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Locks: Centuries of Security

A look at locks through the ages.

Since ancient times, humans have secured their valuables. Enter the lock, for which you need a key to secure or unlock the door. Locks can be hidden, sometimes invisibly electronic, but historic locks are important features of operational doors and should be maintained. Inappropriate replacements are incongruous.

historic lock

17th century lock at a time where keyholes were obscured to slow down lock picking.

The Assyrians developed the first lock in 2000BC, found in the Palace of Khorsbad, Iraq. The wooden pin tumbler system was operated by a wooden key, which would realign the pins to disengage the lock. The Egyptians brought it west, improving on it by the introduction of brass pins, making them more durable and harder to pick. With trade, these locks migrated to Greece and Rome, evolving in their design using iron locking devices with bronze keys. This had the effect of miniaturizing the locks and made keys able to fit in a pocket or purse—sometimes even being made into functional rings. Further development by the Romans brought the warded lock, which had grooves and projections, requiring the right key.

Spurred by the scarcity caused by plagues and wars in the 14th century, these better locks bred better criminals, leading to expert lock-pickers. The locks, in turn, became more complicated, with covers obscuring their location, and the introduction of false keyholes to distract.

historic lock, Bramah lock

Original Bramah lock, with display plate that offered a reward challenge to pick the lock.

The industry changed in the 1770s. A major improvement in design, Robert Barron invented the double acting tumbler lock in 1778. Tumblers were similar to pins, but instead of acting vertically with gravity, they were attached to the ends of levers (or pawls) which were raised to different heights by varying sized “teeth” on the key to operate the bolt.

An English inventor Joseph Brahmah invented a complex lock in 1784, with pieces that were mechanically produced. He was so confident of his lock design that he published how it worked and made a large cash prize contest for a person to pick it. The government was so impressed by the invention that they hosted a competition for an unpickable lock that would ‘break’ if picked. Jeremiah Chubb won the prize with a lock that, when picked, prevented the correct key from opening it, indicating its tampering, and requiring a special key to reset it. Later, Robert Newell devised the Parautoptic lock in 1851, which incorporated a plate that revolved with the key to thwart the lock pickers. In addition, the key had interchangeable bits to change the lock. These inventions created the “era of perfect security.”

Ancient wooden lock

Ancient wooden lock from Roman times.

In 1851, the Great exposition showcased manufactured products. An American Locksmith A.C. Hobbs challenged the Chubb lock, picking it in 25 minutes. He followed up that feat by successfully picking the Brahmah lock right after that. Hobbs shared his method of lockpicking with Chubb, who in turn used it to pick the Newell lock. Chubb went on to publish Dissertation on Locks and Lockpicking and the Principles of Burglarproofing. The era of “perfect security” was defeated.

With the Industrial Revolution, locksmithing was changed into the lock industry. Notably Linus Yale (Jr. and Sr.) invented a ‘pin-and-tumbler’ lock in 1848, made common by its ability to be fully mass produced. In the 1860s, The Yales launched the Monitor Bank Lock, which later became commonly know as the combination lock.

Current Application

There have been many inventions for mechanical locks over time, which can be categorized based on the four basic lock types: the Bramah, the lever, the Yale, and the combination lock. Later modifications include magnetized keys and pins that operate by attracting and repelling forces, and doubling the mechanisms. Keys have varied more in the 20th and 21st centuries, including flat keys with depressions to operate multiple tumblers at a time, magnetic card readers, electronic fobs, push button electronic PINs, and thumbprint or retinal scans. For historic structures, these should be avoided on public doors.

Cast bronze exterior mortise lock with strike and thumb

Cast bronze exterior mortise lock with strike and thumb turn by P. & F. Corbin shown in their 1871 catalog.

Strengths and Weaknesses

As explained in the history, the security of locks varies, and different needs warrant different types of locks. When dealing with an historic door, the lockset is part of its charm and functionality, and a marker of the building’s history. While a skeleton key may not be suitable for day-to-day operation, retention of lock is ideal. Some types of locks can be retrofitted for use with electronics, which will require finesse to hide conduit for operator locations and electrical supply. One successful approach for electronic fobs is to recess the mechanism, mounting the electronic reader slightly recessed, and placing veneer over top. It renders the device not visible, which is good for the retention of the period appearance, but bad for explaining where to use the fob.

Branford Lock Works Reversible Upright Rim Knob Lock

Branford Lock Works Reversible Upright Rim Knob Lock shown in their 1881 catalog.

Rim locks are locks mechanisms which are contained in a case, surface mounted to one side of the door. Similarly, mortise locks are fully contained in a case, but are recessed in mortise (square opening) the edge of the door thickness.

Simple repairs to a lock require only simple tools. If undertaking repairs, it is wise to photograph the lock front, back and sides, before removal, once the case is open, and in various stages of its disassembly. The test of this documentation is back tracking your steps to reassemble the lock. Keep all the parts labelled and together in a baggie. Inspect the pieces for damage and breakage, assessing whether a good cleaning to remove the buildup of “gunk” will be sufficient, or whether replacement parts are needed. Cleaning should utilize the gentlest means first and move to more aggressive methods. It is best to leave the patina and original finishes, as this is part of the character of metals. Ordering replacement parts will require research on the type, brand, and age of lock, in order to get the best replacement.

The specifics of how to repair particular problems within your lock and their repairs can be found in a large number of videos on YouTube. And if, at the end of the day, the lock fails to operate, or it will not go back in place, there are still many locksmiths who understand these old locks, which haven’t changed much over time.

Antique bronze Padlock by Yale & Towne

Antique bronze Padlock by Yale & Towne. This is a cast bronze padlock stamped with the Y & T clover leaf logo on one side and the newer Yale logo on the other side.


When undertaking repairs to a lock, it is important for the case to be restrained while disassembling, to prevent it popping open when the screws are removed, since internal springs have a tendency to spring out suddenly and get lost. Research methods of repair pertinent to your lock, proceed carefully, and always approach the project with the most minimum intervention attempted first. Always repair over replace, and replace with salvaged like, before replacing with new.

Cast iron surface mounted barrel door bolt, Sargent & Co.

Cast iron surface mounted barrel door bolt by Sargent & Co. shown in their 1875 through 1888 catalogs.


Lock by publisher: Encyclopaedia Britannica, Inc. Published: 23 June 2017

Locks and Keys Throughout the Ages by Vincent J. M. Eras ISBN 978-0-9979798-6-2
Publisher Artisan Ideas, 2019
©1957 Vincent J. M. Eras

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