264 Pv/pin — Action of Vacuum Discharge Streamers. 



Each tinfoil covering has a well insulated copper wire attached 

 to it. 



Fig. I. 



After producing a 2 mm vacuum in the apparatus the bulbs A 

 and B were connected to the secondary poles of a small Ritchie 

 induction coil, whose primary was fed by an alternating current 

 of 125 periods per second. The electromotive force in the 

 secondary coil was varied by varying the current in the pri- 

 mary ; this was done by means of a resistance box in the pri- 

 mary circuit. The electric flow between the bulbs is, of course, 

 due to the condenser effect between the tinfoils and the 

 vacuum. 



At the pressure of 2 mm the discharge was easy, steady and 

 very diffuse along its path through the reservoir. Discon- 

 necting AB and connecting CD to the induction coil the dis- 

 charge was the same in character as before. Connecting both 

 pairs of bulbs in parallel to the induction coil, that is, the bulbs 

 A and C to one pole and B and D to the other pole, the two 

 discharges, going on simultaneously, were the same in character 

 as before, except that they were somewhat convex towards 

 each other. 



The pressure was then increased by turning the stopcock 

 once around and allowing some air to get in. The discharges 

 were less diffuse but more luminous, and less convex toward 

 each other. 



With the increase of pressure the discharges became less and 

 less diffuse and their convexity towards each other diminished 

 until, when a certain gas pressure was reached, it disappeared. 

 At this point the discharges were very little diffuse and when 

 allowed to pass through the reservoir simultaneously they re- 

 mained rectilinear, but somewhat unsteady, oscillating quite 

 appreciably about their rectilinear paths through the reservoir, 



