“On the 30th June 1729, Mr. Grey paid a visit to Mr. Wheeler, in order
to give him a specimen of his experiments; but told him of the
unsuccessful attempt he had made to carry the electric fluid
horizontally; Mr. Wheeler proposed to suspend the conducting line by
_silk_ instead of _pack-thread_. For this advice he could give no
reason, but that the silk thread was _smaller_ than the other; however,
with it they succeeded perfectly well. Their first experiment was in a
matted gallery at Mr. Wheeler’s house, on the 2d of July 1729. About
four feet from the end of the gallery they fastened a line across the
place. The middle of this line was silk, the rest pack-thread. Over the
silken part they laid one end of the conducting line, to which was
fastened the ivory ball, and which hung down about nine feet below the
line stretched across the gallery. The conducting line was about 80 1–2
feet in length, and the other end of it was fastened by a loop to the
electric tube. Upon rubbing the tube, the ivory ball attracted and
repelled light substances, as the tube itself would have done. They next
contrived to return the line, so that the whole length of it amounted to
147 feet; which also answered pretty well. But suspecting that the
attraction would be stronger, without doubling or returning the line,
they made use of one carried straight forward, for 124 feet; and as they
expected, found the attraction in this manner, stronger than when the
lines had been doubled. Thus they proceeded with their experiments;
still adding more conducting line, till at last their silk string broke
with the weight. This they endeavoured to supply, first with a small
iron wire, and then with a brass one. The result of these experiments,
however, soon convinced them, that the silk refused to conduct the
electric fluid, not on account of its _smallness_, as they had supposed,
but on account of some difference in the matter. The wires were smaller
than the silk threads, yet the electricity was effectually carried off
by them. They had recourse, therefore, to thicker lines of silk; and
thus conveyed the electric matter to the distance of 765 feet: nor did
they perceive the virtue to be at all diminished by the distance to
which it was carried.” In the manner in which silk was found to be a
non-conductor, the same quality was also discovered in many other
substances, such as hair, rosin, &c.
Public-domain text, read in full here on John Shaqi.
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