At the siege of Mexico by Cortes in 1521, when the ammunition for the Spanish cannon ran short, a soldier with a knowledge of engineering undertook to make a trebuchet that would cause the town to surrender. A huge engine was constructed, but on its first trial the rock with which it was charged instead of flying into the town ascended straight upwards, and falling back to its starting-point destroyed the mechanism of the machine itself.[25] [25] _Conquest of Mexico._ W. Prescott, 1843. Though all the projectile engines worked by cords and weights disappeared from continental warfare when cannon came to the front in a more or less improved form, they--if Vincent le Blanc is to be credited--survived in barbaric nations long after they were discarded in Europe. This author (in his travels in Abyssinia) writes ‘that in 1576 the Negus attacked Tamar, a strong town defended by high walls, and that the besieged had engines composed of great pieces of wood which were wound up by cords and screwed wheels, and which unwound with a force that would shatter a vessel, this being the cause why the Negus did not assault the town after he had dug a trench round it.’[26] [26] Vincent le Blanc, _Voyages aux quatre parties du monde, redigé par Bergeron_, Paris, 1649. Though the accounts given by this author of his travels are imaginative, I consider his allusion to the siege engine to be trustworthy, as he was not likely to invent so correct a description of one. Plutarch, in his Life of Marcellus the Roman General, gives a graphic account of Archimedes and the engines this famous mathematician employed in the defence of Syracuse. It appears that Archimedes showed his relative Hiero II., King of Syracuse, some wonderful examples of the way in which immense weights could be moved by a combination of levers. [Page 35] Hiero, being greatly impressed by these experiments, entreated Archimedes temporarily to employ his genius in designing articles of practical use, with the result that the scientist constructed for the king all manner of engines suitable for siege warfare. Though Hiero did not require the machines, his reign being a peaceful one, they proved of great value shortly after his death when Syracuse was besieged by the Romans under Marcellus, 214–212 B.C. On this occasion Archimedes directed the working of the engines he had made some years previously for Hiero. Plutarch writes: ‘And in truth all the rest of the Syracusans were no more than the body in the batteries of Archimedes, whilst he was the informing soul. All other weapons lay idle and unemployed, his were the only offensive and defensive arms of the city.’ When the Romans appeared before Syracuse, its citizens were filled with terror, for they imagined they could not possibly defend themselves against so numerous and fierce an enemy.