Heron of Alexandria in the context of "Aeolipile"

Ancient Greek technology developed during the 5th century BC, continuing up to and including the Roman period, and beyond. Inventions that are credited to the ancient Greeks include the gear, screw, rotary mills, bronze casting techniques, water clock, water organ, the torsion catapult, the use of steam to operate some experimental machines and toys, and a chart to find prime numbers. Many of these inventions occurred late in the Greek period, often inspired by the need to improve weapons and tactics in war. However, peaceful uses are shown by their early development of the watermill, a device which pointed to further exploitation on a large scale under the Romans. They developed surveying and mathematics to an advanced state, and many of their technical advances were published by philosophers, like Archimedes and Heron.

The gastraphetes (Koine Greek: γαστραφέτης, lit. 'belly-releaser'), also called belly bow or belly shooter, was a hand-held crossbow used by the Ancient Greeks. It was described in the 1st century by the Greek author Heron of Alexandria in his work Belopoeica, which draws on an earlier account of the famous Greek engineer Ctesibius (fl. 285–222 BC). Heron identifies the gastraphetes as the forerunner of the later catapult, which places its invention some unknown time before c. 420 BC.

Unlike later Roman and medieval crossbows, spanning the weapon was not done by pulling up the string but by pushing down a slider mechanism.