The Extinction of the Bascule Lock

It’s likely that few people alive today have even heard of a bascule door lock, certainly not those born and raised in North America.  The word “bascule” itself is more commonly associated with bridges, though the bascule principle can apply to other mechanisms and devices as well.

Bascule locks were once relatively common in Europe and the U.K.  Even today one might find bascule locks on older homes there.  New buildings are rarely outfitted with them, though some owners like them for nostalgic or decorative purposes.  One would certainly not find a bascule lock on any building (commercial or residential) built in the last century in North America.

The bascule principle is most easily explained in terms of a see-saw.  The idea is balancing a lever on a fulcrum (as with a see-saw), and counterbalancing each end with some type of weight.  There are thousands of bridges in North America that function on this principle (i.e. drawbridges.)  Weight is applied to one end of the “lever” or bridge section (referred to as a “leaf”) in order to lift up the other end so large vessels can pass underneath.  The bridge is then lowered into a closed position by counterbalancing the weight again.

Bascule door locks work on a similar principle.  When the lock lever is counterbalanced, the door remains in a locked position.  To open the door, weight must be applied to one end of the lever.  The weight lifts the other end of the lever, releasing the locking mechanism and opening the door.

The bascule lock could be considered a predecessor to the  modern exit device.  It offered a way to keep doors locked from the outside.  When the lock is released and the door opens, the lock re-engages once the door is closed again.

Bascule locks became extinct in the late 1800’s and early 1900’s for a number of reasons.  First, they are unwieldy and somewhat difficult to operate.  Mortise locks had already become favored by American builders by the late 1800’s, though their European and British counterparts were still fond of the bascule lock. 

When inventor Walter Schlage designed and built the first cylindrical lock in the 1920’s, he literally changed the face of security forever.  Cylindrical locks had several distinct advantages over their bascule and mortise-style cousins, the main one being that they were simply easier to install and operate, and therefore far more convenient for most applications.

Another reason bascule locks fell out of favor directly related to their unwieldiness.  Bascule locks took longer to disengage than other types of locks.  Under normal, day-to-day circumstances this may not have posed much of an issue.  However, in emergency situations, such as a fire, precious seconds often make the difference between life and death.  One such example of a situation involving bascule locks that contributed to tragedy is the Iroquois Theater Fire of 1903.

The Iroquois Theater in Chicago was considered to be “state-of-the-art” in the early 1900’s.  However, its many design flaws became apparent after 602 people perished in a tragic fire therein only a month after it opened.  One such “flaw” was the inconsistency of its door locks.

Many of the doors on the Iroquois Theater were fitted with standard mortise-style locks.  But, for reasons that have never been completely understood, some exit doors, particularly ones leading out of the auditorium itself, were outfitted with bascule locks.  Bascule locks may have been a familiar sight in Europe and Britain at the time, but virtually no American had ever seen, much less operated a bascule door lock.

When fire broke out on the Iroquois stage, frightened patrons tried desperately to exit the theater.  Unfortunately, many exit doors were either blocked, covered or locked.  Some of the doors which were locked had bascules.  But since Americans were unfamiliar with them, no one knew how to operate them.  Dozens of theater-goers died right at the door, either from burns or smoke inhalation or from being crushed up against the door by the hordes.  One patron who happened to be an immigrant from Europe managed to open one of the door’s bascule locks, and he is credited for saving dozens of lives that day.

After the tragic Iroquois Fire, hardware salesman Carl Prinzler, who had been scheduled to attend that fated performance at the Iroquois but canceled out at the eleventh hour, wanted to ensure that this kind of tragedy could never happen again.  He went on to invent the world’s first exit device, or panic bar, which was subsequently marketed by Von Duprin.  Von Duprin is still one of the world’s leading manufacturers of exit devices today.

The invention of both the exit device and the cylindrical lock marked the beginning of the end for the bascule lock.  Exit devices accomplished the same purpose as bascule locks, but saved precious seconds and were considerably easier to operate, even for children.  In fact, it’s estimated that these devices have saved millions of lives over the last one hundred years.  It would be extremely difficult for one to find a supplier of the virtually extinct bascule door lock today.