Dr Gillies on a peculiar modification of Vision. 59 
of North and South Uist, and of this chain of islands in gene- 
ral, is so compact as to afford a flaming fuel nearly equal to the 
inferior kinds of coal, while, after being once dried, it is again 
incapable of absorbing water. 
To he concluded in our next.) 
Art. IX. — Account of a Peculiar Modfication of Vision. By 
John Gillies, M. D. Member of the Wernerian Society. 
In a Letter to Dr Brewster. 
Dear Sir, 
In compliance with your request, I now send you an account 
of the singular modification of vision formerly mentioned to 
you, and of which I can find no similar instance on record. It 
occurred frequently to me during the year 1816. Since the 
third day of the following year, with but three exceptions, and 
these at very distant intervals, I have never again experienced 
any return of it. I have to regret much, that my observa- 
tions on this subject have been rather limited and imper- 
fect. On this account I have purposely deferred laying the 
particulars before the public, in the expectation that their recur- 
rence might enable me to render them more complete ; but of 
this there is now very little probability, when so long a period 
has elapsed since this aflcction has visited my eyes with any de- 
gree of frequency. 
This modification of vision usually made its appearance in 
the following manner, without any previous intimation of its 
approach. When sitting in company, or otherwise engaged in 
any occupation not requiring continued or minute attention, all 
objects within the range of my vision, appeared to recede from 
me, and be proportionally diminished in magnitude. These ap- 
pearances at first were generally so very slightly different from 
my natural vision, as to produce in my mind some doubt whether 
I had not been deceived in supposing there was any difference. 
Any doubt of this kind, was, however, soon removed by a gra- 
dual increase from one degree to another, till it had reached its 
maximum, which usually took place in the course of a few 
rninutes from the commencement In this condition, which 
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