1884.] President's 'Remarks on Rainfall, 165 



during the sunspot period. In this paper Mr. Hill puts the actual rain- 

 fall totals through a simple process of smoothing, such as is frequently 

 adopted in dealing with statistical tables. Mr. Pearson takes the un- 

 smoothed totals, and finds that, besides the single oscillation shown in 

 the winter and summer curve during the eleven years of the sunspot 

 period, the winter and summer rainfall show several variations of minor 

 periods, such as might naturally be supposed to be accidental. Mr. 

 Pearson confines his attention to these minor oscillations, and finds that 

 in those years which are years of maximum sunspot, the short period 

 oscillations in the winter and summer rainfall are of the same character ; 

 that is to say, that when there is more winter rain, there is more sum- 

 mer rain, and when there is less of the one, there is less of the other 

 also ; but he finds that in those years, which are years of minimum 

 sunspot, the short period oscillations in the winter rainfall are of opposite 

 character to those in the summer rainfall ; that is, when there is most 

 rain in the winter, there is less during the summer and vice versa. 

 Again, in those years which immediately precede the years of maximum 

 and minimum sunspot the order above pointed out obtains only in a 

 slight degree : in other words, these are years of transition. Mr. 

 Pearson adduces other arguments to show that the above can hardly 

 be the result of accident, and then states that, if this can be established 

 as a general rule, it will be an important one, for it will indicate that, 

 whatever be the cause which produces the general opposition in char- 

 acter between the eleven yearly variations of the winter and of the 

 summer rainfalls, that cause operates chiefly during the years of mini- 

 mum sunspot ; and during three years of maximum sunspot it operates 

 only hr*a very minor degree, and in two of those years (namely, the 

 first and the second) it probably does not operate at all. By thus limit- 

 ing the period during which the cause operates, a valuable point is 

 gained, and a clue to a knowledge of the cause possibly afforded. Mr. 

 Pearson also finds that these rules not only obtain qualitatively, but also 

 quantitatively ; that is to say, that the oscillation which takes place ia 

 not only the same in phase, but is nearly the same in amplitude. 



The President said* : — The relations pointed out by Mr. Pearson be- 

 tween the variations of the summer and winter rainfall, if, as he supposes, 

 they are really the outcome of a general law, are certainly curious. Bat 

 having regard to the amount of the data discussed, and the great local 

 variability of rainfall, it is difficult to resist the impression that they may 

 after all be in some measure fortuitous. To decide this question we should 



* In these remarks some additions have been made to the data actually laid 

 before the meeting. 



