258 Mr. Brougham's Experiments and Observations on 
the white image on the chart (the hole being \\ inch in dia- 
meter) was surrounded by two rainbows, pretty broad and 
bright ; in the colours were red on the outside, and violet next 
the white of the image. These bows must not be confounded 
with one which sometimes appears wholly of a dull red and 
yellow, when the sun or moon shines through a cloud, and 
which is owing to the direct transmission of the red rays and 
reflection of the others ; for not only are the colours different 
in species, in brightness, and in number, in the phenomena 
under discussion, but likewise they are formed by the hole in 
the window, as I knew by altering its shape into an oblong ; 
and the colours now were not disposed in circles, but in broad 
lines of the same breadth as the bows had been, running along 
the shadow of the hole's sides, and in the same position of co- 
lours as before. It is evident that their cause is the inflection 
of the light which comes from the clouds by the sides of the 
hole (for if the sky have no clouds the colours do not appear), 
which separate the white light into the parts of which it is 
composed. 
7. It is observable, that when we look at any luminous 
body, at a distance greater than one or two feet, its flame ap- 
pears surrounded by two bows of faint colours, the innermost 
of them terminating in a white which continues to the flame ; 
and the colours are red outermost, and green and blue inner- 
most : the appearance is most remarkable if we look at a small 
hole in the window-shut, the room being otherwise dark ; and 
if the eye be pressed upon, and then opened, the colours are 
more lively than before, as Des Cartes observed ;* from 
which both he and Newton concluded, that the appearance 
* De Meteoribus. 
