VOL. LX.] PHILOSOPHICAL TRANSACTIONS. Sf 



ramidales raised, not only along the path of the explosion, but also wherever any 

 part of the chain had touched it, though not in the circuit. lb. p. 686. 



It was to ascertain the nature and effects of this lateral explosion, that the fol- 

 lowing experiments were made. Not having the least doubt, but that if any 

 electric spark passed between a body that was insulated, and another, the insu- 

 lated body would appear, either to have received or to have lost electricity; he 

 imagined that nothing more was to be done than to insulate bodies placed within 

 the influence of the electric circuit, with pith balls hanging from them ; and on 

 their diverging with the electric spark, immediately to observe, of what kind the 

 electricity they had contracted was ; and previous to the experiment, he conjec- 

 tured it would be negative; supposing that the discharge from the inside coating, 

 in an interrupted circuit, was not able to supply the outside fast enough. And 

 since, the larger the insulated body was, the greater quantity of the electric fluid 

 it was capable of receiving, or parting with, and consequently the more sensible 

 the eflx)rt would be ; he began with suspending on silken strings, a pasteboard 

 tube, covered with tinfoil, 7 feet long and 4 inches thick, with large knots at 

 each end; and a brass ball (at the end of an iron rod, which communicated with 

 the outside of the jar) was placed within about a quarter of an inch of it; while 

 the discharge was made through an insulated interrupted circuit, no part of which 

 was less than 2 feet from the insulated tube. On making the explosion, the 

 spark appeared as he expected; but to his great surprize, he could not find that 

 either positive or negative electricity was communicated to the insulated tube. 

 Neither the pith-balls, nor the finest threads diverged, or moved in the least, at 

 or after the discharge ; though, every thing else remaining in the same state, the 

 least sensible electricity communicated to this tube (a quantity so small as hardly 

 to be visible, in the form of a spark, at the time of communication) made the 

 balls and the threads separate to a great distance, and would have kept them in a 

 state of divergency more than an hour. Lest a small degree of motion or diver- 

 gency should escape notice, while he was intent on making the discharge, he had 

 an assistant along with him, whose eye was on the threads all the time the Dr. 

 was making the experiment. 



This experiment, as will easily be imagined, shook his whole hypothesis, and 

 confounded all his ideas. He could not question the fact, having repeated the 

 experiment, with precisely the same event, above 50 times, on account of having 

 been hardly able to believe his own senses, or those of others. There was an 

 evident electric spark, sometimes near half an inch in length, between the bodies 

 composing the electric circuit and the insulated tube, in such a state of the air, 

 as he knew, by frequent trials, would have kept it electrified a long time, and 

 yet there was no communication of electricity. He did not remember that he 

 was ever more puzzled with any appearance in nature than he was with this ; and 



