AT KEW OBSERVATORY, 1890 TO 1900. 
223 
Whole year. 
Winter. 
Equinox. 
Summer. 
1 - 
0 . 
?■ 
0 . 
1 • 
0 . 
1 - 
0 . 
244iour term .... 
24-0 
23-5 
54-9 
52-3 
13-5 
9-7 
3-7 
8-3 
12-hour term .... 
15-8 
12-8 
27-7 
28-2 
10-7 
6-2 
9-0 
3-9 
§ 16. Contrasting results from ordinary and quiet days, we observe one remarkable 
difference between the 24- and 12-hour phase angles. As we pass from quiet to 
ordinary days the angle oq invariably increases, whereas in a majority of months 
clo decreases. 
Table XII. coDverts the difference between the ordinary and quiet day phase 
angles into time. The results are from the seasonal diurnal inequalities, not from 
individual months. 
Table XII.—Difference in Minutes in Times of Occurrence of Maxima in Ordinary 
and in Quiet Days (+ denoting Later Occurrence in Quiet Days). 
Whole year. 
Winter. 
Equinox. 
Summer. 
24-hour. 
+ 
12-hour. 
24-hour. 
+ 
12-hour. 
24-hour. 
+ 
12-hour. 
24-hour. 
+ 
12-hour. 
Years of sunspot maximum . . 
27-6 
3-2 
29-0 
7-0 
37-5 
1-2 
16-4 
1-5 
Eleven years. 
27 • 2 
4-8 
26-8 
7-5 
39-8 
2-3 
15-4 
4-6 
Years of sunspot minimum . 
27 • 2 
6-2 
26-6 
6-4 
34-1 
5-7 
20-9 
6-6 
In the case of the 24-hour term the difference in phase between quiet and ordinary 
days seems nearly independent of sunspot frequency. Like the difference in phase 
between years of sunspot maximum and minimum, it is distinctly least in summer ; 
but unlike that difference it is greater in the equinoctial than in the winter months. 
In the case of a 3 and a 4 the difference between ordinary and quiet days appears 
small, and it would probably require a very long series of years to give thoroughly 
representative results. This last remark also applies to the difference between 
disturbed and ordinary days, though in this case there seems no doubt as to the 
sign of the difference. 
§ 17. Table XIII. converts the difference between the disturbed and ordinary days 
phase angles into time. The results are again from the seasonal inequalities. 
The differences in Table XIII. are very substantial. From Tables XII. and XIII., or 
directly from Table XI., we see that, taking the whole year, the maximum in the 
24-hour term occurs no less than hours earlier in disturbed than in quiet days. 
