Experiments and Observations on Electricity Made at Philadelphia in AmericaFranklin, Benjamin
History
Experiments and Observations on Electricity Made at Philadelphia in America
Franklin, Benjamin
Electricity -- Early works to 1850
drawing nigh to the punch and snapping, discharges its fire silently
through the point, and rises higher from the punch. Nay, even if the needle
be placed upon the floor near the punch, its point upwards, the end of the
punch, tho' so much higher than the needle, will not attract the scale and
receive its fire, for the needle will get it and convey it away, before it
comes nigh enough for the punch to act. And this is constantly observable
in these experiments, that the greater quantity of electricity on the
pasteboard tube, the farther it strikes or discharges its fire, and the
point likewise will draw it off at a still greater distance.
Now if the fire of electricity and that of lightening be the same, as I
have endeavour'd to show at large in a former paper, this pasteboard tube
and these scales may represent electrified clouds. If a tube of only 10
feet long will strike and discharge its fire on the punch at two or three
inches distance, an electrified cloud of perhaps 10,000 acres, may strike
and discharge on the earth at a proportionably greater distance. The
horizontal motion of the scales over the floor, may represent the motion of
the clouds over the earth; and the erect iron punch, a hill or high
building; and then we see how electrified clouds passing over hills or high
buildings at too great a height to strike, may be attracted lower till
within their striking distance. And lastly, if a needle fix'd on the punch
with its point upright, or even on the floor below the punch, will draw the
fire from the scale silently at a much greater than the striking distance,
and so prevent its descending towards the punch; or if in its course it
would have come nigh enough to strike, yet being first deprived of its fire
it cannot, and the punch is thereby secured from the stroke. I say, if
these things are so, may not the knowledge of this power of points be of
use to mankind, in preserving houses, churches, ships, &c. from the stroke
of lightning, by directing us to fix on the highest parts of those
edifices, upright rods of iron made sharp as a needle, and gilt to prevent
rusting, and from the foot of those rods a wire down the outside of the
building into the ground, or down round one of the shrouds of a ship, and
down her side till it reaches the water? Would not these pointed rods
probably draw the electrical fire silently out of a cloud before it came
nigh enough to strike, and thereby secure us from that most sudden and
terrible mischief?
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