XXXVl 
General Results of the Makeestoun Observatioxs. 
The conclusion deduced from the numbers for 1844, and which has been deduced from those for the magnetic 
declination, No. 16, is also to be obtained from the numbers for 1845, though with less distinctness, owing to 
the large effect of disturbance in January and December of the latter year (See No, 16.) In the mean of both 
years March and April shew the greatest mean difterence in the first six months (and for the whole year), and 
August and December the greatest in the second six months : the least values are those for June and July, and 
for January and February. 
64. From this result, June and July appear the months best fitted for observations of the horizontal com- 
ponent of magnetic force ; the probable error of an observation from the mean for the corresponding hour in 
these months being under O'OOOS of the whole horizontal force. 
65. Annual Variation of the Number of Observations which were greater than the Monthly Means for the 
corresponding Hour. — The numbers of observations in 100 which were greater than the monthly means for 
each month of the years 1844 and 1845 are as follow : — 
Jan. 
Feb. 
March. 
April. 
May. 
June. 
July. 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
Mean. 
1844, 
53-1 
54-8 
60-1 
52-1 
52-5 
45-7 
47-1 
49-8 
54-3 
61-2 
55-6 
59-6 
53-8 
1845, 
59-6 
56-8 
56-9 
55-0 
53-2 
48-3 
50-8 
53-0 
53-0 
56-2 
56-3 
57-3 
54-7 
Mean, 
56-3 
55-8 
58-5 
53-5 
52-8 
47-0 
48-9 
51-4 
53-6 
58-7 
55-9 
58-4 
54-2 
From these numbers it appears, that in the year there are, in 100 observations, upwards of 8 more in 
excess than in defect of the monthly means for the corresponding hour ; that June and July were the only 
months which shewed more observations less than there were greater than the monthly means ; that in March. 
October, and December, the number of observations in excess of the monthly means was greatest, being 17 in 
100 more than those in defect. Upon the whole it appears probable in this, as in the other cases, that the 
numbers for 1844 exhibit the mean annual law with greatest truth, and that the number of positive observa- 
tions is least at the summer solstice, and is greatest near the equinoxes. 
Monthly Variations for the Horizontal Component. 
Table 28. — Mean Variations of the Horizontal Component of Magnetic Force, free fi'om Regular 
Secular Change, with reference to the Moon's Age and Declination. 
Moon's 
Age. 
1843. 
1844. 
1845. 
1846. 
Mean. 
After 
Moon 
farthest 
North. 
1843. 
i 
1844. 
1845. 
1846. 
Mean. 
d. d. 
0-00 
0-00 
0-00 
0-00 
0-00 
d. d. 
0-00 
0-00 
0-00 
0-00 
14—16 
-0113 
-0229 
+ 0015 
-0005 
-0083 
27— 1 
+ 0059 
+ 0121 
+ 0078 
-0019 
+ 0060 
17—20 
-0021 
- 0250 
-0065 
-0139 
-0119 
2— 5 
-0064 
+ 0008 
-0048 
+ 0076 
-0007 
21—24 
+ 0090 
-0001 
-0042 
-0072 
-0006 
6— 8 
-0070 
-0127 
-0154 
+ 0037 
-007S 
25—28 
+ 0142 
+ 0203 
+ 0085 
+ 0088 
+ 0129 
9—12 
+ 0026 
+ 0012 
-0034 
-0060 
-0014 
29— 1 
+ 0043 
+ 0224 
+ 0040 
+ 0120 
+ 0107 
13—15 
+ 0041 
+ 0157 
+ 0093 
-0048 
+ 0061 
2— 5 
+ 01 12 
+ 0221 
-0047 
+ 0049 
+ 0084 
16—19 
- 0029 
+ 0106 
-0064 
+ 0065 
+ 0019 
6— 9 
-0074 
+ 0095 
-0068 
+ 0039 
-0002 
20—22 
+ 0034 
-0092 
+ 0035 
+ 0013 
- 0002 
10—13 
-0179 
-0259 
+ 0084 
-0079 
-0108 
23—26 
0000 
-0186 
+ 0094 
-0062 
-0038- 
66. Variations of the Daily Mean Horizontal Component with reference to t/ie Jloon'^- Age and Deeli/Kitiiin. 
— Table 28 has been formed from the detailed Tables in former volumes, and from the Tables pp. 11 and 32 of 
this volume. From the means in Table 28 we conclude : — 
1st, That the mean horizontal component is greatest about the time of conjunction, and least about op]Ki- 
sition, or immediately before and after that epoch. This result is sliewn with great distinctness in several single 
lunations in 1844, (sec volume for 1844, p. 358 and Plato XIV). 
2d, That the mean horizontal comjjoncnt is a maximum, both when the moon is farthest north, and when 
it is farthest south, and that it is a minimum when the moon is near tlie equator. This result is shown with 
considerable distinctness in the variations for both 1844 and 1845 and with some irregularity in 1843 and 
1846 ; the less value of conclusions from the observations of the two latter years should alway.* be borne in mind. 
