the near and distant Sight of different Persors. | 341 
inches on one side and eleven inches on the other,) he was 
enabled to see distant objects distinctly... He has continued 
to use glasses of this description for the purpose of seeing 
distant objects from that time to the present 5 but is obliged 
to remove them whenever he reads, and still to employ the 
first number of a convex glass.—In this instance, a pres- 
byopic was changed to a myopic sight, without any known 
efficient circumstance to produce it.—In the two following) 
eases, a similar change took place; and in them it was at- 
tributable to known causes. A woman, about fifty years 
of age, of a full habit, who for several years had been 
obliged to make use of convex glasses, in order to read a 
small print, was seized with a dimness in the sight of the 
right eve, accompanied with a small degree of inflamma- 
tion. ‘The sight of the left eye having been long imperfect, 
this affection of the right eye occasioned a great depression 
of spirits. Recourse was necessarily had to copious evacu- 
ations, by means of which the inflammation and dimness 
of sight were soon removed; but afterwards the patient was 
much’ alarmed on finding that the spectacles she had been 
accustomed to wear, instead of affording their usual assist~ 
ance, confused her sight. Upon this discovery, she was 
induced to look through her husband’s glasses, which, in 
consequence of his being near-sighted, were double con- 
caves of the fifth number, and ground to a radius of eleven 
inches on each side. These did not assist her in looking 
at near objects, but by their aid she saw much more di- 
stinctly those that were distant; and, on attempting to 
read, nothing more was now necessary, than to bring the 
book a little nearer to her, than she had been previously 
accustomed to place it.—The second case occurred in a 
patient about the same age, who, in the course of the last 
year, was attacked with an inflammation in both eyes. By 
the use of leeches and cooling medicines, it was speedily 
removed, and, afterwards, she was much gratified, by find- 
ing that the necessity for using glasses when she read, 
which had existed many years, was removed ; and that she 
could see both near and distant objects correctly, without 
any extraneous help.. The amendment in this lady’s sight 
continued, however, only a few weeks; after which she 
was avain obliged to use the same convex glasses in looking 
at smal! near ohjects, which she had used before her eyes 
hecame inflamed.—In addition to these cases, I beg leave 
to add the information I have received from an eminent 
mathematical instrament-maker, about fifty years of age, 
who has long made use of convex glasses to assist his sight 
Ys in 
