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 w 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 6, we have 
a 
3 b 
w = 90° — 9 . 
