Artillery were essentially torsion weapons. They used animal sinew and hair braided together to make torsion- springs
The Catapulta shot large arrows or bolts at the enemy and could be mounted on carts for mobility. One would be assigned to each century. The name comes from the Greek (katapeltes) because it could pierce (kata) a shield (pelta).
The ballista was typically used as a siege weapon. It was made of wood held together with iron plates around the frames and shot stone balls at the enemy. It had a maximum range of about 460m
The Onager was a siege weapon designed to hurl large boulders at enemy fortifications. The Romans also shot burning embers and rotting flesh over the walls to set fire to buildings or spread disease
