1753
THAT LIGHTNING USUALLY PASSES FROM
EARTH TO THE CLOUDS
by Benjamin Franklin
Electronically Enhanced Text (c) Copyright 1996, World Library(R)
That Lightning Usually Passes From Earth to the Clouds
AT last, on the 12th of April, 1753, there being a smart gust
of some continuance, I charged one phial pretty well with
lightning, and the other equally, as near as I could judge, with
electricity from my glass globe; and, having placed them properly,
I beheld, with great surprise and pleasure, the cork ball play
briskly between them, and was convinced that one bottle was
electrized negatively.
I repeated this experiment several times during the gust, and
in eight succeeding gusts, always with the same success; and being
of opinion (for reasons I formerly gave in my letter to Mr.
Kinnersley, since printed in London), that the glass globe
electrizes positively. I concluded that the clouds are always
electrized negatively, or have always in them less than their
natural quantity of the electric fluid.
Yet, notwithstanding so many experiments, it seems I concluded
too soon; for at last, June the 6th, in a gust which continued from
five o'clock, P.M., to seven, I met with one cloud that was
electrized positively, though several that passed over my rod
before, during the same gust, were in the negative state. This was
thus discovered.
But this was a single experiment, which, however, destroys my
too general conclusion, and reduces me to this: That the clouds of
a thunder-gust are most commonly in a negative state of
electricity, but sometimes in a positive state.
The latter I believe is rare; for, though I, soon after the
last experiment, set out on a journey to Boston, and was from home
most part of the summer, which prevented my making farther trials
and observations; yet Mr. Kinnersley, returning from the Islands
just as I left home, pursued the experiments during my absence, and
informs me that he always found the clouds in the negative state.
So that, for the most part, in thunder-strokes, it is the
earth that strikes into the clouds, and not the clouds that strike
into the earth.
The End
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