Lock and Key
The lock originated in the Near East, and the earliest known lock to be operated by a key was the Egyptian lock. Possibly 4,000 years old, this large wooden lock was found in the ruins of the palace of Khorsabad near Nineveh, the ancient capital of Assyria. The Egyptian lock is also known as the pin-tumbler type, and it evolved as a practical solution to the problem of how to open a barred door from the outside. The first and simplest locks were probably just a bar of wood or a bolt across a door. To open it from the outside, a hand-size opening was made in the door. This evolved into a much smaller hole into which a long wooden or metal prodder was inserted to lift up the bar or bolt. The Egyptians improved this device by putting wooden pegs in the lock that fell into holes in a bolt, which meant that the bolt could not be moved until the pegs were lifted out. This was done by giving the long wooden key some corresponding pins that lifted out the pegs from the holes in the bolt so it could be drawn back. These locks were up to 2 ft (61 cm) long and their keys were long, wooden bars resembling a toothpick. It was this invention of tum blers—small, movable wooden pegs that fell by their own weight into the bolt—that would eventually form the basis of modern types of locks.
The ancient Romans built the first metal locks, and their iron locks and bronze keys are easily recognizable even today. They improved the Egyptian model by adding wards—projections or obstructions inside the lock—that the key must bypass in order to work. Besides these warded locks, the Romans also invented the portable padlock with a U-shaped bolt which is known to have been invented independently by the Chinese. Some Roman locks used springs to hold the tumblers in place, and the Romans made locks small enough that they could wear tiny keys on their fingers like rings. In medieval times, locks and keys changed little in design, with most of the effort directed at making them more elaborate and beautiful. It was during this time that lock-making became a skilled trade, and although there were some design changes, like a pivoted tumbler and more complicated wards, medieval locks are characterized mainly by their high degree of lavish embellishment. Despite this high level of medieval craftsmanship, these medieval locks did not provide a great deal of security against the determined and skilled thief, and even with especially elaborate warding systems, they were still relatively easy to pick or open.