Greece, Ancient Greek Technology

It was a catapult which launched two arrows simultaneuously. The sliding central beam "slider" cocked with the help of a manual windlass. The narrow metal claw (retaining pin) held the two half-springs of the bow via a perforated binding lamina. This ensured the even distribution of force to the two arrows at the launch. The catapult was mounted on a base which allowed the horizontal and vertical regulation of the launch angle.
Sources
Biton, Construction of warengines and artillery

Oxybeles Catapult of Zopyrus from Tarentum. Photo : Augusta Stylianou Artist