232 
Abstracts op the Makerstoun Observations, 1843. 
TABLE IX. — Mean Variations of the Horizontal Component of Magnetic Force, after eliminating 
the Secular Change, with reference to the Moon's Age, Declination, and Distance from the 
Earth, for 1843. 
Variations 
Variations 
After 
Variations 
After 
Variations 
Before 
Variations 
Before 
Variations 
Moon's 
of Hori- 
Moon's 
of Hori- 
Moon 
of Hori- 
Moon 
of Hori- 
and 
of Hori- 
and 
of Hori- 
Age. 
zontal 
A fc e. 
zontal 
farthest 
zontal 
farthest 
zontal 
after 
zontal 
after 
zontal 
Component. 
Component. 
North. 
Component. 
North. 
Component. 
Perigee. 
Component. 
Apogee. 
Component. 
Day. 
0-000 
Day. 
0000 
Day. 
0-000 
Day. 
0-000 
Day. 
0-000 
Day. 
0-000 
15 
000 
6 
288 
6 
263 
14 
224 
7 
328 
7 
145 
16 
199 
l 
213 
1 
211 
15 
182 
6 
256 
6 
061 
17 
117 
2 
322 
2 
292 
16 
103 
5 
249 
5 
232 
18 
245 
3 
260 
3 
246 
17 
119 
4 
000 
4 
173 
19 
169 
4 
288 
4 
013 
18 
204 
3 
091 
3 
225 
20 
246 
5 
311 
5 
000 
19 
234 
2 
239 
2 
191 
21 
299 
6 
242 
6 
034 
20 
274 
1 
192 
1 
242 
22 
300 
7 
115 
7 
126 
21 
138 
P 
197 
A 
144 
23 
196 
8 
178 
8 
243 
22 
228 
1 
242 
1 
320 
24 
328 
9 
083 
9 
188 
23 
191 
2 
251 
2 
256 
25 
251 
10 
038 
10 
089 
24 
182 
3 
219 
3 
253 
26 
313 
11 
090 
11 
329 
25 
224 
4 
263 
4 
238 
27 
350 
12 
125 
12 
223 
26 
151 
5 
311 
5 
250 
28 
359 
13 
043 
13 
247 
27 
223 
6 
338 
6 
364 
29 
229 
14 
173 
7 
222 
7 
342 
Tabic IX. was formed from Table VIII. in the manner indicated for the magnetic declination, Table II. 
Variations of the Horizontal Component op Magnetic Force, with refebence to the 
relative Positions op the Sun, Moon, and Earth, as indicated by the Moon's Age. 
The partial means in the first portion of Table IX. shew distinctly what is more distinctly evident in the 
following means, namely, the maximum about the period of new moon, and the minimum at the period of full 
moon : — 
Means of Groups. 
14 days to 16 days, Full Moon, 0-000124 
17 20 ... 0-000194 
21 24 ... 0-000273 
25 28 ... 0-000318 
29 days to 1 day, New Moon, 0-000243 
2 5 ... 0-000295 
6 9 ... 0000154 
10 13 ... 0-000074 
It, shoidd be remarked that there is a secondary minimum shewn in these means at the time of new moon ; 
this would not have been seen so distinctly, or at all, had larger groups been taken. As this minimum is 
also shewn, and nearly to the same extent in the mean for 1844,* it may be allowable to conclude, that the 
principal minimum of the horizontal component occurs at the period of full moon / a secondary, and not very de- 
cided minimum, at the period of new moon; and maxima, nearly equal, immediately before and after the period 
of new moon. 
* Transactions of the Royal Society of Edinburgh, Vol. XVI., Plate IV. 
