The Greeks and Romans both made extensive use of artillery for shooting large arrows, bolts or spherical stones or metal balls. Occasionally they also used ranged early thermal weapons. There was heavy siege artillery, but more mobile and lighter field artillery was already known and used in pitched battles, especially in Roman imperial period.
The technology was developed quite rapidly, from the earliest gastraphetes in about 399 BC[1] to the most advanced torsion artillery in about 300 BC at the time of Demetrius Polyiorcetes. No improvement, except in details, was ever made upon the catapults of Demetrius.[2] The Romans obtained their knowledge from the Greeks, and employed the Greek specialists.
Five Greek and Roman sources have survived: two treatises by Heron of Alexandria, Belopoeika and Cheiroballistra; and the books by Biton of Pergamon, Philo of Byzantium and Vitruvius[3]
Tarn
was invoked but never defined (see the help page).