whom I am well acquainted, did not take to the use of Spectacles until he was 55 years of Age: since that period, his Glasses have been twice or three times changed; and although he is now but little short of 87, yet the Glasses which he generally uses, and which he can see the best with, are 16 inches focus."

For these last Remarks I am indebted to MR. SAMUEL PIERCE.

The time that the First Glasses of 36 inches focus will sufficiently assist the Sight — depends on the peculiar nature of the Eyes - on the wear they have previously had — on their subsequent exertions—and on the Constitution and general Health of the Individual.

Persons of a strong Constitution, who make more use of their Legs and Arms, than they do of their Eyes, seldom want Spectacles so soon, or want to change them so soon, as the Studious and those Artists who are much employed in fine works, which require not only the most earnest exertions of the Eyes,

but also the application of a powerful Mag

nifier.

As a general Rule, the first Spectacles will last You for reading by Daylight, during your first apprenticeship to Old Age-i. e. about

7 Years.

CHAPTER VIII.

WHEN TO CHANGE THE FIRST SPECTACLES, FOR STRONGER MAGNIFIERS.

WHEN You find a recurrence of the Symptoms which first prevailed upon You to wear Spectacles and begin to see but little or no better with the first Glasses, than you then did with your naked Eye - your Eyes require The Second Sight of 30 inches focus. - But, I most earnestly entreat my friend the Reader, to be content with as little assistance as will enable him to read a Newspaper comfortably by Candle-light,* at about the same distance he did before his Sight was impaired — from 8

*See Reading Candlestick or Lamp, in the Table of Contents.

1

FOR STRONGER MAGNIFIERS.

39

to 10 inches, is the mean distance at which common Eyes, in their mean state, see most distinctly.

When you find that the First Sight of 36 Inches focus, is hardly sufficient help to read by Candle-light to examine any very minute object i. e. to make Pens, &c., You may get the Second Sight, of 30 Inches focus. But pray-only use them, for purposes for which you find the First Sight is quite insufficient.

The following Advice of MR. GEORGE ADAMS, the Optician, is excellent :

"Those who are careful in following a regular gradation in the change of their Glasses, may preserve their Eyes to the latest period of Old Age, and even then be able to enjoy the comforts and pleasures which arise from distinct vision. Do not therefore precipitate these changes, lest you should absorb too soon the resources of Art, and not be able to find Spectacles of sufficient power."

G. A. on Vision, 8vo. 1789, p. 108. Many persons have irreparably injured their Eyes, and indeed have worn out their Sight prematurely by beginning with Spectacles of

too Short focus, i. e. which magnify too much, or as the common expression is, are too Old.

Nature soon bends to Custom. Eyes which have been excessively stimulated by too deep Magnifiers, seldom or never recover their elasticity.

CHAPTER IX.

MY GRANDMOTHER'S SPECTACLES.

How often a story like the following, is told to Opticians by persons coming to change, what They call their First Spectacles.

When their Optical friend expresses his surprise to find them choose very old Glasses of 12 or 10 inches focus, instead of the Second Sight of 30 inches focus,

* There are very few Opticians but what must have seen instances of Persons who by habituating their Eyes to Glasses of too short a focus, i. e. of too great a magnifying power, have so injured those tender organs as to deprive them of future assistance from Glasses.

This not unfrequently happens to BARGAIN-HUNTERS— who buy their Spectacles of - Hawkers and Pedlars Toy-shops, Dealers in Marine Stores, &c.

They say, "Why, when I thought that I began to want Glasses, I recollected - that there was a pair of nice New Spectacles in my Grandmother's old Bureau, - and I had often heard the old Gentlewoman say, when she was past her 70th Year- that she could still see to read Charmingly with her New Spectacles!—and so I thought, that I could not do better than use those Glasses whose sight-restoring power I had been Eye-witness of. I naturally thought, that they must surely be capital Spectacles which enabled so Old a Person to see so well and when I put them on, I was not disappointed for they made every thing appear very big indeed, and I could read the smallest print very nicely indeed — better than I had been able to do with my naked Eye for a long time past."

I must now give you a hint, gentle Reader,— however improper such mighty Magnifiers may be for your Visual Organs - preserve them with all care the occasional use of them will greatly contribute to preserve that Grand Organ your Stomach.

No" Grand Gour

mand" who has any pretensions to prudence,