concertina, free-reed musical instrument patented by Sir Charles Wheatstone in London in 1829. Hexagonal hand bellows are fastened between two sets of boards that carry the reeds in fraised sockets, as well as the pallet valves and finger buttons, by which air is selectively admitted to the reeds. The steel or brass reed tongues are attached to individual brass frames by screwed plates.
The concertina employs “double action,” each note being given by a pair of reeds, one to sound on the press of the bellows, the other on the draw. In the original and most common model, the chromatic scale is divided between the two hands; in some later models, such as the duet-system concertina, a chromatic scale is provided for each hand. The compass extends four octaves upward from the G below middle C. After the great days of the 19th-century concertina virtuoso, the instrument was gradually superseded from about 1910 by the accordion.