The gastraphetes (), also called belly bow or belly shooter, was a hand-held crossbow used by the Ancient Greeks. It was described in the 1st century AD 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 prior to c. 420 BC. Unlike later Roman and medieval crossbows, spanning the weapon was not done by pulling up the string, but by pushing down an elaborate slider mechanism. Description A fairly detailed description and drawing of the gastraphetes appears in Heron's Belopoeica (Ancient Greek Βελοποιικά, English translation: On arrow-making), drawn from the account by the 3rd-century BC engineer Ctesibius. The weapon was powered by a composite bow. It was cocked by resting the stomach in a concavity at the rear of the stock and pressing it down. In this way considerably more energy can be summoned up than by using only one arm of the archer as in the hand-bow. There are no attestations through pictures or archaeological finds, but the description by Heron is detailed enough to have allowed modern reconstructions to be made. According to some authors, the dimensions of the gastraphetes may have involved some kind of prop. A larger version of the gastraphetes were the oxybeles, which were used in siege warfare. These were later supplanted by the early ballista that later also developed into smaller versions supplanting also the gastraphetes. Date According to a long dominant view expressed by E. W. Marsden, the gastraphetes was invented in 399 BC by a team of Greek craftsmen assembled by the tyrant Dionysius I of Syracuse. However, recent scholarship has pointed out that the historian Diodorus Siculus (fl. 1st century BC) actually did not mention the gastraphetes, but was referring to the invention of the "katapeltikon", a mechanical arrow firing catapult. Since Heron states in his Belopoeica that stand-mounted mechanical artillery such as the katapeltikon was inspired by the earlier hand-held gastraphetes, the invention of handheld crossbows into Greek warfare must have thus occurred some unknown time before 399 BC. The terminus ante quem may be more precisely defined as being before 421 BC, since another Greek author, Biton (fl. 2nd century BC), whose reliability has been positively reevaluated by recent scholarship, credits two advanced