380 . Mr Charles Beli on the Motmi of the Eye, 
Let A B (fig. 4.) be the convexity of the cornea, and C the see*, 
tipn of the ridge of fluid ; it is obvious that, as a magnifying lens, 
it would elongate the object; as it is not a drop, but a ridge, it 
would elongate the object in the perpendicular, and not magnify 
it regularly. Dr Brewster’s circular object would become changed 
in a direction opposite to what he has represented. Presuming 
that he has reasoned ill, and observed justly; something there 
must be acting like a concave glass instead of a convex lens. I 
should suppose that the fluid attracted by the margin of the eye- 
lid had taken a concave form, so as to compress the circular figure 
as represented by Dr Brewster ; but I believe the shape of the 
margin of the eyelid will prevent the ray of light from striking up- 
on this fluid in the angle betwixt the cornea and the eyelid. I be- 
lieve the .eflect contemplated, proceeds from another cause alto- 
gether. Something in this experiment disperses the rays, or, to 
speak more accurately, diminishes their convergence, and throvvs 
the image of the object, as it is the license of optical writers to 
express it, behind the retina. When the disc is extended in 
one diameter, the rays from it must have been refracted, so as 
tp magnify the object. When the object is seen compressed, a 
contrary influence must be in operation ; the rays must have 
been dispersed, and the object diminished in that diameter. 
We every day witness in those who are near-sighted the at- 
tempt to diminish the convergence of the rays by peering 
through the shut eyelids. The fact is, I must therefore })re- 
sume, when Dr Brewster looked at this object with his eyelids 
nearly shut, the rays from the object were attracted by the eye- 
laslies, and the image took that irregular figure which he has 
represented. 
It will save Dr Brewster infinite trouble, if, w'hen he sees what 
he supposes an attempt in the human structure, he will commence 
his speculations on the idea, that this intention is perfectly ful- 
filled. As to the present inquiry, he may rest satisfied, that 
when the eye was endowed with sensibility, that the eyelids 
might be regularly moved under that influence, the Power 
which bestowed sensibility, a property of life, did not leave the 
mechanism imperfect ; and that there is no superfluous moisture 
left to fall down on the surface of the eye, unless when intended 
