330 WRITINGS OF JOSEPH HENRY. [1855- 



the upper end of the conductor, will distribute them- 

 selves uniformly, and assume their natural condition. In 

 this experiment the fact is illustrated that all bodies are 

 naturally charged with electricity, which exhibits itself 

 when the equilibrium is disturbed by the action of some ex- 

 traneous force. If the conductor be restored to its former 

 position the excitement will be renewed, provided the globe 

 A has lost none of its charge, and the two pith balls will di- 

 verge as before. If the charge of electricity in the insulated 

 globe be increased, the repulsive action or induction, as it 

 is called, will also be increased ; another portion of electri- 

 city will be impelled down into the lower end, increasing the 

 repulsive action at that point, and also the amount of attrac- 

 tion at the upper end. The middle of the conductor however 

 will still remain in a condition of neutrality. Again, if while 

 the charge in the globe A remains the same, the space be- 

 tween it and the upper end of the conductor is diminished, a 

 greater excitement will be exhibited by the increased diver- 

 gence of the balls at the two extremities ; for since the force 

 increases with a diminution of distance, an additional quan- 

 tity of the natural electricity of the upper end will be driven 

 down into the lower end, and an equal amount of un-satu- 

 rated matter will be left at the upper end. 



We may still further vary the experiment by lengthening 

 the conductor 0, the charge of the globe and its distance 

 from the upper end remaining the same, and for this pur- 

 pose the conductor may be made to draw out like the tube 

 of a telescope. We shall find that the greater the length, 

 the greater will be the intensity of the effect at each end. 

 To understand this we have only to recollect that the atoms 

 of electricity constantly repel each other, and that in the 

 case of a short conductor, but little comparatively can be 

 driven from the upper end, because the self-repulsion of 

 the electricity of the lower end and the attraction of the 

 un-saturated matter of the upper end both conspire to restore 

 the distribution, but when we give a greater length to the 

 conductor for the free electricity of the lower part to expand 

 into, and thereby lessen the intensity of the repulsion and 



