NO. 1.] 



HORIZONTAL INTENSITY. 



99 



According to this, we obtain the difference of the means: 



a 6 



For magnet V . . . + 0'00062 

 VI . . . -0-00056 



From the 24th May to the 26th September, 1895, the vibration box was 

 placed upon the ordinary stand of the apparatus, and the revolver, as usual, 

 between the legs of the stand. The following determinations of H, for the 

 purpose of ascertaining the influence of the revolver in this position, were 

 made: 



According to this, we obtain: 



For magnet V . 

 VI . 



ab 



-0-00008 

 - 0-00031 



When the ice hut was taken into use on the 26th September, 1895, the 

 revolver, as stated in the introduction on page 9, was placed on the ice at 

 a distance of 3 metres to the north of the stand of the instrument. From 



