- Crane
The extent to which human beings extend their natural capabilities through the use of machines is something that disting-uishes us from other members of the animal kingdom. Cranes are an especially
relevant example of this; the ability to raise maneuver weights vastly greater than those that people could lift and move unaided has played a defining role in the development of human society.
The crane is a system of pulleys and cords or wires attached to a framework that enables the movement of heavy weights both vertically and horizontally through the use of mechanical advantage. The earliest cranes have been dated to approximately 550 B.C.E., although there are Greek architectural constructions still in existence that predate this by several hundred years, and that undoubtedly would have required some sort of supporting pulley mechanism. Cranes were used in ancient Greece for a variety of purposes. They were integral to Greek construction and were also used for pulling heavy loads. The Claw of Archim-edes was a wall-based crane used to hoist invading ships to a great height, only to drop them to their destruction.
Cranes continued to be used extensively in ancient Rome, where a "treadmill crane" was used to help in building projects. In reconstructions, single blocks of stone weighing as much as 100 tons have been lifted considerable heights above the ground using this technology. Cranes fell out of use for a while, only to reappear in the late Middle Ages. They have continued to see heavy usage through to the present day.
SEE ALSO: BRAIDED ROPE, PULLEY, WINCH, LEVER, COMPOUND 2 PULLEY
- Crossbow
Chinese pioneer the longbow's smaller rival.
The crossbow originated in ancient China circa 550 B.C.E. and is thought to have been developed from the horizontal bow trap, which was used to kill game. For use as a weapon, the Chinese developed many different designs of crossbows and drawstrings. Some had stirrups attached to them to hold the bow down 03when the bowmen were rearming. Later crossbow-cannons had winches to pull back the strings, because people would not have been strong enough to do this unaided. The Chinese also invented grid sights in 100 C.E. and a machine-gun type of crossbow, which had a magazine of bolts fitted above the arrow groove; as one bolt was fired another dropped into its place. Poisoned crossbow bolts were also used.
Knowledge of the crossbow was probably transmitted from China to Europe via the Greeks and Romans. The weapon could be used by an untrained soldier to injure or kill a knight in armor. The crossbow was adopted in Europe in the tenth century C.E. and used throughout the Middle Ages. William the Conqueror brought the medieval crossbow to England in 1066, but the Welsh longbow supplanted the crossbow during the reign of Edward l (1272-1307). Many viewed it as an inhuman weapon, requiring no skill and having no honor, and in 1139 the Pope, through the Second Lateran Council, condemned the use of crossbows against anyone except infidels.
Today, crossbows are mostly used for target shooting in modern archery. In some countries crossbow hunting is still allowed, such as a few states in the United States, Asia, Australia, and Africa.
SEE ALSO: CARPENTRY, METALWORKING, BOW AND ARROW, HELMET, CHAIN MAIL, CATAPULT