Upon making the discharge, the shock was felt by the observers on both
sides of the river, but more sensibly by those who were stationed on the
same side with the machine; part of the electric fluid having gone from
the wire down the moist stones of the bridge, thereby making several
shorter circuits to the phial; but still all passing through the
gentlemen who were stationed on the same side with the machine.—This
was, in a manner demonstrated, by some persons feeling a sensible shock
in their arms and feet, who only happened to touch the wire at the time
of one of the discharges, when they were standing upon the wet steps
which led to the river. In one of the discharges made upon this
occasion, spirits of wine were kindled by the fire which had gone
through the river.
They afterwards undertook to determine whether the electric virtue could
be conveyed along dry ground, and to distinguish, if possible, the
respective velocity of electricity and sound.
For this purpose, they fixed upon a hill, and made their first
experiment on the 14th of August 1747; a time, when, as it happened, but
one shower of rain had fallen during five preceding weeks. The wire
communicating with the iron rod which made this discharge, was supported
all the way upon baked sticks; as was also the wire which communicated
with the coating of the phial, and the observers were distant from each
other two miles. The result of the explosion demonstrated to the
gentlemen present, that the circuit performed by the electric matter was
four miles, viz. two miles of wire, and two of dry ground, the space
between the extremities of the wires.—A distance which, without trial,
as they justly observed, was too great to be credited. A gun was
discharged at the instant of the explosion, and the observers had stop
watches in their hands, to note the moment when they felt the shock;
but, as far as they could distinguish, the time in which the electric
matter performed that vast circuit might have been instantaneous.
Public-domain text, read in full here on John Shaqi.
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