on Muscular Motion. 
17 
vision than the other, living constantly with those who do 
squint, and, by imitation, acquiring a habit of neglecting to 
use one eye. 
The power of squinting voluntarily may also be acquired at 
any age. This we find to be true in persons who look much 
through telescopes ; they are led to apply the mind entirely to 
one eye, not seeing at all with the other. In this case the 
neglected eye will at first, from habit, follow the other ; but 
in time, if frequently neglected, may lose this restraint, and be 
moved in another direction. Some astronomers, whose eyes 
have been much used in this way, are said to be able to squint 
at pleasure. 
From this view of squinting, it takes place under the three 
following circumstances : where one eye has only an indistinct 
vision ; where both eyes are capable of seeing objects, but the 
one less perfect in itself than the other; and where the muscles 
of one eye have acquired from practice a power of moving it 
independently of the other. 
Where squinting arises from an absolute imperfection in the 
eye there can be no cure. 
Where it arises from weakness only in the sight of one eye, 
it may, in some instances, be got the better of ; but to effect 
the cure there is only one mode, which is that of confining 
the person to the use of the weak eye by covering the other ; 
in this way the muscles, from constant use, will become perfect 
in the habit of directing the eye upon the object, gain strength 
in that action, and acquire a power of adjusting the eye ; when 
these are established in a sufficient degree, the other eye may 
be set at liberty. The time that will be necessary for the cure 
must depend upon the degree of weakness of the sight, and 
MDCCXCVII. D 
