CHAP. 2. 7, OF CLOUDS. 63 



If a cirrus, after it has ceased to conduct 

 electricity, should receive from either mass of 

 air, between which it may have been conducting, 

 an electric charge, agreeably to the present 

 theory it would loose its cirriform figure, and 

 take on some other, perhaps a cirrocumulus, and 

 by degrees would sink down towards the earth. 

 Under such circumstances, it may come into 

 actual contact with a cumulus rising from 

 below by the upward propagation of diurnal 

 temperature. Such a phaenomenon have I 

 several times witnessed; and the result has 

 been the sudden commixture of both clouds 

 into a denser mass of nimbus, which has re- 

 solved itself into a gentle Shower, and all has 

 disappeared ; the union of the two clouds thus 

 apparently effecting the destruction of both. 



Such Showers, by visible inosculation, are of 

 short duration: the process is soon finished; be- 

 cause the nimbus, thus formed, is circumscribed 

 by dry air, and has no source of supply : 

 and clearness returns, because the superfluous 

 aqueous particles, or such as cannot be retaken 

 into composition by the air, have come to 

 the ground in Rain. When the circumjacent 

 atmosphere has been moist, the process has been 

 different, as described in the next Section 



