Accordions are a family of box-shaped musical instruments of the bellows-driven free reed aerophone type. The essential characteristic of the accordion is to combine in one instrument a melody section, also called the diskant, usually on the right-hand keyboard, with an accompaniment or Basso continuo functionality on the left-hand. The musician normally plays the melody on buttons or keys on the right-hand side, and the accompaniment on bass or pre-set chord buttons on the left-hand side. A person who plays the accordion is called an accordionist.
A piano accordion (top) and a button accordion (bottom)
An accordionist
Eight-key bisonoric diatonic accordion (c. 1830)
The first pages in Adolf Müller's accordion book
A bellows or pair of bellows is a device constructed to furnish a strong blast of air. The simplest type consists of a flexible bag comprising a pair of rigid boards with handles joined by flexible leather sides enclosing an approximately airtight cavity which can be expanded and contracted by operating the handles, and fitted with a valve allowing air to fill the cavity when expanded, and with a tube through which the air is forced out in a stream when the cavity is compressed. It has many applications, in particular blowing on a fire to supply it with air.
Hand-made English fireplace bellows
A preserved baker's bellows at Deutsches Werkzeugmuseum (German Tools Museum) at Remscheid.
Old bellows used on goldfield near Milparinka, N.S.W., Australia. 1976.
Pot bellows (excavation)