260 MR HARVEY on an Anomalous Case of Vision 



The day being favourable on which the last experiment was 

 performed, a vivid and well-formed solar spectrum was thrown on 

 the wall. He pronounced it to be composed of two colours, yel- 

 low and light blue ; and which, in a former conversation, he de- 

 scribed as the ordinary appearance of the rainbow. The vivid 

 and brilliant red of the spectrum he could by no means distin- 

 guish. Its general appearance he regarded as in some degree 

 beautiful ; but the bursts of pleasure which escaped from my 

 children, as they contemplated the brilliant colours in succes- 

 sion, appeared to excite in him the greatest surprise. I after- 

 wards found, that he considered the prism as a thing moderate- 

 ly interesting, but as by no means meriting the praises which 

 had been bestowed on it. 



His eyes appear to be exceedingly Well formed, and time has 

 but slightly impaired their powers. According to the opinion of 

 my friend Mr TRACEY, surgeon, they appear to possess all the 

 essentials necessary to good sight, namely, perfect transparency 

 of the several humours, a proper degree of convexity of the cor- 

 nea and ball of the eye, and to which may be added, the perfect- 

 ly healthy functions of its appendages ; the proofs of which are 

 discovered in the just adaptation of the eye to distance. In 

 his communication to me on the subject, Mr TRACEY observes, 

 " If I might adduce any one point (which, under common circum- 

 " stances, I should not be disposed to notice) I should say the 

 " grey colour of the irides is much fainter than usual ; and that 

 " the pupilla? are extremely small." The cause of the last-men- 

 tioned fact, is no doubt to be attributed to the constant exer- 

 cise of the eyes by candle-light, it being known, that, persons 

 similarly occupied, are of necessity obliged to bring the object 

 very near, and thus, from long habit, produce artificially a per- 

 manent diminution in the magnitude of the pupillae. 



In the present limited state of our information on this very 

 interesting and curious subject, and with so few cases that have 



