10 
Mr. Home's Lecture 
does not arise from a change in the general form of the globe 
of the eye ; we therefore abandoned both of these theories. 
It suggested itself that any change in the curve of the cornea 
(could it be produced), would vary the refraction of the rays, 
so as considerably to alter the focus of the eye ; and upon con- 
sidering this subject, Mr. Ramsden made a rough calculation, 
from which it appeared, that a very small alteration in that 
part would vary the adjustment of the eye from parallel rays 
to its shortest distance of distinct vision. 
This opened to us a new field of inquiry, and I endea- 
voured to ascertain how far the cornea admitted of such a 
change, and if it did, how far that change operated in pro- 
ducing this particular effect. 
For the first of these purposes I made the following experi- 
ments in the presence of Mr. Ramsden. 
A portion of the cornea -t of an inch broad, and ~ of an 
inch long, was removed from the eye of a person 40 years of 
age, two days after death, with a part of the sclerotic coat on 
each side attached to it. This was laid upon a piece of glass 
immersed in water, under which was a scale divided into very 
minute parts, these divisions being very readily seen through 
the glass. One end of the cornea was made fast by fixing the 
sclerotic coat, and a force was applied to the other ; this power 
was found capable of elongating the cornea P art °f an inch > 
and on removing it, the cornea recovered itself to its original 
length. In different trials it varied in the quantity of elonga- 
tion, but in all of them it was fully ~ part of the whole 
length, or diameter of the cornea. 
The elasticity of the cornea being thus ascertained, en- 
couraged me to proceed in the anatomical investigation ; and 
