on Muscular Motion. 
17 
At twelve o'clock of the same day, we prevailed on Sir Henry 
Englefield to make the experiment on my eye, without giv- 
ing him any information of the observations that had been 
made in the morning. He was very much struck with the dis- 
tinctness of the cornea ; and told me without difficulty the 
different objects to which my eye was adjusted, and was as 
fully satisfied as either Mr. Ramsden or myself with the result 
of the experiment. 
Mr. Ramsden now made the same experiment on Sir 
Henry's eye, but was unable to retain it in the field of the mi- 
croscope ; the motion of the cornea was always in one direc- 
tion, and very irregular ; after repeated trials, equally unsatisfac- 
tory, the eye became so fatigued that he was obliged to desist. 
August the 4th, Mr. Ramsden repeated the experiment on 
Sir Henry's eye, to ascertain if possible the cause of his former 
want of success, and found the same circumstances again take 
place ; the curve of the cornea moved always in the same direc- 
tion, never returning to the wire. This could not be accounted 
for, till it was accidentally discovered to arise from the motion 
of his hand in touching the knee of the observer, for when that 
was omitted, the experiment was followed by the same results 
as those made on the rest of the company. I have been more 
particular in mentioning this circumstance, as it shows that 
the most trifling things may interfere with the result of the ex- 
periment, and that it required a considerable degree of nicety 
and management in adjusting the instrument, without which 
the experiment could not have been made. 
August the 28th, the former experiments were repeated by 
Sir Henry Englefield, Mr. Ramsden, and myself, upon the 
eye of a young lad, and the result was similar to the others, the 
mdccxcv. D 
