test chart accessory
North America: USA
Mid 20th c.
overall: 240 mm x 54 mm; overall (box): 27 mm x 300 mm x 58 mm
Interchangeable slide from a projection test chart. Black and steel, with transparent panel featuring symbol chart, tumbling E chart, numerical chart and Snellen charts. Together with its original cardboard postage box.
Gift of Glasgow Caledonian University, 2012