Waves along a Line of Negligible Leakage, 297 



that the experimental value of the attenuation would be 

 found considerably higher than the theoretical one due to 

 resistance of the wires simply. 



It immediately occurred to me that the extra attenuation 

 observed over that theoretically expected might be due to the 

 leakage conductance of the wood separators which were used 

 at intervals along the line to keep the two parallel wires pro- 

 perly spaced. But at the time in question the line was 

 already dismantled. It was therefore impossible to say pre- 

 cisely what the resistances of the separators were, nor how 

 many of them were in use, when the attenuation was deter- 

 mined. 



Assuming that the separators occurred on the average at a 

 metre apart along the line, a resistance for each of the order 

 half a megohm would suffice to reconcile the experiments 

 with the theory referred to. On testing a few of the sepa- 

 rators their resistance dry was found to be of the order ten 

 megohms, but the resistance of one about a minute after 

 momentary immersion in water had fallen to 0*2 of a megohm. 

 It therefore seemed desirable to rig up a new line with sepa- 

 rators of such high resistance as to render the leakage con- 

 ductance of the line quite negligible. This was accordingly 

 done and the attenuation again measured. The result, how^- 

 ever, only confirmed the value previously obtained. This 

 value is indeed higher than that predicted by the theory 

 approximately applicable to the case. Still, upon careful 

 examination of the differences between the experimental case 

 and that contemplated in the theory, I think it will be con- 

 ceded (1) that this difference of values is in the right direc- 

 tion, and (2) that it is not large enough to shake confidence 

 in the substantial accuracy of the experiments. This is dis- 

 cussed in detail at the end of the paper. 



Fig. 1. 



T 



-&? 



Z' T< 



Experimental Arrangement. — The arrangement of the ap- 

 paratus adopted in the determination is diagrammatically 

 represented in fig. 1 . In this figure, A denotes the battery 

 of two storage -cells, B and C are the primary and secondary 



