222 
DR. C. CHREE: MAGNETIC DECLINATION 
For purposes of comparison they reproduce some data for quiet days already published 
in A. It should be noticed that G.M.T. is used throughout. If local mean time 
were substituted, the angles would require to be increased, a. x by 19', a 2 by 38', and 
so on. The corrections necessary if local solar time is employed will be found in A, 
Table XIX. 
It should be remembered that an increase in phase angle implies an earlier 
occurrence of the daily maximum, an advance of one hour answering to 15° in a 1} to 
30° in a 2 . and so on. 
Table XI. — -Diurnal Inequality. Phase Angles. 
Angle. 
Season. 
Quiet days. 
Ordinary days. 
Disturbed 
days. 
Sunspot 
maximum. 
11 
years. 
Sunspot 
minimum. 
Sunspot 
maximum. 
11 
years. 
Sunspot 
minimum. 
ii 
years. 
f 
Year. . . 
O f 
221 1 
o / 
222 57 
o / 
224 14 
o / 
238 12 
o / 
230 21 
o / 
232 6 
® t 
257 52 
Winter . . 
235 36 
240 55 
248 49 
242 38 
248 8 
255 40 
271 42 
<%i < 
Equinox . 
221 27 
223 24 
224 51 
230 57 
233 8 
233 22 
261 12 
L 
Summer 
213 47 
214 49 
214 30 
217 54 
218 45 
220 2 
243 16 
r 
Year. . . 
42 57 
45 3 
49 33 
41 15 
42 28 
45 58 
12 26 
Winter . . 
26 3 
30 18 
40 25 
22 50 
26 31 
36 17 
- 12 43 
* < 
CC 2 s 
Equinox . 
40 59 
42 25 
46 24 
39 58 
41 2 
43 14 
31 16 
L 
Summer 
50 50 
52 27 
55 13 
49 58 
50 6 
51 53 
4 27 
r 
Year. . . 
234 41 
237 16 
241 45 
231 37 
236 38 
242 39 
200 11 
Winter . . 
236 7 
243 14 
255 10 
233 0 
243 19 
256 37 
188 35 
a < 
a 3 < 
Equinox . 
229 5 
231 11 
233 51 
227 29 
231 17 
235 14 
186 9 
L 
Summer 
240 29 
241 26 
244 29 
235 51 
239 35 
244 28 
210 15 
Year. . . 
52 13 
56 8 
59 25 
56 46 
57 20 
56 1 
105 0 
Winter . . 
49 25 
55 19 
64 22 
51 4 
53 54 
59 35 
65 50 
a < 
a 4 < 
Equinox 
57 17 
60 45 
59 25 
60 46 
59 44 
56 59 
147 12 
L 
Summer 
37 55 
39 52 
51 45 
56 10 
56 1 
43 55 
136 54 
§ 15. The phenomenon to which I called attention in the case of the quiet days, 
viz., the increase in the phase angles a x and a 2 as sunspot frequency diminishes, 
appears equally decisively in the ordinary days. Turning the difference of angle into 
time, and taking arithmetic means from the individual months, we find for the 
retardation (in minutes) in the time of occurrence of the maxima in years of sunspot 
maximum, as compared to years of sunspot minimum, the following results, q denoting 
quiet, o all ordinary days :—• 
