Lithobolos

A lithobolos (Greek: λιθοβόλος) refers to any mechanical artillery weapon used and/or referred to as a stone thrower in ancient warfare. Typically this referred to engines that propel a stone along a flat track with two rigid bow arms powered by torsion (twisted cord), in particular all sizes of palintonon.

However, Charon of Magnesia referred to his flexion (bow) stone-thrower engine, a 9 feet (2.7 m) gastraphetes shooting 5–6 mina (5 pounds, 2.3 kg), as a lithobolos; Isidoros of Abydos reportedly built a larger 15-foot (4.6 m) version shooting 40-pound (18 kg). Also, the euthytonon, a single-arm torsion catapult, was referred to by contemporaries as a stone-thrower, as was its Roman evolution the onager.

Stone-throwers of the same class looked alike, with their stone capacity scaling mostly with overall size. Machine dimensions can be approximated mathematically based on the equivalent spring diameter.