WHITE LUNAR RAINDOW. 141 



the wind changed to the north-west, from which 

 quarter it continued to blow with considerable, 

 though decreasing force, through the remainder 

 of the day, accompanied with occasional storms 

 of snow and hail. The mercury in the thermo- 

 meter descended gradually to 34°, where it con- 

 tinued stationary during the greater part of the 

 evening; and the barometer, as might be ex- 

 pected, rose rapidly. 



About 8h. 40m. p.m., my attention was arrest- 

 ed by a remarkably well defined arch of white 

 light, beautifully displayed on a dark cloud ex- 

 tending from the north to the south-west: the 

 moon, which shone brightly, was nearly 39 hours 

 past the full, and pretty high above the eastern 

 horizon. 



The phenomenon resembled a solar iris, in 

 every particular, except the absence of prismatic 

 colours : this dissimilarity, however, must not 

 be regarded as a distinguishing characteristic ; for 

 lunar rainbows generally are coloured ; and a de- 

 scription is given in the New Series of the Man- 

 chester Memoirs, vol. III. p. 176, et seq., of an 

 achromatic solar bow. 



How long the arch was visible, I am unable 

 to state, as I did not see its commencement j but 



