Four sided opticians snellen chart by Down Brothers of St. Thomas Street, London
A rather decorative four sided snellen chart by Down Brothers of St. Thomas Street, London. Down Brothers were renowned suppliers or surgical instruments. Snellen charts are named after the Dutch opthalmologist Herman Snellen who developed the chart in 1862.
The chart is constructed of a wooden frame with a chart on each of the four sides an dates to the first quarter of the 20th century.
Measuring: 57 cm x 21 cm x 21 cm
England, London, first quarter 20th century