292 



Dr. W. J. S. Lockyer. 



Since these numbers cover more than a complete cycle, they may be 

 combined so that mean values for the intervals minimum — maximum 

 may be obtained for those epochs when the intervals have their 

 largest, intermediate, and smallest values. Thus in the years 1843 

 and 1879 the maxima followed the minima in 4 - 77 and 5*25 years 

 respectively, the mean interval thus being 4" 91 years. For the inter- 

 mediate stage (combining (3) and (6) ) a value of 4 - 03 years is found, 

 while for the minimum interval combining (1) and (4) this value 

 3-32 years. 



The actual epoch of maximum relative to the preceding minimum oscillates 

 about the mean value, its greatest amplitude being in the mean - 8 year. 



The Total Sunspot Areas, Minimum to Minimum. 



The great divergence in the amount of spotted area during consecu- 

 tive eleven-year cycles suggested that perhaps this periodical retarda- 

 tion of the maxima with respect to the each preceding minimum might 

 be accompanied by variations following the same law. It was observed 

 that when a maximum occurred comparatively soon after a minimum, 

 the tendency of the whole spotted area for that sunspot period was to 

 be increased. 



I have been permitted for this inquiry to utilise the values which 

 have quite recently been obtained at the Solar Physics Observatory 

 from a new reduction of the curve representing the solar spotted area, 

 and these values, representing the total spotted area in millionths of 

 the Sun's visible hemisphere from minimum to minimum, are given in 

 the last column of the following table : — 



Simspot period from 



Total spotted area. 



From minimum 



to minimum. 



1833-9 



1843 -5 



86 003 



1843 -5 



1856 -0 



85 201 



1856 -0 



1867-2 



111 514 



■ 1867 -2 



1879-0 



126 188 . 



J.879 -0 



1890 -2 



78 353 



1890 -2 



1901- + 



96 734 + 



The figures in the last column show a similar but inverted sequence 

 to those in the previous tables. Thus from minimum 1867'2 to the 

 following maximum 1870'6 we have a short interval of time; the 

 spotted area for that period is greatest. If the above values in the 

 last column be graphically .shown, and the curve inverted, we have a 

 remarkable similarity (fig. 2, Curve D) to the two curves B and C 



