DIURNAL VARIATIONS FOR THE ToTAL MAGNETIC FORCE. Ixvil 
142. Diurnal Variation of the Total Magnetic Force.—Table 62 has been computed from Tables 31 and 
48. The following are the approximate epochs of maxima and minima in apparent time, distinguishing those 
of the principal maximum by +, and of the principal minimum by —. 
Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 
h, m. h, m. h. m. h. m. h. m. h. m, h. m bh. m. h. m. h. m. h. m. h. m. 
Max. +535 +5 0 +5 5 +555 +545 +630 +535 +535 4455 +340 +625 +620 
Min. —14 5 -14 0 —13 45 -13 0 —14 35 14 15 1440 -14 5 —18 35 -1615 -1245 —14 45 
Max. 19 5 19 15 19 30 19 0 18 40 18 35 18 30 18 35 18 50 19 45 18 50 19 5 
Min. 22 0 21 55 22 30 2245 -22 45 -23 0 —22 45 22 20 21 35 22 35 -—2250 —22 15 
The principal maximum of the total magnetic force occurs between 3" 40™ and 6® 30™ p.m. in each 
month of the year ; it occurs latest in June and November ; it occurs earliest in February and March, of the 
first six months, and in October and_ September of the last six months of the year. The principal minimum 
occurs near 2° a.m. in each month, with the exceptions of June and July, in which months it occurs near 11" 
A.M. ; in May, November, and December, the two minima are nearly equal. The secondary maximum occurs 
between 63° and 73” a.m., and it is best marked in the months of March, April, and May, August, and Sep- 
tember. 
TABLE 63.—Diurnal Variations of the Total Magnetic Force for Different Periods, deduced from 
Table 62. 
Six Months. 
Nepte)||ia sacs. | aaa 
July. P Twelve 
Oct. Sept. March 
Aug. Nov. ‘6 to Months. 
Feb. Aug. 
0:00 0 0-00 0-00 0-00 
0 13 —0021 | —0102 | —0163 | —0148 | —0001 || —0011 | —0138 || —0074 
113 | +0033 0000 | —0060 | —0021 | +0098 || +0065 | —0027 || +0019 
213 +0085 | +0130 | +0051 | +0106 | +0184 || +0134 | +0096 || +0115 
3 13 | +0133 | +0236 | +0167 | +0258 | +0285 || +0209 | +0220 | +0214 
413 | +0144 | +0305 | +0236 | +0361 | +0313 || +0228 | +0301 || +0264 
5 13 | +0152 | +0408 | +0358 | +0441 | +0313 || +0232 | +0402 || +0317 
6 13 | +0161 | +0399 | +0373 | +0441 | +0284 || +0222 | +0404 || +0313 
7 13 +0142 | +0325 | +0356 | +0378 | +0209 | +0175 | +0353 || +0264 
8 13 | +0107 | +0210 +0264 | +0265 | +0114 || +0110 | +0246 || +0178 
9 13 +0056 | +0074 | +0141 | +0097 | +0020 || +0038 | +0104 || +0071 
10 13 —0020 | —0045 | +0048 | +0018 | —0055 || —0037 | +0007 || —0015 
11 13 —0074 | —0074 | —0038 | —0096 | —0121 || —0097 | —0069 || —0084 
; a Sag a Ne | 
143, The means for groups of months having been obtained, as for the other magnetic elements, we find 
the approximate epochs for the mean diurnal variation in apparent time as follow :— 
Dec. Jan, Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. 
Maximum, +65 10™ p.m. + 55 25m p.m, + 55 45m pm. + 55 35m pM. + 45 50™ p.m. 
Minimum, —2> 10™ am. — 2) 10™ am. 15 45™ am. — 2» 10™ a.m. — 2» 20™ a.m. 
Maximum, 7» 10™ am. 7h 5m am, 6" 35™ a.m. 6h 35™ a.m. 7h 35™ a.m. 
Minimum, 9h 55™ aM, 105 35™am. —105 45m,4.M, —105 35™ a.m. 10" 20™ am. 
MAG. AND MET. OBS. 1845 anp 1846. iP 
