PART in. EARTH CURRKNTS AND EAR in MA;NKTISM. CHAP. i. 



7 8i 



TABLE CXXVI (continued). 



Values of ty, due to rotation. 



->. = 75 



Ju = 1 80 



Jfl = 270 



In fig. 283 the current-system answering to a simple inductive system is given, in fig. 284 the 

 impound effect of two simultaneously occurring systems, situated on the same meridian, each at the 

 ime distance from its pole, i. e. j = 20, % = 160. 



The current-fields given on the charts will have, during the rotation, or displacements, a fixed 

 osition in relation to the outer current-system. We may remark in particular that here in mean 

 .titudes, the direction principally found for the induced currents is N S. These systems will pro- 

 ably have something to say in the explanation of the diurnal variation of the earth-currents, to 

 hich we shall return later. 



The values of t// placed upon the charts answer to a current-system of which the horizontal 

 ortion has a direction W E, and moves from E to W. 



Birkeland. The Norwegian Aurora Polaris Expedition, 19021903. 99 



