450 PHILOSOPHICAL TRANSACTIONS. [aNNO JJSl. 



bore was about an inch: to each end he fitted a cork, to keep out the dust, 

 when the tube was not in use. 



The first experiment he made was to see, whether he could find any difference 

 in its attraction, when the tube was stopped at both ends with the corks, or when 

 left open ; but he could perceive no sensible difference. But on holding a down- 

 feather opposite the upper end of the tube, he found that it would go to the 

 cork, being attracted and repelled by it, as by the tube, when excited by rub- 

 bing. He then held the feather opposite the fiat end of the cork, which 

 several times together attracted and repelled; at which he was much surprised, 

 and concluded that there was certainly an attractive virtue communicated to the 

 cork by the excited tube. 



He fixed an ivory ball of about 1.3 inches in diameter, with a hole through 

 it, on a fir-rod about 4 inches long, thrusting the other end into the cork; and 

 on rubbing the tube, found that the ball attracted and repelled the feather with 

 more vigour than the cork had done; repeating its attractions and repulsions 

 for several times together. He then fixed the bail on longer rods; first on one 

 of 8 inches, and afterwards on one of 24 inches long, and found the effect 

 the same. He then made use of iron, and next of brass-wire, to fix the ball 

 on, inserting the other end of the wire in the cork, as before; and he found 

 that the attraction was the same, as when the fir sticks were used ; and that 

 when the feather was held against any part of the wire, it was attracted by it; 

 but though it was then nearer the tube, yet its attraction was not so strong as 

 that of the ball. When the wire of 2 or 3 feet long was used, its vibrations 

 caused by rubbing the tube, made it somewhat troublesome to be managed. 

 This put Mr. Gray on thinking, whether if the ball were hung by a pack- 

 thread, and suspended by a loop on the tube, the electricity would not be car- 

 ried down the line to the ball; he found it to succeed accordingly: for, on 

 suspending the ball on the tube by a packthread about 3 feet long; when the 

 tube had been excited by rubbing, the ivory ball attracted and repelled the leaf- 

 brass, over which it was held, as freely as it had done, when it was suspended 

 on sticks or wire; as did also a ball of cork, and another of lead, that weighed 

 I pound and J-. 



After he had found that the several bodies abovementioued had an electricity 

 communicated to them ; he then went on to try on what other bodies the tube 

 would have the same effect, beginning with the metals, suspending them on 

 the tube by the method abovementioued; first in small pieces, as with a guinea, 

 a shilling, a halfpenny, a piece of block-tin, and a piece of lead; then with 

 larger quantities of metal, suspending them on the tube with packthread. Here 



