( 533 ) 



Neither can it be explained by mutual induction of the two lines, 

 passing partij alono- the same telegraphpoles, as that influence would 

 just work inversely. 



There is a circumstance which causes the lines to Anjer and Cheribon 

 to differ greatly from those to Semarang and Soerabaja ; that is 

 the greatest depth below the surface of the earth which the chord 

 reaches between those places and Bataxia. 



It is for Batavia — Anjei- 1 K. M. 



Batavia — Cheribon 3 ,, 

 Batavia — ^Semarang 14 

 Batavia — -Soerabaja 37 



When thus the variations of short duration cause a current chiefly 

 at a greater depth, where the conductivity is very different from than 

 at the surface, a distinct difference might appear. The opposite however 

 is more to be expected. 



To conform that difference it will be necessary to register at Semarang 

 the current between Cheribon-Semarang and Soerabaja-Semarang. 



If we find for that the same as for Batavia-Cheribon and Batavia- 

 Anjer, then indeed we must attribute the greater increase of ampli- 

 tude with short duration foi" the lines Batavia-Semarang and Batavia- 

 Soerabaja to the greater distance. 



ERRATUM. 



In the Proceedings of the Meeting of March 30, 1907 



p. 770 I. 3 from the bottom: for 46.419 read 46.491. 

 p. 779 1. 10 from the top: for VII H, 1 read VII H, 2. 



(February 20, 1908). 



