An apparatus to be used by opticians for testing defective vision / [Sydney Lawrence].

  • Lawrence, Sydney.
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: An apparatus to be used by opticians for testing defective vision / [Sydney Lawrence]. Source: Wellcome Collection.

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    N° 8036 A.D. 1880 Date of Application, 14th May, 1889 Complete Specification Left, 13th Feb.. 1890—Accepted, 15th Mar., 1890 PROVISIONAL SPECIFICATION. An Apparatus to be used by Opticians for Testing Defective Vision. I, Julia Lawrence, of 20 Tyndale Place, Upper Street, Islington, in the County of Middlesex, Clerk, do hereby declare the nature of this invention, a communication to me. from abroad by Sydney Lawrence, of 4 Hare Street, Calcutta, India, Ophthalmic Optician, to be as follows :— .> The invention has for its object an apparatus to be used by opticians for testing detective vision with accuracy by day or by night. The invention consists of a number of known appliances confined in a special and ingenious manner, whereby accuracy and facility in the testing of defective vision are secured. The invention consists essentially of an adjustable chair, electric or other 10 light, and adjustable type stand to be used therewith. The chair, which may be con¬ structed ot wood or other suitable material, is in two parts ; the upper part or seat revolves freely and with perfect smoothness and steadiness, preferably by means of a pivot and four castors, which are concealed from view, and which run in a groove let into a plate fixed in the lower frame-work or legs of the chair ; the legs of the chair 15 are terminated bv brass or other wheels, which rest on the horizontal rail hereafter described. A foot.rest, adjusted to the upper portion of the chair, completes this part of the combination for which protection is sought. Two steel or other rails, laid flush with the floor, bear the chair as above described, the pedal castors resting and running on 20 the rails, and thereby admitting of the chair being smoothly and steadily moved to any required distance from the type stand, while the revolving seat admits of the patient being placed to any distance from, and at any angle to, the source of light. To ensure accuracy and facilitate the determination of distances, brass or other figures are fitted flush into the floor and parallel to the rails aforesaid, say, at distances of one foot 25 apart from one to twenty feet, an inner series of such numbers denoting the number ot feet, and an outer series of numbers from one to six, denoting the number of metres measured accurately from the type stand. At each end of the rails, and perpendicular to them, two polished wooden stands are placed, which have adjustable frames fitted to them, which frames can be raised and lowered to the required height, by means of 30 pulleys ; such adjustable frames have skeleton frames attached to them to admit of one set of types being removed and replaced by another without loss of time. Attached to each or either stand are wooden or other trays on hinges, to hold a case of trial lenses, and a rod or measure, which is marked off, say, in inches, from one to twenty faur, and to which a frame fixed to an arm is attached, whereby a card of types can be adjusted 35 to any required distance from the patient, or any required height above the ground. By this contrivance, the type cards are kept on a true level with the patient’s eyes. Subsidary to these contrivances, is an electric lamp with a highly polished reflector, so as to throw a brilliant light from behind the patient on to the types, and thus to enable an ophthalmic optician or an oculist to test sight at night a desideratum 46 in the case of invalids and others who may not be able to expose themselves by day. The special novelty claimed consists in the combination of parts described above, whereby in eye infirmaries, hospitals, and other places, a large number of cases of errors ot refraction can be rapidly, conveniently and accurately tested. 45 Dated this 14th day of May 1889. JULIA LAWRENCE. By Harris & Mills, 23, Southampton Buildings, London, Agents. (Pri’w WJ