442 METEOROLOGY. 



tnulo-stratus^) the upper part becoming roimded by degrees. Thus the 

 fracto-cumuliis is the iufancy of the cumulus, other^vise called cumulo- 

 stratus, the terms being syuouj-mons. 



This ud'w classiiicatiou is ^vholiy based upou the nature, the form, the 

 quantity, tlie direction, the vclocitij, and azimuthal rotation of the clouds 

 of each stratum, fully characterized hy the origin, intimate constitution, 

 and meteoric products of the vesicular vapors and congealed particles 

 which constitute them ; for, in the intimate nature of clouds, there is 

 one fundamental condition to be established, depending upou the phy- 

 sical force which first acts upon their constitution: it is the element of 

 heat. Clouds are therefore distinguished into snow-clouds and ice-clouds, 

 of which the constituent particles are more or less congealed; then into 

 clouds of aqueous vapor, of which the vesicles, empty or full, float in a 

 medium above the freezing-point. 



Under this fundamental aspect, there are but two types of cloiuls, 

 properly so called, the cirrus and the cumulus. To the cirrus are attached 

 three transitional forms, the cirro-stratus, cirro-cumulus, andpalUo-cirrus ; 

 and to the cumulus, two other transitional forms, the paUio-cumulus and 

 the fracto-cumulus. 



The following is a table of my new classification of clouds compared 

 with that of Howard : 



NOMEKCLATUKE OF HOWARD. 



First typo Cirrus. 



„ . , . ( Cirro-stratus. 



Derivatives .. .. { 



(. Cirro-cumulus. 



SccoucI type Cumulus. 



Derivatives Cumulo-stratus. 



Third tyi)o Stratus. 



Derived from tlie three types.. Nimbus. 



NEW NOMENCLATUr.E OF POiCY. 



First typo Cirrus ^ 



f Cirro-stratus 



T^ . ,. ; ^,. . > Ice clouds; snow clouds. 



Derivatives < Cirro-cumulus ! ' 



I^Pallio-cirrus J 



Second type Cumulus \ 



T^ . ,. S Pallio-cumulus }• Clouds of an ueous vapor. 



Derivatives < i 



i Fracto-cumulus .... ' 



The nomenclature I have adopted appears more in accordance with 

 the nature of clouds, for this reason, that the two types, cirrus and cumu- 

 lus, are strictly based upon the constitution of ice and snow clouds and 

 of clouds of aqueous vapor ; while there is no proof of the existence of 

 Howard's third type, since, according to this savant, it is a onist which 

 overspreads the earth at sunset, but is raised in the morning at the first 

 appearance of the sun. My nomenclature offers the same number of 

 cloud forms ; that is to say, seven, two types and five derivatives. 



The order in which the clouds are placed in my table corresponds at 

 the same time to the order of their. ai^pjearance, from the highest regions 



