A Brief History of Locks

By Kathleen Rice Adams

For as long as there have been haves and wanna-haves, the haves have sought ways to secure their valuables from thieving wanna-haves. History no longer remembers the inventor of the first lock, but it is said the key was invented by Theodore of Samos in the sixth century B.C., which leads to the suspicion locks have been around much longer. In fact, crude locking mechanisms dating to the early Pharaonic period have been found in Egyptian ruins.

Bodie [California] Bank's vault, mid-1870s.
Dick Rowan, photographer (National
Archives and Records Administration)

The first devices resembling what we know today as door locks were discovered in the palace of Persian king Sargon II, who reigned from 722 to 705 B.C. They were large, clumsy devices made of wood; nevertheless, they served as prototypes for contemporary security devices.

The first all-metal locks, probably made by English craftsmen, appeared between 870 and 900 A.D. in Rome. A row of bars of varying lengths, called tumblers, dropped into holes drilled through the horizontal bolt securing a door or gate. Only the person who possessed a metal bar fitted with pins corresponding to the tumblers could shove the tumblers upward through the holes, thus freeing the bolt.

No great advancements in lock technology occurred until about the fourteenth century A.D., when locks small enough to carry appeared. Traveling tradesmen used the “convenient locks” to secure their money and other valuables.

Although padlocks were known to ancient Egyptians, Greeks, and Romans, the first combination lock didn’t appear until the eighteenth century. Until 1873, most banks used combination locks of some kind to secure their vault. The secret to effective combination locks was creating a complex series of letters and numbers that would frustrate anyone who tried to disarm the mechanism. The code for the combination lock securing the mid-nineteenth-century safe in the U.S. Treasury in Washington D.C., for example, could not be opened without a lengthy series of letters and numbers that provided 1,073,741,824 possible combinations. Because cracking the code by organized guesswork would require 2,042 years, 324 days, and one hour, the lock was considered burglar-proof.

Combination locks had one big Achilles heel, though: It didn’t take long for criminals to figure out they could kidnap a bank employee and require him or her to dial in the correct code.

Ruins of the 1906 Nye & Ormsby County Bank
in Manhattan, Nevada. The bank crumbled,
but the vault survived.

In 1873, James Sargent invented what he called a theft-proof lock. Theft-proof locks combined a combination lock with a timer that prevented the safe from opening until a certain number of hours had passed, even if one knew the combination.

By the late 1870s, theft-proof locks were de rigueur in banks all over the U.S. Though they weren’t quite unbreakable — thieves simply swapped dynamite or liquid nitroglycerin for captive bank employees and blew open safes — theft-proof locks thwarted more thieves than any previous mechanism. Called time locks these days, much more sophisticated descendants of Sargent's invention remain popular devices for banks and other high-security areas.