384 



"WELLS'S NATURAL PHILOSOPHY. 



How is a Ley' 

 den jar dis- 



within two or three inches of the mouth, 

 or to the line a b, with tin-foil. A wooden 

 cover, well varnished, is fitted into the 

 mouth of the jar, through which a stout 

 brass wire, furnished with a ball, passes, 

 having a chain or wire attached to its 

 lower end, so as to be in contact with 

 the inside coating. 

 „ , r -A- Leyden jar is charged 



How IS a Ley- . 



d«,i jiir charg. bv presenting the brass ball 

 at the end of the rod of the 

 jar to a prime conductor of an electrical machine in 

 action, or to any other excited surface. To charge a jar 

 strongly, it is necessary that the outside coating should be 

 directly or indirectly connected with the ground. 



A Leyden jar is discharged by effecting a 

 communication between the outer and inner 

 surfaces by means of a good conductor. 



If; when we have charged the jar, we hold the exterior coating in one 

 hand and touch the knob with tiie other, a spark is observed, and the peculiar 

 sensation of the electric shock experienced. 



Any number of persons can receive a shock at the same time by forming a 

 chain by holding each other's hands — the first person in the circle touching 

 the external coating of the jar, and the last the knob. 



"^'hen a Leyden jar is charged, the electricity resides wholly 

 on the surfoce of the glass; the metallic coatings having no 

 other efl'ect than to conduct the electricity to the surface of 

 the glass, and, when there^ aflbrd it a free passage from point 

 to point. 



The power of a Leyden jar will therefore depend upon its size, or extent 

 of surface. 



As very large jara are inconvenient and 

 expensive, very strong charges of electricity 

 are obtained by combining a number of jars 

 together. 

 _ A combination of 



what is an , 



Electrical Bat- Levdeu lars, so ar- 

 tery? , , 1 



ranged that they may 

 be all charged and discharged 

 together, constitutes an Electri- 



Where does 

 the electricity 

 of a Leyden jar 

 reside i 



FlO. 323. 



