Horizontal Component of Magnetic Force. 237 
TABLE XIII.— Continued. 
Civil 
Day. 
January. 
February. 
March. 
April. 
May. 
June. 
July. 
August. 
September. 
October. 
November. 
December. 
0-0 
0-0 
0-0 
0-0 
0-0 
0-0 
0-0 
0-0 
0-0 
o-o 
OO 
0-0 
21 
0075 
0101 
0206 
0166 
[0251] 
0263 
0229 
0206 
0191 
0130 
0124 
0089 
22 
[0089] 
0110 
0218 
0144 
0220 
0187 
0173 
0346 
0246 
[0186] 
0042 
0039 
23 
0094 
0083 
0140 
[0193] 
0236 
0297 
[0561] 
0439 
0362 
0165 
0107 
0066 
94. 
uuoy 
091 ft 
0195 
0165 
0298 
0227 
0703 
0371 
[0245] 
0183 
v Lou 
25 
0096 
0164 
0119 
0235 
0224 
[0278] 
1627 
0341 
0188 
0211 
0128 
0104 
26 
0075 
[0119] 
[0161] 
0257 
0438 
0340 
0421 
0241 
0235 
0202 
[0107] 
0074 
27 
0094 
0092 
0146 
0357 
0331 
0278 
[0297] 
0249 
0188 
0064 
0192 
28 
0160 
0119 
0151 
[0312] 
0285 
0231 
0213 
0334 
0209 
0099 
0187 
29 
[0100] 
0215 
0230 
0339 
0308 
0372 
0371 
0261 
[0214] 
0096 
0095 
30 
0115 
0240 
[0231] 
0252 
0349 
[0277] 
0246 
0139 
0163 
0077 
0128 
31 
0086 
0206 
0266 
0285 
0221 
0330 
[0135] 
Mean 
01061 
01191 
01774 
03116 
03130 
02899 
036S3 
03139 
02484 
02227 
01278 
01223 
From the means at the foot of Table XIII. it will he seen that the least mean is that for January, and the 
greatest that for July ; the same results may be deduced from these quantities as from the ranges of the monthly 
means, thus — 
Jan. & Dec. Feb. & Nov. March & Oct. April & Sept. May & Aug. June & July. 
Ranges, 0-001141 0-001234 0-002000 0-002802 0-003134 0-003291 
Differences, 0-000093 0-000766 0-000802 0-000332 0 000155 
The mean of the diurnal ranges is about three times as great for the summer months as for the winter 
months. 
If we take the differences of the monthly means of the diurnal ranges, and of the diurnal ranges of the 
monthly means, we shall have some measure of those irregularities which cause the two to differ. 
From the means for each couple of months we have the following differences : — 
Monthly means of the diurnal ranges, minus the diurnal ranges of the monthly means. 
Jan. & Dec. Feb. & Nov. March & Oct. April & Sept. May & Aug. June & July. 
0-000514 0-000507 0-000527 0-000558 0-000493 0-000449 
The difference is greater at the solstices than in the winter or summer, and is least in summer. 
TABLE XIV. — Diurnal Ranges of the Horizontal Component of Magnetic Force, with reference to 
the Moon's Age and Declination for 1843. 
Moon's 
Age. 
Mean 
Diurnal 
Range. 
Moon's 
Age. 
Mean 
Diurnal 
Range. 
After 
Moon 
farthest 
North. 
Mean 
Diurnal 
Range. 
After 
Moon 
farthest 
North. 
Mean 
Diurnal 
Range. 
Day. 
0-00 
Day. 
0-00 
Day. 
0-00 
Day. 
0-00 
15 
2525 
0 
2217 
0 
2931 
14 
2375 
16 
2232 
1 
1792 
1 
2672 
15 
2022 
17 
2445 
2 
2015 
2 
3249 
16 
1960 
18 
2183 
3 
2198 
3 
3050 
17 
2026 
19 
2082 
4 
2237 
4 
2981 
18 
2166 
20 
1941 
5 
2037 
5 
2248 
19 
1858 
21 
2093 
6 
3207 
6 
2370 
20 
2168 
22 
1865 
7 
3227 
7 
2332 
21 
2146 
23 
2024 
8 
2756 
8 
2211 
22 
2057 
24 
1630 
9 
2337 
9 
2185 
23 
1925 
25 
1996 
10 
2303 
10 
1942 
24 
2124 
26 
2131 
11 
2405 
11 
2116 
25 
2088 
27 
2596 
12 
2430 
12 
2593 
26 
1962 
28 
3254 
13 
2422 
13 
2438 
27 
2437 
29 
2310 
14 
2321 
Table XIV. was formed from Table XIII. in the manner indicated for the declination Table II. 
MAG. AND MET. OBS. 1843. 3 O 
