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



during the expedition for the calculation of the total intensity, and leave the 

 deflection observations made with the Fox apparatus as a check on the 

 intensity determinations, altogether out of consideration. I have, however, 

 as demonstrated above, found employment for the deflection-observations with 

 both deflectors, in the determination of the index-error of the inclination- 

 needle. 



In the following list, however, I have entered all the deflection obser- 

 vations, partly for possible future utilisation, and partly, too, to show what 

 might have been done in this direction with the instrument, if the necessary 

 determinations of the constants had been forthcoming. 



The temperature given in the list is the mean of all the temperatures 

 taken during both the simultaneous inclination determinations, and the deflection 

 observations, corrected for the error of the thermometer used. In the column 

 containing the readings of the needle's position, when it was deflected "directly" 

 (within one quadrant), and when "past the vertical", the figures given are 

 the mean of the readings of the north and south ends of the needle. The 

 angle of deflection ip is calculated in the following manner. If we call the 

 mean of all readings with the needle deflected directly a, and the mean of 

 all readings with the needle deflected past the vertical b, we have 



