The starting post mechanism in the classical stadiums. Model of one of the two agones of the hysplex, which is the system that, when placed in front of the starting point of the runners, prevented the premature set off during the speed contests. The hysplex was composed by two horizontal ropes stretched in front of the runners at the level of the knees and the chest, as is observed in a scene on a Panathenaic amphora from Athens, dated 344-343 B.C. The ropes were held at the edges by vertical wooden posts, the agones, which were implanted inside simple mechanisms, predecessors of the spring, made by twisted animal nerves. These mechanisms were placed on rock bases, remnants of which were found at the edges of the starting point of three ancient Greek stadiums, of Isthmia, of Epidauros, and of Nemea, as well as in the Agora of Corinth. The agones were kept standing, probably stranded by a ring on a stable pillar, which was placed behind them. The starter, who was standing behind the runners holding the two control ropes, set the mechanism in motion. With one sudden move he released the stretched agones, which fell suddenly to the ground dragging along the whole barrier and thus providing the runners the freedom to run. In the picture the model of the entire system of the hysplex is depicted in natural size, which, placed at its original position in the stadium of Nemea, functioned perfectly in July 1996, during the conduct of the contests, according to the ancient prototypes.