448 -Transactions. — Miscellaneous. 



prophets, it is not for us to forget or disparage our own, the 

 highest of whom may fairly rank above statesmen or men of 

 science, and who are— it is not too much to say — a century 

 in advance of the great body of their fellow-men. 



Art. LXII. — Observations on Rainboivs. 



•By E. Coupland Harding. 



[Read before the Wellington Philosophical Society, 7th December, 1892.} 



So many conditions are necessary for the appearance of a per- 

 fect rainbow that the sight of one is really very rare. The sun 

 must be shining clearly in one quarter of the heavens, and in 

 the opposite quarter there must be an unbroken rain-cloud 

 screen of sufficient extent for the projection of the bow. In 

 nearly all cases one or both bows are only fragmentary. I 

 have not the knowledge of optics necessary to deal with the 

 subject in a scientific manner, and only wish to note some 

 unusual phenomena in connection with rainbows, of a kind not 

 provided for in popular text-books. 1 should like to know if 

 others have observed similar appearances. That they may, if 

 they watch for them, I do not doubt. Usually one sees no 

 more than one looks for or expects to see, unless for some 

 reason special attention is given to the object observed. 



The ordinary primary and secondary rainbow of the text- 

 books are familiar to us all. But the first point I would note 

 is that the closest observation often fails to detect any sign of 

 the secondary rainbow, even when all the conditions are 

 apparently favourable for its appearance. 



About three years ago, in Napier, looking at an unusually 

 brilliant rainbow, I was struck with the great breadth of the 

 band of colour. Looking more closely, I saw that the spectrum 

 was double. This was also the case with the portion of the 

 secondary rainbow which was visible at the time ; but in this 

 case the additional bands were so faint that I should not have 

 seen them had I not been led to look for them through having 

 noticed them in the primary bow. 



Shortly afterwards, looking at another bow, I was unable 

 to discern the second series of colours either in the primary or 

 secondary ; but, to my surprise, I distinctly saw a tertiary 

 bow, the colours, as might have been expected, following the 

 order of the primary. 



Both of these phenomena — the double series of colours in 

 one bow, and the tertiary bow — I noticed on other occasions 



