Mechanical crossbow on stand (euthytonon) attributed to Philo of Byzantium (active 150-100 BC). When arms CC wound back against skeins or sinews, the ends of ropes, here shown hanging down from ends of arms, were connected to hook, so holding arms back. Tension was increased by a ratchet, a large arrow was placed on front of arm and fired by releasing the rope. From Poliorceticon sive de machinis tormentis telis by Justus Lipsius (Joost Lips) (Antwerp, 1605). Engraving.