It was a powerful V-spring catapult which launched stones at long range. It was invented by Alexander the Great’s engineer, Diades of Pella . It consisted of an oblong case (“syrinx”) which had a ratchet internally and powerful frames at the top. The frames held specially designed hole-carriers with ingenious washers and flanges which in turn supported by a pair of torsion springs (“neura”) 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 stone. The slider was cocked with the help of a powerful manually-operated winch and secured in the prongs of the ratchets. Its rapid release was achieved with the help of a special claw.

SOURCES: Philon of Byzantium, Belopoietica, Heron of Alexandria, Belopoietica.