Explanation: Pictured is a Graeco-Roman torsion engine. The Romans used a particular size of torsion engines like these, the scorpio, as a form of light field artillery that could be brought along on the march (typically disassembled and packed, and then re-assembled for siege or battle). They fired a projectile about the size of a small javelin ('dart') with incredible power and precision. They're often noted as 'skewering' individual targets through their armor, piercing shields, and in general being quite devastating towards enemy forces.

In Caesar's Commentarii, he relays a story of a scorpio crew safe at the edge of friendly lines repeatedly bulls-eyeing individual man-sized targets on a single narrow section of wall. This reliable localized pressure kept the enemy from relaying torches to throw at the oncoming siege tower - an impressive enough feat for an individual marksman, but almost unheard of for siege weapons of antiquity!

Since passing along incendiaries to that section of wall was their only hope to stop the incoming Roman siege tower, Caesar also praised the bravery and duty of the Gauls who kept filling that gap. Respect where respect is due, even to the enemies of Rome!

Modern estimates put their firing rate of scorpiones at about ~4/minute in the hands of a skilled crew - quite an output! In addition, the Legions typically carried one-per-century, meaning each Legion (roughly ~5000 men) would be carrying 59 scorpiones - that's some 236 shots-per-minute from a single artillery battery!