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that hereafter. Having got the vapour aloft attended 
by this fire, without aligning any caufe for its afcent, 
fo, without aligning any caufe for its defcent, I fhall 
let it come down as ufual, which is in drops much 
larger than the veficles, in which it afcended. Now, 
in the collifion to form thefe drops, we muff con- 
fider what becomes of our f re ; for the furface of 
thefe larger drops increafing only as the fquares, but 
their folids as the cubes of their diameters, the fire, 
which furrounded the fuperficies of the veficles, muff 
be protruded to a much greater diftance from the 
fuperficies of the larger drops, and by that means 
made more in proportion to the larger drops, than 
its natural affection would have made it join them 
with ; and, confequently, render’d more apt to fly 
off to the next approaching or approached body, not 
fo fully impregnated by this fire. 
I have obferved before, that the conftant feat of 
thunder is in thofe clouds, which are mod compact 
of humid vapour, and which defcend in the heaviefl 
fhowers, and that generally in warm weather, when 
the adjacent atmofphere is ferene; fo that the humid 
vapours are almoft all collected into this chain of 
clouds ; where, according to the compaction, there 
will be a body of this fire collected, and ready to fly 
off, fufficient to perform the greateft effects of thun- 
der. Which may be eafily computed, from the 
force of eleCtrical experiments, where the fmalleft 
portion of this fire, flying off from an electrified 
body, makes an audible crack, and is able to give a 
considerable fhock. What then muft be the force 
of this fire, when it is fo collected, as to break from a 
cloud in a body of fire two or three hundred yards in 
length ? 
