ELECTRICITY. 



It must, therefore, be constantly borne in mind, that, 

 to discharge any electrified body, we must form a com- 

 munication between it, and the other bodies electrified in 

 an opposite manner, and we have been thus particular in 

 explaining the cause of this, because ignorance or forget- 

 fulness of this principle, is the source of a vast number 

 of mistakes among young persons, who are attempting 

 electrical experiments. 



The surrounding bodies which will be oppositely elec- 

 trified, as above described, are generally the nearest. 

 Suppose a cloud to be positively electrified, and to be 

 suspended over a particular region of the earth. This 

 region we will imagine to be electrified in, an opposite 

 manner. Now let the cloud move over a fresh portion ; 

 by its repulsive power it will force off from this new re- 

 gion, the share of electricity which naturally belongs to 

 it, into the vacancy which existed in the region over 

 which it originally stood, and thus, whenever it moves, 

 the opposite electricity of the surrounding bodies will 

 accompany it, and the fluid will always be seeking to 

 dart off from the place of its excess in the cloud to the 

 place off its deficiency in the ground below. And it is 

 only by a communication from one of these to the other, 

 that the cloud can be discharged. 



In the case of the prime conductor, the same is true. 

 When it is charged, the experimenter touches it with his 

 finger and it is discharged. His own body and other 

 surrounding bodies connected with his, were in the op- 

 posite electrical state, to an extent just sufficient to bal- 

 ance the electricity of the conductor. By touching it 

 then, he forms a communication between the two, the 

 fluid passes, and the equilibrium is restored. 



In the Leyden jar, this principle of the necessity of 

 forming a communication between bodies electrified in 

 an opposite manner, in order to discharge them, is still 

 more strikingly exemplified. For here it will be recol- 

 lected, the outside of the jar is electrified in one way 

 and the inside in another, as was stated in the descrip- 

 tion of the theory of the jar. The very object of its con- 

 struction is to bring as nearly as possible together, the 

 surfaces thus brought into opposite states. In order, 



