AND OF TERRESTRIAL MAGNETISM. 



269 



u + 4 to 7i + 9, and three days in columns n+10 and w-f II, fell in 1911. As no 

 siins|Hii data for 1911 \vciv availalili-, \\liil.- sutis|xt areas in December, 1910, were 

 veiy small, it was decided to treat the few days specified as spotless. The percentage 

 figures in columns u + 4 to n+11 may thus !* slightly too small, hut the error* is 

 unlikely to exceed <>'_'. 



The highest and lowest percentage's in the table are in heavy type. 



Table IX. appears at first sight to demonstrate a very definite relationship between 

 contemporaneous suns]x>t area and magnetic disturbance. It shows a regular pulse 

 in siinspot area whose crest ataolutely synchronises with that in magnetic " character." 

 The form however of the two pulses is widely different. This is readily seen on 

 consulting fig. 3, which represents graphically the sunspot figures in Table IX., and 



130 



Swnspot Area, 

 o MagrieCic Character. 



n-20 



zoo 



ta 

 o 



150 



o 

 o 



1 



<3 



H- 

 O 



100 



w-no 



the corresponding " character " figures expressed as percentages of the mean 

 " character " figure for the 5 years. The ordinate scale, it should be noticed, is 

 five times as open for the sunspot areas as for the magnetic " character." The 

 " character " percentage is above 100 only on 5 days, rising from 87'6 on day n 3 to 

 T.iS'2 on day n. The sunspot area, on the other hand, is above its mean from days 

 n 6 to + 8 inclusive, and the change from column to column is very gradual 



* July 2, 1913. The correction required is +0'1 from day n + 7 today n+ 11. 



