the Inflection, Reflection, and Colours of Light. 243 
at the other ; yet still this only confused the colours of the 
image, without changing them. Farther, if the prism was 
moved on its axis, the violet was lifted higher than the red or 
any of the other colours. Nor was the constitution of the co- 
lours at all changed by reflection from a pin or mirror, except 
in so far as they were mixed by a concave one, as mentioned in 
the last experiment. If a pin was held behind the hole to re- 
flect the colours, it formed other images of the colour in which 
it was held, and, as far as I could judge, threw the red to the 
greatest distance, and breadth, and inclination. Nor were the 
colours of the image changed by reflection from natural bo- 
dies, for these were all of the colours in which they were held, 
but brightest in that which they were disposed to reflect most 
copiously. Likewise the rings of colours made by thin plates 
were broadest in the red, and narrowest in the violet; and the 
like happened to the fringes that surround the shadows of 
bodies. Lastly, the shadows of bodies were themselves broad- 
est in the violet, and narrowest in the red. 
Obs. 8. I filled with water a glass tube, whose diameter was 
■Jth of an inch, and consequently the radius of curvature -fth, 
and whose sides were ^th of an inch thick ; then standing at 
four feet from a candle, I held the tube ^th of an inch from 
my eye, so that the light of the candle might be refracted 
through it, and moved my eyelids close enough to prevent 
the extraneous scattered light from entering along with that 
which was regularly refracted. I saw several images of the 
candle all highly coloured, and the colours were in order, from 
the candle outwards, red, orange, and so on to violet ; I then 
filled the tube with clear diluted sulphuric acid, and dropped 
a small piece of chalk to the bottom, when immediately 
I i 2 
an 
