22 



ACCOUNT OF A BOY 



usual could be discovered in the conformation of the parts 

 about the fauces. 



" From the motions which were produced in the iris, by va- 

 rying the quantity of light admitted to the eyes, I should alone 

 have been inclined to hope, that the retina was not altogether 

 wanting, and to have urged the propriety of attempting to re- 

 move the opaque lens from the axis of vision by a surgical ope- 

 ration. But the following circumstances served to confirm 

 this opinion. In the first place, Mr Mitchell informed me, 

 that he had often observed his son, sitting for an hour at a 

 time, opposite to a small hole in the south wall of a hut ad- 

 joining to the manse, so as to receive the beams of the sun, 

 which shone through the hole during part of the forenoon, di- 

 rectly on his eyes. The boy could have no other motive for 

 placing himself in this situation, but to enjoy a certain agree- 

 able sensation of light ; and it is not improbable, that the par- 

 ticular pleasure which he seemed to derive from the light of 

 the sun, admitted in this manner, arose from the eyes having 

 been rendered more susceptible to impressions, by being pre- 

 viously directed to the darker parts of the hut. Secondly, I 

 observed, that he very frequently turned his face towards the 

 window of an apartment, and then pressed his finger forcibly 

 backwards between the eyebrow and upper eyelid of one of 

 his eyes, so as to occasion a slight degree of distortion, and a 

 very disagreeable appearance of protrusion of the ball. I sup- 

 posed, that when he compressed the eye-ball in this manner, 

 either some change in the organ was produced, by which he 

 obtained a more distinct impression from the light of the win- 

 dow, or else that the pressure on the retina simply, occasioned 

 the sensation of a luminous ring or spot, which he had plea- 

 sure in contemplating. When I put my silver pencil into his 

 Jiand, after turning it quickly round in the points of his fingers, 



and 



