Hydraulis of Dion

The hydraulis of Dion is a first-century BC water organ excavated in 1992 at the ancient Macedonian city of Dion near Mount Olympus, one of the best-preserved examples of the worlds earliest keyboard instrument. The hydraulis itself was invented by the third-century BC Hellenistic engineer Ctesibius of Alexandria, and worked by using water flowing from a height to compress air, which then drove a set of organ pipes; the Dion instrument preserved twenty-four pipes of varying height, the first nineteen tuned to the ancient Greek musical scale. Archaeologists finished a working reconstruction of the instrument by 1999 using both the excavated fragments, now held at the Archaeological Museum of Dion, and surviving ancient texts describing how a hydraulis was built and played.