66 OF CLOUDS. CHAP. 2. 8. 



afforded by the humidity of the air, it may 

 readily be imagined that the cumulus below, 

 and the cirrus above, differently electrified, 

 would mutually attract each other; and that 

 the cumulus, being the larger body, would 

 draw down the particles of the cirrus, while it 

 appears to be drawn upward in a proportionate 

 degree, and rises into mountains. The sudden 

 loss of the cirriform cloud above, instead of a 

 visible descent, is not at all surprising ; for its 

 electric state being destroyed, and its particles 

 being more powerfully attracted by the greater 

 aggregate, they cease to be held together in a 

 body. This suggests another reason for thinking 

 that it is not the simple attraction of aggregation 

 alone which keeps the particles of clouds to- 

 gether in a mass. 



When the cirrus above has been very large, I 

 have observed the process to vary, in a manner 

 quite conformable to my notion of the princi- 

 ples of action of the two clouds on each other. 

 A sort of haziness having appeared between 

 the two clouds, the cirris loses its cirriform and 

 fibrous figure, increases in density, and swells 

 downward, to meet the cumulus rising from 

 below and also changing its structure, till they 

 have both united and formed a nimbus. The 



