FROM ORDINARY DAYS OF THE ELEVEN YEARS 1890 TO 1900. 
249 
Table XXVIII. contrasts the sunspot maximum and minimum values of the 
amplitude for the year and seasons in both H and V. In H the sunspot maximum 
value of the amplitude is always the greater. Its excess, however, relatively considered, 
diminishes as the order of the harmonic increases, and except in c 2 it is least marked 
in summer. 
In V the sunspot maximum value is also always the greater, except in the case of 
the summer value of c 4 ; but the pre-eminence of the sunspot maximum value is not 
specially conspicuous in c x . 
Table XXIX. contrasts the ratios borne to by c 2 , c 3 , and c 4 in the seasonal diurnal 
inequalities in the sunspot maximum and sunspot minimum groups of years. In the 
case of V the ratios seem little dependent on sunspot frequency, whereas in H with 
one exception they rise as sunspots diminish, especially in winter. In that season, in 
fact, in sunspot minimum the amplitude of the 24-hour term is exceeded by that of 
the 12-hour term and even by that of the 8-hour term. 
§ 22. Table XXX. contrasts the phase angles in the diurnal inequalities for the year 
and seasons in the six elements H, V, T, N, W, and I. An increase in the phase 
angle as we pass from winter to equinox, and from equinox to summer, is shown by 
H, N, and T in all four Fourier waves. It is also shown by V in the case of a 4 , and 
by W in the case of a 2 . A fall as we pass from winter to equinox, and from equinox 
to summer, is shown by V in the case of a u a 2 , and a 3 , and by W in the case of a v 
T is remarkable for the smallness of the seasonal variation in the phase angles, 
especially in the case of a 2 . 
Table XXXI. contrasts the seasonal and yearly diurnal inequality phase angles in 
years of sunspot maximum and minimum. In the case of a 2 the sunspot minimum 
angle is invariably the greater for both H and V. The same is true of a 3 , except in 
the case of H in equinox, when the sunspot minimum angle is slightly the smaller. 
The same rule is observed by a 4 in H, except in summer ; but in V the sunspot 
maximum value of a 4 is the larger, though its excess is generally small. The sunspot 
maximum value of «i is the larger in summer and winter in H, and in all cases 
in V. 
Table XXXII. shows the difference between the phase angles found in the present 
paper for ordinary days and those found in a previous paper* for quiet days. It gives the 
excess of the ordinary day over the quiet day phase angle converted into time at the 
rate of 1 hour = 15° in a h 30° in a 2 , 45° in a 3 , and 60° in a 4 . The plus sign is equiva¬ 
lent to an earlier occurrence of phenomena in ordinary days. The values under the 
seasons, it should be noticed, are from the seasonal inequalities, and are not arithmetic 
means from the months included. 
The outstanding feature is the preponderance of plus signs in the case of the 24-hour 
term in V, and the large size of most of the differences from this term. 
* ‘Phil. Trans.,’ A, vol. 202, p. 335. 
