WINTER'S ELECTRICAL MACHINE. 601 



This is one form of what is called the brush discharge. 

 If the machine works well, these discharges from the 

 small ball take place spontaneously. The longer sparks 

 obtained from the small ball when the ring is placed on 

 the conductor, do not exhibit many ramifications ; they 

 resemble more the simple sparks obtained from the 

 large ball, but differ from them in having a zig-zag 



FIG. 317 (I real size). 



form, like flashes of lightning. Sometimes fine ramifi- 

 cations proceed from the angular points of the zig-zag 

 line which forms the main track. 



The discharge from a point is characterised by a faint 

 light or glow. If a wire be placed in the upper 

 opening of the large ball, a luminous point, or a very 

 small glow is seen, and similar appearances present 

 themselves upon bodies with rough or pointed surfaces 



