XXVlll 
General Results of the Makerstoun Observations. 
1st, The average westerly excursion from the mean position for the hour is greatest in the winter and 
spring quai'ters about 1*^ or 2^ p.m. ; and about 8^ a.m. in the summer and autumn quarters, although the 
values vary little in the summer quarter from 4^ a.m. to l** p.m., and in the autumn quarter a secondary 
maximum occurs at 3** p.m. 
2d, The average easterly excursion is least about 8^ a.m. in each quarter, with the exception of summer, 
in which it is equally small at 5*^ p.m. : the average easterly excursion from the hourly mean of all the obser- 
vations (Table 18) has the minimum decidedly marked at 6^ p.m. 
3d, The minimum westerly excursion occurs about 9^ p.m. in all the quarters. 
4zth, The maximum easterly excursion occurs earliest in vnnter, about 6*^ p.m., and latest in summer, 
namely after midnight ; while in the equinoctial quarters it occurs betwixt these epochs, the values varying 
little from 6^' p.m. till midnight. 
5th, The mean excursion, withovit reference to direction, has its greatest value earliest in winter, about 
6** p.m. ; about 9^ and lO"^ p.m. in the equinoctial quarters ; and in summer there are two maxima of nearlv 
equal value, immediately after midnight and at ll'^ a.m., mth a secondary minimum about a.m. 
6th, The mean excursion has its least value about 5^ to G** a m. in winter and spring ; a secondary mini- 
mum, as noted above, occurs about the same hour in summer, and 4^ in autumn ; but the actual minimum 
occurs, distinctly marked, between 6'^ and 10'^ p.m. in summer, and, less distinctly marked, about p.m. in 
autumn. 
45. It appears from these results, that the diurnal law of mean disturbance is not constant throughout the 
year, as has been supposed ; in fact the law for summer is nearly the reverse of that for winter, while that for 
autumn is neai'ly intermediate between the two, a secondary maximum occurring in the latter at 9^ a.m. la 
the winter and spring quarters there is a tendency to a secondary minimum about 4^ or 5^ p.m. 
Table 19. — Mean Disturbances of Magnetic Declination, or Differences from the Monthly Means, at 
the corresponding Hours in 1844 and 1845, as deduced from the selected series in each Year. 
Mean 
Westerly Disturbance. 
Mean Easterly D 
isturbanoe. 
Mean 
Disturbances. 
JviaK. 
Mean 
■Nov. 
Feb. 
May. 
Aug. 
N 
ov. 
Feb. 
May. 
Aug. 
Sept. 
Nov. 
Feb. 
May. 
Aug. 
Time. 
Dec. 
Mar. 
June. 
Sept. 
Year. 
Dec. 
Mar. 
June. 
Year. 
Dec. 
Mar. 
June. 
Sept. 
Year. 
.Jan. 
April. 
July. 
Oct. 
Jan. 
April. 
July. 
Oct. 
.Jan. 
April. 
July. 
Oct. 
i 
h. 
12 
m. 
