1896.] Electricity thro Dielectrics traversed by Rontgen Rays. 137 



The results are plotted in the curve shown in Fig. 6, where the 

 ordinates are the square roots of the times and the abscissas the 

 distance of the centre of the discs from D. We see that the 

 measurements are represented by a straight line cutting the hori- 

 zontal axis at a point corresponding to a point in the tube about 

 6 cm. behind D. Thus the rate of leak varies inversely as the square 

 of the distance from a point distinctly behind the fiat aluminium 

 plate, which in this experiment is used as the positive electrode. 



Experiment 5. In this experiment the same tube was used 

 as in Experiment 4, but in this case C was the positive electrode, 

 while B was again the negative electrode. The following results 

 were obtained. 



Distance of centre of discs from I). Time required to leak 50 scale divisions. 



4 - 5 6'7o 



9 15 



13*5 29-5 



18 54-5 



22-5 85 



-10 



10 



20 



30 



X 



x 



Fig. 7. 



These results are plotted in the curve shown in Fig. 7, where 

 the ordinates are proportional to the square roots of the time of 

 leak and the abscissas proportional to the distances of the centre of 

 the discs from the point D. The observations are well represented 

 by a straight line cutting the horizontal axis at a point correspond- 

 ing to the point in the tube about So centimetres behind D. This 

 point is very nearly on the flat plate A, so that in this case the rate 

 of leak varies inversely as the square of the distance from the plate. 



Experiment 6. In this experiment C was the negative and 

 B the positive electrode. The following results were obtained. 

 Distance of centre of discs from Z). Time required to leak 50 divisions. 



6 4-5 



12 11 



18 22 



24 33 



30 60 



VOL. IX. PART II. 10 



