25R DR. C . CHKKK: SOME PHKNO.MKNA OF SUNSPOTS 



,,,,lik,-ly be iiuite as satisfactory. As an example of the methods actually used, take 

 tin- data f..r days 52 to 57 in Table IV. The maximum obviously comes between 

 days 54 and 55, say at 54+ a 1 . Assume the slopes from the maximum down to days 

 ;,1 and 55 to be the same, and to be the arithmetic means of the slopes from days 

 :>:! and 54 (129 per diem), and from days 55 to 56 (151 per diem). 



Then we have 



454 + 140Z = 403 + 140 (1-x) 



or 



x = 0'318. 



Thus twice the period is 54 '3 18 days, i.e., the period is 27 '16 days. 



If we take the same days, but assume the slope on the two sides of the maximum 

 to Ixj the mean of those from days 52 to 54 and from days 55 to 57, the only difference 

 is that we replace 140 in the above calculation by 141, and again find for the single 

 period 27' 16 days. 



Treating the data for days 79 to 84 in the same way, taking first the arithmetic 

 mean of the slopes from days 80 to 81 and 82 to 83, and then the arithmetic mean of 

 the slopes from days 79 to 81 and 82 to 84, we get as estimates for the triple period 

 81*29 and 81*31 days, both giving 2710 days for the single period. 



12. An inspection of fig. 2 suffices to show that the ratio borne by the maximum 

 ordinate of the first associated pulse whether for disturbed or quiet days to the 

 maximum ordinate of the primary pulse is notably less than the ratio borne by the 

 maximum ordinate of the second associated pulse to that of the first. These ratios 

 and those between the maximum ordinates of the several associated pulses are fairly 

 alike, whether we take subsequent or previous days, and whether we take disturbed 

 or quiet days. Thus the most accurate information on the subject is probably that 

 derivable from the data in the last line of Table IV. The ratios between the successive 

 maximum ordinates deduced from the data in question are as follows : 



The maximum ordinates of the first, second, and third associated pulses stand to 

 one another almost exactly in the ratio 3:2:1. It is easily seen in fact in fig. 2 

 that the summits of corresponding first, second, and third associated pulses lie nearly 

 on straight lines, which, if produced, would cut the zero line at points answering 

 roughly to days 110. This linearity in the summits cannot well represent the true 

 phenomenon exactly, because it would imply that no finite associated pulse existed 

 except those shown in fig. 2, whereas there can be but little doubt that if data existed 

 for a really long series of years, pulses could be recognised considerably beyond the 



