THUNDER STORMS. 87 
As in, the former experiment made with the pane of 
glafs, the charges, both pofitive and negative, refide in the 
glafs itfelf, and not in the coatings, thofe remaining after 
thefe are removed; {o in the latter, which is completely 
analogous to it, the charges are accumulated and refide in 
the air fituated between the boards, and not in their tin 
linings, which ferve only as condudtors, to diftribute the 
fluid equally over, or to convey it equally from, the whole 
furface of air which is limited by, and in conta&t with 
them, on either fide; whereby the whole of each furface 
may be equally charged at the fame time, or difcharged 
by the fame explofion. 
If two or more regions of the atmofphere, when free 
from vapors, become thus differently eleCtrical in their 
ftate and capacities, which, that they may, from the heat 
and confequent rarefaction in a fummer’s day, we have al- 
ready feen, and perhaps from a variety of other caufes to 
us unknown; and if from the contrary currents of air 
which frequently take place at different heights, they 
fhould perchance become fituated one over or adjacent to 
another, like {trata of minerals within the bowels of the 
earth; what the metalline coating is to the pane of glafs, 
or the tinned boards to the plate of air in the laft experi- 
ment, the fame would clouds, formed and floating therein, 
be to thefe regions of air; the electric equilibrium between 
which might be reftored through their intervention, either 
by {fpontaneous. difcharges through the pure air between 
them in fevere flafhes of lightening or through the falling 
drops of rain, which in their fucceflive defcent form a chain 
of natural conductors between one region of the air and 
another, and betwixt each of them and the earth; the 
paflage of the electric fluid through which would alfo be 
attended with lightening and thunder, but not fo fevere as. 
when the difcharge is made through the pure air; the moft 
fatal lightening ufually preceding the fall of the rain. 
Tt. 
