Lock and Key | Research & Encyclopedia Articles

Lock and Key

Ever since people first began having private possessions, locks to keep that property out of the hands of thieves have been designed. It has been an evolutionary process: As each lock eventually yielded to thieves' attempts to pick, or open, it, ingenious locksmiths came up with new lock and key designs.

The earliest known lock is the wooden Egyptian pin-tumbler type. It was opened by a pegged wooden key, often more than a foot long, so large that it had to be carried over the shoulder. When the key was inserted into the lock, its pegs lifted pins that held the bolt in place. The ancient Chinese used a leaf-spring padlock; the key depressed the spring, allowing the bolt to slide back. The Greeks used primitive locks with large, sickle-shaped keys.

The Romans introduced metal for locks and keys and also invented the warded lock. Wards are projections inside the keyhole; only a key whose bit (flat face) is cut with projections that pass over the wards can rotate to open the lock. The Romans also independently invented the padlock, and made small keys that were worn as finger rings.

As Europe passed out of the Dark Ages into medieval times, nobles and the new merchant class acquired money and possessions that needed safeguarding. Locksmithing flourished during this period, with very intricate and precise moving parts and elaborately decorated exteriors and keys. These were still warded locks, and since most could be fairly easily bypassed, extra security was provided by hidden and dummy keyholes--even by locks with spring-loaded knives. The skeleton key emerged in this era, a long, straight key with a single tooth that could be slipped around the wards to open the lock.

Important improvements were made in lock design during the eighteenth century. The Englishman Robert Barron patented the double-action tumbler lock in 1778. Tumblers fell into place in slots in the bolt, which was held in place until the correct key raised each tumbler to the correct height, which lifted a pivoted lever and freed the bolt to move. In 1818 another English inventor, Jeremiah Chubb, improved the lever tumbler lock by adding a detector tumbler. If a tumbler was raised too high by an improper key, the detector jammed the lock, which could then only be opened by the correct key being turned backwards. Chubb was a Portsmouth ironmonger who later established a factory that produced fireproof safes. He was inspired to design his lock after the British government, alarmed by the high incidence of thefts and the 1817 robbing of the Portsmouth dockyard, offered a reward to the person who could invent a pick-proof lock. Chubb won the prize.

Another ingenious lock was the Bramah, patented by Englishman Joseph Bramah in 1778. In this lock, a tube-shaped key with a number of slots depressed a corresponding number of slides, each by a different amount depending on the length of the slot. Bramah's advertised claim that his lock was pick-proof--he offered a 200-guinea reward to the first person who could open it--held up for sixty-seven years. Finally, in 1851, an American expert, A. C. Hobbs, picked the Bramah lock, but it took him fifty-one hours to accomplish the feat.

Because Bramah's lock was complicated, he invented a number of machine tools to manufacture it, turning locksmithing away from handcrafting. This changeover was cemented by the invention of Linus Yale, Jr. (1821-1868), an American from Connecticut. Born in New York in 1921, Yale originally intended to become a portrait painter but instead emulated his father and began designing bank locks. In 1861 he patented a small, cylindrical pin-tumbler design that was an adaptation of the ancient Egyptian locks. A small, serrated key raised pins in the cylinder to proper heights, allowing the cylinder to turn. The key and pin design allowed for a vast number of possible configurations, so that no two Yale keys were alike. The small, flat keys as well as the locks could be easily mass produced and machine-made, which meant that inexpensive, secure locks were now available to the mass public. Today, Yale locks are used on most outside doors of houses and businesses. Combination locks go back to the sixteenth or early seventeenth century. A number of slotted rings, or tumblers, imprinted with numbers or letters, turn; when lined up correctly, the lock opens.

Combination locks became the favored type for tone safes because they had no keyhole in which robbers could insert explosives. James Sargeant of Rochester, New York, invented a time lock for banks in 1873; a clock controlled the hour at which the safe could be opened.

In the 1970s electronic locks were introduced. Spring-loaded buttons sound different electronic tones when pushed, like touch-tone telephones. The lock opens only when the right sequence of tones is sounded. Despite the advent of combination locks, touch-tone locks, and other keyless entry systems, there are still many times when a key of some sort is preferred, since access to it can be more easily controlled. In addition, electronic technology has made the simple key more useful and sophisticated. Resembling a credit card, flat plastic "key cards" with a magnetic strip have become popular with hotels, businesses, and universities. When the keyholder inserts the card into (or "swipes" it through) an electronic card reader, the door's lock is opened. Inexpensive to manufacture and easily re-coded, this lock and key system can also provide information, such as the identity of the keyholder and the time of entry. In this way, the lock and key have become a form of surveillance equipment.

The traditional metal key has also been reinvented. In the 1990s Charles Hall, Rick Hyatt, and Doug Treat of the Medeco lock company developed a way to attach a handheld computer to a conventional key. Dubbed by its inventors the "V-Lock" and the "V-Key," the system was developed for use on pay telephones to eliminate the need for a different key for each of thousands of telephone coin boxes. The V-Key activates the V-Lock when inserted, and opens the lock when the attached computer provides the lock's identification number. Therefore, a single V-Key can open thousands of V-Locks as well as record inventory data. The continuous reinvention of the lock and key demonstrates the flexibility and genius of this ancient invention.