30 



AKSEL S. STEEN. 



[2nd arc. EXP. FRAM 



As will be seen from the table, the magnets have evidently under- 

 gone some change during the 2nd Fram Expedition. For both magnets, 

 /.t has become less, i. e. their magnetic moment is weakened. 



(.1, as we know, can be determined independently of the absolute value 

 of the horizontal intensity, as we obtain, from equations (1) and (2). 



log ^1 = ^ log sin cpo — log To- 

 ll should thus be possible to verify the value of /j. by means of 

 the observations made during the Expedition itself, under the assumption 

 that H might be supposed to have remained approximately constant 

 during the time required to take a complete set of deflections and vi- 

 brations. 



I have also attempted a verification such as this, but unfortunately 

 with not altogether satisfactory results. 



Even at Station I it proved to be impossible to use magnet VI at 

 the short distance, e, and at Station III magnet V could not be used at 

 that distance either. At Station IV, neither of the deflectors could be 

 used, even at the longer distance, E, and therefore, as mentioned in the 

 introduction, a new, longer rod for the deflection observations was made. 

 There was thus only an opportunity of making a calculation of /.i 

 for Ve, Ve and VIe from the observations at the first three stations. 

 After having selected the observations that seemed most suitable for 

 such a calculation, I have found the following values for ;<: 



Station I. 1899. 



Mean 



0.11382 0.07392 0.08921 



Station II. 1900. June 29 0.11892 0.07926 



July 2 7944' 0.09486 



Mean 



0.11892 0.07935 0.09486 



Station III. 1901. July 10 



- 11 



- 12 



Mean 



0.07579 0.()8834 

 499 828 

 621 899 



0.07566 0.08854 



