ELECTRICITY FROM THALES TO FARADAY. 247 



the addition operated to upset the balance, so to speak, and the elec- 

 tricity escaped by a sudden (disruptive) discharge, or spark, or by the 

 brush discharge already alluded to. With the Leyden jar, however, 

 as fast as electricity was supplied to the inside coating it became 

 " bound " there by the charge of opposite sign accumulating on the 

 outside, and the limit of capacity of the jar was simply one of strength 

 of the glass : if too much electricity was supplied, the stress of mutual 

 attraction between the two charges relieved itself by destroying 

 the jar. 



Although Professor Muschenbroeck discovered the principle in 

 the manner above referred to, it appears extremely probable that 

 two other investigators, working independently, also did the same. 

 One Cuneus and a monk named Kleist each claimed the honor of 

 original invention of the condenser. 



About 1747 the first gun was fired by electricity; this was ac- 

 complished by Sir William Watson, who also succeeded in kindling 

 alcohol and gas by means of a drop of cold water and even with ice. 

 The same experimenter reversed the ordinary procedure of causing 

 the electric influence to pass from an electrified body to the one to 

 be experimented upon, the latter being unelectrified, by electrifying 

 the latter, and then producing the desired effect by approaching it to 

 an unelectrified one. 



A party of the Royal Society with Watson as chief operator in- 

 stituted a series of researches on a grand scale to determine, if pos- 

 sible, the velocity of the electric discharge, and arrived at a number 

 of conclusions which, however, were of a decidedly negative nature. 

 The most important of these were as follows: That they could not 

 observe any interval between the instant of applying the discharge 

 to one end of the line and its reception at the other; that the de- 

 structive effects of discharge are greater through bad conductors than 

 through good ones; that conduction is equally powerful whether 

 occumng through earth or water. 



Just previous to this there had been some brilliant experiments 

 carried on in France, and the discharge had been conveyed through 

 twelve thousand feet of circuit, including the acre basin of the Tuile- 

 ries, but they had not been performed as systematically, or with the 

 definite objects in view, as had the English experiments. 



The following year the Royal Society continued its researches 

 on a larger scale than previously, using 12,276 feet of wire, and found 

 that even through that length the velocity was practically instan- 

 taneous. 



Watson urged as a theory that electrical disturbances were caused 

 by influx or efflux of a single electric fluid from the state of normal 

 electrification, thus differing from Dufay in his opinion as to the 



