Anyone interested to-day in weather phenomena is acquainted with the terms used in cloud classification - Cirrus, Cumulus, Stratus, and Nimbus. These have come so far into general use that it is not easy to realize that, until Howard's paper, On the Modification of Clouds, appeared in 1803, no names for classifying clouds were available. Superficially, it may seem that Howard had done nothing more than science has so often done in grouping and classifying and naming the contents of nature. In fact, however, he did something essentially different.