100 



AKSEL S. STEEN. TERRESTRIAL MAGNETISM. [NORW. POL. EXP. 



this time until October 3rd, the double declination needle was used for 

 quieting the magnet during the vibration observations; and during the vibra- 

 tions themselves, it was standing in a vertical position in the revolver's 

 place. On the 4th and 17th October, 1895, several series of vibration obser- 

 vations were made with magnet V, to ascertain the influence of the decli- 

 nation needle, when placed in the above position. 



The differences of the means are: 



Oct. 4th . . . 

 17th . 



a 6 cb 



-0-00052 +0-00009 

 + 0-00002 - 0-00071 



As will be seen from the results here given of the observations, no 

 decided effect upon the vibration observations, either from the revolver or 

 from the declination magnet in the above-mentioned positions, can be proved. 



