ScHAw. — On Tico Triple Boivs seen at InvercargilL 545 



Art. LXIV. — On a Bemarkable Appearance of Two Triple 

 Boios, seen at InvercargilL 



By Major-General Schaw, C.B., E.E. 



[Read before the Wellington Philoso2)hical Society, 20th September, 1893.] 



Towards the end of August last a very remarkable and beauti- 

 ful appearance was witnessed, and carefully recorded by Mr. 

 A. H. Stock, at InvercargilL He was returning home from 

 special work at the bank at eleven o'clock at night when he 

 observed towards the north three consecutive arches of light, 

 the two inner arches coloured, the outer silvery-white. Turn- 

 ing round, he observed a similar appearance in the southern 

 sky, but not so complete as towards the north, as the southern 

 arches faded away and disappeared towards the east. Ap- 

 parently the two sets of triple arches started from the same 

 point in the west, and if the southern arches had been com- 

 plete they would have sprung from the same point as the 

 northern arches on the eastern horizon. The colours seen in 

 the inner arches were in the same order, and were chiefly 

 those at the violet end of the spectrum . 



The night was frosty, and the sky was clear overhead and 

 towards the west, but there was a thick mist all round the 

 rest of the horizon. The moon was gibbous, shining brightly, 

 and about 5° above the western horizon. The appearance 

 lasted for about fifteen minutes, and for a short time a ray of 

 white light appeared shooting upwards into the sky as a 

 tangent to the western end of the northern white bow. 



As far as I am aware there is no record of a similar appear- 

 ance having been observed before, and its explanation is not 

 easy. Clearly the phenomenon was totally different from a 

 lunar rainbow, which would have been seen opposite to the 

 moon in the east. Neither was the appearance due to aurora, 

 for in these southern latitudes auroral displays are seen 

 towards the south, and the most brilliant appearance in this 

 case was seen towards the north, while it vras repeated also 

 towards the south. I think that the key to the solution of 

 the problem is to be found in the observed facts, that it was 

 freezing, and that there was a bank of mist or fog all round 

 the observer, except towards the moon and overhead. It 

 would seem therefore that he was standing, as it were, in a 

 sort of avenue of clear, dry air, bounded to the north and 

 south by walls of frozen mist, and tliat the moonlight was 

 streaming down this avenue ; and by reflections and refrac- 

 tions in the myriads of ice-crystals forming these walls the 

 appearances of the arches were formed. Perspective would 

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