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: 



The two values of E 2 (1 -(- tt) 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 z (1 -f- C<) 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 1 . 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. 



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 /' - - the uncorrected value of the inclination observed directly 

 with the apparatus, simultaneously with the deflection observations -- exhibit 



