( 520 ) 



Billiton 

 Variations of short duration. 

 28° 



Nightly variation. 

 26° (?) 



Ratio of amplitude. 



The accurate indication of the moment of maximum or minimum 

 of a vibration is sooner impossible than (he measurement of an 

 amplitude on account of the interference of smaller superposed 

 variations. 



I have therefore been able to select a much greater number 

 — 346 — of cases for measurement ; the results are as follows : 



Batavia — Cheribon . 

 Amplitude Earth-current in Volt p. Kilom. 



Amplitude magnetic component in C.G.S. 



o 



c 



Cq^ O 



Magnetic Component in 10— s C. G. S. 



23 0.37— 0.40 0.50— 0.79 0.90-1.501.7— 1. 812.8-3. 2 



5.5—7 615.1—18.6 



0.3 m 



9.5 



0.8 



1.2 



3.7 



7.6 



15.2 



29 



36.3 



39.6 



120.— 



114.— 



180.— 



240.— 



360.— 



720,— 



22.8 

 19.4 



21.1 



14.8 



10.0 



22.5 



16.9 



19.1 

 17.8 

 14.3 

 15.9 



9.4 



15.6 

 14.0 



12.1 



5.7 



10.8 



4.0 



