268 Mr. Brougham’s Experiments and Observations on 
by the under eyelid, or at least by the moisture adhering to 
the under ciliary process, and those which appear from the 
bottom of the body, by the upper eyelid ; which could not be, 
either if they were formed by reflection from the processes, or 
by inflection through the lashes. 
I have, however, observed another kind of streaks, mottled 
with broken colours of all kinds, and formed by reflection 
from the moisture on the processes ; in these the under streak 
corresponds to the under process, and vice versa : they may be 
formed by any polished body held in the proper position be- 
tween the pupil and luminous body. The colours are very 
beautiful when made by the sun, and resemble, in form and 
irregularity of arrangement, some of the streaks made by large 
half-polished bodies, as described in Part II. of this paper. 
2. The next object of attention is one of the greatest im- 
portance to our theory, namely, the formation of images by 
reflection : three things here require explanation, the number 
of the images, their colours, and their variations in point of 
size. 
Obs. 15. I have uniformly found that no reflecting surface 
forms them, except it be curve, and '(its surface) of a structure 
somewhat fibrous. A plain mirror, nor a concave, nor a con- 
vex one do not make them, unless they are of that structure ; 
and, for the same reason, quicksilver, when held so as to reflect 
the light incident upon it, forms them not, but by triturating 
it, so as to divide it into small particles, and by placing these 
in the beam of the sun’s light, each particle formed an image, 
with the colours in the regular order and very bright : on 
holding a cylinder in the rays, and observing the lengths of 
the images, I found that if the curvature was increased, the 
