In 1992, the remains of a 1st-century BC hydraulis were found at Dion, an ancient Macedonian city near Mount Olympus, Greece, during excavations under Prof. D. Pantermalis. This instrument consisted of 24 open pipes of different height with a conical lower ending. The first 19 pipes have a height from 89 to 22 cm (35 to 8 inches). Their inner diameter gradually decreases from 2 to 1.5 cm. These 19 pipes correspond to the perfect system of the ancient Greek music which consisted of one chromatic and one diatonic scale. The pipes No. 20 to 24 are smaller and almost equal in height and they seem to form an extension of the diatonic scale. The conical end of the pipes is inserted in a metal plate. At a point just before the narrowing part of every pipe there is an opening producing the turbulence of the pressurized air and the sound. The pipes are stabilized by two metal plates. The one facing outwards has decorative motifs. The instrument had one row of keys. The lower part of the organ, with the air-pressing system, was missing.