185 
Mr. Bell on the motions of the eye , 
could not be elevated for the purpose of vision, owing, as we 
have supposed, to the injury of the rectus attollens, at the 
same time that it was thus raised involuntarily, in the at- 
tempt to shut the eye ; a proof that this insensible motion is 
performed by the lower oblique muscle, and not the superior 
rectus muscle. 
The circumstance of the lower eye-lid assuming the func- 
tions of the upper one, and moving like the lower eye-lid of 
a bird, reminds me of an omission in the account of authors. 
They have sought for a depressor of the inferior eye-lid, 
which has no existence, and is quite unnecessary ; for the 
motion of the M. elevator palpehrce superioris opens wide the 
eye-lids, and depresses the lower eye-lid, at the same time 
that it elevates the upper eye-lid. If we put the finger on 
the lower eye-lid when the eye is shut, and then open the 
eye, we shall feel that during this action the eye-ball is 
pushed outwards ; and we may observe, that the lower eye- 
lid is so adapted as to slip off the convex surface of the ball, 
and is consequently depressed. The reason of this is, that 
the muscle which raises the upper eye-lid passes over a con- 
siderable part of the upper and back part of the eye-ball, and 
the origin and insertion of the muscle being under the highest 
convexity of the ball, that body must be pressed forwards in 
proportion to the resistance of the upper eye-lid to rise. In the 
preceding case the upper eye-lid being stiff and unyielding, 
both the origin and the insertion of the elevator palpehrce became 
fixed points ; consequently, the action of the muscle fell en- 
tirely on the eye-ball itself, whereby it was forced downwards 
and forwards in an unusual manner, and so depressed the 
lower eye-lid to an unusual degree. Thus the muscle became 
a depressor of the inferior eye-lid, instead of an elevator of the 
MDCCC XXIII. B b 
