.206 



The scarcity of auroral phenomena in a western direction 

 (over the plateau of South Victoria Land) and its frequency 

 in the Eastern skies (over the Ross Sea and the flat, floating 

 barrier ice) are specially noticeable. 



Auroral phenomena, as seen from Cape Royds, are shown 

 to be most frequent between N.E. and E. 



No doubt the curve is somewhat flatter in the N. than 

 it should be, for it is likely that the short twilight at noon 

 obscures some faint effects. 



6. Diurnal Frequency and Geographic Direction con- 

 sidered Conjointly. 



Account is taken only of the months June, July, and 

 August because of their more complete record. The method 

 of observation practised does not supply data sufficient to 

 make an accurate statement of the exact number of hours 

 during which auroral phenomena were observed in any par- 

 ticular portion of the heavens. 



After a careful analvsis I have, however, been able to 

 prepare a diagram (pi. xx.), which indicates the periods 

 during which auroral phenomena were observed in the various 

 portions of the heavens. The figures represent hours, but 

 are to be regarded as approximately correct in a comparative 

 sense only. The absolute time, it is believed, is really 

 approximately correct, but may range from once to twice the 

 figures given. 



Auroral glows upon the horizon are not included. The 

 periods chosen are two-hourly. The sixteen principal geo- 

 graphic (true-bearing) directions and the zenith are con- 

 sidered. In the case of the latter, aurorae occurring within 

 20° of the zenith-point are regarded as appearing in the 

 zenith. 



The somewhat smaller values for E.N.E. and E.S.E., as 

 compared with those of N.E., E., and S.E., suggest that 

 in logging the more fundamental points of the compass have 

 received from the observer more than their fair share of 

 favour. The curves show at a glance the hour of maximum 

 auroral frequency for each case, and it is to be noted that, 

 generally speaking, this bears a specific relation to the par- 

 ticular portion of the heavens under consideration. For 

 instance, in the S.E. and N.W. the maximum occurs at 

 3 a.m. ; in the S. and N. at midnight; etc. 



Making due allowance for the obscuring effect of daylight 

 and for the daily average maximum and minimum frequency, 

 auroral phenomena, as seen at Cape Royds, favour the 

 portions of the sky which are (a) directed towards, (b) 

 directed away from the sun, having regard for the position 



