If You obstinately strive against Nature, and barbarously refuse your Eyes that assistance from Art- which will enable You to see with great ease, but without which, you cannot see without great difficulty - You will act as absurdly, as if You refused to eat when hungry, or to sit down when You are tired and will soon strain and weaken your Sight, which will receive more injury in a few Months by such forced exertion, than it would in Years, if assisted by proper Glasses which render Vision

easy.

However, some people seem to be about as unwilling to acknowledge this Truth as they are to confess that they do not feel quite so frisky at 45- as they did at 25.

The common objection which people make to put on Spectacles, is, that "if They once begin to wear them, They are afraid they can never leave them off again:" this is true enough; —but why should they? if by such aid, their Sight is relieved and preserved, and They are enabled to see easily and distinctly, and when they attempt to read without, their Eyes ache, their Head aches, and every bit of 'em aches.

A man afflicted with incurable Lameness, who cannot move without Crutches, would act just as wisely, in refusing to avail himself of them, - because he can never hope to walk again without.

"Timely assistance from Glasses will ease the Eyes, and in some degree check their tendency to grow flatter- whereas, if they be not assisted in time, the flatness will be considerably increased, and the Eyes be weakened by the efforts they are compelled to exert; all delay is dangerous, and the longer those who feel the want of assistance, defer the use of Spectacles, the more they will increase the failure of the Eye." - ADAMS on Vision, 1792, 8vo. p. 109.

"The change in the conformation of the Eyes, which renders Spectacles useful, seems to be one of those which Nature has destined to take place at a particular period of Life, and to which there is no gradual approach through the preceding course of Life. A person for instance at 40, sees an object distinctly, and at the same distance that he did at 20. When he draws near to 50, the change I have spoken of, commonly comes on, and obliges

him in a short time to wear Spectacles. As it proceeds he is under the necessity of using others of a higher power. But, instead of supposing that his Sight is gradually becoming worse, from a natural process, he attributes the increase of the defect in it, to his too early and frequent use of Glasses. Upon the whole, I should draw this inference from what has been said, that no person whose Sight begins to grow Long, ought to be in the least prevented from enjoying the immediate advantage which Spectacles will afford him, by the fear that they will ultimately injure his Eyes." — DR. WELLS on Vision.

CHAPTER VI.

OF PRESERVERS.

By the help of Convex Glasses* of 36 or 30 Inches focus, if your Eyes are in the state above mentioned, You will be enabled to read with the same ease, and at the same distance,

* Of Convexes, -i. e. Glasses for assisting those Eyes which are too Long Sighted—or what is commonly called

that you did before your Sight was altered by the inevitable decrees of Old Time - such Glasses, will make things appear clear, and distinct as they did before your Eyes were impaired; and if judiciously chosen, lessen the labour of the Eyes- and enable them to do their work with more ease, and therefore, I suppose, do, in a certain degree, preserve the Sight.

This Title of PRESERVERS, which some sagacious name-giver gave to Spectacles of 36 Inches focus or the First Sight, is an admirable appellation to attract the attention of people but is equally applicable to all the following gradations of Glasses; for the term is generally misunderstood, - people seem to suppose, that Spectacles of 36 Inches focus, have the magic power of arresting the progress of that failing of the faculty of Sight,

an Old Sight, are named from their focal length; the highest number, No. 36, magnifies least, and is called the 1st Sight: See Figure 5 in the Plate facing the Title.

Of Concaves, i. e. Glasses for a Short Sight, that which is the least concave, and gives the least assistance to the Eye, is called No. 1. See Figure 7 in the Plate fronting the Title.

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which is one of the natural and unavoidable consequences of Age.

When once the Sight begins to fail, it continues to decay, till in extreme Age, our Eyes, like our other Senses, become of almost as little use to us, as they were in our Infancy. It is very common for Persons after they have worn Spectacles of 36 Inches focus for a Year or two, to complain that they think that 'their Glasses cannot be of the right focus for their Eyes, for when they do not wear them, they certainly cannot see so well without them as they did before they used them, therefore, they certainly cannot be Preservers.”

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After the process of deterioration has been proceeding for 12 months—it would be wonderful if it had not made some perceptible progress! It is as ridiculous, to expect that it is in the power of an Optical Instrument to entirely prevent the Eye undergoing that invariably certain, although almost imperceptible change which accompanies the advance of Age, as it would be to suppose that Art can prevent the failing of any of our other faculties.

I make these remarks, because, I know that the prepossessing term has induced some ex