136 



AKSEL S. STEEN. TERRESTRIAL MAGNETISM. [NORW. POL. EXP. 



whence we obtain = 215 8' 



p= 47-8'. 



With these values substituted in formula (5) I have calculated ^/ for the 

 4 cases in which the inclination has been determined with needle B 1 . The 

 calculation gave the following result: 



The value of H for Aug. 8th, 1893, was determined directly by obser- 

 vation. I have determined the horizontal intensity for the remaining 3 days 

 by graphic interpolation. 



THE OBSERVATIONS. 



No advantage was taken during the expedition of the opportunity afforded 

 by the Fox apparatus of also determining the inclination indirectly by the 

 aid of deflectors. 



The following list contains in chronological order all the inclination obser- 

 vations taken, with a statement of the assumed value of the horizontal 

 intensity for the place of observation, found by graphic interpolation from 

 direct determinations of this element made at neighbouring places. As pre- 

 viously mentioned, no note was made of the time at the setting of the incli- 

 nation-needle, and therefore no exact time can be given for the calculated 

 mean value of the inclination. On a few occasions, however, a statement 

 has been added in the observation-journal as to whether the inclination deter- 

 mination was made in the morning or the afternoon, this being indicated in 

 the list with a. m. and p. m. respectively. When no time of day is stated, 

 the given latitude and longitude apply to about midday, while a. m. is con- 

 sidered as about 10 a. m., and p. m. as about 4 p. m. The mean of the 

 meridian readings is entered under the heading "Mer." and the readings of 

 the north and south ends of the needle are indicated with N. and S. 

 respectively. 



