CLOUDS. 439 



to perceive them. So true is this, that these two savants are nowise 

 agreed upon this point, which has given rise to the new variety of Kiimtz. 

 With Kiimtz, the cloud of night is the strato-cumulus, while with How- 

 ard it is the stratus. On the other hand, since the stnitus is not a true 

 cloud according to Howard himself, but simply a mist or hoar-frost, the 

 distinction between the cloud of night and the cloud of day must be- 

 come wholly sui)erlluous. I will close this proof of the non-existence of 

 strato-cumulus by reminding the reader that Kiimtz himself told me 

 before his death, without discussion, that he no longer attached any im- 

 portance to his cloud of night, and authorized me to erase it from the 

 nomenclature of Howard. In the exposition of my new classification of 

 clouds, published in 1855, in the Annual of the Meteorological Society of 

 France^ while pointing out the identitj^ of the cumulus and cumulo-stratus, 

 I retained both these determinations, because the term cumulus did not 

 designate its i)eculiar cloud-type as well as cumulo-stratus. But, as cumu- 

 lo-stratus is derived from two species of clouds, it is i^referable to keep 

 the generic name of c««/M(Zzts for the two identical clouds described by 

 Howard, attributing to them the character given above. 



DEFINITION OP CLOUDS. 



Every country, according to its geographical position, topography, &c., 

 has its own type of clouds. Here the cirrus predominates 5 there the 

 cumulus. All these different appearances of clouds are everywhere in- 

 timately connected with some particular condition of climate, which 

 powerfully influences health, agriculture, navigation, and a thousand 

 other objects of importance to humanity. They show us at e^'ery in- 

 stant the direction, the velocity, and the altitude of the superior cur- 

 rents which afterward determine the winds at the surface of the earth. 

 We may regard the clouds as a weathercock in the sky, constantly indi- 

 cating changes so long as a single one, however small, exists, and there- 

 fore a profound gtudy of them, in their diverse, scientific, and social ap- 

 plications, becomes of high importance. For this we should consider 

 their natnre, form, quantity, direction, velocity, and azimuthal rotation. 



Despite the scientific interest and the practical value which is attached 

 to this subject, the study of clouds is unhappily in its infancy. It is rarely 

 we find clouds included in the meteorological registers, and when they 

 are so the characteristics above mentioned are omitted. Some observers 

 simply write " clouds; " others denote the form, or, it may be, the quantity, 

 the direction, or perhaps all these three elements, but neglect the velocity, 

 and especially the azimuthal rotation to which I was the first to call 

 attention and which is not yet understood. 



We now proceed to present the basis of a new classification more in 

 harmony with the actual facts of the science, and which is the fruit of 

 twenty years' assiduous study of clouds in the Antilles, Mexico, the 

 United States, and Europe. From the beginning of my meteorological 

 investigations in the tropics, where the entire phenomena of the atmo- 



