n one direction or another, and sometimes fifteen hundred,
or more. Distinct showers cover but a small surface, sometimes not more
than forty to one hundred rods, as in the tornado, and rarely more than
ten miles. Belts of showers, each new one forming a little more to the
south, often, in summer, pass across the country, following each other in
succession; and these belts may be of considerable width, say thirty to
one hundred and fifty miles.

The clouds which constitute the storms and showers differ in appearance
and character, as well in the active as in the forming state. Clouds are
of distinct characters, alike, substantially, every where under like
circumstances; and a distinct nomenclature has been applied to them by Dr.
Howard, of London. He notes three kinds of primary clouds: _viz._, cirrus,
stratus, and cumulus; and inasmuch as the boundary line between them is
not very distinct, certain compounds of the three, _viz._: cirro-stratus,
cirro-cumulus, and cumulo-stratus. This nomenclature is every where
received, and portions of it are of great practical importance.

The three principal descriptions of cloud, _viz._: the cirrus, the
stratus, and the cumulus, we have very much as they have in Europe, and
doubtless as they exist every where outside of the tropics. The nimbus,
another cloud described by him, is not distinct from the cumulus or
stratus. An isolated, limited thunder-shower in a clear sky, presents the
appearance of a nimbus, as shown in the cuts, but the basis of it is a
cumulus, and it differs from an ordinary fair-weather cumulus merely in
the dark and fringe-like appearance of the rain as it is falling from its
lower surface, and sometimes in the existence of a stratus above and in
connection with it. A similar form is often assumed by the peculiar clouds
of the N. W. winds in March or November, when they assume the form of
_squalls_, and drop flurries of snow. The nimbus, therefore, is not a
distinct cloud, but an appearance which the cumulus, stratus, or
cirro-stratus has in a stormy or showery state, and does not deserve a
distinct name. It is but a cumulus, or a stratus, or cirro-stratus
dissolving in snow or rain. It is important that this term should be
abandoned. It tends to confuse and prevent a clear understanding of the
difference in the character of the clouds, and in relation to which
precision is both difficult and desirable.

The figures on pages 27 and 29, show the different kinds