212 DR. C. CHREE: MAGNETIC DECLINATION 
Diurnal Inequality. 
§ 10. Tables III. and IY. give the mean diurnal inequalities for the several months 
of the year derived from the “ ordinary ” days (including the “ quiet ” days) and the 
“ disturbed ” days respectively. Non-cyclic changes have been eliminated in the usual 
Table III.—Diurnal Inequality. Ordinary Days (+ to West). 
Hour. 
Forenoon. 
1. 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9. 
10. 
11. 
12. 
January . 
-1-24 
-1-01 
/ 
-0-80 
-0-76 
/ 
-0-72 
-0 70 
/ 
-0-74 
/ 
-085 
-0-63 
/ 
+ 0-36 
+ 1-61 
/ 
+ 2-78 
February. 
-1-74 
-1-46 
-1-34 
-1-25 
-1 -24 
-1 '22 
-116 
-1-26 
-1-17 
-0-05 
+ 1-78 
+ 3-32 
March. 
-1-75 
-1-68 
-1-70 
-1-72 
— 1 ‘75 
-1-79 
— 2 *27 
-3-02 
—2‘76 
-0-94 
+ 2-02 
+ 4-77 
April. 
-1-42 
-1-47 
-1-63 
-1'93 
-2*19 
-2-74 
-3-64 
-4-22 
-3-53 
-1-22 
+ 2-04 
+ 5'19 
May. 
-1'38 
-1-58 
-1-86 
-2-37 
-3-26 
-3-98 
— 4 46 
-4-17 
-2-85 
-0*27 
+ 2-76 
+ 5-24 
June. 
-1-24 
-1-48 
-1-88 
-2-61 
-3-71 
-4-61 
-4-91 
-4-61 
-3-39 
-0-99 
+ 2-00 
+ 4-61 
J uly. 
-1 '28 
-1-63 
-1-93 
-2-53 
-3'68 
-4-43 
-4-54 
-4-19 
-3-07 
-0*91 
+ 1-90 
+ 4 ’56 
August. 
— 1 '66 
-1-86 
-2'13 
-2*49 
-3-19 
-3'88 
-4-21 
-3-82 
-2-30 
+ 0-34 
+ 3-29 
+ 5-87 
September. 
-1-88 
-1-93 
-2-10 
-2'24 
-2-35 
-2'65 
-3 07 
-3-06 
-1-85 
+ 0-60 
+ 3-46 
+ 5-75 
October. 
-1-02 
-1-49 
-1'41 
-1-31 
— 1-31 
-1-37 
-1-72 
-2 40 
-2-27 
-0-47 
+ 2-45 
+ 4-58 
November. 
-1-31 
-0-99 
-0-81 
-0-78 
-0-79 
-0-85 
-0-85 
-112 
-1-11 
+o-oi 
+ 1-76 
+ 3-18 
December. 
-1'18 
-0'84 
— 0 *66 
-0-48 
-0-47 
-0-46 
-0-49 
-0-53 
-0 54 
+ 0-19 
+ 1-32 
+ 2*41 
Afternoon. 
Sum of 
24 
Hour. . . 
1. 
2. 
3. 
4- 
6. 
7. 
8. 
9. 
10. 
H. 
Midt. 
from 
mean. 
January. . . . 
+ 3-26 
+ 2-66 
+1 -75 
/ 
+ 1-23 
1 
+ 0-80 
/ 
+ 0-30 
/ 
-0-28 
/ 
-0-88 
-1-37 
' 
-1-66 
/ 
-1*64 
-1-49 
/ 
4-92 
- 
29-52 
February . . . 
+ 4-08 
+ 3-99 
+3'01 
+ 1-82 
+ 1-12 
+ 0*55 
-0*04 
— 0 '66 
-1-33 
-1-74 
-1-96 
-1-98 
6 *06 
39-27 
March .... 
+ 6 06 
+ 5-85 
+ 4-41 
+ 2-52 
+ 0-99 
+ 0-24 
-0*34 
-0-76 
-1-24 
-1-55 
-1-68 
-1-80 
9-08 
53*61 
April. 
+ 6-73 
+ 6 *40 
+ 4*79 
+ 3-05 
+1 -50 
+ 0'31 
-0-34 
-0-71 
-0-96 
-1 -26 
-1-36 
-1-40 
10-95 
60 -03 
May. 
+ 6 20 
+ 5 '86 
+ 4 '55 
+ 3'07 
+ 1-74 
+ 0-62 
-0-06 
-0-38 
-0-58 
-0-77 
-0-96 
-1-16 
10 ‘66 
60-13 
June. 
+ 5-82 
+ 6 01 
+ 5-14 
+ 3-81 
+ 2-30 
+ 1-17 
+ 0-41 
+ 0-10 
-0-16 
-0-32 
-0-61 
-0-93 
10-92 
62-82 
July. 
+ 5-92 
+ 6-05 
+ 5*04 
+ 3-52 
+ 2-03 
+ 0-93 
+ 0-36 
+ 0-10 
-0-14 
-0-38 
-0'70 
-0-98 
10-59 
60 -80 
August .... 
+ 680 
+ 8-19 
+ 4*57 
+ 2-54 
+ 0-91 
+ 0-02 
-0*22 
-0*44 
-0-67 
-0-98 
-1-21 
-1-45 
11-01 
61*04 
September. . . 
+ 6-42 
+ 5 *53 
+ 3-81 
+ 2-02 
+ 0-73 
+ 0-08 
-0-36 
-0-82 
-1-16 
-1 *43 
-1-89 
-1-85 
9*49 
56 *84 
October.... 
+ 5 33 
+ 4-74 
+ 3-48 
+ 1-94 
+ 0-94 
+ 0-28 
-0'37 
-1-01 
— 1 ‘52 
-1*81 
-1 90 
-1-77 
7-73 
47 -47 
November . . . 
+ 3-61 
+ 3-00 
+ 2-13 
+ 1 47 
+ 0-84 
+ 0-27 
-0-29 
-0-89 
-1-47 
-1-73 
-1 76 
-1-03 
5*37 
32-71 
December . . . 
+ 2-86 
+ 2-43 
+ 1-77 
+ 1-22 
+ 0-67 
+ 0-13 
-0'42 
-0-91 
-1-37 
-1-60 
-1-58 
-1-50 
4*46 
26-03 
way. The data in Table III. represent arithmetic means from the 11 months of the 
same name in the 11 years. All the ordinary day curves were smoothed, when 
necessary, as already described. In the case of the disturbed days the different 
