(519) 



appear distinctly from ^is material of registering curves with its 

 thousands and thousands of shorter and slower vibrations. 



To deduce the real amplitudes and phases of those variations we 

 should have to execute for each separate case an immensely extensive 

 harmonic analysis and, this being quite impossible, corresponding 

 variations had to be chosen and measured discriminately. Therefore 

 all the measurements have been done by me personally. 



The precedence of the earth-current. 



This precedence was rule; it was quite exceptional if it was not 

 met with. When choosing cases for measurement I always avoided 

 those where by a superposed oscillation of greater length and ampli- 

 tude the time of the turning point was made to appear much earlier 

 or later. 



The difference of phase proved to vary from case to case but 

 to be already constant in the mean of a small number. 



For the lines Batavia — Soerabaja and Batavia — Poerwakarta the 

 difference in phase was determined with respect to that of Batavia — 

 Cheribon and not with respect to the magnetic component. 



For the lines Batavia — Buitenzorg and Batavia— Billi ton the deduction 

 was accompanied by great difficulties, as perfectly corresponding cases 

 between earth-current and the magnetic component seldom made their 

 appearance on account of the interference of the east- west component. 



For Batavia — Soekaboemi I have therefore desisted from making 

 a calculation and the difference in phase for the two first lines must 

 be mentioned with reserve. 



Difference in phase. 



Batavia — Poerwakarta 22° Batavia — Buitenzorg 23° (?) 



„ —Anjer 14 „ — Billiton 28 (?) 



,, — Cheribon 22 



,, — Semarang 36 



,, — Soerabaja 32 



The difference in phase found here for Cheribon and Billiton shows 

 a striking resemblance to that found for the daily variation. 



Cheribon. 

 Variations of short duration. Average of 6 terms of the daily variation. 

 22^ 27° 



