﻿244 Intelligence and Miscellaneous Articles. 



length which is cut off on the normal to the surface by the adjacent 

 level-surface. 



(7) If on a surface of greatest brightness which encloses the 

 whole of the sources of light electricity is so distributed that its 

 density is everywhere proportional to the brightness prevalent there, 

 the electricity on this surface would be in equilibrium if it were the 

 surface of a conductor. — Poggendorff's Annalen, No. 9, 1870. 



Munich, April 1870. 



A SOLAR FOG-BOW. BY R. C. CARRINGTON. 



On the morning of November 27, at five minutes to ten, I saw a 

 curious bow formed in a mist which was just rising ; the sun was 

 shining brightly ; and on the principle of our motto, " Quicquid nitet 

 notandum," I took immediate note of it. It was the smallest bow I 

 have seen, not more than twenty-five paces from where I stood, and 

 it measured thirty-five paces from bow to bow. I stept a yard at a 

 pace very nearly. The colour was white, like a lunar bow. But 

 what was more remarkable was the appearance of a centre in which 

 I could see the reflection of my head, which moved as I moved. I 

 remember having seen a centre before in a rainbow, which I witnessed 

 near Cader Idris, in Wales, in July 1847, in a splendid bow of two 

 arches, but which I never mentioned before, having never heard of 

 the like. — Monthly Notices of the Astronomical Society, January 13, 



ON THE REFRACTIVE PHENOMENA OF AN ALCOHOLIC SOLUTION 

 OF FUCHSIN. EXTRACT FROM A LETTER TO PROF. POGGEN- 

 DORFF BY M. C. CHRISTIANSEN. 



Copenhagen, Nov. 18/0. 

 Permit me to inform you that I have been for some time occupied 

 with investigations on the refractive power of red concentrated ani- 

 line (Fuchsine), and have obtained very curious results. Reserving 

 for a future communication further details, I give here the ratios of 

 refraction for an alcoholic solution containing 18*8 per cent, of 

 aniline : — 



Fraunhofer's lines. Refraction-ratio. 



B 1-450 



C 1-502 



D 1-561 



F 1-312 



G 1-285 



H 1-312 



The refraction- ratio increases from B to D and a little beyond, 

 sinks then very rapidly to G, and then again increases. 



This is readily observed by filling a very acute prism with the 

 liquid ; if a luminous slit be looked at through it, the colours are 

 seen in the following order, — violet, red, yellow, in which the devia- 

 tion of the latter is the greatest. The consequences are most easily 

 and beautifully seen when the hypotenuse of a rectangular prism 

 containing the solution is illuminated and the reflected light observed. 

 Then, instead of the colours at the limit of total reflection, coloured 

 light, rose-red, violet, blue, green, are observed under all incidences. 

 — Poggendorff's Annalen, No. 11, 1870. 



