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a Pound - his Hunger, ought, to be as fully satisfied.

MEM. The Addition to your Optician's Bill-will soon be overpaid by the subtraction from your Butcher's and Baker's.

CHAPTER X.

HINTS TO PERSONS CHOOSING SPECTACLES TO READ WITH.

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A PART of the paraphernalia of an Optician's counter, is a Book* of rather a small print, (about the size of the Note at the foot of this Page) — which is presented to those who come to choose Spectacles and such Glasses are very properly recommended, as will enable the person to read it—at the same distance, and with the same ease, that he could before his Eyes were impaired, i. e. through which the Letters appear perfectly distinct, and of their

natural size.

The first thing to attend to, is to look at a Book with each Eye alternately (shutting the other), and carefully ascertain, if you see equally

* The Author will be sadly disappointed if in future this Work is not the Volume chosen for that purpose.

well, with both Eyes, with the same Glass, at exactly the same distance. Persons are quite unconscious of the frequent inequality in the focus of the two Eyes till they thus try them separately; when they often find that a Glass which will do very well for one Eye - is of little or no use to the other, which to be rendered effective must have a Glass of a different focus.

With Glasses not Convex enough, or, according to the common expression, which are too Young, You will not see clearly, unless the Book is placed so far from your Eyes, that the Letters cannot be seen distinctly.

With Glasses too Convex - or too Old - You will be obliged to bring the Book nearer to your Eyes than you did when your Sight was good-and the Letters will appear larger, than they really are. Spectacles which magnify too much, will strain the Eyes even more than those which do not magnify enough—and instead of retarding, will accelerate the defect which age brings on.

"When persons apply to an Optician for Spectacles to read or work with; they should clearly understand, that the Objects for which such Spectacles are solely calculated, are not

placed more than 12 or 14 Inches from their Eyesi. e. whether Reading, Writing, Sewing, &c. for there seems to be a natural impulse in most persons, that after a printed Book has been handed them for trial to read, they will presently look off-to some object on the other side of the Room, or across the Street, and say, 'Why now I can see well enough to Read with these Glasses but I cannot discern what that word is over yonder Door;' and the Optician has oftentimes no little trouble to convince them, that such Spectacles are not intended to show objects at a distance to see which, their Sight is as strong as ever; and in fact, that they can see distant objects best with their naked Eye."

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"A person in business, with whom I was acquainted, began to want the common Optical assistance, especially for Writing, when about 40 years of Age- the Glasses he first used were of 30 Inches focus, but he soon found them useful to look at the labels on the parcels of Muslin arranged on the shelves around his Shop after a while, he found it easy and convenient to keep them on during the Day, to

serve his Customers, or occasionally to look along the Street for a passing friend. Another pair of deeper focus, was a repeated necessary consequence, for the mechanism of his Eyes naturally formed themselves to the power of the Convex Glasses, and his Eyes still growing older and strained by too strong excitement, at last would not perform their office distinctly, unless assisted by Spectacles of 11 Inches focus so that he became literally half-blind in the course of about 10 Years.

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"This, is not a very singular, but a very common case, - and one of the most frequent causes of irreparable injury to the Eyes, and is one of the first cautions to be given to those who are choosing Convex Spectacles.

"From not being aware of this, I have known several Painters and other Artists, who have, in their natural anxiety to see as well as possible, irremediably injured their Sight― so that when they became 60 or 70 years of age, they were obliged to use Two half glasses of different foci fixed in the rings of a Spectacle frame-the upper half to help them to observe a distant picture or sketch, &c. and the lower half to transmit it to canvas."-MR. S. PIERCE.

With such divided Glasses, it requires considerable attention to raise or depress the Eyes sufficiently, so as only to look through one half,—and that the rays from the other half, may not confuse the Eye and distress its adjustment - which would be extremely perplexing and detrimental to the Eyes, to which it would be as bothering, as it would be to the Ears to have two Barrel Organs at the same moment, — One playing " Sally in our Ally,”— and the Other " Ally Croaker.”

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There have been several other plans for obtaining the convenience of Two pairs of Spectacles in One frame- by having the glasses to turn up on the side, &c. but all such contrivances are at the expense of the Eye - the Magnifying power of Spectacles has also been made to vary from 36 to 12 Inches focus, by having two Eye-glasses, of 72 inches focus, one before the other, and separating them; but the vision cannot be so good as with the simple single Eye-glass- and those who value their Eyes- will use no other. I think the most convenient plan, and also the least injurious to the Eyes, would be to have a pair of Spectacles glassed with Glasses of the focus

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