The water organ or hydraulic organ is a type of pipe organ blown by air, where the power source pushing the air is derived by water from a natural source or by a manual pump. Consequently, the water organ lacks a bellows, blower, or compressor.
Musicians with cornua and a water organ, detail from the Zliten mosaic, 2nd century CE
Hydraulis, 1st century BCE, Archaeological Museum of Dion, Greece
Reconstruction of hydraulic organ
The pipe organ is a musical instrument that produces sound by driving pressurised air through the organ pipes selected from a keyboard. Because each pipe produces a single pitch, the pipes are provided in sets called ranks, each of which has a common timbre, volume, and construction throughout the keyboard compass. Most organs have many ranks of pipes of differing pitch, timbre, and volume that the player can employ singly or in combination through the use of controls called stops.
Pipe organ in the collegiate church of St. Michael in Neunkirchen am Brand
Hydraulis from the 1st century BC, oldest organ found to date, Museum of Dion, Greece
4th century AD "Mosaic of the Female Musicians" from a Byzantine villa in Maryamin, Syria.
9th century image of an organ, from the Utrecht Psalter.
