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 of clouds as designated by Howard. They are copied from the engravings in the sixth edition of Maury’s “Sailing Directions.”

Fig. 5.

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Fig. 6.