( 527 ) 



The resistance of the former circuit was generally about '10 times 

 smaller than that of the other. 



At Batavia the two circuits were on the same groundplate, at Cheribon 

 the two groundplates hung in the same well. Moreover the wires 

 ran for the greater part on the same telegraphpoles. 



An all but perfect correspondence was now found, so that all 

 influence of the material (especially with respect to magnetic induc- 

 tion) may be regarded as non-existing. 



Injluence of the current of polarisation. 



I was more anxious about a disturbing influence of the polarisa- 

 tion of the ground-plates to which repeatedly from various sides 

 attention has been drawn. For, the polarisation might be able to 

 explain the difference in phase and the change in the ratio of 

 amplitudes. 



Let us suppose that the earth-current together with the magnetic 

 component increases, then the resisting current of polarisation also 

 grows. If now the increase of the earth-current and of the magnetic 

 component passes into a decrease, the current of polarisation will 

 for the moment keep increasing and consequently the observed 

 current (i.e. earth-current minus current of polarisation) will sooner 

 reach its turning-point than the magnetic component. If the vibration 

 increases in duration the current of polarisation will also increase 

 first faster, then slower, and therefore the observed current will 

 always lose with respect to the magnetic component and the ratio 

 of amplitudes — as was really found — will decrease first faster, 

 then slower. 



Though the influence to be expected of the polarisation had there- 

 fore to agree with what was found, yet we could not believe 

 that it could be the cause of those phenomena, as for the 

 observations made at the office of the Telephone Company the con- 

 nection with the earth was made every hour only for a few moments 

 and so there could be no question about a continual increase of 

 the polarisation. 



To find out the influence of the polarisation I have taken the 

 following experiment. To begin with I measured the current of 

 polarisation directly. To that end I buried a second ground plate 

 a few meters from the old one and made a new connection: old 

 earthplate — galvanometer — new ground-plate. 



The old ground-plate I polarised strongly by switching on a 

 cell into the line (Cheribon — Batavia). After breaking the con- 



