452 PHILOSOPHICAL TRANSACTIONS. [aNNO 1731. 



rubbing the tube, made it more troublesome to manage the experiment. This 

 put him on making the following experiments. 



May 19, about 6 in the morning, the ivory ball being suspended on the tube 

 by a line of packthread 26 feet long, and then the tube being rubbed, attracted 

 the leaf-brass to the height of near 2 inches. This was repeated with the cork- 

 ball with the same success. 



May 3 1 , in the morning, a line of 34 feet in length was tied to a pole of 

 18 feet: so that the pole and line together were 52 feet. With the pole and 

 tube Mr. Gray stood in the balcony, the assistant below in the court, where 

 he held the board with the leaf-brass on it; then the tube being excited as 

 usual, the electric virtue passed from the tube up the pole, and down the line 

 to the ivory-ball, which attracted the leaf-brass; and as the ball passed over it 

 in its vibrations, the leaf-brass would follow it, till it was carried off the board: 

 but these experiments are difficult to make in the open air, the least wind 

 carrying away the leaf-brass. 



Sometime after he made several attempts to carry the electric virtue in a line 

 horizontally ; since he had not the opportunity here, of carrying it from greater 

 heights perpendicularly, but without success, for want of then making use of 

 proper materials, as will appear from what follows. The first method he tried, 

 was by making a loop at each end of a line, and hanging it on a nail, driven 

 into a beam, the other end hanging downwards; through the loop at this end, 

 the line with the ivory-ball was put, the other end of this line was by a loop 

 hung on the tube: so that the part of the line next the ball hung perpendicu- 

 larly, and the rest of the line horizontal: then the leaf-brass being; laid under 

 the ball, and the tube rubbed, there was not the least sign of attraction per- 

 ceived. Hence he concluded, that when the electric virtue came to the loop, 

 that was suspended on the beam, it went up the same to the beam : so that 

 none, or very little of it at least, came down to the ball; which was afterwards 

 verified, as will appear by the experiments mentioned hereafter. 



June 30, 1729, Mr. Gray went to Otterden-place, to give Mr. Wheler a 

 specimen of his experiments. The first was from the window in the long gal- 

 lery, that opened into the hall, the height being about 16 feet. The next ex- 

 periment was from the battlements of the house, down into the fore-court, 29 

 feet. Then from the clock-turret to the ground, which was 34 feet; this 

 being the greatest height they could come at: and notwithstanding the small- 

 ness of the cane, the leaf-brass was attracted and repelled beyond what Mr. 

 Gray expected. As they had no greater heights here, Mr. Wheler was desirous 

 to try, whether they could not carry the electric virtue horizontally: Mr. Gray 

 then told him of the attempt he had made with that design, but without sue- 



