A CCUMULA TORS. 89 



SILENT DISCHARGE. But when the discharge takes 

 place through a good conductor of sufficient size, it is 

 termed silent; since light and sound are absent; the 

 resistance encountered being only sufficient to produce 

 a slight amount of heat. 



The discharge through a point is also termed silent ; 

 since a point, as already shown, offers no resistance ; 

 and hence there is little or no sound, even when the 

 discharge passes through intervening air. A battery 

 discharge, sufficient to destroy life, may be received 

 with impunity through the point of a cambric needle, 

 held in the hand, without producing any unpleasant 

 sensation. 



LICHTENBERG'S FIGURES. If, on a plate of ebonite, 

 or of glass varnished with shellac, figures be traced with 

 the knob of a positively charged Leyden jar, and sulphur 

 dusted over the surface, inclining the plate and tapping it 

 to remove the surplus ; the sulphur will adhere to the 

 lines traced, spreading out in a beautiful fringe, as shown 

 in Fig. 26, which is from a photograph of a figure made 

 in this way. 



A similar result can be obtained by tracing lines 

 with the outside of this jar, or with the knob of a 

 negatively charged jar, and dusting the surface with 

 red lead. 



Or a mixture of sulphur and red lead may be used, and 

 separate figures traced ; the jar being charged positively 

 for one figure, and negatively for the other. The sulphur, 

 it is claimed, adheres to the positive, and the lead to the 

 negative lines. Any non-conducting surface may be 

 used, also various other powdered substances. 



It should be noticed that the loss of charge, whether 

 positive or negative, from the inner coating, while tracing 



