BARREL-ORGAN, a small portable organ mechanically played by turning a handle. The barrel-organ owes its name to the cylinder on which the tunes are pricked out with pins and staples of various lengths, set at definite intervals according to the scheme required by the music. The function of these pins and staples is to raise balanced keys connected by simple mecha nism with the valves of the pipes, which are thus mechanically opened, admitting the stream of air from the wind-chest.
Barrel-organs have been made with as many as three or four cylinders set in a circular revolving frame, but these more elabo rate instruments were mainly used in churches and chapels, a purpose for which they were in great demand during the i8th and early 19th centuries. As long ago as the 15th century barrel organs were known in Holland, where they are believed to have been invented.