300 



Scientific Proceedings, Royal Dublin Society. 



Table 5. 



Sample B. 



Thickness, 0"65 cm. 



The results for samples A and B, the low tension porcelain insulators 

 supplied by the same company, clearly show that the material is practically 

 the same as far as insulation resistance is concerned. 



In Fig. 6 the results for A and B fall upon the same straight line ; 

 B being represented by the full line and A by the small circles associated 

 with it. The straight line relation of Basch and Hinrichsen is thus practically 

 true for these two samples. 



Figs. 4 and 5 also show the nearness of the curves relating insulation 

 resistance and temperature in the cases of A and B. 



It may also be deduced from Fig. 6 that the value of a, namely 118 x 10 6 

 megohms per cm. cube for temp. 25° C, is probably somewhat underestimated, 

 as the point representing this value lies a little above the line drawn for B- 



