Unifilae Magnetometer. 



XXV 



Table 2. — Determination of the Induction Coefficient for the large Deflecting Bar. 



Gottingen 

 Mean Time. 



Position of 

 Deflector. 



Bifilar 

 Reading. 



Interpolated 



Reading, 



Deflector 



Away. 



Deflection. 



Sum of 

 Deflections. 



Difference 

 of Deflec- 

 tions. 



Value of l!!! 



m, 



d. 



li. m. 





Sc. Div. 



Sc. DiT. 



Sc. Div. 



Sc. Div. 



Sc. Div. 





1847. 



















Nov. 5 



11 



Away 



157-12 















15 

 19 



N. Pole S. 

 N. Pole N. 



265-35 



42-57 



156-05 

 154-97 



109-30 

 112-40 



221-70 



3-10 



0-0140 





23 



Away 



153-90 















24 



Away 



154-22 















27i 

 30 



N. Pole S. 

 N. Pole N. 



263-60 

 43-47 



154-95 

 155-47 



108-65 

 112-00 



220-65 



3-35 



0-0152 





33 



Away 



15610 















36 



Away 



156-75 















40i 

 44 



N. Pole S. 

 N. Pole N. 



266-90 

 46-75 



157-32 

 157-72 



109-58 

 110-97 



220-55 



1-39 



0-0063 





48 



Away 



158-20 













Nor. 6 



1 12 



Away 



150-50 















15 

 18 



N. Pole S. 

 N. Pole N. 



259-12 

 39-57 



150-42 

 150-35 



108-70 

 110-78 



219-48 



2-08 



00095 





21 



Away 



150-27 















1 23 



Away 



150-75 















26 

 29 



N. Pole S. 

 N. Pole N. 



259-46 

 39-67 



150-97 

 151-18 



108-49 

 111-51 



220-00 



3-02 



0-0138 





33 



Away 



151-47 















1 34 



Away 



151-27 















37 

 40 



N. Pole S. 

 N. Pole N. 



261-10 

 40-60 



151-44 

 151-60 



109-66 

 111-00 



220-66 



1-34 



0-0061 





43 



Away 



151-77 















1 45 



Away 



152-17 















48 

 50 



N. Pole S. 

 N. Pole N. 



260-97 

 39-97 



151-98 

 151-85 



108-99 

 111-88 



220-87 



2-89 



0-0131 





54 



Away 



151-60 



• 











h m 



27. The adopted value of -- = 0-0112 



This value is very large, more than twice as great as that obtained for small 

 4-inch bars, and is evidently not to be neglected in the rudest mode of observation 

 for the horizontal intensity. [For the final results, see the addendum to the In- 

 troduction.] 



Bifilar or Horizontal Force Magnetometer. 



28. This instrument was made by Geubb of Dublin, and is similar in its general 

 construction to the declinometer, having two boxes, gilt internally and externally as 

 in the latter instrument. The magnet a a, whose dimensions are 15 inches, ^ inch, 

 and ^ inch, is placed in a stirrup 6, which carries below it a tube c, having a lens d 



MAG. AND met. OBS. 1845 AND 1846. g 



