ble with contemporary doors. The doorplates, and in particular keyhole escutcheons, however, are well-loved. These come in a wild variety of shapes and designs, some with double keyholes, others with swinging covers often featuring animal designs.
Finally, in 1848, Linus Yale and his son began to develop the cylinder lock, also known as the modern pin-tumbler lock, which is the lock that’s most commonly used today in doors and padlocks. The key has a blade instead of a shank, and the blade is cut with horizontal grooves that allow the key to be inserted past the wards in the cylinder. Then, when the key is turned, the “bittings” carved along the bottom of the blade operate the pins or wafers inside the lock, allowing the cylinder to turn freely.
Bank robbers found safes with key locks relatively easy to crack. In 1861, Linus Yale, Jr., introduced the first modern combination lock, which used a combination of numbers, instead of a key, to open the locking device. This concept was quickly adapted for bank locks—nearly as quickly, resourceful thieves figured out a way to crack such locks. Safes and bank-vault locks are also popular with collectors.
James Sargent, an employee of Yale’s, added an improvement to the combination lock when he developed his “theft-proof lock,” which added a timer to the device so it could only be opened during certain hours. In response, bank robbers turned to explosives to open bank safes. Sargent went on to form his own esteemed lock company.
In the 1920s, hardware makers began to reconsider door hardware. With an old mortise-style lock—which are still seen in old houses today—the locking mechanism is a separate device from the door knob that turns the latch. The two are connected by a spindle inside the mortise lock set installed on the door. This allows the lock, operated a by a key usually below the door knob, to hold the knob and latch in place or release them so the knob turns freely.
In an effort to improve upon this technology, manufacturers figured out a way to integrate a cylinder lock inside the door knob, making the knob and lock one device and paving the way for the modern cylinder lock sets we use today.