In 1803 the English meteorologist Luke Howard published the system of classification that, with some additions and modifications, is now in general use. This system is based upon three fundamental forms; viz., fibrous or feathery clouds (_cirrus_), clouds with rounded tops (_cumulus_), and clouds arranged in horizontal sheets or layers (_stratus_). Intermediate forms are described by compounding the names of the primary types; e. g., _cirro-cumulus_, _cirro-stratus_, etc. The rain cloud is called _nimbus_. Howard’s classification was quickly adopted in all countries. His definitions were translated into German by no less a personage than Goethe, who, in his enthusiasm over Howard’s achievement, wrote a poem about it, and also a separate poem about each of the principal types of cloud! The Latin names that Howard gave to the clouds made his system immediately available for international use; and in nearly all of the many systems of cloud nomenclature that have since been proposed the excellent plan of using Latin names has been preserved. Very soon, however, after Howard’s classification appeared, a list of proposed English equivalents of his names was published in the “Encyclopædia Britannica”--which, nevertheless, did not change its name to “British Encyclopædia”--for the benefit of the unlettered majority, supposed to be incapable of using a few Latin terms that were, in fact, shorter and no more difficult to pronounce than their suggested English substitutes! A piquant sequel to this episode is that these superfluous English cloud names, “curl cloud,” “stackencloud,” “fall cloud,” “sondercloud,” “wane cloud,” and “twain cloud,” still survive in the dictionaries--and nowhere else. They are practically unknown to meteorologists, and were never adopted generally by the laity. Of course some English names, which have been evolved and not deliberately invented, are applied to certain types of cloud in English-speaking countries; but the Latin names, comprised in the International Cloud Classification, should be learned by everybody. This classification, which has been adopted by the International Meteorological Committee and is used by all official weather services, is a little more detailed than Howard’s, upon which it is based; and there is a tendency to add new terms to it from time to time. There are ten principal types of cloud in the International Classification, and the name of each type has an official abbreviation (a great convenience for those who record the clouds from day to day). The following definitions, translated from the French text of the “International Cloud Atlas,” have been published by the British Meteorological Office: 1. CIRRUS (CI.)--_Detached clouds of delicate appearance, fibrous (threadlike) structure and featherlike form, generally white in color._