The ballista, plural ballistae or ballistas, sometimes called bolt thrower, was an ancient projectile weapon that launched either bolts or stones at a distant target.
Reconstructed small Roman ballista
One talent ballista (26 kg [57 lb] weight projectile) was typical for Roman era ballista. The heaviest version ever made was built by Archimedes, and used stones up to three talents (78 kg [172 lb]).
Roman 'catapult-nest' on Trajan's Column
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 B
A modern reconstruction of the scorpio.
Modern reconstruction of a Scorpio