228 Observations upon .Auroral and Optical Phenomena. 



still beneath, fainter and of but half the extent. Below this a third 

 was just discernible. The successive intervals between the interior of 

 the primary and the colored arcs were equal, — each being less than 

 the breadth of the bow. It appeared to me that all were distinct bows 

 lapping upon one another, — the single color above mentioned of the 

 supernumeraries was however alone seen, leaving apparently an un- 

 occupied interval upon each side of it ; probably because the inter- 

 vening colors — being some compound of blue — could but feebly 

 contrast with the cloud itself. The other colors mingling with the 

 superior bows and chiefly with the violet could not be perceived ; 

 except in enhancing the dulness of that color, already mentioned. 



I have at other times seen a single violet supernumerary arch, 

 sometimes exterior and sometimes interior to the primary, but noth- 

 ing in the least comparable to the foregoing. I had imagined also 

 that I noticed the same phenomenon in the spray at Niagara Falls. 



So many supernumerary bows as existed in the case mentioned 

 by me as being visible at Montreal, form a combination of rare oc- 

 currence. The writer of the article " Optics," in the Library of 

 Useful Knowledge, relates the occurrence of the phenomenon to his 

 own view with four successive supernumeraries, — the red of each 

 lower bow mingling with the violet of the bow next above.* The 

 cause of the phenomenon appears yet to be unexplained. 



While on the subject of rainbows, I must not neglect to notice a 

 remarkable attendant upon one of great beauty, which appeared at 

 seven o'clock, A. M. on or about Oct. 25, 1836. From the southern 

 extremity of this bow, and tangent to it where it met the horizon, 

 there arose a vertical column of the same apparent breadth with the 

 bow, and having its colors, according to my recollection, in the same 

 order. The appearance was faint, but too indisputable to be classed 

 as an optical illusion. It did not rise so high as to cut the secondary; 

 indeed, at its upper extremity, it evidently began to have a deviation 

 to the right or towards the primary. This phenomenon was witness- 

 ed by many persons in different situations, and was a subject of gen- 

 eral remark at the meeting of the Connecticut Academy in the eve- 

 ning of the day. 



* Whether the supernumeraries seen by myself were four in number, or only 

 three, would depend upon the question whether the colored arcs were to be esteem- 

 ed violet or red, — a point respecting which I had expressed myself doubtfully 

 in my minutes. 



