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required to see the distant object or sketch, &c. and other Glasses in a frame attached to the Spectacle frame, and moving on hinges which, when brought down before the Glasses fixed in the Spectacle frame might make combined the focus required for painting the Picture, and which, when it was requisite to refer to the Object or Sketch, might be turned up on the Forehead, quite out of the way.

"The late President of the Royal Academy - BENJAMIN WEST, ESQ. was in the habit of using Divided Glasses for many years; the upper half was of 30 inches focus, and the lower of 12. But for some time before his death, which happened when he was about 90 years of age, he had the upper half of 30 inches focus, and the under half of only 8 inches focus." The Glasses were round and an inch and a half in diameter.

The above account of Mr. West's Spectacles is another of the contributions of Mr. S. Pierce, who made the Spectacles.

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By trying a variety* of Glasses at an Opti

Though in the choice of Spectacles, every one must finally determine for himself, which are the Glasses

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cian's, the Sight soon becomes confused and tired, and for the moment quite unfit to appreciate with proper accuracy, what Glasses are exactly the best for it.

I advise persons who have never worn Spectacles or are uncertain what Glasses will suit their Eyes best, to borrow One of the Sets of Glasses, which consist of Spectacles, of regular gradations of power, set in a framethe first Set of Convexes usually contains the first Seven Glasses mentioned in the Table at page 33 or, if these cannot be had choose at the Optician's, those Spectacles which they

through which he obtains the most distinct Vision; — yet

some confidence should be placed in the judgment of the Artist of whom they are purchased, and some attention paid to his directions.

"By trying many Spectacles the Eye is fatigued, as the Pupil varies in size with every different Glass, and the Eye endeavours to accommodate itself to every change that is produced. Hence the purchaser often fixes upon a pair of Spectacles not the best adapted to his sight, but those which seem to relieve him most, while his Eyes are in a forced and unnatural state; and consequently, when he gets home, and they are returned to their natural state, he finds what he had chosen, fatiguing and injurious to the sight." Mr. G. ADAMS on Vision, 8vo. 1789, p. 96.

think they can see best with, and take home with them also, Two other pairs, one a degree more, the other a degree less Convex, or Concave, as they happen to be either Long, or Short-Sighted: they should try these repeatedly for whatever purpose they wish to employ them: should take care, that the Glasses they try are all perfectly clean and that they hold them as close and parallel to the Eye as Spectacles are placed.

They will probably find, if they try them by Candlelight, especially with a very small print or fine work—that one degree of magnifying power more than they require by Daylight, will show very small objects most distinctly but I protest against such indulgence at first when the Sight is much impaired by Age -a pair of Glasses for use by Day, and another for Night, are advisable comforts for the Eyes.

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The best plan for the Preservation of the Eyes,

is not to employ them in any work at Night that gives them any trouble:- let all Business which requires intense attention, such as mending Pens, &c. be done by "the better Day."

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At any Age, the less the Eyes are actively employed at Night, the better - after the labours of the Day, the Eye participates in that languor which every other part of the System suffers, and the tone of the Visual Organ is comparatively feeble- therefore avoid as much as possible, reading a small print, or any business which requires the earnest exertion of the Eyes-and always use a shaded light.

The moment that your Eyes, by beginning to feel hot and fatigued, give you a hint, that they have done as much work for you as is agreeable to them - leave off exerting them.

Forcing the Eyes to Work at Night,* even for a few moments after they are tired, — will often, put them out of humour for the whole of the following Day, and is of all Eye-spoiling Acts the most mischievous;-want of Mercy in this respect, has prematurely ruined the Eyes of Thousands!

Several Young Ladies, of only about 25

"The frivolous attention of a quarter of an hour of an Evening, has cost many, the comfortable and perfect use of their Eyes for many years: the mischief is effected imperceptibly the consequences are irreparable.” — Mr. G. ADAMS on Vision, 8vo. 1789, p. 98.

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years of Age, have complained to me that they could not work without Spectacles of 30 Inches focus-who I found, on inquiry, very justly attributed this premature failure of their Sight to having been obliged frequently to sit up at Needle-work half the Night during the time they were with Dress-makers.

Those who have any regard for the Eyes of their Children will make it part of the agreement, when they article them to any Business requiring the earnest exertion of their Eyes, that they shall never be required, on any pretence, to use them at latest after Nine o'clock at Night.

A friend of the Author, who has passed his 60th year, and has found it necessary to use Spectacles ever since he attained the age at which they are usually wanted; whose occupations have occasioned his Eyes to be constantly employed on small objects in print, writing, and drawing, by Candlelight as well as in the Day, by careful management, is still enabled to see with Spectacles of the

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