CHAPTER VI, 



ACCUMULATORS. 



THE CHARGED PANE. The electric charge which 

 be condensed on the surface of an insulated con- 

 ductor is comparatively small, when such a conductor 

 is remote from inductive influence. 



But when another conductor, having a connection 

 with the earth, is placed in its immediate vicinity, 

 the charge may be greatly increased. 



To prove this, let a sheet of good insulating glass, 



varnished with shellac, be 

 coated on opposite sides with 

 tin-foil, to within about two 

 inches of its, edge, and placed 

 on an insulating support, as 

 shown in Fig. 18. A small 

 charge can be given to the 

 Fig. 18-The Charged Pane, tin-foil, on the upper surface, 

 which will be indicated by sparks passing between it 

 and the body from which the charge is given. But the 

 limit is soon reached, and no more sparks will pass. 



Now let the lower surface be connected with the earth 

 by a strip of tin-foil, and sparks will again pass freely 

 between the charging body and the upper surface, till 

 a charge greatly in excess of the former is given. 



If the tin-foil strip be suspended with its lower end 

 near a conductor, as shown, sparks will pass between 



