( 786 ) 



If now the earth-ciirrent were onl}^ a current from groundplate to 

 groundpiate then during these changes it might change but slightly 

 in intensity, as the total resistance changed so little. 



On the other hand, if the earth-current were for a part not origin- 

 ating from the plate, but was immediately caused by induction or 

 an other influence (e.g. the catching of electrons moving in the 

 atmosphere) then that part when connected with one wire would be 

 half of that when connected with two wires and so a considerable 

 diiference in intensity of the current would be noticeable. 



It might be possible that this influence differed with the duration 

 of the oscillation of the magnetic component and were different in 

 the coastregion from that in higher volcanic regions in South-Java ; in 

 this way the difference in character found above might be explained. 



Before mentioning the results of this experiments I wish to con- 

 sider what the influence is of Ihe loss by isolation. 



The loss by isolation will chiefly take place along branches and 

 poles accidentally touching the wire. The first influence will be 

 irregular and in general for both lines alike. 



With the second each telegraphpole will give an earth connection 

 with great resistance for both wires at the same time, as the wires 

 run across the same yokes. 



Along this earth connection a current will run if the earth-poten- 

 tial at that place differs from that in the wire. 



That current will then feel little influence of the fact whether 

 one or both wires are connected with the galvanometer. 



The result of the experiment for the lines to Cheribon as well as 

 for those to Soerabaja was not ambiguous, as the figures below indicate. 



^ ^. n ir ti f Amplitude earth-current in m.m. reading. 

 Duration of half an oscillation -i-..:_,,^:^z v . „,_^;., ^- 



Both lines 

 1.0 min. 



5.4 „ 



0.6 min. 



8.3 „ 



This simple experiment is in my opinion of fundamental import- 

 ance, as it shows that no electromotoinc force is roused in the line 

 itself, a fact that a priori cannot be called so improbable. 



Nothing remained now but to assume that the difference in character 

 of the current in the North-line and in the South-line is caused by 

 the fact that by the loss by isolation the current is partly taken up 

 out of the ground over which (he line runs and that that current 



