Locks of Ancient Civilizations
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The oldest known mechanically functioning lock was an Egyptian door lock used about 2000 B.C. A forerunner of modern pin-tumbler security, the lock consisted of a vertical wooden housing containing several loose wooden pegs of different lengths. These pegs fitted into holes bored in the top of a wooden bolt, preventing the bolt from being moved and the door from being opened.
An oblique slot in the bolt provided access for a long wooden key with pegs of various lengths located on one surface and corresponding to the pegs in the vertical housing. When the key was inserted into the bolt and lifted, the pegs inside the housing lined up evenly at the top of the bolt, releasing the bolt and permitting the door to be opened.
Moreover, since the lengths of the individual pegs were concealed in the housing, only a key with pegs of the correct length could release the particular bolt. Similar locks were used by other civilizations in places as widespread as Japan, Scotland, and the Pharaohs.
The early Greeks utilized the first keyhole by fastening the wooden bolt and staple to the inside of the door. A long sickle-shaped wooden key conforming to the configurations of the keyhole was inserted through the door and manipulated to lift the bolt. More a barricade than a lock, this device offered little security.
The Romans fabricated the first metal locks. Improving upon the Egyptian principle, they designed pins of various shapes with conforming keys and unusual keyholes, lessening the possibility of an intruder fashioning duplicate keys.
To reduce the size of the key and facilitate opening of the lock, they supported the pins in the locks with bronze springs. As the Romans’ skill grew, they embellished and camouflaged the locks, making them in the shape of animals, flowers, and birds. The keys were similarly decorated and hung about the neck as pendants.
The Romans also are credited with inventing the first warded locks, the principle of which is still being used.
Wards, or projections, are affixed to the inside of the lock. The key is slotted so that only the proper one can clear the projections and engage the bolt, which can then be released by turning the key. Since the wards can be constructed of tiny bits of metal, the locks and keys can be small.
Some keys were designed as finger rings. But warded construction also led to comparatively easy lock picking, as a strip of metal could be slipped past the wards and actuate the bolt.
Oriental and Western European Innovations
The principle of warded security was eventually applied to portable locks, later identified as padlocks.
Early Chinese, Turkish, East Indian, and Russian cultures used ornate metal padlocks, many of which were designed in unusual shapes resembling idols, flowers, or animals. Often the keyhole was cleverly concealed.
As civilization spread into Europe, locks became more intricate, and craftsmen vied with each other for recognition of their ingenuity and skill. Some locks were designed to eject needles, poison darts, or knives when a foreign key was inserted.
During the Renaissance a lever tumbler was added to the warded locks for extra security. Besides passing the fix ed projections, the key raised a lever that released the bolt. Nevertheless, an adept individual could manipulate the lever with a tool and pick the lock.
By the late 16th century, combination, or keyless, locks came into use throughout Europe for jewelry cases and strongboxes. The basic concept of these locks had originated in ancient China, where it was first applied to number tricks or puzzles.
The numbers were inscribed on the edges of a series of disks that revolved around a spindle. Slots in the disks corresponded to the numbers. When the correct numbers were aligned, all the slots lined up evenly, permitting a bolt to be withdrawn.
A new era in lockmaking began in 1778 when Robert Barron, an Englishman, invented the lever-tumbler lock, a refinement of the warded lock, with two levers projected into slots in the bolt. The bottom of each lever was of a different size, and only the correspondingly cut key could lift each lever to the same height, permitting the lock to open. This lock was more difficult to pick than ordinary warded locks because both levers had to be lined up on the exact level.
In 1784, Joseph Bramah, another Englishman, discarded the principle of warded security and patented a greatly improved lock, which had a cylindrical key with slots of varying depths cut in its end. The bolt was controlled by a cylindrical plug. Grooves in the plug contained notched slides, which were locked by notches in a round plate.
When the key was inserted it aligned the slide notches with the locking plate, permitting the key to turn the slides and plug and thus release the bolt.
An improved lever-tumbler lock, called a detector lock, was invented by Jeremiah Chubb in 1818. It incorporated six regular levers plus an additional lever that remained in a raised position -rendering the lock inoperable-if a foreign key was inserted, thus revealing attempted entry. By the middle of the 19th century, England had become the lock manufacturing center of the world.
The first Yale lock was patented in 1861, and an improved model followed in 1865. Yale used a rotating plug slotted to accept pins of different lengths. The edge of the key was notched to depths corresponding to the length of the pins. The notches on the key, when inserted, raised all of the pins to the same height. This freed the plug to turn in the cylinder and release the locking bolt.
Inasmuch as the key did not actuate the locking bolt, the cylinder could be separated and contact made with the bolt by means of an extension on the cylinder. Thus the lock could be applied to any thickness of door. The lock could also be mass-produced economically with a variety of different keys by changing the length of the pins.
As improved over the years, Yale’s pin tumbler principle has been accepted throughout the world as providing the most dependable, secure, and pick-resistant locks. This includes most of todays standard locks to automotive locksmith Brea, CA.
Yale’s father, Linus Yale, Sr., also a lock inventor, had concentrated on developing combination locks. His ideas were refined by James Sargent of Rochester, N.Y., who perfected combination locks for safes and vaults. Sargent mounted a numbered dial on the outside of a door and attached it to a spindle that drove the rotating disks on the inside of the safe.
The face of the dial was divided into 100 spaces. The dial was rotated clockwise, then counterclockwise, a specified number of turns, stopping at predetermined numbers. This lined up the slots in the disks, permitting the bolt to be withdrawn.
The weakness of these locks was that they failed to thwart robbers who used coercion and torture to force their victims to reveal the combination. However, in 1873, Sargent patented a time lock that became the prototype of those used in modern bank vaults. The time mechanism was concealed inside the vault, utilizing as many as three clocks to cover a total of three days, where necessary.
When the specified time was reached, a pin obstructing the bolt was released, and the safe responded to the correct combination.