CHAPTER III.

“Every day’s observation shews how far some men may be carried from the most evident and obvious truths, to support a new hypothesis, which has no foundation either in nature or reason; but truth will ever control and prevail over error, though supported with all the powers of rhetoric and novelty.”—B. Martin.

Wheredistance, or any other cause, prevents our having access to persons who are competent to suit us properly with spectacles, great care should be exercised to choose those which cause the print of a newspaper, or the ordinary types of a book, to appear of their natural and proper size, while they are viewed at the distance most agreeable for reading, viz., twelve inches from the eye. It is evidently better to “try spectacles” on such ordinary printing as they will be generally exercised upon, than to test them by the very small print with which persons frequently provide themselves. To decipher this, a greater power is demanded than is requisite for usual reading, writing, and needlework, which are the purposes for which we require them, and not for microscopic observation, nor for distant views.

The eyes in which no malformation or disease exists, but which simply partake of constitutional decay, or, from too continued application to sedentary and studiouspursuits, are beginning to feel a want of assistance, should have spectacles of sixty-inch focus, which is an exceedingly slight magnifying power; and if these are found to be insufficient to afford an agreeable and natural perception (not an enlarged or magnified image of the letters of a book, &c., held in the hand at the distance of twelve or fourteen inches from the eye), then apply those of the next power, viz., forty-eight inches’ focus. If these again are unequal to supply the loss of power or incapacity of the eye to converge the light to a point at the instant it reaches the retina, then lenses of thirty-six inches focus are to be had recourse to; and when these fail to afford agreeable vision, thirty, twenty-eight, twenty-four, twenty, must be progressively adopted, thus gradually descending the scale until the eyes receive such compensation for their progressive decay and loss of power, as spectacles carefully suited to the sight are capable so effectually to supply.

The period at which the sight begins to fail does not at all depend on age, but varies in different persons according to the formation of the eyes, the treatment they have received, and the constitutional capability; therefore, the age of the person requiring spectacles gives but a vague general idea to the optician as to what is required, unless other particulars are stated; such as whether glasses have been used before; the distance at which writing and printing is seen pleasantly without assistance, the focus of those last used, or sending even but a broken piece of the same.

“The proper selection of spectacles for imperfect vision is a point of much deeper importance than is generally believed. Anoculistwho is only acquaintedwith the diseases of the human eye, without possessing any knowledge of it as an optical instrument, is often led professionally to recommend glasses when they ought not to be used, or to fix on focal lengths entirely unfit for the purpose to which they are applied, and themere venderof spectacles and lenses is still more frequently in the habit of proffering such counsel.”—Brewster.

The near-sighted, or those who require concave spectacles should use those of the slightest power; No. 0, or No. 1, will generally be sufficient at first, but this, by the aid of the trial box, can readily be determined by the wearer himself. There is such an immense benefit experienced by the short-sighted from spectacles which suit their sight, that to argue for their adoption of them would be quite superfluous. Without spectacles they are excluded from observing beautiful landscapes, recognizing individuals, or viewing to advantage any of the crowd of interesting objects around them; but by adopting them they are placed on a par with the long-sighted in such circumstances, while the sharp and microscopic character of their sightwithoutspectacles, gives them many advantages over those possessing ordinary vision.

The short, or near-sighted eyes, have the cornea, and often the crystalline lens, more convex or arched out than in long-sighted eyes. This formation causes the rays to converge to a focus before they reach the retina, but by the application of a concave lens the difficulty is corrected, and the rays are carried on to their proper point for giving a perfect representation on the retina.

This character of sight is very frequent, and is moreparticularly remarkable among those whose mode of life restricts them to crowded cities, sedentary employments, and confined situations. Those whose infantine and youthful years have been passed in the country, or where the eyes have had a free range of view, not circumscribed by the walls of the nursery, or limited to the observation of objects near at hand, rarely require concave spectacles.[4]

The spectacle-frames next demand our attention, as our utmost care in judiciously selecting lenses of the proper focus for our sight will be neutralized if the frame or mounting in which they are placed does not apply comfortably to the head, leaving the lenses they carry fair and parallel before the eyes. If the front of a pair of spectacles is too short for the wearer’s face, he will look upon the edge of the lens, and a portion of the exterior rim of the frame; if they are too long his eye will meet the opposite edge and inner curve of the rim.

