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Mengenlehreuhr, the Berlin Clock

The Mengenlehreuhr, also known as the Berlin Clock, is a unique and iconic timepiece located in Berlin, Germany. Installed on June 17, 1975, it holds the distinction of being the first public clock in the world to tell time using illuminated, colored fields, earning it a place in the Guinness Book of Records.

Design and Concept

The Mengenlehreuhr was commissioned by the Senate of Berlin and designed by Dieter Binninger. The clock's name translates to "Set Theory Clock," reflecting its use of set theory (go nuts!), a branch of mathematical logic, to display time. The clock face consists of 24 light switches arranged in a specific pattern to represent hours, minutes, and seconds in a 24-hour format.

How To Read Mengenlehreuhr

The clock is read from top to bottom, with each row of lights representing different units of time:

  • A single blinking light at the very top:

    • - indicates even and odd seconds.

  • Top Row (Red) – Hours in Blocks of 5:

    • - Each red light represents 5 hours.
    - There are 4 red lights, so they can show 0 to 20 hours (0, 5, 10, 15, 20).
    - Example: If 3 red lights are on, it's 15 hours (3 × 5 = 15 hours).

  • Second Row (Red) – Single Hours:

    • - Each red light represents 1 hour.
    - There are 4 red lights, so they can show 0 to 4 hours.
    - Example: If 2 lights are on, add 2 hours to the total.

  • Third Row (Yellow/Red) – Minutes in Blocks of 5:

    • - Each light represents 5 minutes.
    - There are 11 lights (some are red for 15, 30, and 45 minutes to mark quarters).
    - Example: If 6 lights are on, it's 30 minutes (6 × 5 = 30 minutes).

  • Bottom Row (Yellow) – Single Minutes:

    • - Each light represents 1 minute.
    - There are 4 yellow lights (showing 0 to 4 minutes).
    - Example: If 3 lights are on, add 3 minutes.

History and Relocation

The clock was first installed in 17.6.1975. Originally, the Mengenlehreuhr was located at the intersection of Kurfürstendamm and Uhlandstraße in West Berlin. However, in 1995, the clock was decommissioned and relocated to Budapester Straße, where it stands today. The relocation was necessary due to high maintenance costs associated with the frequent burnout of incandescent bulbs. The introduction of newer, longer-lasting bulbs and subsidies from local shops helped keep the clock operational.

The Mengenlehreuhr quickly became a popular landmark in Berlin. Its unique design and innovative use of set theory to tell time captured the public's imagination. Small desktop versions of the clock were sold in department stores, allowing people to own a piece of this iconic timepiece. And of course today we can make one with JavaScript, or even with Arduino, if the more common style binary clocks seems boring.

Connection to Kryptos

Interestingly, the Mengenlehreuhr is believed to hold a clue to solving the Kryptos sculpture at the CIA headquarters. The sculptor, Jim Sanborn, revealed that part of the deciphered text of Kryptos reads "BERLIN," and "CLOCK" suggesting a connection to the Berlin Clock. This has drawn code breakers and enthusiasts to study the clock in hopes of solving the remaining K4 section of the Kryptos riddle.

Conclusion

The Mengenlehreuhr stands as a testament to human ingenuity and the intersection of art and mathematics. Its popularity and cultural significance make it a must-see attraction in Berlin. Whether you're a local or a visitor, decoding the time on this retro-futuristic clock blends curiosity with a sense of discovery.