No. 7.] INCLINATION. 131 
the total intensity is known. Deflection observations with the employment 
of both deflectors together were taken before leaving, in Hamburg, with both 
needles, and after the return, at Wilhelmshaven, with needle B, although in 
both places in a rather uniform temperature. The observations gave the 
following results: 
Needle B Neeele B! 
W 
eC. | Ws | Ba (t+ £0) 2°, | Ys | Bo (t+ 0) 
Hamburg, 1893 047842 | 13:0 |58°31:25') 0°40492 13:0 | 57° 57:0! 0:40024 
Wilhelmshaven, 1897} 0:47630 | 183 |57 150 0:40059 
The two values of R, (1 + C#) for needle B indicate that the aggregate 
magnetic moment of the deflectors has become weaker in the course of the 
4 years, if the decrease in the value of R, (1+ ¢t) is not assumed to be 
due exclusively to the higher temperature noted during the experiment at 
Wilhelmshaven, which would give for € a value of — 0:00258. 
The observations from the expedition, however, afford an opportunity for 
the calculation of an approximate value for ¢. As already mentioned, deflec- 
tion observations with the employment of both deflectors were made 5 times, 
4 times with needle B, and once with needle B'‘. The results of the obser- 
vations on the days on which needle B was used, are placed in the following 
table, which also contains the assumed value of the horizontal intensity, H, 
for the places of observation concerned, found by graphic interpolation by 
the aid of the direct determinations of H, made in adjacent places. 
52° 40°4 
52 462 
GS} 4b) 
March 30 51 44-1 
As shown by the table, the total intensity of the 16th October and the 
2nd December, 1893, may be assumed to have been very nearly the same, 
as both H and J’ — the uncorrected value of the inclination observed directly 
with the apparatus, simultaneously with the deflection observations — exhibit 
