50 



we obtain 



BIRKELAND. THF. NORWEGIAN AURORA POLARIS EXPEDITION, IQO2 1903. 



I'd 



= -- coj 



lt>d 



Our calculations have been made according to these formulae. 



In the determination of sensibility, the following mode of operation has been used in the main for 



all the four stations: 



TABLE I. 



DETERMINATIONS OF SENSIBILITY FOR KAAFJORD AND BOSSEKOP. 



18. The apparatuses were in position at Kaafjord from the igth August, 1902, up to, and 

 including, the i3th March, 1903. During this time they underwent no changes of any importance. 



From the i5th March, 1903, to the 2nd April following, the apparatuses were set up at Bossekop. 

 During this time, considerable changes were made in them, a new thread having been put in on the 25th 

 March, in the H. I. variometer, and 6 astatising magnets placed beneath the declinometer. 



On the 2gth March, another new thread was put in the H. I. variometer, and the astatising magnets 

 were moved higher up. These alterations were made for the purpose of increasing the sensibility. 



In the table below will be found the quantities that come into the formulae, and the calculated 

 scale-values, for the determinations of sensibility that were made, as also the date of the determinations, 

 and the temperature at the beginning of each measurement. 



As a unit for scale values we use iy=io-s abs. magn. units, referred to i mm. deviation on the 

 magnetogram. See art. 14. 



TABLE II. 



Scale- values for Kaafjord. 

 HO = 0.1248 rj = 1708 mm. /. = 0.00465 u>dHo = 3.67 



