1 16 Mr. Bell on the motions of the eye, &c. 
pupil was not turned downwards and outwards, therefore 
both oblique muscles must have been in action. Their com- 
bined action draws the eye-ball towards the nose. 
In the violent spasmodic affection of the eye, when it is pain- 
fully irritated, I believe that all the muscles, both of the eye- 
ball and eye-lids, are excited. In quadrupeds, I have ascer- 
tained that the oblique muscles act when the haw is protruded, 
but I have also found that the retractor oculi alone, is capable 
of forcing forwards the haw. 
But quadrupeds having an additional apparatus of muscles 
to those of the human eye, are not suited for experiments 
intended to illustrate the motions of our eyes. The monkey 
has the same muscles of the eye with man. 
III. I cut across the tendon of the superior oblique muscle 
of the right eye of a monkey. He was very little disturbed 
by this experiment, and turned round his eyes with his cha- 
racteristic enquiring looks, as if nothing had happened to 
affect the eye. 
IV. I divided the lower oblique muscle of the eye of a 
monkey. The eye was not, in any sensible manner, affected ; 
the voluntary motions were perfect after the operation. 
V. On holding open the eyes of the monkey, which had the 
superior oblique muscle of the right eye divided, and waving 
the hand before him, the right eye turned upwards and in- 
wards, while the other eye had a scarcely perceptible motion 
in the same direction. When the right eye was thus turned 
up, he seemed to have a difficulty in bringing it down again. 
From these experiments it is proved, that the division of 
the oblique muscles does not in any degree affect the volun- 
tary motions by which the eye is directed to objects. 
