270 !;. Q niKKK: SOME PHENOMENA OF RUNSPOTS 



throughout. Thus there is nothing in the observed sunspot variation to account for 

 the rapidity of the variation in magnetic " character." 



Taking the individual years, the largest sunspot area occurred in 1906 in column 

 n-7, in 1907 in column +3, in 1908 in column n + 10, in 1909 in column n-2, and 

 only in 1910 a year of small sunspot area did it occur in column n. Thus the 

 occurrence in column n of the highest percentage met with in Table IX. is a fact of 

 somewhat doubtful significance. A considerably longer series of years would be 

 required to give a result whose representative character could be relied on. 



18. In S.M., in the comparison made between sunspot area and magnetic 

 " character," the representative, days n were the days of largest spot area. On the 

 average of the 11 years 1890 to 1900, magnetic "character" was below its mean 

 from days n 7 to n inclusive, and above its mean from days n + l to w + 11. The 

 highest " character " figures appeared in columns n+4 to n + 6, that in column n + 4 

 being slightly the highest. In this case the sunspot area (primary) pulse was much 

 more concentrated than the " character " (secondary) pulse, and there was a marked 

 "character" crest in columns n-12 to n-W, but little inferior to that in columns 

 n+4 to n + 6 to which nothing in sunspot areas corresponded. Thus the apparent 

 connection between magnetic " character " and sunspot area was much more 

 ambiguous than that between H daily ranges and sunspots. Still the 11 -year mean 

 " character" figure in column n + s was very decidedly in excess of that in column 

 ns, for all values of s from 1 to 7, and the natural inference was that in the 

 average year there is a distinct tendency for maxima in magnetic disturbance to 

 follow maxima in sunspot area. Thus one would have expected to find in Table IX., 

 not an array of figures symmetrical about column n but a decided excess of the figure 

 in column n * over that in column n + s for small values of s, the largest value 

 occurring prior to day n. 



It was obviously desirable to ascertain whether the departure from the result 

 anticipated represented a real difference between the two periods dealt with, or arose 

 from the difference in the procedure followed. Accordingly a second investigation 

 was made, adopting the same procedure for 1906 to 1910 as had been followed in the 

 case of 1890 to 1900, the selected days n being now the 5 days of largest projected 

 spot area in the month. 



The calculations were made for the " character " figures assigned at Kew alone, as 

 well as for the international choice at de Bilt, in view of the possibility that the 

 results for 1890 to 1900 in S.M. might have been influenced by some peculiarity in 

 the choice of Kew " character" figures. This contingency could be provided for only 

 in part, because the date at which "character" figures were assigned to the years 

 1890 to 1900 was subsequent to 1910, and undoubtedly 2's were more freely given 

 than in dealing with the years 1906 to 1910. During the latter 5 years 2's were 

 given only 48 times at Kew, as compared with 37 times at Greenwich ; whereas in 

 1911 the number of 2's was 38 at Kew, as against 6 at Greenwich. The Kew 



