BETWEEN SUN-SPOT FREQUENCY AND TERRESTRIAL MAGNETISM. 165 



The calculated values of H and V employed in Table VIII. for the inequality 

 ranges were taken only to the nearest ly, because the Pawlowsk tables go no nearer 

 than this; but in the "all" days' D and I, both tables and calculation go to /- 01. 

 The agreement between calculated and observed values is much closer in D, H, 

 and I than in V ; and in D and H it is considerably closer for the " all" day than the 

 "quiet" day results. Probably this only means that the fewness of the "quiet" 

 days (sometimes only two or three a month) introduces an element of uncertainty 

 which more than neutralises the effect of the greater regularity in these days. 



16. If the range of magnetic elements were largely dependent on influences 

 which did not proceed pari passu with sun-spot frequency, then what we should 

 expect to see in Table VIII. would be a notable occurrence of large -\- values in all 

 the elements in some years, and of large values in other years. The same result 

 would follow if, while an intimate connection subsisted, it were not of the linear type 

 assumed in (l). 



So far as the inequality ranges in D, H, and I are concerned, there is no 

 indication of such a phenomenon. There is indeed an excess of -4- signs from 1890 

 to 1894 and of signs from 1895 to 1899, but the differences themselves are small, 

 and those for the " all " and the " quiet " days show no kind of regular relationship. 

 In the case, however, of the "all" day V inequality, and of the absolute daily ranges 

 for all the elements, especially H and V, the observed values are conspicuously in 

 excess of the calculated in 1892, and as conspicuously below them in 1893. This 

 phenomenon seems due beyond a doubt to the influence of the disturbance 

 element. 



17. With a view to further elucidation of the phenomenon described in the last 

 paragraph, I have placed side by side in Table IX. data as to the mean value for 

 each year of a variety of quantities which are affected in different degrees by 

 magnetic disturbance. The small figures in brackets attached to the annual figures 

 show the position which the year in question would occupy on a list which followed 

 the order of magnitude of the quantity in question. If two yearly items are equal, a 

 common number is attached. In the case of the years themselves, the attached 

 figures indicate the order when the arrangement follows sun-spot frequency. It 

 should, however, be noticed that the excess of sun-spot frequency in 1898 over 1897 

 was very trifling, and that the differences between 1899, 1900, and 1890 were not 

 large. 



In the case of the diurnal inequalities in D and H, quantities but little affected by 

 disturbance, 1893 heads the list, just as it does in sun-spot frequency. In the case 

 of the mean daily range a quantity more influenced by disturbance 1892 and 1894 

 come to the front, and 1893 falls to the fourth place. Coming to the mean of the 

 monthly ranges, we see 1892 and 1894 still more in advance, while in the case of 

 H and V 1893 stands lower than 1898, a year of less than one-third its sun-spot 

 frequency. 



