[ROBERTSON] INSULATED METALLIC CONDUCTORS 129 



TABLE XIV. 

 Upper plate zinc. Distance between plates, 2mm. 



there was a gradual decrease in positive values or an increase in nega- 

 tive ones until a minimum point was reached. After this there fol- 

 lowed a slight increase in the positive or a decrease in the negative 

 readings. The appearance of a final maximmii is suggested but not 

 well marked by the form of each of the curves. 



TABLE XV. 

 Upper plate zinc. Distance between plates, 10mm. 



Distance of radium. 



Deflection. (1 volt=522_mm.) 



7.3 cms. 

 14.4 

 21.9 

 17.6 

 27.5 

 32.6 

 37.4 

 42.2 

 48.6 

 56.8 

 68.1 

 79.6 



+ 215.5 

 + 114.5 



51.5 

 81 



26.5 

 11.5 



4.5 



1 



4 



6 



4.5 



0.5 



In order to ascertain exactly whether the potential acquired by the 

 free plate continued to approximate to a final steady value, a set of 

 observations was taken with the two copper plates at 2 mms. apart, 

 when the radium was moved througli a uiore extensive range of distance. 

 These results, which are recorded in Table XVII. and are represented 

 by the curve given in Fig. 15, shew that the charge on the free plate 

 did not continue to approach a steady value, but that as the radium 



Sec. III.. 1908. 9. 