Spectacle-frames are fashioned to suit the variety of formation in different individuals, and therefore such should be applied as adapt themselves pleasantly to thetemples, across the forehead and before the eyes. The pupil of the eye should, when looking at an object directly before it, see through the centre of the spectacle-eye, so that if the whole of the glass, except the small centre, were painted black, the rays of light would pass through it without distortion of the pupil. The bridge or nose-part of the spectacle-frame should be arched out, made like the crank of a lathe, or perfectly parallel with the knuckles of the sides, according to the formation of the wearer’s nose, otherwise the spectacles sit awkwardly on the face too far from or too near to the eye-lashes, with their centres too high or too low for the natural exercise of sight. Trifling as these particulars may seem, they cannot be neglected with impunity. Where these defects are unattended to, the eye is tortured by straining to overcome the difficulty, and striving to accommodate itself to them, instead of their being shaped to meet its requirements. Some old-fashioned spectacles have short side-pieces, which press most unpleasantly on one point of the temples, and when closed scratch and rub the lenses. Others have very cumbrous and heavy sides, with double lift or common hinge-joints. These also scratch the lenses when folded up, and can only be worn with any degree of comfort when the head is uncovered. Decidedly the best constructed spectacle-frames are those which, without being clumsy, have enough strength to admit of the sides being extended the full width of the face without bending the front, with single sides rather longer than their front for ladies’ use, and with turnpin sides (an extending joint, turning on a pivot,) for gentlemen.

The material of which they are composed should beeither gold, silver, or enamelled blue steel. Tortoiseshell, also, when well made, is very light and pleasant to wear, particularly for ladies. There is no advantage in large size, or round-eye spectacles, to compensate for their clumsy appearance and great weight; we get a sufficient expanse of observation with the oval-shape glasses without harassing the eye with an excess of light, which the large glasses admit.

Solid blue steel mountings are a decided improvement, and are invaluable for persons who constantly require spectacles. They are wrought from a plate of steel, and shaped as light and uniform as any other town-made elastic blue-steel spectacles, with the advantage of being more durable, and eventually less expensive; for as they have no soldering in their composition, it is scarcely possible to break them, and therefore they rarely want repairing. Blue steel spectacles, in consequence of their being so much in request, are coarsely imitated, and vast numbers are sold by the pretended cheap shops, at apparently low prices which the wearer will find to be immensely beyond their real value. There are thirteen different qualities of the spectacles termed blue steel. The chief part are country made, and roughly put together, some being all iron, others having iron fronts and steel sides; others again bear a tolerably close resemblance to the best town-made articles, and unless the two are compared together, are likely to deceive a casual observer.[5]

The fine elastic blue steel, of the best quality, are exceedingly light, highly polished, and beautifully enamelled. They will retain their appearance for two or three years, when carefully used; and they can be restored to their original appearance at any time for a few shillings’ expense.

The anti-pressure spectacles are made of gold, silver, or the elastic steel. They are not adapted for ladies’ use, but for gentlemen have been much in demand, as they obviate the necessity of opening and closing a second joint or lengthening piece, and do not press or annoy the nose or temples, but by an equal tenacity preserve their proper position before the eyes.

Single eye-glasses, though very convenient for occasional use, are not to be compared with spectacles for the agreeable and natural assistance they give to vision. The eye should not be dependent on them for continuous assistance. Those who persist in using them should do so as little as possible; but the wiser course is to discard them entirely, and adopt the double eye-glasses where it would be tedious to apply spectacles of the usual kind.

That the vision is more natural and perfect when both eyes are employed than when one glass only is used, must be self-evident, as the axis of each glass, placed as they should be in the spectacles, coincides with the axis of each eye, and the rays of light are thus equally refracted to the eye. Again, the eyes have a most acute and sensitive sympathy with each other, and when a single eye-glass is constantly used they are unnaturally exercised, and prevented from acting in concert. One eye (generally the right eye) has the glass perpetually applied to it; and very frequently, in consequence ofthis pernicious practice, becomes of a different focus to the other. Mr. George Adams informs us that he did not recollect an instance of a short-sighted person who had occasion to increase the focus of his concaves if he began by wearing spectacles, but that the cases were frequent, where a single eye-glass had been used, in which the persons had frequently required a change of glasses.

