Vision in health and disease; the value of glasses for its restoration, and the mischief caused by their abuse. Being the substance of lectures delivered at the Central London Ophthalmic Hospital / by Alfred Smee ... ; illustrated by one plate and numerous woodcuts.

  • Smee, Alfred, 1818-1877.
Date:
1847
Catalogue details

Licence: Public Domain Mark

Credit: Vision in health and disease; the value of glasses for its restoration, and the mischief caused by their abuse. Being the substance of lectures delivered at the Central London Ophthalmic Hospital / by Alfred Smee ... ; illustrated by one plate and numerous woodcuts. Source: Wellcome Collection.

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    simultaneously, it is either doubled or rendered very confused, because two eyes cannot regard one object through a lens without its appearing double. Sometimes, indeed, the impression of one eye is instinctively neglected, and then but one object is seen; nevertheless, in all cases and under all cir¬ cumstances, if we really see any object through a lens with both eyes simultaneously, the two objects must appear in different places, and conse¬ quently double. In my peregrinations about London I have been surprised at seeing glasses labelled “Binocular,” at some apparently respectable shops, which well indicate the knowledge possessed by even the better order of spectacle-sellers. (151.) It becomes practically a serious and important affair to get over the indistinctness of these reading-glasses; and by far the best mode with which I am acquainted is to place a large plano-convex lens in a tube about eight inches long, with its plane surface directed towards the object. The tube tapers to the ocular end, which has an aperture suitable for vision. The working-men amuse themselves by calling these tubes ear-trumpets for the eye, because they fancy that they are somewhat of that form, but the name which I have assigned to the instrument is “ the amplifier.” (152.) In the manufacture of this instrument it is important that the lens be large, and, at the same time, that the tube should be constructed as slightly as is consonant with proper strength. It is very useful at times to fix it upon an universal joint attached to a reading-desk; and its employ¬ ment will enable many elderly persons to read small print comfortably, who had previously been unable to attempt it. To healthy persons the ampli¬ fier is really a charming instrument. At first sight you may really fancy that there is nothing of importance in it; but the exquisite beauty with which it brings out the noble workmanship of the ancient coins or the modern triumphs of Wyon’s art, entitles it to a place in every numismatic cabinet. Flowers, insects, and small plants appear of singular beauty through this really magical tube. (153.) One of the most difficult classes of cases to treat, and cases which in reality frequently occur, are those in which the eye is very short-sighted, and at the same time has its power of seeing diminished; that is to say, the object must be magnified to render it distinct. For years these cases used to consult me, and I tried all the combinations which occurred to my mind without being able to give relief; that is to say, I could not think of any means which could be employed to render an object, such as a page of print, distinct to the party so afflicted. I used to tell them that neither medicine nor surgery, neither science nor experience, has found a remedy for their special case. Every person so sent away was a great annoyance to me, for I thought it a disgrace to the surgeon not to be able to furnish a remedy. One day, however, I thought of using a concave glass sufficient to compensate the defect in the ordinary refracting power of the eye, and