It was a powerful straight-spring catapult that launched arrows at long distances. It consisted of an oblong case (“syrinx”) that had ratchets at each side and a powerful frame at the top. In the frame, a pair of torsion springs (“neura”) supported the two arms that had the string. The torsion springs were comprised of twisted ropes from animal sinews or women’s hair spread with oil. In the case slid a central beam (“slider”) that had the dovetail cross-section and at the top a groove for the reception of the arrow. The “slider” was cocked with the help of a powerful manuallyoperated winch and secured in the prongs of the ratchets. Its rapid release was achieved with the help of a special claw. It was first used by the Macedonian army of Philip II and was further developed by Alexander the Great’s engineer, Diades of Pella.