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Mr. Bell on the motions of the eye , &c. 
Motions of the eye-ball and eye-lids. 
Two objects are attained through the motion of the eye-ball. 
First, the controul and direction of the eye to objects ; se- 
condly, the preservation of the organ itself, either by with- 
drawing the surface from injury, or by the removal of what is 
offensive to it. Without keeping this distinction before us, 
we shall not easily discover the uses of the parts. 
There is a motion of the eye-ball, which, from its rapidity, 
has escaped observation. At the instant in which the eye-lids 
are closed, the eye-ball makes a movement which raises the 
cornea oinder the upper eye-lid. 
If we fix one eye upon an object, and close the other eye 
with the finger in such a manner as to feel the convexity of 
the cornea through the eye-lid, when we shut the eye that is 
open, we shall feel that the cornea of the other eye is instantly 
elevated ; and that it thus rises and falls in sympathy with 
the eye that is closed and opened. This change of the 
position of the eye-ball takes place during the most rapid 
winking motions of the eye-lids. When a dog was deprived 
of the power of closing the eye-lids of one eye by the division 
of the nerve of the eye-lids, the eye did not cease to turn up 
when he was threatened, and when he winked with the eye- 
lids of the other side. 
Nearly the same thing I observed in a girl whose eye-lids 
were attached to the surrounding skin, owing to a burn ; for 
the fore part of the eye-ball being completely uncovered, when 
she would have winked, instead of the eyelids descending, the 
eye-balls were turned up, and the cornea was moistened by 
coming into contact with the mouths of the lacrymal ducts. 
