however, remarkable in that neither maximum nor minimum azimuth is very clearly 

 shown. As will be seen later, the time when aurora) are most likely to be seen at high 

 altitudes (the hour at which aurora is most likely to be reported simultaneously in 

 all sectors) is also near this time. 



As at Cape Evans, aurora? are seen in the sectors of maximum frequency even at 

 times when aurora are least likely to occur, appearing in the minimum sectors, however, 

 only at times of extensive display. 



6. DISTRIBUTION OF AURORA WITH RESPECT TO TIMK. 



The analysis of all observations at Cape Adare with respect to both azimuth and 

 time has been shown in Table 10. As before, it will be seen that for almost all hours 

 of the day, the distribution of aurora in azimuth is the same as for the whole day. 

 Further, in each sector, there is evidence of two maxima with a minimum between 

 them at about 22 hours. Usually, the chief maximum is at 4 or 6 hours, with the 

 subsidiary maximum at 20 hours, though in the case of the sector N. to N.E., the 

 relative importance of the two maxima is reversed. Another point which seems to be 

 of interest is the fact that the morning maximum occurs somewhat later in the sectors 

 lying between south and north-west. Though the evening maximum is usually less 

 pronounced than the morning one, it is certainly very definitely indicated. It will be 

 observed that in the evening the number of aurorse between north-east and north-west 

 is generally greater than in all other sectors combined, though this is far from the 

 case during the morning hours. 



As in the case of the Cape Evans observations, the last two columns give the 

 number of occasions on which aurora? were seen in any sector, and the number which 

 is the sum of all the numbers referring to the various sectors. The figures in the 

 penultimate column, therefore, correspond to the figures in the last column weighted 

 by a number representing in some measure the extent of the aurora. Though both 

 chief and subsidiary maxima are indicated in both columns, the maxima are most 

 pronounced in the penultimate column, indicating that at times of maximum frequency 

 of aurora, the aurora is also of greater extent. 



7. DIURNAL FREQUENCY OF DIFFERENT TYPES OF AURORA. 

 (a) Aurora of 70 Altitude or over. 



In the period May 26th to July 31st, aurora? were seen on 148 occasions at an 

 altitude of 70 or over. The analysis of these observations, which includes all 

 observations during this period (not only those at even hours), shows a most definite 

 maximum in the period 2-4 hours, an even more striking maximum between 18 and 

 20 hours (though of smaller amplitude), followed by a very definite minimum between 



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