29 



University Observatory, Christiania, in 1871, February 22nd,. 

 March 1st, May 10th ; 1874, January 13th ; 1875, February 

 17th ; 1882, Jamiary 11th, February 22nd, July 13th ; 1884, 

 December 8th, 9th, lOth, and 12th. 



The following is an extract from the observations of Chris- 

 tiania, January 11, 1882: — "At 3.30 p.m., sun having set 

 at 3.20, extremely beautiful cirro-stratus iridescent clouds- 

 in south-west, at' an altitude of 8° to 12° were seen. The 

 upper borders, and later on the lower borders, were red,, 

 with yellow brims, the red of the borders and the inner 

 parts were variegated, and very variable, resembling the 

 red light commonly seen in mother-of-pearl. This changed 

 through crimson into blue-green, and then into grass-green. 

 The most striking cases of the phenomenon have been observed 

 here when mild and dry weather set in after frost." 



The extracts from my own notes also show that these clouds 

 occur frequently. Thus : — 



" In 1884, June 12, D.B., 78°; AY.B., 67° ; iridescent* clouds, 

 and fine glow. 



"June 15, D.B., 83°; W.B., 56°; iridescent clouds, beautifully 

 tinted. 



"In 1885, January 16, D.B., 80°; W.B., 61°; edges of clouds 

 tinted pink, with green farther in. The red extended beyond 

 the edge, like the red glow seen above the horizon ; clouds of a 

 heavy cumulus kind. 



"January 26, D.B., 70°; AY.B., 58°; iridescent clouds, very 

 fine, all being high cirro-cumulus. 



"January 28, D.B., 71°; W.B., 55°; barometer falling, very 

 short glow in morning, faint clouds, and an ice-cloud halo visible 

 nearly all day ; the green very bright ; clouds were very high 

 cirro-films. Iridescent clouds seen about 10 a.m., just before 

 halo formed. 



"January 30, D.B., 80°; W.B., 60°; iridescent clouds like 

 Herschel's present. The light appeared to be polarised in 

 planes tangential to the sun ; colours very varied. A fine pink 

 halo existed round the sun. 



"February 21st, D.B., 71°; W.B., 62°; clouds rather high, 

 clearing off towards noon ; beautiful pink halo round sun ; 

 iridescent clouds appeared ; fine glow, and afterglow in the 

 evening. 



"March 9th, D.B., 71°; W.B., 58°; iridescent clouds of filmy 

 character, halo very pink ; splendid afterglow in evening ; not 

 very fine in the morning. 



"March 10th, D.B., 75°; W.B., 61°; barometer falling, tem- 



* In my original notes I described these clouds as Herschers clouds but 

 have here termed them iridescent clouds for the sake of uniformity. — 

 W.A.J. 



