Renseignements généraux

Nº de série

S/O

Nº de partie

1

Nombre total de parties

3

Ou

S/O

Brevets

S/O

Description générale

Instrument is all metal, with exception of clear glass lenses; folding handle has silver metal finish; metal disks housing silvered mirror and rotating lenses have darkened finish.

Dimensions

Remarque : Cette information reflète la taille générale pour l’entreposage et ne représente pas nécessairement les véritables dimensions de l’objet.

Longueur

9,4 cm

Largeur

3,1 cm

Hauteur

S/O

Épaisseur

S/O

Poids

S/O

Diamètre

S/O

Volume

S/O

Lexique

Groupe

Technologie médicale

Catégorie

Instruments

Sous-catégorie

S/O

Fabricant

Ou

DOWN

Pays

England

État/province

Inconnu

Ville

London

Contexte

Pays

Inconnu

État/province

Inconnu

Période

Inconnu

Canada

Part of a collection of medical instruments used by J.R Jackson and W.A.L. Jackson, father and grandfather of donor. [Ref. 1]

Fonction

Inconnu

Technique

One of the early problems when using the direct ophthalmoscope with the light placed to the side was the need to tilt the mirror at an angle to the line of observation for the light to enter the patient's eye. This meant that the observer was viewing the fundus obliquely through the correcting lenses. For low lens powers this was not a problem but in the higher ranges it produced a reduction in vision and a shifting of the image due to the prismatic effect. In 1875 John Couper of the Royal London Ophthalmic Hospital overcame this problem by dissociating the round disc of lenses from the mirror. By this means the observer was able to look through the centre of the lenses perpendicularly. Couper's design, made by Pickard and Curry of London, went through several models and effectively made redundant the fixed-mirror design. Edward Loring of the USA improved on Couper's model in 1877 with his vertically tilting mirror. This consisted of a round mirror with the sides cut off, rotatable on its vertical axis. [Ref. 2]

Notes sur la région

Inconnu

Détails

Marques

Rotating lenses are labelled. "LONDON/ DOWN" stamped into back of mirror housing.

Manque

Appears complete.

Fini

Instrument is all metal, with exception of clear glass lenses; folding handle has silver metal finish; metal disks housing silvered mirror and rotating lenses have darkened finish.

Décoration

S/O