MAGNETIC OBSERVATIONS 



ii 



Observations in the United States before and after the instrument was used at Teplitz Bay 

 show very little change in the magnetic moment of the intensity magnet. The observations at 

 Teplitz Bay, however, indicate a gradual increase from beginning to end of the series. The 

 cause of this change is not clear, as magnets are usually found to lose their strength with age. 

 It is clearly not due to an erroneous temperature coefficient, as the mean temperatures of three 

 of the groups are nearly the same. An error of .00087 i Q 1 m corresponds to an error of one 

 part in 500 in H, which at Teplitz Bay would be only 13 7-. 



DIP CIRCLE CONSTANTS 



So little time was available between the return of the instrument by the first Ziegler 

 Expedition and its reissue to the second, that no extended comparisons could be attempted. 

 Observations were made at the Coast Survey Office in Washington as follows on May i r, 1903 : 



Needle No. 3 

 Needle No. 4 



69 5 5 '.8 N 

 69 56'-3 



The normal dip for the station was 69 56'. o N. Observations were also made in two planes 

 making an angle of 60 with the magnetic meridian, so that the needles rested upon nearly 

 the same parts of the pivots as at Teplitz Bay. These observations of May 23, 1903, resulted 

 as follows : 



Needle No. 3 69 50'. 2 N 



Needle No. 4 69 53'. 6 



Upon the return of the dip circle in the autumn of 1905 observations were made at the 

 Cheltenham Magnetic Observatory as follows : 

 (a) In the magnetic meridian : 



