204 
MANUAL OP MODERN FARRIERY. 
the weight of the eye, they might not have power to turn it 
so quickly and to such an extent as the animal might wish 
or require ; therefore the eye is furnished with two other 
muscles, whose entire office is to turn it. They are placed 
obliquely, and in consequence are call ed the oblique muscles. 
The upper one, a b, is curiously constructed. It emanates 
from the back part of the orbit, and follows a direction 
upwards, and towards the inner side, and there, immediately 
under the ridge of the orbit, it passes through a perfect 
mechanical pulley, and turning round takes a direction 
across the eye, and is inserted a little beyond the middle of 
the eye, and towards the outer side. Thus the globe of the 
eye is evidently directed inward and upward. This is not 
all which is accomplished by this remarkable mechanism. 
That the eye may be completely defended, it is sunk deep 
in the orbit, but it may be occasionally requisite to bring 
the eye forward and enlarge the held of vision. Under the 
influence of fear the eye is positively protruded, and it is 
not only forced more forward, but the lids are opened more 
widely. It may be asked, how can this be possibly accom¬ 
plished? The remarkable pully-muscle, or trochlearis, at 
b c, readily effects this, while the straight muscles at the 
same time do not oppose it, or only regulate the direction 
of the eye, it is really brought forward. The lower oblique 
muscle has its insertion just within the lachrymal-bone, n, 
and proceeding across the eye is fixed into part of the 
sclerotica, opposite to the other oblique muscle, and turns 
the eye in an opposite direction, and also assisting the 
upper oblique muscle in bringing the eye forward from its 
socket. 
There is another beautiful provision preventing impurities 
or insects from being carried to and lodging in the comer 
of the eye, which would, if allowed to accumulate at the 
