AURORAL OBSERVATIONS AT WINTER QUARTERS, CAPE EVANS, 1912. 



Originally it was not intended to discuss the observations of 1912 in view of the 

 restricted opportunities for observation during that winter, caused by the extraordinarily 

 unfavourable weather. As Bernacchi, however, had found that the daily variation 

 of the aurora in 1902 differed from that in 1903 by the suppression of the secondary 

 auroral maximum in the afternoon, it seemed desirable to ascertain if there was any 

 such difference between the years 1911 and 1912. 



The data have, however, been found to be much too scanty for any definite 

 decision to be given on this point. Even in 1911, the number of afternoon observations 

 at any hour was small, and in 1912 the number was even smaller. 



The figures available are given in the Table below for each hour of the day in the 

 period May 13th-July 31st, 1912. The numbers are comparable with those in the 

 last column of Table 5. 



The total number of occasions on which aurorse were observed during this period 

 in 1912 was 108, corresponding to 267 in the same period of 1911. 



In view of the fact that 1911 was magnetically more disturbed than 1912, there 

 is the possibility that the poverty of aurora in the second year owed something to 

 this fact. It is to be noted, however, that the ratio of the number of occasions on 

 which aurora was not observed, though conditions were favourable, to the number of 

 occasions on which aurora was observed at exact hours during the period is almost 

 the same in the two years, suggesting that the poverty of auroral observations in the 

 second year was primarily due to the unfavourable weather conditions. 



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