and distant Sight of different Persons, 35 



reflected from the bulb of a small thermometer, five-sixteenths 

 of an inch in diameter, at the distance of three inches and three 

 quarters from the eye ; and he could also see the same image 

 at the distance of two feet seven inches. The belladonna 

 produced a conspicuous dilatation of the pupil in less than an 

 hour ; after which, on viewing the apparent lines on the op- 

 tometer, he was unable to make them meet at a nearer dis- 

 tance than seven inches, or to gain a distinct image of the 

 candle reflected by the bulb of the thermometer nearer than 

 this distance ; but he could discern it at two feet ten inches 

 from the eye, which was three inches further than he was 

 able to see it, before the belladonna was applied. During the 

 time of the experiment on the right eye, the left eye possessed 

 its usual range of vision, but the sight, when both eyes were 

 open, was rather confused, in consequence of the unequal foci 

 of the two eyes ; and it did not become clear until the pupil 

 of the right eye recovered its usual power pf contracting, 

 which power was not acquired till the third day after the 

 apj^ication of the belladonna. 



It is remarkable that a different effect is sometimes produced 

 on a near sighted eye by the application of the belladonna, 

 from that which it lias on an eye that enjoys a distant sight. 

 Dr. Wells made an experiment of this kind on a friend of 

 his, who was near sighted ; and he informs us, in the paper 

 above referred to, that in this instance, the nearest point of 

 perfect vision was moved forwards during the dilatation of 

 the pupil, whilst its remote point remained unaltered. I have 

 made a similar experiment on the eyes of several such per- 

 sons ; and though in two of these the result appeared to be 

 similar to that which has been mentioned by Dr. Wells, yet. 



