1854.] observed at Darjiling in the Himalayah Mountains. 51 



Mariotte, Arago, Herschell and others have referred the appear- 

 ance of corona or halos to the refraction and reflection of minute 

 crystals of ice, floating in the atmosphere. 



This grand picture lasted about a quarter of an hour and was suc- 

 ceeded by heavy rain at Darjiling, and a fall of snow upon the 

 higher and neighbouring peaks. 



In the next phenomenon witnessed, a totally different arrange- 

 ment of colours to the last, consequent upon the refrangibility of 

 light when passing through a bank of frozen clouds was observed. 



On the 21st September, 1852, at 6-45 a. m. Thermometer 62°. 

 The heavens to the East were overspread with fleecy cirro-cumuli 

 at an elevation of five miles ; beneath the cirro small, light and 

 transparent cumuli occupied a lower region at a probable elevation 

 of 10,000 feet. Upon the frozen clouds above and a little to the 

 South of the sun, there was projected a portion of an arc whose 

 radius might be 35° of the most brilliant and vivid colours, the 

 edge away from the sun being yellow, and the edge nearest to the 

 sun red ; the intermediate space being occupied by a combination 

 of all the prismatic colours, not a perfect amalgamation of the co- 

 lours, otherwise the colour would have been white, but small 

 particles of each colour appeared sparkling and wavering like the 

 colours seen upon the inside of a pearl oyster shell. 



At the lower end of the main segment, a distorted but very brilli- 

 ant corona, was joined to it at an angle of 35°. This latter corona 

 was about one-half the width of the larger segment, but much longer 

 and with a similar arrangement of colours. Its shape, which re- 

 sembled an S, threaded its way amongst a series of light flying 

 cumuli until it disappeared amongst the small cirro-cumuli of the 

 back ground. 



A light easterly wind was blowing at the time with a drifting 

 scud below the cumuli which occasionally obscured portions of the 

 brightly-coloured coronae. The two coronse had a gentle motion 

 towards the South. 



The group was seen between the sun and spectator, and lasted 

 twenty-five minutes. 



The planet Venus shone brightly the whole time between the two 

 coronse. 



H 2 



