740 



BIRKELAND. THE NORWEGIAN AURORA POLARIS EXPEDITION. 1902 1903. 



TABLE CXIII. 

 Mean Values for Kaafjord. 



The number of jags used in the calculations are indicated in the columns "N". The numbt 

 Pfjc are expressed in the units y/microvolt; de corresponds to a distance of 400 metres 



In the calculation of the above, a number of the jags that agreed ill were left out of consideratio 



The table also gives the relations P^I^CEW and P h jJcss- 



These quantities only acquire physical importance if we assume that the currents within the area i 

 which they influence the magnetometers, are of so local a character that the observed Je^ and Jo 

 cannot be said to represent the corresponding earth current components, or in other words, if the eartl 

 currents here flow along comparatively very sinuous current-lines. We have here included tin -i 

 they can be employed for the purpose of eliminating the effect of the earth-current in cases in whic 

 we have only successful records of one earth-current component. 



These figures show how great accuracy we attain by this method. 



Among similar synchronous oscillations may be noted those occurring in the interval betwet- 

 2i b and 22'' on February 10. 



Here too, however, there are evidently considerable direct effects of the extra-terrestrial curren 

 systems; but they do not appear to have so rapidly changing a character as the variations that are du 

 to the earth-currents. 



An examination of the remaining curves will show similar synchronous oscillations throughou 

 I will here draw attention to a few of the more characteristic in Series I. 



January 13, time about i6 h 



18, I5 b IS 1 /-/ 1 



20, 

 February 1 3, 



I9 h 



23, 



19'' 21" 



4 h 6 h and 



2I b 22 1 /, 1 ' 



i6 h 2 4 h , 

 especially about I7 h . 



