PROGRESS IN ELECTRICITY 



of twenty-four inches long, and found the effect the 

 same. Then I made use of iron, and then brass wire, 

 to fix the ball on, inserting the other end of the wire in 

 the cork, as before, and found that the attraction was 

 the same as when the fir-sticks were made use of, and 

 that when the feather was held over 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 two or 

 three feet long was used, its vibrations, caused by the 

 rubbing of the tube, made it somewhat troublesome to 

 be managed. This put me to thinking whether, if the 

 ball was hung by a pack-thread and suspended by a 

 loop on the tube, the electricity would not be carried 

 down the line to the ball; I found it to succeed ac- 

 cordingly; for upon suspending the ball on the tube 

 by a pack-thread about three 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 one pound and a quarter." 



Gray next attempted to determine what other bodies 

 would attract the bits of paper, and for this purpose he 

 tried coins, pieces of metal, and even a tea-kettle, 

 "both empty and filled with hot or cold water"; but 

 he found that the attractive power appeared to be the 

 same regardless of the substance used. 



"I next proceeded," he continues, "to try at what 

 greater distances the electric virtues might be carried, 

 and having by me a hollow walking- cane, which I sup- 

 pose was part of a fishing-rod, two feet seven inches 



263 



