Engenheiro

The Trebuchet
Recent reconstructions and computer simulations reveal the operating principles of the most powerful weapon of its time by Paul E. Chevedden, Les Eigenbrod, Vernard Foley and Werner Soedel

C

enturies before the development of eÝective cannons, huge artillery pieces were demolishing castle walls with projectiles the weight of an upright piano. The trebuchet, invented in China between the Þfth and third centuries B.C.E., reached the Mediterranean by the sixth century C.E. It displaced other forms of artillery and held its own until well after the coming of gunpowder. The trebuchet was instrumental in the rapid expansion of both the Islamic and the Mongol empires. It also played a part in the transmission of the Black Death, the epidemic of plague that swept Eurasia and North
Africa during the 14th century. Along the way it seems to have inßuenced both the development of clockwork and theoretical analyses of motion.
The trebuchet succeeded the catapult, which in turn was a mechanization of the bow [see ÒAncient Catapults,Ó by Werner Soedel and Vernard Foley;
SCIENTIFIC AMERICAN, March 1979]. Catapults drew their energy from the elastic deformation of twisted ropes or sinews, whereas trebuchets relied on gravity or direct human power, which proved vastly more eÝective.
The average catapult launched a missile weighing between 13 and 18 kilo-

66

SCIENTIFIC AMERICAN July 1995

Copyright 1995 Scientific American, Inc.

powerful trebuchets, in contrast, could launch missiles weighing a ton or more.
Furthermore, their maximum range could exceed that of ancient artillery. grams, and the most commonly used heavy catapults had a capacity of 27 kilograms. According to Philo of Byzantium, however, even these machines could not inßict much damage on walls at a distance of 160 meters. The most

1

Recovering Lost Knowledge

W

e have only recently begun to reconstruct the history and operating principles of the