Cheiroballistra

The cheiroballistra (Greek: χειροβαλλίστρα) was a small, two-armed, torsion-powered, metal-framed catapult known from an anonymous Greek treatise titled "Heron's Construction and Dimensions of the Cheiroballistra" (Ἥρωνος χειροβαλλίστρας κατασκευὴ καὶ συμμετρία). The name breaks into two parts: cheiro- (χειρο), a combining form of the word "hand," and ballistra (βαλλίστρα), from the Greek ballein ("to throw"). The weapon is known almost entirely from the manuscript; no archaeological find matches the proportions of a cheiroballistra as described in the text. The treatise survives only in later copies, the earliest dating to perhaps the 10th century AD, preserved in a Byzantine compilation of Greek poliorcetic treatises. The lettering is almost complete, but captions survive only for the first diagram and are corrupt. Modern attempts to reconstruct the weapon have fallen into two broad camps. The first follows the text with as little emendation as possible, producing a personal-sized weapon operated by a single soldier: carried by hand rather than mounted on a stand, and drawn using the operator's body weight rather than a winch. This is the same operating style as the gastraphetes. The second holds that the manuscript's proportions are corrupt, particularly the spring diameter that powers the projectile, and that a machine built to the stated figures would be too weak to be effective; this camp reconstructs the cheiroballistra as a stand-mounted machine drawn by a windlass.