de the discovery
that silk, for example, was a poor conductor, and could be turned to
account in insulating the conducting-cord.

A certain Mr. Wheler had become much interested in the old pensioner and
his work, and, as a guest at the Wheler house, Gray had been repeating
some of his former experiments with the fishing-rod, line, and ivory
ball. He had finally exhausted the heights from which these experiments
could be made by climbing to the clock-tower and exciting bits of
leaf-brass on the ground below.

"As we had no greater heights here," he says, "Mr. Wheler was desirous
to try whether we could not carry the electric virtue horizontally. I
then told him of the attempt I had made with that design, but without
success, telling him the method and materials made use of, as mentioned
above. He then proposed a silk line to support the line by which the
electric virtue was to pass. I told him it might do better upon account
of its smallness; so that there would be less virtue carried from the
line of communication.

"The first experiment was made in the matted gallery, July 2, 1729,
about ten in the morning. About four feet from the end of the gallery
there was a cross line that was fixed by its ends to each side of the
gallery by two nails; the middle part of the line was silk, the rest at
each end pack-thread; then the line to which the ivory ball was hung
and by which the electric virtue was to be conveyed to it from the tube,
being eighty and one-half feet in length, was laid on the cross silk
line, so that the ball hung about nine feet below it. Then the other
end of the line was by a loop suspended on the glass cane, and the
leaf-brass held under the ball on a piece of white paper; when, the tube
being rubbed, the ball attracted the leaf-brass, and kept it suspended
on it for some time."

This experiment succeeded so well that the string was lengthened until
it was some two hundred and ninety-three feet long; and still the
attractive force continued, apparently as strong as ever. On lengthening
the string still more, however, the extra weight proved too much for the
strength of the silk suspending-thread. "Upon this," says Gray, "having
brought with me both brass and iron wire, instead of the silk we put up
small iron wire; but this was too weak to bear the weight of the line.
We then took brass wire of a somewhat larger size than that of iron.
This supported our line of communication; but though the tube was