Mechanical organ
A mechanical organ is an organ that is self-playing, rather than played by a musician. For example, the Barrel Organ is activated either by a person turning a crank, or by clockwork driven by weights or springs.
Usually, mechanical organs are pipe organs although some instruments were built using reeds similar to those found in a harmonium. Since the 1950s, some instruments have been built using electronics to generate the sound, though still operated by mechanical or pneumatic means. From the 1990s pipe organs have been built that are operated by MIDI rather than the earlier mechanical means.