XXX 
General Results of the Makerstoun Observations. 
Horizontal Component of Magnetic Force. 
48. The observations in connection with this element are of two classes : — 1st, Observations for the abso- 
lute value of the component, made by the method of Gauss ; and, 2c?, Observations of the bifilar magnetometer for 
the variations of the component. The observations for the absolute value were made with two different iastm- 
ments ; first, from 1843 till April 1846, with a 15-inch deflecting bar, by Gauss's original method ; and 
second, after April 1846, with 3-6o-inch deflecting cylinders, by Dr Lamont's modification of Gauss's method: 
the whole processes have been already described in the Introductions to the diflerent volumes of Makerstoun 
Observations. The following Table contains the computed values of (X) the horizontal component corre- 
sponding to the reading of the bifilar magnetometer at the time of vibration, and also the values reduced to the 
mean reading of the bifilar for the year of the observations ; to these are affixed approximate weights, dependiag 
upon the number and agreement of the partial results, and employed in obtaining the mean in the last column : 
Table 21. — Results of Observations for the Absolute Value of the Horizontal Component of Magnetic 
Force, made in the Years 1843 — 1849, with the Eesulting Mean Value, corresponding to the 
Mean Reading of the Bifilar Magnetometer for the respective Years in which the Observations 
were made. 
During Observation. 
X Reduced to 
the Mean 
Bifilar for the 
Year. 
Mean Value of 
X for the Mean 
Bifilar Reading 
of each Year. 
Date. 
Values of X. 
Mean Bifilar 
Weight. 
( 
1843. 
August 1 1 
August 21 
Nov ember 8 
November 14 
December 18 
1844. 
February 1 7 
March 23 
May 29 
August 5 
December 26 
December 30 
1845. 
December 29 
December 30 
1846. 
February 1 6 
April 1 4 
3-3556 
3-3849 
3-3773 
3-3792 
3-3840 
511.5 
511-1 
510-9 
507-6 
515-2 
3-3512 
3-3807 
3-3732 
3-3757 
3-3813 
1 
3 
3 
2 
2 
3-3752 
15-inch Deflecting B 
3-3836 
3-3759 
3-3853 
3 3913 
3-3844 
3-3760 
3-3921 
3-3812 
3-3929 
3-3904 
524-6 
520-8 
535-7 
540-7 
539-5 
534-9 
548-9 
539-1 
553-2 
562-3 
3-3851 
3-3793 
3-3816 
3-3852 
3-3789 
3-3727 
3-3870 
3-3807 
3-3910 
3-3843 
1 
2 
2 
2 
2 
2 
2 
3 
3 
2 
3-3801 
3-3832 
3-3SS3 
3-65-inch Deflect- 
ing Bar. 
1847. 
May 31 
June 15 
September 1 1 
1849. 
June 1 9 
October 1 1 
3-3918 
3-3927 
3-3791 
3-3963 
3-3913 
574-8 
576-7 
545-0 
598-0 
568-0 
3-3842 
3-3843 
3-3852 
3-3873 
3-3961 
3 
3 
3 
3 
3 
3-3846 
3-3917 
49. The results for the large bar indicate an increase of absolute horizontal force from year to year Wtweenj 
1843 and 184G ; those for the small bar exhibit a similar fact, altliough the considerable difl'oroncc betn^oen thel 
results for June 19 and October 11, 1849, throw some doubt on the amount of increase. 
From these observations the increase of the horizontal component in absolute measure (see No. 53.) 
From 1843 to 1845, = 0-0080 = 0-00400 yearly. 
From 1844 to 1846, = 0-0082 = 0-00410 Mean of all. = 0-00388 yearly. 
From 1847 to 1849, = 0-0071 = 0-00355 
I 
