of inquiry, and
bear very materially on the successful prosecution of the occupation of
the voyager.

In order to place the subjects above alluded to in such a point of view
that the connexion between them may be readily seen, it will be
important to notice the principal phænomena presented by each. Without
going over the ground so well occupied by those able writers on the
subject of storms--Redfield, Reid, Piddington, and Thom--it will be
quite sufficient for our present purpose simply to notice the essential
phænomena of revolving storms as manifested by the barometer and vane.
The usual indications of a storm in connexion with these instruments are
the _falling_ of the barometer and the _freshening_ of the wind, and it
is generally considered that a _rapid_ fall of the mercury in the
hurricane regions invariably precedes the setting in of a storm.

There are three classes of phænomena that present themselves to an
observer, according as he is situated _on_ the line or axis of
translation, or _in_ either the right or left hand semicircle of the
storm. These will be rendered very apparent by a little attention to the
annexed engraving, fig. 1.

[Illustration: Compass rose]

In this figure the arrow-head is supposed to be directed true north, and