.,-, DR. C. CHREE: SMMK I'HKNaMKNA OF SUNS POTS 



,.\| ..... t.-.l .. marked difference if the proximity of the spot supposed to 

 disturbance to the central meridian had been an important element. 

 Win. n:i:'s frequencies give results of (he same general character as spot areas, but 

 tin- percentages are decidedly smaller. Also the percentages in the last two lines 

 derived from the Wolfer frequencies are less symmetrical with respect to column n, 

 IKMIIJJ distinctly larger for the previous than for the succeeding days. This a-symmetry 

 is still more developed in the percentages based on facuhe. 



On the average of the five years, the maximum magnetic disturbance was 

 preceded by two days by the Wolfer frequency maximum, and by at least four days 

 by the maximum faculse area. 



On the average highly disturbed day, the faculae area was almost exactly normal. 



Whether we take spot areas or frequencies, 1906 shows a markedly diminished 

 solar activity for days 2 to n + 3 ; and 1910 -a year of small solar activity and 

 very quiet magnetically is the year which most strongly suggests a parallel variation 

 between magnetic disturbances and solar activity. 



20. It appeared desirable to ascertain the extent to which a 27-28 day period of 

 the type here considered manifests itself in sunspots themselves. The selected days 

 of the investigation were the five days of largest projected spot area in each month 

 of the five years 1906 to 1910. Projected spot areas were entered in the columns for 

 days n-30, n-28, n-27, n-25, n, n + 25, n + 27, n + 28, and n+30. That seemed 

 likely to be a sufficient choice of days to show the nature and amplitude of the 

 anticipated phenomenon. The results obtained are given in Table XII. In the first 

 five lines the projected spot areas are expressed in terms of the Greenwich unit. 

 The five subsequent days associated with the five selected days of December 1910 had 

 to be omitted, so the entries for columns n + 25 to n + 30 in that year were based on 

 55 days oidy. 



The results for the 300 (or 295) days included in each column were summed, and 

 each sum was expressed as a percentage of that for the normal day. 



The last line in Table XII. gives for comparison corresponding results calculated for 

 the first previous and first subsequent pulses in " character " figures, the selected 

 days ?i in this case being those of maximum " character" for the sixty months of the 

 five years. 



If we take a mean from the previous and subsequent pulses in Table XII., the 

 largest excess above the normal in the first subsidiary pulse bears to that in the 

 primary pulse the ratio 27 : 122, or 0'221 : 1, for the spot areas, and 21 "5 : 98, or 

 1, for magnetic " character." This is a very striking resemblance. It did not, 

 however, extend to individual years. Thus the previous and subsequent sunspot area 

 curves were better developed in 1907 than in the other years, but the development 



the previous "character" pulse was best in 1908, and that of the subsequent 

 " character" pulse was better in 1908, 1909, and 1910 than in 1907. 



A noteworthy difference is that the crests of the subsidiary sunspot area pulses in 



