Defects of sight and hearing : their nature, causes, prevention, and general management / by T. Wharton Jones.

  • Thomas Wharton Jones
Date:
1859
Catalogue details

Licence: Public Domain Mark

Credit: Defects of sight and hearing : their nature, causes, prevention, and general management / by T. Wharton Jones. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    that it is necessary to hold the object nearer in order to see it. When we use artificial light for working by, it should be, as far as possible, sufficiently bright without being dazzling. For reading, writing, or sewing by, the light yielded by two or three composite candles is, perhaps, the best. The light is sufficient in quantity, and, at the same time, mild and not very much colored; and if there be no draughts of air in the apartment, sufficiently uniform and steady. The candles should be placed to the left of the desk, and a lit- tle in front, and still less brought between the eyes and the object looked at, as is sometimes done by far-sighted people. If the room be large, it is well, in addition, to illuminate it generally, and for this purpose nothing is better than a moderator lamp, placed somewhere in the middle. If gas light be employed, the burners should be suspended from the middle of the ceiling and provision made for due venti- lation. [The best form of gas burner is the Argand, being free from the flickering light of the common gas burners in use.] In either case the light should be moderated and diffused by means of an obscured glass globe. The light from lamps with opaque shades and the light concentrated by glass globes filled with water, as used by watchmakers, jewelers, and other such workmen, are by no means favor- able to the eyesight. They should be used, therefore, as little as possible. Glaring and flickering lights irritate the eye even when not employed in any examination; but when so employed such light is extremely detrimental. We should not read, 3*