No. 7.] TOTAL INTENSITY. 167 
It is true that in Hamburg, after the return, on March 6th, 1897, a series 
of observations were also made by Captain Scorr-Hansen with needle B de- 
flected by means of only the one deflector N, the result yielded being 
w, = 31° 43:5’ 
at a temperature of 66°C. Assuming, for the place of observation in Ham- 
burg on that day, an inclination of 67° 21’ and a horizontal intensity of 
0°1812, we obtain 
R,a@+ 6,8) = 02474. 
I have already pointed out, however, that the constant-determinations made 
in Hamburg after the return, cannot be considered thoroughly reliable, owing 
to the proximity of the electric tramway. Considering also the uncertainty 
prevailing with regard to the changes that the magnetic moment of the 
magnets may have undergone during the voyage, it seems to me hardly fair 
to make this one uncertain constant-determination the basis for a calculation 
of the absolute value of the total intensity, the more so as the determinations 
of the angle of deflection w, with the one deflector, were made in tempera- 
tures varying between + 61/2° and — 361/2°, while no notice can be taken of 
this fact, there being no material forthcoming for the determination of the 
temperature-coefficient. 
It might perhaps be thought that out of the values of the angle of 
deflection w, found when drifting with the ice, a few data might be picked 
out, to which there were corresponding values of the horizontal intensity and 
inclination sufficiently well determined to justify an attempt at an approxi- 
mate calculation of R, and £,, according to formula (1), by the method of 
least squares, when the formula will become 
abn) exe COS ees I 
R, ism oH sini. 
But to this it must be remarked that the observation-material that would 
then be employed, would have to be selected within sufficiently narrow time- 
limits for R, to be supposed to have remained constant, which, in its turn, 
would occasion the risk of there being too little variation in the temperature 
in which the observations were made. 
I have nevertheless made some experiments in this direction, but unfortu- 
nately without success. I am therefore convinced that it is best to make 
direct use of the determinations of horizontal intensity and inclination made 
