Pupin — Action of Vacuum Discharge Streamers. 267 



sure. These photographs belong to my collection of photo- 

 graphs of corona-like vacuum discharges, an account of which 

 I expect to give at some future time. 



The question arose then, naturally, what is the cause of this 

 repulsion % Electrostatic action suggested itself first, of course. 

 But various observations which I made during my investiga- 

 tions on vacuum discharges made me favor another view, the 

 view namely that the repulsive force between vacuum dis- 

 charge streamers is due to a strain in the vacuum produced by 

 the peculiar distribution of the gas pressure resulting from the 

 peculiar distribution of temperature. If this view is correct 

 then there should be no action between two vacuum streamers 

 passing in two separated vacua. This suggested the following 

 experiment : 



Investigate the action of two discharge streamers upon each 

 other when two separate discharge reservoirs are employed. 

 Fig. 6, represents the apparatus (with its dimensions in cm. 



Fig.6. 



marked), containing one of the reservoirs, two of which were 

 placed side by side in the experiment. The bore of the capil- 

 lary tubes e, c, d, f was about l - 5 mm . The bulbs AB were 

 coated with tinfoil and the whole arrangement was the same as 

 in the experiments with the apparatus given in fig. 1. The 

 two apparatus communicated with each other by means of a 

 stopcock, so that the pressure was the same in each. The dis- 

 charge in one apparatus did not influence the discharge in the 

 other, no matter what the pressure was, up to the limit at 

 which I could still obtain a discharge, which was about 60 mm . 

 From this I conclude that the repulsion which 1 observed in 

 the previous experiments was probably not clue to electrostatic 



