88 . TH #0 R-Y> wor 
It is not uncommon, during the rife and progrefs of a 
thunder ftorm, to fee different fets of clouds, at various 
heights in the atmofphere, moving promifcuoufly in all 
directions, as though they were impelled hither and thi- 
ther by contending winds; when probably the whole phe- 
nomenon arifes from the different electrical ftates of the 
regions of the air in which they float; as they approach 
one or other of which, they are attracted or repelled, and 
move accordingly, communicating, receiving, or tran{mit- 
ting the eletric fluid, to or from them refpectively, as they 
may be either deficient of their natural quantity, or poflefs 
a redundancy of this fluid. And as in the experiment of 
Mefirs Wilkie and A“pinus mentioned above, the two tin 
plates with the boards they covered, would have rufhed 
together had they not been kept afunder by the ftrings, fo 
thefe clouds floating freely in air, and being at liberty 
to act upon every impulfe, gradually coalefce, reftoring 
the eleGtric equilibrium to the neighbouring atmofphere 
by repeated difcharges as they unite*; till at length they 
form one denfe mafs of humid vapors, which precipitating 
in a heavy fhower of rain, refreth the thirfty foil, leaving 
the atmo{phere above in a homogenous eleétric ftate, calm 
and ferene. 
How thefe clouds are generated, formed, and adapted 
to thofe grand purpofes in the ceconomy of nature, is next 
to be confidered: In profecution of which inquiries I fhall 
fubmit the following obfervations to the candor of the 
reader. 
Whatever the immediate caufe of evaporation may be, 
it is certain that the fuperficial moifture of all bodies is 
perpetually exhaling in vapors, which afcend into the 
higher regions of the atmofphere, where they gather and 
are formed into clouds, and at length recondenfe, defcend- 
ing 
* It is certain that in moft thunder ftorms the flafhes of lightening are chiefly difcharged 
from cloud to cloud, very few, and frequently none at all taking place between the cloud and 
the earth, 
