402 DE. C. CHREE: AX.VLYSIS OF RESULTS FROM THE KEW MAGNETOGRAPHS 
The years 1892 to 1895 stand out as years of largest magnetic ranges, but their 
superiority is not quite so prominent as in the case of sun-spot frequencies ; 1890 shows 
a distinctly smaller sun-spot frequency than any of the 10 following years, but the 
mean magnetic ranges in 1890 appear slightly greater than in 1899 and 1900. In 
these two latter years, somewhat curiously, the mean percentages are alike in the 
case of both D and H. The rise to the maximum is more sudden for magnetic ranges, 
as well as for sun-spot frequency, than the subsequent decline. This phenomenon 
has been remarked on by Mr. Ellis and others. 
It will be observed that the percentages in Table XXXIV. show a wider range 
than in Table XXXIII. The full significance of this will appear presently. 
Curves illustrative of Sun-Spot Relations. 
§ 45. In the tables devoted to the diurnal inequalities of D, H, N and W the 
mean inequality for the year is shown not merely for the combined 11 years, but also for 
two groups of years, viz., 1890, 1899 and 1900, representing small sun-spot frequency, 
and 1892 to 1895 representing large sun-spot frequency. The great excess of the 
ranges and the sums of the 24 hourly differences in the second group as compared to 
the first is conspicuous, but at first sight there is no appreciable difference in the 
nature of the inequalities shown in the two cases. Fairly definite though minor 
(tifi 0 j‘ 0 nces do however exist. If the amphijude of the diurnal inequality alone varied, 
then curves representing the inequalities for the two groups of years in the ordinary 
way should transform into one another by merely changing the scale of ordinates, and 
the same should be true of the difference curve, whose ordinates represent the excess 
of the ordinates of the sun-spot maximum curve over those of the sun-spot minimum 
curve. A glance at the curves for D and H, in figs. 18 and 19, shows that this is 
not the case. The difference curves, due allowance being made for their smaller 
amplitude, are very decidedly flatter topped than the curves for either group of 
years. The same phenomenon would be equally shown by N or W curves. 
§ 46. Perhaps an even better way of showing the difterence in the diurnal 
inequalities to the eye is to employ vector diagrams. This has been done m figs. 20 
and 21. In fig. 20 the mean vector diagram for the whole year has been drawn from 
the same origin for the two groups of years, while fig. 21 represents a difteience 
vector diagram whose radius vector is the difference between corresponding radii 
vectors in the two curves of fig. 20. The scale in fig. 21, it should be noticed, is 
double that in fig. 20. The mean magnetic meridians for the two groups of years are 
not absolutely identical, but could hardly be shown apart on the scale of the 
figures. 
§ 47. If the sole difference between the inequalities in years of sun-spot maximum and 
sun-spot minimum were one of amplitude, then the points answering to the same houi 
