Adolf Sonnenschein's 'Arithmometer', late 19th century.
© Science Museum / Science & Society Picture Library
This device, which showed units, rods of 10s, and squares of 100s, anticipated many 20th century arithmetical teaching aids. Adolf Sonnenschein was an enlightened teacher and innovator who devised arithmetical aids and wrote textbooks for very young children. Made by George Philip and Son of London and Liverpool.