1 6 Mr. Home’s Lecture 
till six o’clock, we were obliged to postpone any further obser- 
vations upon it, 
August the 3d, at seven o’clock in the morning, Mr. R a ms- 
den and myself resumed our experiments, Sir Henry Engle- 
field being unable to attend at that hour. The eye of the 
person under observation was shaded from the light by shut- 
ting the half of the window-shutter directly before it, and to 
direct the sight to pass through it, a hole was bored in the 
shutter ; the other half of the shutter was turned back, so as 
to take off the side light, only letting in enough to illuminate 
the cornea ; in this state the cornea was very distinctly seen, 
and the former experiments were repeated upon it, with a mi- 
crometer wire in the focus of the eye-glass, so placed as ac- 
curately to oppose the anterior edge of the cornea. 
The motion of the cornea became now perfectly distinct ; 
its surface remained in a line with the wire when the eye was 
adjusted to the distant object, but projected considerably be- 
yond it when adapted to the near one ; and the space through 
which it moved was so great as readily to be measured by mag- 
nifying the divisions upon a scale, and comparing them ; in 
this way we estimated it at the 800 part of an inch, a space 
distinctly seen in a microscope magnifying 30 times. 
It may not be improper, for the sake of accuracy, to mention 
that the hole made in the window-shutter did not admit of see- 
ing up Sackville-street, so that the distant object was now only 
at 90 feet, which is rather less than is necessary for parallel rays ; 
a circumstance, so far as it can be considered, in favour of the 
experiment, as a more distant object must have increased the ef- 
fect upon the cornea. Having satisfied ourselves fully respect- 
ing the result of this experiment, we desisted from further trials. 
