so 
Mr. Home's Lecture 
by the muscles, so that the radius of curvature of the cornea will 
be rendered shorter, and its distance from the retina increased. 
That the eye-ball cannot be made to recede in the orbit by 
any of these actions, is sufficiently proved by its not having 
done so in any of the experiments. 
These muscles are uncommonly large, and come much fur- 
ther forward than appears necessary for the purposes generally 
assigned to them ; but when applied to so important an office 
as that we have just stated, their size, and anterior insertion, 
are easily explained. 
It may be imagined that I have allotted to these muscles a 
greater variety of uses than is compatible with the simplicity 
of the general laws of the animal ceconomy ; but to prove this 
not to be the case, I shall only bring the biceps flexor cubiti as 
an instance of a similar kind. That muscle is attached to the 
scapula by both its heads, one of which passes through the joint 
of the shoulder, they afterwards unite, and their common ten- 
don is inserted into the radius ; when the muscle contracts, the 
first effect will be to steady the joint of the shoulder ; if the 
contraction is increased, it will rotate the radius, and if still 
more increased, bend the fore-arm. 
There are many instances in animal bodies of elasticity be- 
ing substituted for muscular action, but this in the eye is by 
much the most beautiful of those applications. 
In the vascular system the arteries are composed of muscu- 
lar fibres, and an elastic substance ; in the natural easy state 
of the circulation, the re-action in the larger vessels is princi- 
pally the effect of elasticity, but when increased, it is the ef- 
fect of muscular contraction. 
The claws of the lion are drawn up, and supported from 
