Gastraphetes

The gastraphetes, literally belly-bow in Greek, is an early mechanical crossbow-like weapon described by the Greek engineer Heron of Alexandria as originating in the Greek world of the early fourth century BCE, generally credited as one of the earliest handheld mechanical missile weapons in the historical record. It consisted of a stock with a sliding drawing mechanism and a lock to hold the bowstring under tension, drawn by bracing the concave end of the stock against the operator's stomach and body weight to pull the string back, which allowed a single user to store far more energy in the bow than an ordinary handheld bow could manage, giving the weapon greater range and penetrating power. Ancient sources associate the gastraphetes with the military engineering tradition of Syracuse under the tyrant Dionysius I, and larger torsion-powered descendants of the same basic mechanical principle developed into the larger Greek and later Roman siege artillery such as the ballista.