Diurnal Vaeiatioxs foe the Total Magnetic Force. 
Ixix 
Table 65. — Differences of Disturbed and Undisturbed Diurnal Variations of the Total Magnetic Force, 
as deduced from Tables 63 and 64, exhibiting the effect of Irregular Disturbance on the Hourly 
Mean Positions. 
Mak. 
IVTpn n 
Time. 
Dec. 
Feb. 
March. 
April. 
May. 
June. 
July. 
Aug. 
oept. 
Oct. 
Isov. 
1 'Six i\! 
Sept. 
to 
Feb. 
onths. 
to 
Aug. 
Twelve 
Months. 
b. m. 
- 
0-00 
0-00 
0-00 
0-00 
0-no 
0-00 
0-00 
0-00 
12 13 
— 0075 
— 0207 
AAA O 
— 0092 
A 1 OO 
— 0 1 22 
— 0129 
— 0102 
— 0140 
— 0120 
1.3 13 
— 0057 
— OzOo 
A 1 OA 
— uizy 
A 1 /I Q 
— U14o 
— 0133 
— 0095 
— 0159 
— 01 28 
14 13 
— 0094 
— OZDl 
A 1 /I 
— 0146 
A 1 CA 
— Oloy 
— 0149 
— 01 21 
— 0192 
— 0158 
lo IS 
— 0071 
A 1 O /I 
A 1 o 
— Ulo2 
n I *7A 
— 0140 
A 1 A S 
— OlOo 
A 1 /2 A 
— 01d9 
— 0138 
16 13 
— 0054 
— 0 1 DO 
A 1 ^ X 
A 1 A 1 
— OlOl 
— 0137 
A A A ^ 
— 009d 
— 0150 
— 0123 
17 13 
— 0042 
A 1 O 1 
— Olal 
A 1 1 A 
— Ul 10 
A 1 C O 
— OlDO 
— 01 10 
— 0076 
— 0130 
— 0103 
18 13 
— 0023 
— 0077 
— 0U7 1 
A 1 Orf^ 
— U 1 2d 
A A*7 O 
— 0073 
— 0048 
— 0091 
— 0070 
19 13 
— 0014 
AA ^ 
— OOoo 
A A /I A 
— 0049 
AAAA 
— 0090 
— 0051 
A A O O 
— 0033 
— 0065 
— 0049 
OA 1 O 
ZU 16 
— 0016 
— 0U47 
AAQn 
— UUD/ 
AAOO 
— 0022 
AA 1 A 
— 0019 
A A A O 
— 004o 
A A O /I 
— 00.54 
ell 1 o 
— 0016 
AAQ 1 
AA 1 
— OUlo 
AAQ Q 
AAA"T 
— 0007 
AA 1 I 
— 00] 1 
A A 0*T 
— 002/ 
A A OA 
— 0020 
OO 1 o 
22 16 
— 0014 
AAAA 
UOUO 
AAA 1 
— OUOl 
AA 1 n 
— 00 ly 
+ 0022 
+ 0004 
— 0006 
— 0002 
23 13 
+ 0006 
1 AA O A 
+ 00o4 
1 AA O 1 
+ 0021 
AAA 1 
— 0001 
+ 0030 
+ 0018 
+ 0018 
+ 0018 
0 13 
+ 0007 
+ 0079 
+ 0037 
+ 0028 
+ 0088 
+ 0047 
+ 0048 
+ 0048 
1 13 
+ 0016 
+ 0100 
+ 0045 
+ 0063 
+ 0100 
+ 0058 
+ 0069 
+ 0063 
2 13 
+ 0032 
+ 0135 
+ 0075 
+ 0093 
+ 0109 
+ 0070 
+ 0101 
+ 0086 
3 13 
+ 0062 
+ 0167 
+ 0103 
+ 0150 
+ 0159 
+ 0111 
+ 0140 
+ 0125 
4 13 ' 
+ 0069 
+ 0192 
+ 0097 
+ 0204 
+ 0161 
+ 0115 
+ 0165 
+ 0139 
5 13 
+ 0083 
+ 0265 
+ 0157 
+ 0245 
+ 0173 
+ 0128 
+ 0222 
+ 0175 
6 13 
+ 0102 
+ 0254 
+ 0158 
+ 0244 
+ 0158 
+ 0130 
+ 0218 
+ 0174 
7 13 
+ 0094 
+ 0188 
+ 0157 
+ 0202 
+ 0106 
+ 0100 
+ 0182 
+ 0141 
8 13 ' 
+ 0068 
+ 0105 
+ 0104 
+ 0120 
+ 0028 
+ 0048 
+ 0109 
+ 0079 
9 13 
+ 0024 
-0006 
+ 0035 
+ 0011 
-0031 
-0003 
+ 0013 
+ 0005 
10 13 
-0036 
-0095 
+ 0003 
-0024 
-0071 
-0053 
-0039 
-0045 
11 13 
-0060 
-0082 
-0038 
-0092 
-0085 
-0072 
-0070 
-0072 
145. Diurnal Variation of the Effect of Disturbance on the Total Magnetic Force. The remark made 
No. 102, for the vertical component, will apply also to the following conclusions obtained from Table 65. 
\st, The greatest effect of disturbance in increasing the total magnetic force occurs 
In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. 
About 30™ P.M. 5"^ 30™ p.m. 6*^ 15™ p.m. 5^ 40™ p.m. 5*^ 10™ p.m. 
The hours, it will be seen, agree very nearly with those found as tlie epochs of the maximum total force in the 
disturbed diurnal variation. The maximum positive effect of disturbance on the total force, occurs latest near 
the solstices and earliest near the equinoxes. 
2d, The greatest effect of disturbance in diminishing the total magnetic force occurs 
In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. 
About 2h 0" A.M. 2h 15™ A.M. 31^ 0™ a.m. 2*' 45™ a.m. 2^ 10™ a.m. 
These hours are nearly the same as those for the after-midnight minimum of the diurnal variation ; the 
difference is greatest in the summer months when the maximum negative effect occurs latest. 
M, The effect of disturbance on the total magnetic force is zero 
In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. 
lO*' 45™ A.M. 10»i 15™ A.M. 101^ 10™ A.M. 11*^ 15™ A.M. 9^ 45™ A.M. 
gh 40m P.M. 91* 10™ P.M. lO** 15™ p.m. 30™ p.m. 8*^ 45™ p.m. 
The one of these epochs is nearly the same as that of the principal minimum in the undisturbed diurnal varia- 
tion ; the other occurs about twelve hours after. • 
About 
