A pneumatic organ is a type of musical instrument that produces sound using air pressure. It operates by forcing air through pipes, which creates different musical notes. The instrument is often powered by a bellows, which compresses air and directs it into the pipes. This design allows for a wide range of sounds and dynamics, making it popular in various musical settings. These organs were commonly used in the 19th century and are often associated with theater and church music. They can vary in size, from small portable versions to large installations found in concert halls. The pneumatic organ is a precursor to modern pipe organs, which continue to be used today.