TABLE 16. Relation between Auroral Intensity and Mean .Magnetic Character Number. 



( 'iijir /''runs, 1911. 



Cape Adare, 1911. 



This Table (and figs. 5 and 6) shows most clearly that, in the case of aurora' <>l 

 the first two classes (brightness above normal), there is a real relation between 

 brightness of aurora at a station and mean magnetic character number at the same 



O 



station in the same hour, the correlation between diameter number and bright:- 

 of aurora being greater, the greater the auroral intensity, but inappreciable for aurora 

 of less than average brightness. 



The Table further brings out the point that the maximum mean char.ieler number 

 at Cape Evans occurs at about the same time as the maximum of bright aurora' a1 

 Cape Adare, some 400 miles distant. 



Fig. .3 shows most clearly that the correspondence between even the brilliant 

 aurora.- and magnetic disturbance at the same hour is slight in comparison with the 

 correspondence between yr/Ws of brilliant aim me and in rimls ol' magnetic disturbance. 

 Though there is a real correspondence between the two Ivnes of disturbance of tin- 

 lowest classes, this correspondence is not particular, but general, and refers to the 

 period, not to the particular hour of observation. 



* The figures in this class arc- too few to ^ivc a nood mean i-lmraetrr number. In the case of ilie 

 Cape Ailav observations, it has been assumed that loeal time at Cape Adare and time of the isuth 

 meridian differed by exactly 1 hour ; if the maximum auroral display enincided with maximum maynetie 

 disturbance, the mean character number would be greatest between liour- (/<) and hours (/( I). 



37 



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