Water organ

A water organ, also called a hydraulic organ or hydraulis, is a type of pipe organ that is powered by water rather than the bellows used in later organs, its name coming from the Greek words for water and pipe. It is credited to the Hellenistic engineer Ctesibius of Alexandria in the third century BCE, and it is regarded as the world's earliest keyboard instrument and the ancestor of the modern pipe organ. Water flowing down from above entered a chamber where air was drawn in by suction, and inside a wind chamber called the camera aeolis the water and air separated, with the compressed air then pushed into a wind trunk that blew the organ's pipes, while the player pressed a set of balanced keys, reportedly requiring only a light touch, to produce sound.