AURORAL OBSERVATIONS AT WINTER QUARTERS, CAPE EVANS, 1911. 



1. SCOPE AND METHOD OF OBSERVATIONS. 



The original plans for auroral observations in the Antarctic included provision 

 for photographic determination of the height of the aurora after the method used by 

 Professor Stormer in the Bossekop Expedition. For this purpose, portable telephones 

 were kindly supplied by the National Telephone Company. Unfortunately, it was 

 decided, after consultation with the photographer of the Expedition, that special 

 lenses and photographic plates would not be necessary for this purpose. Repeated 

 attempts, however, to photograph the aurora at Cape Evans, even with lengthy 

 exposures, gave no results with the plates and cameras available, so this portion of 

 the projected programme had to be abandoned. 



For visual observations of the aurora, an " aurora watch " was established on 

 the April 23rd, 1911, on the return of the various sledging parties. The duties of the 

 watchmen of the night were to take meteorological observations at four-hourly intervals 

 and to make hourly observations of the form, intensity, azimuth, and altitude of the 

 aurora. Any very bright, or otherwise unusual auroral phenomena were to be reported 

 to the meteorologist, and sketches were to be made of bright aurora?, or auroree of 

 unusual form. The whole of the " Afterguard " took turns in the aurora watch in 

 1911. Generally speaking, the watch was continuous only between 6 p.m. and 8 a.m., 

 but commonly embraced the whole of the hours of darkness. Instructions were also 

 given that any of the staff who were outside during the " daylight " hours should jot 

 down in the aurora diary on their return any notes of aurora? they might have wit- 

 nessed. It is possible, however, that this arrangement was not particularly satisfactory, 

 judging by the very small number of observations recorded in " daylight" hours. 



Though an attempt was made to record auroral observations at each exact hour 

 during the darker portion of the day, observations at the exact hour were occasionally 

 missed, but taken a few minutes before or later. For statistical purposes, such 

 observations are treated as if they had been made at the exact hour, and it is unlikely 

 that any appreciable error has been introduced thereby. On other occasions, pressure 

 of more important work has precluded the taking of auroral observations for short 

 periods, but these periods during 1911 were few and far between. On the other hand, 

 a considerable number of additional observations, especially of aurorse of striking 

 character, were recorded at times not falling on the exact hours. Except where 

 specifically stated to be otherwise, such observations have been included in the formation 

 of the Tables. It should be noted, however, that such observations were not recorded 

 except in the case of a " positive " result, and the inclusion of these additional 

 observations will, naturally, have most effect in increasing the number of aurora? of 

 intensity greater than normal. It is, in fact, found that nearly all the intense aurorse 

 are logged as occurring at times other than at an exact hour. 



