( 782 ) 



of a proper magnetism of the earth; it also fjeems to change during 

 the increase in intensity and situation. For the magnetic disturbance 

 itself following immediately upon the initial impulse we must assume 

 that especially extra terrestrial currents are the cause; at least for 

 the magnetic after-disturbance as well as for the part that shows a 

 regular daily variation I have made this probable '). Moreover the 

 Aurora Borealis points to this. The magnetic vector of after-disturb- 

 ance is the mean vector of disturbance depri\'ed of its greater and 

 smaller oscillations during the disturbance. It increases rapidly after 

 the initial impulse and then slowly decreases. 



As here the horizontal intensity just decreases we must conclude 

 to a likewise W-E. current of negative electricity in these higher 

 atmospheric layers. It remains an open question why the intra-terres- 

 trial current at the outset and the extra-terrestrial current during the 

 further course of the disturbance have both a constant East-West 

 direction. 



Geophysics. — "Registration of the earth current at Batavia" 

 2"'^i part. By Dr. W. v. Bemmelen. 



In my first paper on the registration of electric earth-currents at 

 Batavia, to investigate the connection between the oscillations in 

 earth-current and magnetic force, I had to point to several unan- 

 swered questions. 



First of all the fact that the earth-current between Anjer and 

 Batavia is four times greater than the one between Batavia and 

 Cheribon. I hope soon to be able to measure the current between 

 Batavia and a place E. and S. of Anjer to try to shed light on this 

 abnormality. 



Further more it remained a mystery why that connection with 

 the magnetic force showed such a characteristic difference for the 

 current between Semarang and Batavia with that for the current 

 between Batavia and places closer by. That difference consisted chiefly 

 in the fact, that when the duration of a magnetic oscillation becomes 

 shorter, the amplitude of the earth-current increased much more for 

 the long line than for the short one. 



I pointed out, that perhaps an influence of the distance might 



1) Met. Zeitschrift 1895. p. 321. T. M. VIII p. 153. 



