BIFILAR OR HorizONTAL ForcE MAGNETOMETER. XX1X 
2d, The same deflecting bar was placed to the north and south of the bifilar 
magnet, and to the east and west of the declinometer magnet, the prolongation of 
the axis of the deflector in both cases passing through the centre of the suspended 
bar. The results are given in the 2d portion of Table 3. 
35. 3d,A large deflecting bar (15 inches long) was employed in the same manner 
as the small bar in the Ist instance. 
4th, The large deflecting bar. was employed in the same manner as the small 
bar in the 2d case. 
36. In the 3d case, deflections of the bifilar could only be obtained to the E, and, 
in the 4th case, to the S of the bifilar magnet, owing to the proximity of the bifilar 
to the walls of the Observatory. It was easy, however, from the observations with 
the small bar to make the requisite corrections for the difference of deflection on 
the opposite sides: the correction is small. The results for the 3d and 4th cases are 
contained in the 3d and 4th portions of Table 3. 
TABLE 3.—Observations of Deflection for the Determination of the Coefficient of 
the Bifilar Magnetometer. 
Deflections of Bifilar Magnet. Deflections of Declination Magnet. 
Resulting 
Value of k. 
Distance. |Deflection.| Mean. Distance. |Deflection.| Mean. | Therm. 
Se. Div. Sc. Div. 
136-0 ace 6 | 0-0001345 
45-85 
45-00 ‘6 || 0-0001359 
24-20 
23.70 -6 || 0-0001342 
65-4 
34-9 
81-60 
89.40 -O0 || 0-0001350 
42-05 
ae : 0 | 0-0001364 
14-34 
14.58 ‘0 || 0-0001346 
119-0 
a ees 
Hah BAZnARA 
60-8 
-_—— 
21-0 
peor 0-0001351 
> : 
eo} 
= 
I 
ES 
Se 
eel 
to 
S 
co 
0-0001370 
0-0001350 
nienZ 
0-0001357 
37. 5th, In May and August 1847, a theodolite magnetometer by Mr Jonzs of 
London was converted into a unifilar horizontal force magnetometer, the suspended 
MAG. AND MET. ops. 1845 anp 1846. h 
