438 METEOROLOGY. 



upon the greater density, dark coloring, and semblance of their isolated 

 masses to a monntain chain. These differences are so accidental and 

 insignificant that Howard and Forster could not distinguish them 

 in their definitions, and they are forced to aver that these characters 

 were found here and there at such points that tliey were easily con- 

 founded. We see there is no -reason to maintain a radical separation 

 and a double denomination for two forms of clouds which are of the same 

 kind and whose slight modifications are not even continued. It is 

 therefore more exact to i)reserve the siogie denomination of cumulus for 

 this second type, which embraces at once the two characteristic forms 

 of cloud — on the one side the accumulation of hemispheres, and on the 

 other the horizontal base, which are always inseparable. 



Let us now pass to Kiimtz's description of strato-cuimdus : "It is 

 comj)osed of dense cloudy masses, round or extended, badly defined at 

 the edges, which appear in the afternoon, increasing toward evening, 

 until during the night the whole sky is completely covered, disappearing 

 the next morning some hours before sunrise and finally replaced by the 

 true cumulus. These strato-cumuU are composed of very dense versicular 

 rapor, like the cumuli and cumulo-strati. They differ by their dependence 

 on different hours of the day ; they have also some analogy with the 

 strati by reason of their extension, but are distinguished by greater 

 altitude; yet they approach the cumuli. In winter the strato-cumulus 

 often covers the sky during entire weeks ; but as the sun approaches 

 the zenith, his rays dissolve these clouds, the vapors rise, and the 

 cumuli are formed." We find again in Kamtz's definition of strato- 

 cumulus the same confusion as in Howard's description of cumulo-stratus, 

 which I pointed out above. The terms "cloudy masses rounded^ ex- 

 tended, or yet badly defined at the edges," embrace three expressions 

 which are mutually exclusive, so that it is impossible to know the trne 

 form of the cloud, for if the cloudy masses are rounded they are not 

 extended in Kamtz's sense, and still less are their edges badly defined. 

 As to the physical constitution of the strato-cumulus, it is the same, 

 according to Kiimtz, as that of cumulus and cumulo-stratus, that is to 

 say, composed of very dense versicular vapor. 



In fine, "the strato-cumulus a\}]}Yoa.ch.Qs the stratus by its exterior, but 

 is separated from it by greater altitude." I have already said that we 

 can comjiare the stratus-mist with no other form of cloud. Hence no- 

 thing remains but the hour of the appearance and disappearance of the 

 strato-cumulus, (which seems to be the fundamental distinction Kamtz 

 wished to establish,) to separate them from the cumulus and cumulo- 

 stratus, added to their continuance in winter for whole weeks at a time. 

 In a word, the strato-cumiiU, with Kiimtz, are the clouds of the night 

 and of winter, predominating during the absence of the solar rays, and 

 dissolved on the appearance of the sun. On this latter circumstance, 

 we remark that the distinction of clouds of the night made by Kiimtz 

 and Howard appears to have no foundation ; I have never been able 