The prices of spectacles are diversified and fluctuating, like all other manufactures, so that to publish a list of prices would only tend to mislead and deceive my readers. For instance, the price of a pair of pebbles, used formerly to be one guinea extra to the charge for glasses; they are now reduced to half that sum. A pair of pebbles, of the concave or of the periscopic figure, were at the same time charged twenty-five shillings. These have been reduced in the same proportion. And it cannot be too universally known, that a person can have a pair of good convex glasses fitted into his spectacles, and correctly suited to his sight, at from one shilling and sixpence to two shillings per pair, by any respectable optician. The poorest person may be defended against the tender mercies of the spectacle speculators; for he really can obtain a better article for his money, both in quality and suitableness to his sight, of the respectable optician, and, upon an average, ata less costthan the cheat contrives, by dint of manœuvring, to extract from him. Good lenses, in plain frames, or, in other words, a good pair of spectacles, may be had, correctly suited to the sight, for two shillings and sixpence. Who then, knowing this, would suffer his sight to be tampered with? Truly, those who wouldstickle for a shilling in the price of such valuable and essential instruments

“Deserve not the comfort they shed o’er the soul.”

Yet, at the same time, there is no reason why those exorbitant charges should be submitted to, which are often paid without hesitation by the delighted purchaser, when a pair of spectacles appears to suit his sight.

The love of the marvellous, and the insane thirst for novelties, are strikingly displayed in many inquirers for spectacles. The honest, straight-forward, and disinterested counsel of the established tradesman, is looked upon with scowling suspicion; but the preposterous and shallow pretensions of the empiric, decked with all the paraphernalia of fudge and falsehood, are listened to with eager curiosity. If the writer looked to self-interest as his guiding star, his course would be to preserve silence on these subjects; since it needs not to be demonstrated, that the practice and the profit of the regular practitioner are increased by the patched-up and mangled cases, which are, as it were, provided for him, over and above the number wholegitimately requirethe exercise of his skill. But he despises such mercenary calculations, and contends that “The happiness of mankind at large is a principle that ought to be followed out by all individuals at every personal cost, and against every kind of opposition.”—Medical Examiner.

FOOTNOTES:[4]In Russia the person having short sight is seated in a chair for several hours daily, with the head placed in a natural position for reading, but prevented from pressing forward. The page is at first placed at the short distance at which the eyes have been accustomed to observe; but this distance is gradually extended, until the humours of the eyes, constantly exercised in endeavouring to accommodate their powers to the gently increased demand upon them, at length acquire the capability of observing at the usual distance.It is undoubtedly the fact that this character of sight may be acquired; many instances could be adduced of watchmakers and others, whose employments are of a sedentary or studious character, becoming short-sighted.[5]It will be perceived that it is the workmanship and nice finish of the best town-made spectacle-frames which necessarily increases the price. Thus, a single pound of pig iron, which costs one penny, can be manufactured into watch-springs of the value of £240.

[4]In Russia the person having short sight is seated in a chair for several hours daily, with the head placed in a natural position for reading, but prevented from pressing forward. The page is at first placed at the short distance at which the eyes have been accustomed to observe; but this distance is gradually extended, until the humours of the eyes, constantly exercised in endeavouring to accommodate their powers to the gently increased demand upon them, at length acquire the capability of observing at the usual distance.It is undoubtedly the fact that this character of sight may be acquired; many instances could be adduced of watchmakers and others, whose employments are of a sedentary or studious character, becoming short-sighted.

It is undoubtedly the fact that this character of sight may be acquired; many instances could be adduced of watchmakers and others, whose employments are of a sedentary or studious character, becoming short-sighted.

[5]It will be perceived that it is the workmanship and nice finish of the best town-made spectacle-frames which necessarily increases the price. Thus, a single pound of pig iron, which costs one penny, can be manufactured into watch-springs of the value of £240.

Back to Index Next