Locks Have Changed Over the Years, but Key to Security Has Not

No home today is without a lock--on exterior and even interior doors and sometimes special places such as chests or lids. And so it was in antiquity, with the earliest known lock, a wooden mechanism in Egypt, dating from around 2000 BC.

The challenge for early locksmiths, after the Romans introduced the first metal models, was devising a gizmo to permit usage only by the person holding the appropriate key, as well as to ensure against breakage by a thief.

The ward lock was the simplest mechanism, with a metal bolt moved back and forth by a key that fit exactly into a keyhole to activate the bolt’s movement.

By medieval times locks were massive, often exceptionally ornamented, with keys that were so large they were difficult to carry and use.

Not until the 19th Century did real improvements emerge, mostly in England, which would become a leading center for lock production.

The tumbler, or lever lock, moved in the direction of complexity to defy “picking” by a transgressor. It contained various metal pieces of different sizes, dubbed latches, levers or tumblers, that prevented the bolt from moving until a key was employed.

The key had ridges and protrusions that fit exactly into the corresponding tumblers. Still, the tumbler locks and keys were large.

Then Linus Yale (1821-1868), born in Salisbury, N.Y., and a portrait painter by training, followed the lead of his locksmith father to begin a revolution in the industry.

Yale devised both the dial lock for safes and a pin-and-cylinder device, now known as the Yale lock, that permitted locks to be strong and small.

Yale’s secret was a cylindrical plug that rotated as a key was inserted. The plug moved the bolt but only if five pins of various sizes were raised by the key into five corresponding holes in the plug.

By changing the size of the pins in the manufacturing process (and matching the keys to fit the changes), the locks could be mass-produced and sold inexpensively.

By the time Yale became president of the Yale Lock Manufacturing Co. in Stamford, Conn., in 1868, the pin-and-cylinder mechanism was on its way to becoming synonymous with the best “night latch” available for the home.

By 1897, the lock had become inexpensive, as illustrated by Sears, Roebuck’s model No. 14144:

“The Genuine Yale Paracentric Night Latch . . . is so well known as the most perfect and secure lock made that our recommendation is unnecessary. Japanned iron case. Size, 2 3/8-x-3 5/8, bronze escutcheon, bronze knob, three paracentric keys, reversible and adjustable for doors from 7/8 to 2 3/4 inches thick. Price, each . . . $1.35.”

Yale’s lock principle was the foundation for 20th-Century variations, which could be improved thanks to advances in manufacturing methods that turned out harder metals and more finely tuned keys. Double-locking mechanisms also were introduced.

In recent times, homeowners have augmented advances in locks with security systems that sound alarms when locks and other secure areas are tampered with. Some locks no longer use keys, responding instead to electronic codes that are punched in or strips touched with the appropriate sensitized card.

Still, as in medieval times, no lock is really secure without other precautions.

In February, 1990, Consumer Reports subjected numerous door locks to kicking, jimmying, prying, hammering, drilling and picking. In ranking each lock according to these six standards, it admonished:

“In choosing door locks for this report, we passed up the run-of-the-mill hardware available in the typical home-center store in favor of more substantial devices. They ranged in price from $42 to more than $200. But even the most rugged-looking locks, we found, could be defeated by a swift kick or two unless we added some reinforcement to the door or the door jamb.”

More than 350 years earlier, an anonymous epitaph suggested that even the Pearly Gates might not be secure:

“A zealous locksmith died of late,

And did arrive at heaven gate,

He stood without and would not knock,

Because he meant to pick the lock.”