Optical Accessory, by Watkins & Hill, London

Instrument is a metal and card disc with a glass lens and gradated apertures set in a circular pattern. Gradated openings consist of triangular and circular shapes, as well as openings obscured by vertical bars. Disc rotates freely upon an axle held at a sloping angle between two wooden arms which extend from a turned wooden mount with central pillar for attaching instrument to a support.