The pieces of music are encoded onto wooden barrels (or cylinders), which are analogous to the keyboard of the traditional pipe organ.
The French name orgue de Barbarie, suggesting barbarians, has been explained as a corruption of, variously, the terms bara ("bread") and gwen ("wine") in the Breton language, the surname of an early barrel-organ manufacturer from Modena, Giovanni Barberi,[3] or that of the English inventor John Burberry.
Although the hurdy-gurdy is also powered by a crank and often used by street performers, it produces sound with a rosin-covered wheel rotated against tuned strings.
The organ barrels must be sturdy to maintain precise alignment over time, since they play the same programming role as music rolls and have to endure significant mechanical strain.
Damage to the barrel, such as warpage, would have a direct (and usually detrimental) effect on the music produced.
The size of the barrel will depend on the number of notes in the organ and the length of the tune to be played.
A worm gear on the crank shaft causes the barrel to rotate slowly and its pins and staples lift the fronts of the keys.
There were many larger versions located in churches, fairgrounds, music halls, and other large establishments such as sports arenas and theaters.
They could also be hydraulically powered, with a turbine or waterwheel arrangement giving the mechanical force to turn the barrel and pump the bellows.
Such instruments are furnished with a normal organ keyboard, in addition to the automatic mechanism, making it possible to play them by hand when a human organist is available.