The Evolution of the Lock

By Lindsay Tucker | Boston Magazine |

FOR JUST ABOUT AS LONG as we humans have had things to call our own, we’ve had the locks with which to shut them away from everybody else. And after a couple millennia of this, the variety of systems that we’ve innovated, discarded and reimagined border on the countless. Now, in honor of our recent profile of master lock picker Schuyler Towne, we take a look at some of the more defining moments in the evolution of the lock:

1. Ancient Egyptian Pin Tumbler   The Egyptians, as is often the case, were way ahead of the game when it came to their locks. Back around 2000 B.C., they invented what remains the dominant concept in today’s residential locks: the pin tumbler lock. The Egyptian tumbler was one of the first to use a key, and featured a wooden casing containing several loose pegs of varying length — pins, as they’re called now. When loose, the pins kept a bolt in place, locking the door. The right key lined these pins up evenly, permitting the bolt to be opened. The only major difference between this lock and that on your own house? The keys were more of than not more than a foot long and resembled oversized toothbrushes — the longer the key hole the less likely the pins could be manipulated by a picker. 

2. Gordian Knot    Unlike the Egyptians, the Ancient Greeks are known not for a lock-and-key system, but for their knots — specifically, the Gordian knot. As legend has it, a Greek peasant named Gordius strolled into the town square of Phrygia with nothing to his name but a small oxcart and his wife — precisely the manner, as it so happened, as an oracle had told the people of Phrygia their the king would arrive. So king he became. Filled with gratitude, newly-promoted Gordius dedicated his oxcart to Zeus, tying it up with the unusual knot that would become known as the Gordian knot.

3. Living Locks   The locking mechanisms of the Medieval period lacked the sophistication of the Egyptian locks, though they compensated for this with sheer brute force. Valuables were sealed into large wooden boxes and placed on small islands or submerged in pools where they were protected by hungry crocodiles, and many estates were similarly protected by moats. Stephen Tchudi, author of Lock & Key: The secrets of locking things up, in, and out, calls these guard crocs “living locks.” “A lock, after all,” he says, “is simply a barrier or closure, a way of sealing up an entryway, of keeping what you want in, in, what you want out, out.” Those desperate enough to try lock picking had no choice but to drug or kill the croc — pretty risky for a petty larceny.

4. Latchstring Locks   Invented by prehistoric man and perfected in Colonial America, the latchstring came to prominence in the American west. One of the first “keys” used in America, it operated on a very simple premise: a string was hung outside of the door, through a small hole near the door handle. Pulling the string lifted a bow behind the door, allowing it to open. Those who came calling knew the dangling string as a sign of welcome, and eventually someone coined the phrase "the latch string is always out." Mind you, the system was nearly impossible to lock from the outside, but some inventive settlers took to hiding the latchstring by threading it out through a second hole placed along the house but away from the door and bow.


5. Bramah’s Safety Lock   In 1784, Joseph Bramah patented his Safety Lock, the most sophisticated lock of its time and for the next 50 years, the hardest lock to pick. Bramah’s was the first locking mechanism to be set with marked precision, and he used six sheet metal plates, arranged in a circle and engaged by a tiny pipe key. Plates were positioned to the right height by the depth of the cuts in the key. In other words, each plate corresponded with the depth of a specific slot cut in the front end of the key. Upon entry, the key positioned the plates in line with a fixed circular locking plate. The slightest misalignment blocked rotation of the key barrel, making it very tough to crack.

6. The Yale Lock
  Famous in New England as a pioneer in lock making, Linus Yale Sr. patented the “Quadruplex” in 1844. A resurrection of the ingenious Egyptian design, Yale Sr.’s lock increased the number of pins, and change their orientation — essentially, the modern pin tumbler lock so many of us use today. His son Linus Yale Jr., the better known of the Yales, further improved on his father’s innovation and went on to introduce the concept of the Monitor Bank Lock, the principles of which also surive today in the combination padlock. Between them, the pair are perhaps the most recognizable and influential conceptual developers of the modern lock.   

7. The Push-Button  Another important milestone in American lock history occurred in the 1920’s with the arrival of Walter Schlage’s cylindrical push-button system — the lock that now dominates bathroom doors across the nation. The basic concept was simple: when the button in the center of the doorknob was pushed in, the mechanism remained locked. Turn the interior door knob and voilà — an unlocked door. Schlage passed away in 1946, but not before winning the coveted inventor’s "Modern Pioneer Award" for his innovation.

8. The Kwikset SmartKey   Following Yale’s reinvention of the pin tumbler, the fundamentals of the American residential security market changed remarkably little until very recently. It was just in 2007 that Walt Strader’s Kwikset SmartKey, based on the concept of the earlier Rielda lock, began to make a dent in the markets. It’s one of the first popular rekeyable locks, able to be reset to a new key in literally seconds using only the unlocking key and a small piece of metal (the SmartKey). The SmartKey lifts and separates a system of pins and metal wafers, freeing the unlocking key such that a new key can be inserted and the pins and wafers will fall into place for the new system. Mighty convenient if your keys are lost or stolen, or if your ex-boyfriend keeps showing up in your apartment unannounced.


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