201 

 II.— SUMMARY. 



1. Frequency in Relation to Sun-spot Cycle. 



The aurorae logged by the "Discovery" Expedition from 

 its base, twenty-two miles to the south, were much more 

 scant than ours. Some allowance should be made for the 

 •difference in locality and also because of the fact that we 

 made a special feature of the auroral observations. Making 

 every necessary allowance, it seems certain that there was a 

 real paucity of auroral phenomena during the stay of the 

 "Discovery" Expedition. 



The year 1908, when our observations were made, was 

 one of abundant sun-spots, though not an actual maxima 

 period. During the years 1902-1903 but few sun-spots 

 occurred. According to Wolfer's lists, the following sun-spots 

 were observed : — 



Year. Sun-spots. 



1902 5'0 



1903 24-4 



1908 ... ' 48-5 



The "Discovery" Expedition found aurorae more preva- 

 lent during 1903 than during the vear of fewer sun-spots, 

 1902. 



The connection between sun-spot and aurora frequency 

 is therefore borne out. 



2. The Annual Variation of Frequency. 



On account of continuous sunlight during December, 

 •January, February, and the greater part of October and 

 March, no aurorae were visible during those months, with the 

 exception of odd streamers logged towards the end of March 

 and early October. During the months of May, June, July, 

 and August, when the sun remained continuously below the 

 horizon and when at the most but a twilight distinguished 

 mid-day, auroral phenomena were seldom absent from at least 

 some part of the sky. Even during the remaining months 

 the darker hours were always accompanied by displays, some 

 of which were the finest noted during the year. Occasional 

 aurorae were seen during bright twilight, indicating that the 

 phenomena continued, though most of the effects would be 

 too weak to overpower the daylight. Each day as evening 

 closed in we invariably expected to witness aurorae as soon 

 as the daylight had faded sufficiently to allow of delicate 

 phenomena being noted. 



Nevertheless, there did appear to be a real direct effect 

 of daylight upon auroral frequency. Considering the dark 



