AT KEW OBSERVATORY, 1890 TO 1900. 
245 
Applications of Wolf’s Formula. 
§ 33. If any element, It, varies in a linear way with sunspot frequency, its value 
must be expressible by a formula of the type 
If = a + 6S, 
where S denotes sunspot frequency, while a and b are constants. This formula, 
originally due to Wolf, has been applied to the range and the sum of the 24 
differences in the diurnal inequality derived from individual months of the year. The 
inequalities employed in the calculation were not those from individual years, but 
those from the sunspot maximum years 1892 to 1895 combined, the sunspot minimum 
years 1890, 1899, and 1900 combined, and the whole 11 years combined. The method 
followed was that explained in A, p. 418. The results appear in Table XXVII. 
Table XXVII.—Diurnal Inequality from all Ordinary Days. 
Range. 
Sum of 24 differences. 
a. 
b x 10b 
(b/a) x 1CK 
a. 
CO * 
O 
f“H 
X 
(b/a) x 104 
January .... 
3-97 
238 
60 
21-26 
207 
98 
February .... 
4-26 
422 
99 
24-04 
357 
149 
March. 
6-72 
665 
99 
35-03 
523 
149 
April. 
8-69 
542 
62 
45 • 36 
352 
78 
May. 
8-46 
509 
60 
45-97 
328 
71 
June. 
8-84 
458 
52 
48-96 
305 
62 
July. 
8-18 
537 
66 
45 • 65 
338 
74 
August .... 
9-40 
354 
38 
52-44 
190 
36 
September . . . 
7-39 
466 
63 
40-83 
355 
87 
October .... 
6-11 
388 
64 
34-22 
341 
100 
November 
4-28 
312 
73 
23-16 
272 
118 
December 
3-44 
254 
74 
17-95 
201 
112 
Year. 
6-65 
428 
67 
36-24 
314 
94 
Winter .... 
3-99 
304 * 
76 
21-60 
259 
119 
Equinox .... 
7-23 
515 
72 
38-86 
393 
103 
Summer .... 
8-72 
465 
54 
48 • 25 
290 
61 
The values assigned to the year and the seasons are arithmetic means from the 
months included. The results correspond exactly to those given in A, Table XLI., 
for quiet days. 
Absolutely considered, b is least in winter, but relatively to a it is then greatest. 
In this respect the phenomena are similar to those observed on quiet days, but b/a is 
less variable with the season on ordinary than on quiet days. 
It will be noticed that b/a is larger for the sum of the differences than for the 
range; the same phenomenon appeared in the case of the quiet days, but less 
conspicuously. 
