94 HEIGHT OF CLOUDS. CHAP. 2. 17- 



tain hardly seemed to bring me nearer to it ; 

 but the most exalted clouds of all were the 

 flimsy cirrocumulative forms of cirrostratus. 

 Indeed it may often be observed that these 

 transient features of cirrostratus, which appear 

 in the intervals of Storms, are elevated much 

 above the tops of cumulostratus, or cumulus, 

 which may be seen lower down. Future 

 observations by means of trigonometrical 

 measurement may, when the differences of 

 clouds become more generally known, lead to 

 a more accurate estimate of the height of the 

 different varieties. In general, the regular 

 ephemeral cumuli have much the same eleva- 

 tion, which somewhat increases during the day 

 from the rising of the Vapour Plane whereon 

 they float. I have made observations with a 

 view to determine whether cumuli were not 

 usually higher over some soils than over others, 

 but I cannot perceive much difference in this 

 respect; they certainly have appeared some- 

 what lower when over the sea, than when they 

 have come over the land; I noticed this at 

 Hastings, in August and September of the 

 year 1814. Before Rain they descend lower, 

 increase irregularly in size, and are condensed 

 into cumulostratus. I have noticed that when 



