

fiLfcCTIUClTY. Hl§ 



tened to the lower end, which touches the bottom. 

 To charge this jar, a communication is made be- 

 tween the electrical machine and the brass knob, 

 while the outside of the jar communicates with the 

 earth by the table or the hand. After a few revo- 

 lutions of the machine, it is charged, and ready 

 to exhibit the usual effects. D is an instrument 

 called a discharger, which is used for discharging 

 the jars when required, without the shock passing 

 through any thing besides. It consists of two 

 knobs attached to brass wires, which move round 

 a joint fixed to a glass handle. E is a simpler 

 kind of discharger, consisting only of two knobs, 

 connected by a bent brass wire. 



When one of these knobs is applied to the ball 

 on the jar, and the other to the outside coating, it 

 establishes a communication between the outside 

 and inside of the jar, by which the equilibrium is 

 restored, from the superabundant electricity passing 

 with great rapidity from one to the other, and ap- 

 pearing in the form of a vivid flash, accompanied 

 by a loud report, which will be in proportion to the 

 size of the jar, and the degree of the charge. If 

 the discharger is used, and you want to see the 

 flash, it is necessary first to apply one of the knobs 

 to the side that does not communicate with the 

 electrical machine, which is generally the inside ; 

 because if the knob be applied first to the side that 

 receives the electricity from the machine, the jar 

 will be discharged by establishing a communica- 

 tion with the other side through the hand and 

 body, which would produce the electric shock. 



The most convenient method of receiving the 

 electric shock is to place the jar (after having 

 charged it in the manner mentioned above) upon a 

 piece of chain laid upon the table ; then laying one 



z 2 



