54 Notes upon some Atmospherical Phenomena [No. 1. 



The bank of cloud becomes suffused with a shining opalescent 

 light, too delicate to be described either by words or by colours ; 

 mingled with this opalescent tinge, distinct prismatic streaks or 

 bands are observed following the order of the prismatic colours as 

 arranged in the rainbow, but only displaying the three primary 

 colours, viz. blue, yellow and red, which are repeated over and over 

 again in succession. 



The finest bank of this description I ever saw, was upon the 9th 

 August, 1852 ; when standing upon the Singaleelah range at an 

 elevation of 12,000 feet above the sea, I looked down upon a bank 

 of snow-white cumuli that were about 5,500 feet below me, in the 

 Nepal Territory. The Thermometer stood at 58°. These appear- 

 ances so soft and delicate, last but a few minutes and then disappear. 



It is an axiom in optics that a rainbow cannot be seen unless rain 

 is falliDg between the spectator and that part of the sky which is 

 opposite to the sun ; the following description of a rainbow seen by 

 me requires more explanation than I am capable of giving to it, to 

 account for its appearance and anomalous position. 



Upon the 25th September, 1852, at 2 p. m. Ther. 68° whilst 

 standing at an elevation of 7,165 feet above the sea, the heavens 

 partly overcast by heavy cumuli, and looking down in a North 

 Easterly direction into one of the deep valleys, I perceived at 3,000 

 feet below me and two miles distant, a magnificent rainbow follow- 

 ing for about one mile the exact wavy outline of the crest of a slop- 

 ing mountain ; the colours being, a very brilliant violet nearest the 

 spectator, and then a dark and very vivid green, then yellow, red, 

 then yellow ; and upon the next mountain another red was 

 shown ; the trees in the forest, the Native clearances and their 

 houses were all seen bathed in these vivid colours, but there was no 

 apparent rain falling, only a brightly transparent mass of cumuli 

 was passing over the sun, which obscured my position, whilst the 

 bow and the mountain upon which it was projected were in bright 

 sunshine. 



The colours of the bow were far more brilliant than those seen in 

 the brightest usual rainbow. 



