10 
Mr. Homes Lecture 
the organ, and erroneously treated. The fact has been long 
established by philosophers that a defect in the muscles may 
produce such a disease, but as other causes may likewise do the 
same, I believe that such a defect has not been practically con- 
sidered, as one of the diseases of the eye; certainly not as a very 
common one, which undoubtedly it will be found. 
The first case of this kind which led me to pay attention to 
the subject, was that of a friend, a lieutenant colonel of en- 
gineers, who was in perfect health, shooting moor-game upon 
his own estate in Scotland. He was very much surprised 
towards the evening of a fatiguing day's sport, to find all at 
once that every thing appeared double ; his gun, his horse, and 
the road, were all double. This appearance distressed him ex- 
ceedingly, and he became alarmed lest he should not find his 
way home ; in this, however, he succeeded by giving the reins 
to his horse. 
After a night's rest the double vision was very much gone 
off; and in two or three days he went again to the moors, 
when his complaint returned in a more violent degree. He 
went to Edinburgh for the benefit of medical advice. The dis- 
ease was referred to the eye itself, and treated accordingly ; the 
head was shaved, blistered, and bled with leeches. He was 
put under a course of mercury, and kept upon a very spare 
diet. This plan was found to aggravate the symptoms ; he 
therefore, after giving it a sufficient trial, returned home in 
despair, and shut himself up in his own house. He gradually 
left off all medicine, and lived as usual. His sight was during 
the whole time perfectly clear, and at the same time near ob- 
jects appeared single ; at three yards they became double, and 
by increasing the distance they separated further from each 
