ACCUMULATORS. 75 



THE LEYDEN JAR. The first discovery of an accu- 

 mulator was made by Kleist, a clergyman of Cammin, 

 in Pommerania, who stated in a letter to Dr. Lieber- 

 kiihn, of Berlin, Nov. 4, 1745, that by pouring a little 

 mercury, " spirits," or water, into a phial and con- 

 necting it with a nail through the cork, he could 

 electrify it through the nail, ignite "spirits of wine" 

 with it, and receive a shock by touching the nail with 

 his finger. 



The same discovery was made in the following year 

 in Leyden, by Cuneus, a pupil of Musschenbroek, who 

 electrified some water in a flask, which he held in his 

 hand, by bringing it into contact with a chain from the 

 conductor of an electric machine. On attempting to 

 remove the chain with his other hand, he received an 

 electric shock which so frightened him that he dropped 

 the flask. Musschenbroek, having tried the experiment, 

 said he would not take a second shock for the crown 

 of France. 



The discovery created great excitement, and led to 

 the construction of improved instruments, to which 

 the name "Leyden jar" was given. 



The water in this instance constituted the inside 

 coating, the hand the outside coating ; and, when the 

 other hand touched the chain, both surfaces were con- 

 nected by a conductor, and a discharge followed, which 

 produced the shock. 



Fig. 20 represents the Leyden jar as it is usually 

 constructed. The essential elements are two conduct- 

 ing surfaces separated by a dielectric ; but, for conven- 

 ience in charging and discharging, a wooden cap is 

 fitted to it, through which passes a brass rod, terminat- 

 ing in a ball above, and to its lower end is attached a 



