lvi GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. 
TABLE 53.—Mean Difference of the Observations of the Vertical Component of Magnetic Force, 
in 1844 and 1845, from the Monthly Means at the corresponding Hours in each Year, as deduced 
from all the Regular Observations. 
Mean Positive Difference. 
Mean Negative Difference. Mean Difference, 
Nov. | Feb. | May. | Aug. Nov. | Feb. | May. | Aug. . | Feb. | May. | Aug. 
Dec. | Mar. | June. | Sept. || Year. | Dec. | Mar. | June. | Sept. . | Mar. | June.) Sept. 
Jan. | April.) July. | Oct. Jan. | April.) July. | Oct. . | April.| July. | Oct. 
|| 0-00 0°00 0-00 0-00 || 0-00 0-00 0-00 000 || - 0-00 0-00 | 0-00 
0159 | 0229 | 0151 | 0187 0199 | 0533 | 0208 | 0379 0320 | 0175 | 0250 
0147 | 0222 | 0183 | 0187 0191 0431 | 0252 | 0379 0293 | 0212 | 0250 
|| 0138 0226 0197 0259 | 0567 | 0283 | 0400 0323 | 0215 | 0264 
|| 0142 | 0203 | 0206 0196 | 0497 | 0293 | 0409 0288 | 0223 | 0274 
0136 | 0185 0214 0195 | 0487 | 0263 | 0389 | 0268 | 0192 | 0276 
0139 | 0173 | 0181 0185 | 0403 | 0237 | 0351 0242 | 0180 | 0239 
0135 | 0148 | 0153 0179 | 0274 | 0201 | 0304 0192 0165 | 0204 
0134 | 0124 | 0143 d 0151 | 0171 | 0167 | 0198 | 0144 | 0149 | 0166 
0133 | 0101 31 | 0130 0141 | 0145 | 0154 | 0156 0119 | 0142 | 0142 
|| 0125 | 0097 0120 0147 | 0126 | 0160 | 0122 0110 | 0138 | 0121 
0120 0101 2/0111 0141 | 0112) 0137 | 0120 0106 | 0129 | 0115 
|| 0120 | 0115 0112 0120 0124 | 0106 0115 | 0128 | 0109 
0137 | 0157 3 | 0163 0122) 0131 | 0121 | 0111 0143 | 0122 | 0132 
0140 | 0146 0180 0127 0125 | 0123 0134 | 0120 | 0146 
| 0163 | 0174 0183 0123 0135 | 0133 0150 | 0123 | 0154), 
0289 0251 31 | 0246 0155 0139 | 0157 p 0183 | 0135 | 0192 
0333 0260 36 | 0282 0179 0147 | 0180, 0182 | 0156 0220 
| 0392 0368 0359 0189 0152 | 0198 0243 | 0166 | 0255 
0447 | 0341 0285 ¢ 0187 0151 0157 2 0242 | 0157 | 0202) 
0336 | 0227 2/0213 0166 0130 | 0175|0140 | 0175 | 
| 0209 | 0153 | 0124 | 0131 0131 0122) | 0139 0123 0131 | 
0172 | 0131 | 0110 0138 0119 018 0143 | 0113 | 0137 | 
|| 0150 | 0160, O114 0176 | 0246 | 0121 0194 | 0111 | 0142 
0150 | 0150 0148 0199 | 0273 | 0137 0194 | 0125 | 0203 
— 5 hs 
KBOCOCONOAUKWNK OWN 
105. The approximate epochs of maxima and minima for the mean positive and negative differences, the 
principal being indicated by + and —, are as follow :— 
Mean Positive Difference. Mean Negative Difference. 
SS OO _—_—_——_—_———  ——— 
Min. Max. Min. Max. Min. Max. Min. Max, 
Nov. Dec. Jan. —1045 a.m. 42625) Panes) py. Se. ee Bee ens — 0% Noon. 545 p.m. 835 pM. +245 a.m. 
Feb. Mar. April, — 9}> A.M. +5)> P.M. 9b P.M, lam. —10}> a.m. 65 pm. Sj) P.M. +2}> aM. 
May, June, July, 2h PM. +55 pM. —10 pm. +24 a.m. — 0» Noon. 595 p.m. —9" P.M. +235 aM. 
Aug. Sept. Oct. —10}" a.m. +55 pM. — 945 PM. dham. —11}> am. 5b pM. 68h PM. 6+ oh AM. 
106. The mean positive difference has two maxima and two minima in each quarter excepting winter ; the 
principal maximum occurs between 5h and 6 p.m.; in summer the two maxima have an equal value; the 
values of the two minima differ little. 
107. The mean negative difference has two maxima and two minima in each quarter; the principal maxi- 
mum occurs between 2h and 3" a.m. ; in winter the two maxima differ little in value; in the other quarters the 
secondary maximum is very smal] compared with the other; the values of the two minima in each quarter 
differ little. 
108. It appears, therefore, that the principal maximum of the mean positive difference occurs at the same 
time as the secondary maximum of the mean negative difference, and vice versa. It seems probable that if differ- 
ences were taken with reference to mean wndisturbed positions, the secondary maximum would disappear in 
each case; thus, if we consider that the effect of disturbance is to increase the mean vertical component to a 
large extent about 6" p.m. (No. 103, 1st), it is obvious that both the value and the number of the negative 
departures from this increased mean will be greater than if the undisturbed mean were taken as the zero, It was 
accordingly found in the discussion of the observations for 1844, (pp. 388, 389), when the mean position was 
employed as deduced from the days selected nearly free from intermittent disturbance, that the maximum of 
