XXVI 
General Results or the Makeestoun Obseevations. 
41. If we consider the mean position as deduced from all the observations in each month, we find that the 
number of observations for which the declination was to the west, is least from 6*^ a.m. to 10^ a.m., and greatest 
from 6^ P.M. to lO'^ p.m. ; the reverse of course holding for the deviations to the east : if, however, we consider 
the hourly mean position deduced from the days selected free from disturbance, we find that the number of 
westerly observations is greatest from about 9*^ a.m. till noon, and that it is least from 8"^ p.m. till 1*^ a.m. ; which 
result is nearly the reverse of the other. As the maximum effect of disturbance, in increasing the westerly 
declination (No. 36), occurs about the same time as the maximum fi'equency of westerly excursions fi'om the 
undistui'bed position (as seen in the second result), the displacement westerly of the mean position, by dis- 
turbance, reduces the number of westerly excursions from that position to a minimum (as seen in the first 
result). The same explanation applies to the other epoch. 
Diurnal Variation of the Sums of Disturbances of the Hourly values of Magnetic Declination in 1844 and 
1845. — The following table contains the sums, for 100 observations, of the deviations of the north end of the 
declination magnet from the monthly mean positions at the corresponding hours, the latter being deduced ft-om 
the days selected as free from irregular disturbance. 
Table 17. — Hourly sums, for 100 Observations of Westerly Declination in 1844 and 1845, of the 
Positive and Negative Excursions from the Approximate Normal Positions for each Hour. 
Mak. 
Positive (W.) Disturbances. 
Negative (E.) Disturbances. 
Mean 
Nov. 
r eb. 
May. 
Aug. 
Nov. 
Feb. 
May. 
Aug. 
Time. 
Dec. 
March. 
June. 
Sept. 
Year. 
Dec. 
March. 
June. 
Sept. 
Year. 
Jan. 
April. 
July. 
Oct. 
Jan. 
April. 
July. 
Oct. 
li. m. 
12 10 
77 
138 
73 
101 
97 
272 
305 
259 
339 
294 
13 10 
87 
144 
73 
107 
102 
277 
300 
253 
313 
286 
14 10 
114 
159 
88 
157 
129 
198 
264 
215 
270 
237 
15 10 
135 
146 
135 
177 
148 
178 
208 
159 
225 
193 
16 10 
128 
190 
138 
141 
149 
147 
171 
172 
190 
170 
17 10 
109 
167 
157 
225 
164 
123 
110 
134 
135 
126 
18 10 
178 
189 
176 
286 
207 
69 
72 
116 
83 
85 
19 10 
209 
203 
164 
294 
218 
43 
55 
118 
78 
74 
20 10 
236 
218 
216 
344 
254 
38 
69 
80 
48 
59 
21 10 
275 
258 
252 
335 
281 
40 
56 
77 
73 
62 
22 10 
249 
230 
261 
260 
251 
51 
59 
66 
92 
67 
23 10 
217 
206 
243 
260 
232 
66 
72 
98 
67 
76 
0 10 
294 
241 
219 
250 
251 
55 
79 
88 
67 
73 
1 10 
288 
250 
224 
250 
253 
72 
66 
99 
94 
S3 
2 10 
279 
257 
219 
268 
256 
64 
77 
81 
91 
78 
3 10 
260 
243 
188 
244 
234 
112 
91 
109 
131 
111 
4 10 
233 
213 
159 
197 
201 
122 
93 
108 
109 
108 
5 10 
160 
149 
95 
157 
141 
150 
212 
113 
127 
150 
6 10 
159 
108 
71 
123 
116 
294 
309 
125 
251 
244 
7 10 
97 
108 
56 
97 
89 
274 
292 
168 
240 
243 
8 10 
62 
95 
40 
70 
67 
382 
304 
194. 
364 
311 
9 10 
76 
120 
42 
52 
72 
303 
348 
170 
399 
305 
10 10 
77 
101 
48 
62 
72 
345 
312 
158 
393 
302 
11 10 
52 
94 
45 
87 
70 
374 
311 
220 
355 
315 
42. The results from the Table are as follows : — 
1.9^, The sum of positive or westerly disturbances 
In Nov. Dec. Jan. 
Is a maximum at 0'> Noon. 
Is a minimum at 11'' p.m. 
Feb. March, April. 
9'' A.M. and 2'' p.m. 
8'» P.M. — 11'' p.m. 
2d, The sum of negative or easterly disturbances 
Is a maximum at 8'' — 11'^ p.m. 9'' p.m. 
Is a miuiiuum at 8'' a.m. 7** a.m. — 10'' a.m. 
May, .Tune, July. 
101' ^.ji. 
8i'' P.M. 
I2h^ A.M. 
10^ A.M. 
Aug. Sept. Oct. 
8i" A.M. 
9'' P.M. 
9^" P.M. 
A.M.— 0^* Nooa. 
