The double-bladed Berlin Key, a clever design to ensure everyone locks up properly.
The Berlin key (in German, Schließzwangschlüssel—try saying that five times fast!) is a unique type of forced-locking key that was invented to solve a very 19th-century problem: making sure folks remembered to lock the gate behind them.
Picture this: you’ve got a bustling tenement block in Berlin, and the gate leading to the communal courtyard is often left wide open. Cue Johannes Schweiger, a crafty locksmith who said, "Not on my watch!" and gave us this ingenious, albeit slightly quirky, key.
This isn’t your typical key—nope! The Berlin key has two blades, one on each end. Imagine a double-headed snake, except a lot friendlier and focused on security. Here’s how you use it:
Thanks to this design, it’s pretty much impossible to forget to lock the door without realizing you've also left the key in the lock. Forgetful tenants, rejoice!
The Berlin key came into existence thanks to Johannes Schweiger and was produced by Albert Kerfin & Co, beginning in 1912. That's over a century of keeping doors locked—talk about a solid security track record! Today, it’s a rare sight, but it’s estimated that around 8,000-10,000 of these keys are still in use in Berlin. If you find one, consider it a piece of locksmith history!
Professor Bruno Latour, a big thinker in Science and Technology Studies, wrote an essay all about this key. According to him, the Berlin key is a bit of a social enforcer—it tells people, "Please lock the door behind you." It's like your mom, but in metal form.
Latour says this humble key performs what he calls a "program of action"—which, in locksmith speak, means it encourages a specific behavior: "Bolt the door at night, but leave it open during the day." With this, the Berlin key becomes both a lock and a social boundary: it’s us (tenants) vs. them (strangers).
These days, newer technologies have largely replaced the Berlin key. Electronic locks, smart locks, and other shiny new tech are all the rage. But, there's something charming about a mechanism that does more than lock doors—it shapes behavior. And maybe, just maybe, that’s why some Berliners still trust their old double-bladed companion.