Nipher — The Nature of Electrical Discharge. 



81 



No creeping of the wire occurs except at the instant 

 when the sparks occur. The gaps may be made so long 

 that no sparks can pass. Electrostatic attractions are 

 then greatest and point effects at the ends of the wire 

 can be observed in a dark room. The wire does not then 

 move. The arrangement of the apparatus is shown in 

 the annexed figure. 



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Fig. 1. Apparatus showing the gradual creeping of a wire in a 

 direction opposite to that of the corpuscular discharge. 



It is found that the wire creeps to the right as shown 

 in the figure, when it is unsymmetrically placed with the 

 end on the right hand even with the end of the glass 

 tube. It then projected from the left end of the tul3e a 

 distance of 2.4 cm. It would require over 7,000 discharges 

 with the apparatus used to displace the wire 2.4 cm. into 

 the position formerly described. The amount of displace- 

 ment per spark does not seem to depend upon the posi- 

 tion of the wire between such limits, although no precise 

 measurements have been made. 



Tlie question arises whether the observed creeping of 

 the wire is due to a differential action between the ends 

 of the wire and the air which surrounds these ends, at 

 the instant when the spark occurs. 



This was examined by means of a differential electric 

 whirl constructed as follows: 



Two small hollow spheres of metal were mounted upon 

 the ends of a thin metal tube about 50 cm. in length. 



Curved and pointed wires having a length of 18 cm. 