10 
0-96 
1 
47 
1-02 
L56 
1^25 
I 
26 
2-88 
2^02 
2-50 
2^40 
L74 
2^22 
L66 
2^21 
' 1 
•95 
13 
10 
1-00 
1 
47 
117 
L68 
L32 
45 
2^94 
L98 
2^29 
2^33 
L82 
2^22 
L63 
2-10 
1 
•94 
14 
10 
1-23 
1 
56 
L09 
L85 
1-44 
1 
84 
2^69 
L81 
234 
215 
L56 
2-12 
L52 
2^14 
1 
•83 
15 
10 
1-25 
1 
43 
L50 
2^09 
L54 
1 
92 
2-12 
1.44 
L96 
L85 
L56 
L77 
L47 
201 
1 
•70 
16 
10 
1-37 
1 
77 
L92 
L86 
1-71 
1 
38 
b84 
1-34 
1-53 
L51 
L38 
LSI 
L55 
L66 ' 
1 
•60 
17 
10 
M8 
1 
56 
L82 
2-37 
171 
1 
14 
1-24 
M8 
L29 
L21 
L16 
L39 
L46 
LSO ' 
1 
•45 
18 
10 
1-53 
1 
•39 
1-74 
2^57 
1-79 
0 
82 
L08 
M8 
093 
LOl 
L24 
L29 
L46 
L85 i 
•46 
19 
10 
1-57 
1 
■55 
L72 
2-52 
183 
0 
64 
0^80 
M2 
0^93 
0^90 
L26 
L29 
L41 
L86l 
1 
46 
1 20 
10 
1-74 
1 
•83 
\-92 
2^77 
2^07 
0 
59 
0^86 
0-92 
063 
0-76 
L37 
L43 
L48 
L96 1 
1 
56 
21 
10 
1-92 
1 
83 
1-94 
2^73 
2-09 
0 
69 
0^95 
Ml 
095 
0-93 
L5S 
L57 
L65 
204 
71 
22 
10 
1-76 
1 
•78 
L88 
2-23 
L90 
0 
87 
0^84 
LOS 
Lll 
0-99 
L50 
1-45 
L64 
1 -c 1 
L/6| 
! 
59 
23 
10 
1-78 
1 
66 
b98 
L96 
L85 
0 
84 
0^95 
L26 
LOO 
L02 
L42 
L39 
L71 
L64! 
1 
54 
0 
10 
2-17 
1 
•84 
L6S 
L83 
L89 
0 
86 
M4 
1-27 
L06 
LOS 
L75 
L60 
L54 
L59 
1 
62 
1 
10 
2-27 
1 
•84 
L92 
1-90 
1-98 
0 
98 
1-03 
LIS 
L38 
L14 
LSO 
L58 
L62 
L72 
1 
68 
2 
10 
210 
1 
98 
1^73 
2^10 
b99 
0 
90 
L08 
Lll 
L26 
109 
L72 
L67 
L50 
LSO \ 
I 
67 
3 
10 
1-98 
1 
•82 
161 
2^27 
1-91 
1 
63 
136 
LSI 
L42 
L42 
LS6 
L67 
L49 
LSS ! 
1 
72 
4 
10 
L88 
1 
51 
1-41 
174 
L63 
1 
60 
158 
L23 
L27 
L39 
L7S 
L53 
L34 
L53 
1 
54 
5 
10 
1-34 
1 
43 
M4 
1-48 
1-36 
1 
85 
223 
0-97 
L36 
L55 
L55 
LSI 
L04 
1-42 ' 
1 
45 
6 
10 
1-37 
1 
10 
0^82 
M4 
M3 
3 
52 
303 
109 
2^72 
2^49 
2^27 
2^09 
098 
L87 
1 
SO 
7 
10 
0-99 
1 
15 
0^72 
0^95 
0-96 
2 
67 
2-75 
L37 
243 
2-26 
LS5 
2^00 
112 
L69j, 1 
217 : 1 
66 
8 
10 
0-82 
1 
05 
0^58 
0-91 1 
0-8() 
3 
OS 
2-77 
L4S 
2^96 
254 
2. 22 
200 
117 
89 
9 
10 
0-70 
1 
35 
051 
0-77 1 
0^83 
3 
33 
3^13 
L43 
303 
2-69 
L90 
2-34 
106 
2-26 
! 
89 
10 
10 
0.99 
1 
14 
0^62 
L07! 
0^95 
2 
84 
2^80 
L29 
2-77 
2-43 
211 
206 
103 
2^28 ! 
•87 
1 1 
10 
0-71 
1 
00 
0.64 
L05 
0-86 
2 
95 
2^94 
L70 
3^02 
2-63 
2^13 
203 
L33 
2-21 
1 
•92 
46. Diunial Variation of the probaMc error of a» Observation of JIagnetic Declination. — It appears from 
the previous conclusions, that the best hour to make an obsei'vation of magnetic declination in winter and 
spring, is about 6'' a.m. ; in the summer quarter, from 5'' p.m. to lO"^ p.m. ; and in autumn from 4** to o** p.m. 
