Note 62 — Chapter II · MAN’S FIRST WEAPONS—THE STONE AND THE STICK. THE EARLIEST AGES OF WEAPONS. THE AGES OF WOOD, OF BONE, AND OF HORN.

The military engines of the ancients were chiefly on the torsion principle; those of the mediævals were of two types, the sling and the crossbow. The ‘tormentum’ was so called because all its parts were twisted; the ‘scorpion’ (or catapult), because the bow was vertically placed, like the insect’s raised tail; and the ‘onager,’ because the ‘wild asses, when hunted, throw the stones behind them by their kicks, so as to pierce the chests of those who pursue them, or to fracture them.’ So at least says A. Marcellinus (Hist. xxiii. 4). I cannot but suspect that Anna Comnena’s τζάγρα is a corruption of onager (Yule’s Marco Polo, ii. 144).