Sir C. Blagden's Appendix, &c. ill 



the degree of near sightedness was then so small, that I found 

 a watch-glass, though as a meniscus it made the rays diverge 

 very little, sufficient to enable me to read the table as before. 

 In a year or two more, the watch-glass would no longer serve 

 my purpose ; but being dissuaded from the use of a common 

 concave glass, as likely to injure my sight, I suffered the in- 

 convenience of a small degree of myopy, till I was more than 

 thirty years of age. That inconvenience, however, gradually 

 though slowly increasing all the time, at length became so 

 grievous, that at two or three and thirty, I determined to try a 

 concave glass; and then found, that the numbers 2 and 3 were 

 to me in the relation so well described by Mr. Ware ; that is, 

 I could see distant objects tolerably well with the former num- 

 ber, but still more accurately with the latter. After contenting 

 myself a little time with N"*. 2, I laid it wholly aside for 

 N". 3; and, in the course of a few more years, came to N°. 5, 

 at which point my eye has now been stationary between fif- 

 teen and twenty years. An earlier use of concave glasses 

 would probably have made me more near sighted, or would 

 have brought on my present degree of myopy at an earlier 

 period of life. If my friends had persuaded me to read and 

 write with the book or paper always as far from my eye as I 

 could see; or if I had occasionally intermitted study, and 

 taken to field sports, or any employment which would have 

 obliged me to look much at distant objects, it is very probable 

 that I might not have been near sighted at all. Possibly the 

 persons who become near sighted by having constantly to 

 adjust their eyes to near objects, may not usually change to 

 be long sighted by age. 



On the subject of vision, I may be allowed to take this 



