Early 20th c.
metal; brass; box wood; glass
overall: 71 mm x 435 cm x 62 mm
Optometer comprising two brass cylindrical tubes either side of a revolving box wood rule (to which there are four faces, marked 6, 8, 10 and 14). The sliding target at one end features a revolving disc of eight charts that appear in the round aperture. The fixed upright at the other end features a revolving brass disc of alternately glazed and unglazed apertures (spinning this disc causes the box wood rule to rotate as well). The lower side of the upright has a dovetailed notch for slip-attachment to a metal foot (missing).
Gift of the Worshipful Company of Spectacle Makers 2016