270 Mr. Brougham's Experiments and Observations on 
vex fibres on the surface of the reflector, and let the ray AB 
be reflected from ef, separated into Br red, and Bz> violet ; 
then if AB was so inclined to ef, that Br and Bz; fell upon er , 
the side of the fibre next to ef, and a little larger than ef, it 
is evident that Bz; will be reflected into z>V , and Br into rR, 
and an image VR will be formed, having the violet outermost 
and the red innermost, the intermediate colours being in their 
order, from V to R. Lastly, it is evident that the greater 
the angle of incidence is, the longer will be the image, and 
the farther separated its colours ; for which reason the farther 
the images are from the shadow, the less dilated and coloured 
will they be. Nor will they have the same appearance at all 
distances from the point of incidence ; very near it, they will 
be all in the form of fringes across the streak, the breadth be- 
ing greater than the length (if I may use the expression), but 
as we recede from it, they will become distended, as before 
described, the length increasing faster than the breadth, and 
at one point or distance they will be just as long as broad ; all 
which agrees with experiment ; and it is needless to show by 
particular demonstration, the manner in which one image is 
divided from another, the reason obviously being the manner 
in which the fibres on the reflecting surface are arranged and 
inclined to one another. 
3. A number of phsenomena, involved in that of the images, 
are explicable by what has been said on them. If a piece of 
metal be scratched, and then exposed in the sunshine, a num- 
ber of broken colours will be formed by the scratches, as may 
be seen either by letting them fall on the eye, or by receiving 
them on a white object. This is evidently owing to the diffe- 
rent reflexibility of the rays incident on the scratches, which 
