To do this he suspended the pack-thread by pieces of string looped over nails driven into beams for that purpose.

But when thus suspended he found that the ivory ball no longer excited the leaf-brass, and he guessed correctly that the explanation of this lay in the fact that "when the electric virtue came to the loop that was suspended on the beam it went up the same to the beam," none of it reaching the ball.

As we shall see from what follows, however, Gray had not as yet determined that certain substances will conduct electricity while others will not.

But by a lucky accident he made 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.