xlii 
General Results of the Makeestoun Observations. 
The hours for the months December to February are very uncertain, owing to the irregularity and smallness 
of the variations. Throughout the year the effect of disturbance is zero about \ a.m. and about &i 
Diurnal Variation of frequency of the Positive Departures from the Hourly Mean Positions. — The number 
of observations having been obtained for each month in 1844 and 1845, which shewed a greater value of the 
horizontal component than the monthly means at the corresponding hours, the means of quarterly groups were 
formed, and the numbers per cent, are given in the following Table. 
Table 35. — Numbers of Obsei'vations of the Horizontal Component of Magnetic Force in 100, which 
were greater than the Monthly Mean at the corresponding Hour in the Years 1844 and 1845, 
for each Quarter, and for the Year. 
Mali. 
Nov. 
Feb. 
May. 
Aug. 
Mak. 
Nov. 
Feb. 
May. 
Aug. i 
Mean 
Dec. 
March. 
June. 
Sept. 
Year. 
Mean 
Dec. 
March. 
June. 
Sept. 
Year. 
Time. 
Jan. 
April. 
July. 
Oct. 
Time. 
Jan. 
April. 
July. 
Oct. 
li, ni. 
12 12 
63-3 
59-7 
49-4 
59-5 
58-0 
h. m. 
0 12 
52-5 
51-9 
50-6 
51-9 
51-7 
13 12 
62-0 
64-3 
50-6 
55-7 
58-1 
1 12 
52-5 
48-7 
51-3 
47-5 . 
50-0 
14 12 
65-8 
68-8 
50-0 
58-9 
60-9 
2 12 
55-7 
46-1 
46-2 
53-2 , 
50-3 
15 12 
60-8 
60-4 
50-6 
56-3 
57-0 
3 12 
55-7 
390 
47-5 
45-0 , 
46-8 
16 12 
55-7 
58-5 
56-3 
53-2 
55-9 
4 12 
63-3 
45-5 
46-2 
41-8 ' 
49-2 
17 12 
57-0 
57-1 
54-4 
62-7 
57-8 
5 12 
57-6 
49-4 
51-9 
44-9 
50-9 
18 12 
50-6 
53-2 
51-3 
57-0 
530 
6 12 
48-1 
51-9 
44-9 
51-3 
49-0 
19 12 
51-9 
571 
48-7 
56-3 
53-5 
7 12 
59-5 
50-6 
46-8 
53-2 
52-5 
20 12 
51-9 
59-1 
48-7 
57-6 
54-3 
8 12 
55-7 
56-5 
42-4 
55-7 
52-6 
21 12 
55-7 
61-7 
51-3 
55-1 
55-9 
9 12 
58-2 
57-8 
45-6 
57-0 
54-6 
22 12 
56-3 
59-7 
51-3 
61-4 
57-2 
10 12 
65-2 
60-4 
48-7 
58-9 
58-3 
23 12 
54-4 
57-1 
48-1 
57-6 
54-3 
11 12 
59-5 
59-1 
52-5 
601 
57-8 
74. The following are the approximate epochs of maximum and minimum frequency of positive departures, 
as deduced from Table 35. 
Nov. Dec. Jan. Feb. March, April. May, June, July. -^ug- Sept. Oct. Year. 
Maximum, 1^^ a.m. 2'' a.m. 4*^ a.m. ll'^ p.m. to 11^ a.m. 2'* a.m. 
Minimum, 7'^ a.m. and 1'^ p.m. 3** p.m. 8*^ p.m. ■P' p.m. 3^' p.m. 
The numbers in Table 35 present considerable irregularities ; two years' observations appear too few to 
remove these. In the winter and spring quarters, there is a secondary maximum of frequency of positive de- 
partures about 9'^ A.M., a secondary miuinuim occurring in the winter quarter about noon, and in the spring 
quarter about 6'^ a.m. The variation of the numbers is greatest in the spring and autumn quarters, it is least 
in summer. Every hour in winter, with one exception, had more observations greater than the moutMy mean 
for the hour, than there were less ; in spring and autumn, all tlie hours had a greater number of positive than 
of negative departures, excepting those from 1*^ to 5'! p.ji. The minimum of positive frequency occurs 
about 7'' A.M. in winter, but in summer it occurs nearer 7'^ p.m. The hours of maximum frequency of tlie 
positive departures, are obviously those of minimum freqitcncy of negative departures. 
75. It may be remarked here, that these departures arc from the mean position of all the ordinary observa- 
tions, which mean position is more or less affected by disturbance ; could the luidisturbed mean position be well 
ascertained it would probably be found, as it has been in the case of the declination, No. 41, that the hour of 
maximum freqtiency of the positive departures from the disturbed mean position, is nearly tliat of tlieir mini- 
mum frequency from the undisturbed mean position ; this, it will be seen, was the case when the selected days 
were assumed as the normal means, as in 1844. (See volume for 1844. page 372). 
76. Diurnal Variation of the Mean Differences of the Values of the Horizontal Component from the Monthly 
Mean V alues for the corresponding Hours. — Table 36 has been formed in the manner already indicateil, No. 
43, for Table 18. The numbers in Table 36 exhibit such considerable irregularities, that it is difficult in some 
cases to determine real secondary points of maximum and minimum from those which maybe merely accidental, 
and which miglit liave disappeared in tlie combination of a larger scries of observations ; the following how- 
ever, are the approximate epochs as nearly as they can be determined. 
