time zones

3 Articles

Railway Time: Why France’s Railways Ran Five Minutes Behind

July 31, 2025 by 10 Comments

With us chafing at time zones and daylight saving time (DST) these days, it can be easy to forget how much more confusing things were in the late 19th century. Back then few areas had synchronized their clocks to something like Greenwich Mean Time (GMT) or other standards like London time or Paris time, with everyone instead running on local time determined by as solar time. This created a massive headache for the railways, as they somehow had to make their time schedules work across what were effectively hundreds of tiny time zones while ensuring that passengers got on their train on time.

In a recent video [The Tim Traveller] explains how the creation of so-called Railway time sort-of solved this in France. As railroads massively expanded across the world by the 1850s and travel times dropped rapidly, this concept of Railway time was introduced from the US to Europe to India, creating effectively a railway-specific time zone synchronized to e.g. London time in the UK and Paris time in France. In addition to this, French railways also set the clocks inside the stations to run five minutes behind, to give travelers even more of a chance to get to their train on time when stuck in a long goodbye.

By 1911, across Europe GMT was adopted as the central time base, and the French five minute delay was eliminated as French travelers and trains were now running perfectly on time.

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Hackaday Links: December 24, 2023

December 24, 2023 by 10 Comments

Back near the beginning of the current Solar Cycle 25, we penned an article on what the whole deal is with solar cycles, and what could potentially lie in store for us as the eleven-year cycle of sunspot population developed. Although it doesn’t really come across in the article, we remember being somewhat pessimistic about things, thinking that Solar Cycle 25 would be somewhat of a bust in terms of increased solar activity, given that the new cycle was occurring along with other, longer-period cycles that tend to decrease solar output. Well, looks like we couldn’t have gotten that more wrong if we tried, since the Sun lashed out with a class X solar flare last week that really lit things up. The outburst came from a specific sunspot, number 3514, and clocked in at X2.8, the most powerful flare since just before the end of the previous solar cycle. To put that into perspective, X-class flares have a peak X-ray flux of 10-4 watts/m², which when you think about it is a lot of energy. The flare resulted in a strong radio blackout; pretty much everything below 30 MHz was unusable for a while.

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The Database Of The Time Lords

November 20, 2017 by 71 Comments

Time zones have been a necessity since humans could travel faster than a horse, but with computers, interconnected over a vast hive of information, a larger problem has emerged. How do you keep track of time zones? Moreover, how do you keep track of time zones throughout history?

Quick question. If it’s noon in Boston, what time is it in Phoenix? Well, Boston is in the Eastern time zone, there’s the Central time zone, and Phoenix is in the Mountain time zone; noon, eleven, ten. If it’s noon in Boston, it’s ten o’clock AM in Phoenix. Here’s a slightly harder question: if it’s noon in Boston, what time is it in Phoenix during Daylight Savings Time? Most of Arizona doesn’t observe Daylight Savings Time, so if it’s noon in Boston, it’s 9 AM in Phoenix. What about the Navajo Nation in the northwestern part of Arizona? Here, Daylight Savings Time is observed. You can’t even make a rule that all of Arizona is always on Mountain Standard Time.

Indiana is another example of bizarre time zones. For most of the 20th century, Indiana was firmly in the Central time zone. Starting in the 1960s, the line between Eastern and Central time slowly moved west from the Ohio border. Some countries opted not to observe Daylight Savings Time. In 2006, the entire state started to observe DST, but the northwest and southwest corners of the state remained firmly in the Central time zone. The odd geographic boundaries of time zones aren’t limited to the United States, either; Broken Hill, New South Wales, Australia is thirty minutes behind the rest of New South Wales.

Working out reliable answers to all of these questions is the domain of the Time Zone Database, a catalog of every time zone, time zone change, and every strange time-related political argument. It records Alaska’s transition from the Julian to the Gregorian calendar. It describes an argument in a small Michigan town in 1900. It’s used in Java, nearly every kind of Linux, hundreds of software packages, and at least a dozen of the servers and routers you’re using to read this right now.

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