54 2 



HIRKELAND. THE NORWEGIAN AURORA POLARIS EXPEDITION, lgO2 1903. 



S"' is the average storminess for the principal maxima. There is one principal maximum for each 

 thirty-day period, and for each principal maximum we have taken the storminess of the five-day period, 

 which contains the principal maximum, and which will be the same for all stations. 



Sf represents the total storminess left when the maximum five-day periods are taken out. We have 



T _ 



m S 



m 



n is the total number of five-day periods in the interval, m is the number of those five-day periods which 

 contain the principal maxima. 



If all storms, large and small, had their centres distributed around the same zone, we should expect 

 S'"ls T t be about equal for all stations. We see from the table, however, that the values of S"'/5 T show 

 great differences, and in such a way that the ratio is smallest for Axeloen and Dyrafjord with the smallest 

 angular distance 6. 



Consequently in beliveen the principal maxima there are a number of storms which have their centra 

 situated nearer the magnetic axis than those of the great storms producing the principal maxima. 



Thus the very great storminess at Axeloen compared with that of the other stations is partly dm 

 to a number of storms, generally quite small, which have their centres to the north of the auroral zone. 



Axeloen also takes up a singular position with respect to the diurnal variation. To show this we 

 shall introduce a quantity, -which we shall call the calmness of the station (c), and which is defined as 

 follows : 



c = 



and 



S T is the total storminess 



Sj for the calm period only 



/ is the length of the calm period expressed in hours. 



TABLE 1C. 



The numerals 1 and II have the same meaning as in table XCVIII. 



The calmness is about equal for Matotchkin-Schar and Kaafjord. For Dyrafjord it is about half 

 the value of the two former stations, and for Axeloen only about Va f tnat value. 



It is very remarkable that this peculiarity in the position of Axeloen as will be seen from the 

 curves, fig. 196 - - is almost entirely restricted to the negative storminess in the horizontal force, while 

 the storminess in the vertical direction follows the same characteristic course as that found for the 



