scorpio

The scorpio or scorpion was a type of Roman torsion siege engine and field artillery piece. It was described in detail by the early-imperial Roman architect and engineer Vitruvius in the 1st century BC and by the 4th century AD officer and historian Ammianus Marcellinus. Design Two versions are known: a horizontal two-armed variety like a ballista and a one-armed, vertical version otherwise referred to as an onager. The scorpion was made of a ground frame made of two beams joined together with crossbeams. Spring holes were drilled into the sides of the beams to allow for ropes to be placed in, thus allowing them to serve as sinew-springs. This gave the weapon more power. An arm made of wood known as the stilus, with iron hooks at the end, was used to hold the stone or bolt which was to be fired. The fourth century army officer and historian Ammianus Marcellinus witnessed the use of scorpiones during several engagements in the Persian wars of Constantius II, and described the one-armed version as synonymous with the onager, with the vertical upraised arm as the 'scorpion's sting'. The complexity of construction and in particular the torsion springs (which the Romans referred to as tormenta) led to great sensitivity to any variation in temperature or moisture, which limited their use. While this type of technology continued to be used in the Byzantine Empire, which was the continuation of the Roman Empire through the Middle Ages, it had disappeared in the Middle Ages in Western Europe. Unlike the onager, the scorpion only required one man to operate it. Use