CLOUDS. 435 



with their corresponding elements, and esi^ecially the considerable 

 length of time that an observatory must spend in making a good obser- 

 vation, according to our x)resent faulty method, we are less .surprised 

 at the little progress that a study so interesting has hitherto made. I 

 must add an important fact, which has passed completely unnoticed : that 

 the classification of Howard also is faulty in the definition of stratus 

 and nimbus. Kiimtz's treatise on meteorology gives the following defi- 

 nition of stratus, which has been since blindly adopted by all meteor- 

 ologists : " It is a horizontal hand, formed at sunset and disappearing 

 at sunrise." On the contrary, Howard's definition has alvrays been that 

 the stratus '•' is the lowest of clouds, since its inferior surface commonly 

 rests on the earth or water ; this is properly the cloud of the night, the 

 time of its first appearance being about sunset. It comprehends all 

 those creeping viists which, in calm evenings, ascend in spreading 

 sheets (like an inundation) from the bottom of valleys and the surface 

 of lakes, rivers, and other pieces of water to cover the surrounding 

 country." In continuation, Kiimtz, describing the cirrono- stratus, re- 

 marks that "these clouds form horizontal strata, which, at the zenith, 

 seem composed of a great number of thin clouds, while at the horizon, 

 where we perceive the vertical projection, we see a long and very narrow 

 band." Thus for the stratus we have a horizontal band, and for the 

 cirro-stratus at the horizon another band, long and very narrorc. Accord- 

 ing to this savant, between these two bauds there is no distinctive mark 

 save the hour at which they appear. But as the bands cirro-stratus are 

 frequent exactly at the rising or setting of the sun, it is very difficult to 

 distinguish these two orders of clouds. It must be added that the cirrus 

 and the cirro-cumuhis show a tendency to dispose themselves in bands 

 parallel with each other, which at the horizon may be equally confounded 

 with those of stratus and cirro-stratus. As to the origin of the stratus 

 can we, without confusion, give the name of cloud to a phenomenon 

 already designated as onist f The sole connection which exists between 

 a cloud and a mist is in the first iDrecipitation of vapor of water in the 

 atmosphere, and its greater or less condensation. It is when the mist 

 is elevated to the region of inferior clouds that it is condensed under the 

 form of a cumulus, and the visible vapor of water takes its first forms. 

 Hitherto the mist was but a shapeless mass of vapor molded, so to 

 speak, by the accidents of the earth and sheets of water, and following 

 the permanent or transient outlines of these surfaces. It seems that 

 Howard's first error was calling a mist a cloud, and the grave responsi- 

 bility rests upon his successors of giving the mist of this writer as a 

 true cloud under the form of a liorizontal hand. This error has been 

 extended to the different plates published in 1815 by Forster, in which, 

 nevertheless, the stratus is not given as a band, but rather as a mist 

 raised at the horizon. But this representation is equally faulty, as it 

 gives no idea of a mist covering the surface of the earth. As early as 

 1820, in Braude's* work, i\\Q stratus appeared as forming a liorizontal 

 ^.BRjVNDES.^^Untersucliungen zur Witterungskunde. Leipzig, 1820, p. 385. 



