V.— CHEMISTRY AND PHYSICS. 



Akt. L. — Notes on the Aurora in the Southern Hemisphere. 



By Henky Skey. 



[Read before the Otacjo Institute, 8th July, 1902.} 



The advances which have been recently made by European 

 observers in their endeavours to discover the " secret of the 

 aurora" will, I trust, be considered as sufficient excuse for 

 giving a special description of a peculiarity of appearance 

 which the aurora sometimes exhibits in southern latitudes, 

 more especially as this phenomenon in its completeness has 

 not hitherto been described. The most brilliant display 

 was witnessed on the 18th March, 1870, at Dunedin, New 

 Zealand, at 8.30 p.m. From recorded observations at that 

 time, arches of clear white light were first observed extending 

 from east to west, and stretching like bands across the whole 

 of the southern portion of the sky, the summit of the highest 

 and largest arch being somewhat south of the zenith. This 

 highest arch then appeared gradually to enlarge by moving in 

 a lateral direction untii it crossed over the zenith, when by 

 continuing this motion it formed a lower arch on the northern 

 side of the zenith. These arches were then observed to 

 gradually increase in number until they formed symmetrical 

 bands of light across the whole sky, the eastern and western 

 points of the horizon forming as it were pivotal centres. 

 This display lasted fully two hours ; no coruscations were 

 detected, the bands remaining perfectly steady with the ex- 

 ception of the slow lateral movement alluded to. The moon, 

 which had a small halo round it, was near full at the time, 

 and not far from the eastern extremity of the bands, but 

 higher and more to the northward. The sky was free from 

 clouds, and the air calm. On this occasion the ordinary 

 characteristics of auroral light were entirely absent, there 

 being no polar illumination nor coruscations radiating there- 

 from (but aurora was generally observed in New Zealand en 

 the 12th, 18th, and 22nd, and in New South Wales on the 

 22nd). 



It was otherwise, however, with the fine display ot polar 

 aurora which occurred on the 23rd November, 1870, when 

 similar arches or bands of light were observed at the same 



