12 STATIC ELECTRICITY 



gas or water pipes. At the level of the hori/ontal radius I he plate 

 passes between two metal combs c the collectors. These combs 

 have sharp teeth pointing to the plate and separated from it by a 

 small interval to allow of free running. Two silk flaps .9 attached 

 by their lower left-hand edges to the rubbers extend nearly to 

 the combs and are held so as loosely to cover the section of the 

 plate between rubber and collector. " The combs are connected to 



FIG. 10. 



a metal body PC, called the prime conductor, which is supported 

 by an insulating pillar and is terminated by a small knob /.. rr 

 represents a wooden ring with a metal wire as core. This ring \ V;l s 

 introduced by Winter and is named after him Winter's ring. 



If the plate is turned the glass is electrified positively and the 

 rubbers negatively. The + on the glass surface is carried round, 

 the silk flaps appearing to protect it in some way till it comes 

 under the combs. There it acts inductively, and draws into. the 

 points while the complementary + goes into the rest of the prime 

 conductor. Now electrification is discharged through the air from 

 points with great ease, so that the passes from the points on to 

 the glass plate, which is thus neutralised, leaving the prime con- 

 ductor charged with +. Sparks may then be drawn from the 

 knob A*, their length and brilliancy increasing rapidly with the >i/e 



