3 ms·

When I did my deep dive on time (a rite of passage for any serious programmer) it took surprisingly long to realise that having a single clock to which everyone

When I did my deep dive on time (a rite of passage for any serious programmer) it took surprisingly long to realise that having a single clock to which everyone around the world synchronises is something we take for granted but is something that needed inventing. GMT became the standard just because they did it first.

defrost 3y ago
The Paris meridian is a meridian line running through the Paris Observatory in Paris, France – now longitude 2°20′14.02500″ East. It was a long-standing rival to the Greenwich meridian as the prime meridian of the world. The "Paris meridian arc" or "French meridian arc" (French: la Méridienne de France) is the name of the meridian arc measured along the Paris meridian. https://en.wikipedia.org/wiki/Paris_meridian https://en.wikipedia.org/wiki/Paris_meridian It (the Greenwich meridian) became the standard via weight of maps and naval strength of the British, there are many maps from the early days that don't follow the Greenwich standard, enough so that "wrong longitude because we assumed wrong meridian" is a minor trope in treasure map stories.
perilunar 3y ago
Not so much first as most: Greenwich was the prime meridian because "Britannia ruled the waves", and Britain made most of the nautical charts.
- mikhailfranco 3y ago
  There is a feedback loop between accuracy of clocks and accuracy of charts. Measuring longitude requires an accurate clock on a ship, which can keep a reference time to compare with local solar time. The obvious challenges include motion of the ship and huge ranges of temperature encountered on global voyages. Britain invented the best maritime clocks by encouraging open competition for a large prize. https://en.wikipedia.org/wiki/Longitude_rewards https://en.wikipedia.org/wiki/Longitude_rewards See the book Longitude by Dava Sobel. You can see John Harrison's chronometers at the Royal Observatory in Greenwich - on the top of a small hill in a park in south-east London. It really is amazing how the original desktop clock monsters were shrunk down to a pocket watch that had better accuracy. Greenwich was the prime meridian because Britain invented the best clocks.
  - perilunar 3y ago
    > Measuring longitude requires an accurate clock Not 'requires' — there are other ways to determine longitude. I've read the book and seen the clocks. They are amazing. > Greenwich was the prime meridian because Britain invented the best clocks. I think that's backwards though. They would have ruled the waves regardless, and Greenwich would have still been the prime meridian.
    - mikhailfranco 3y ago
      Trafalgar 1805. Waterloo 1815. International Meridian Congress (Washington) 1884. France waits until they can adopt a name that does not mention Greenwich ... 1978. The French are very tenacious in their (to put it politely) arrogant obstructionist individualism. Shrug. https://en.wikipedia.org/wiki/International_Meridian_Conference https://en.wikipedia.org/wiki/International_Meridian_Confere... Resolution 2, fixing the meridian at Greenwich, was passed 22–1 (San Domingo, now the Dominican Republic, voted against); France and Brazil abstained. The French did not adopt the Greenwich meridian as the beginning of the universal day until 1911. Even then it refused to use the name "Greenwich", instead using the term "Paris mean time, retarded by 9 minutes and 21 seconds". France finally replaced this phrase with "Coordinated Universal Time" (UTC) in 1978.
jgrahamc 3y ago
GMT became the standard just because they did it first. Sort of. Lots of countries used a local meridian as their 0 degrees reference for longitude. Then in 1884 there as the International Meridian Conference (https://en.wikipedia.org/wiki/International_Meridian_Conference https://en.wikipedia.org/wiki/International_Meridian_Confere...) which chose Greenwich as the reference line. The same conference also voted to have midnight be the start of the day for astronomical and nautical purposes (instead of noon). The French objected to using Greenwich and hung on to the Paris meridian until into the 20th century. But the practicality of lots of maps using Greenwich (because of Britain's naval power) swayed people to have Greenwich as the Prime Meridian.

defrost 3y ago

The Paris meridian is a meridian line running through the Paris Observatory in Paris, France – now longitude 2°20′14.02500″ East. It was a long-standing rival to the Greenwich meridian as the prime meridian of the world. The "Paris meridian arc" or "French meridian arc" (French: la Méridienne de France) is the name of the meridian arc measured along the Paris meridian. https://en.wikipedia.org/wiki/Paris_meridian https://en.wikipedia.org/wiki/Paris_meridian It (the Greenwich meridian) became the standard via weight of maps and naval strength of the British, there are many maps from the early days that don't follow the Greenwich standard, enough so that "wrong longitude because we assumed wrong meridian" is a minor trope in treasure map stories.

perilunar 3y ago

Not so much first as most: Greenwich was the prime meridian because "Britannia ruled the waves", and Britain made most of the nautical charts.

mikhailfranco 3y ago
There is a feedback loop between accuracy of clocks and accuracy of charts. Measuring longitude requires an accurate clock on a ship, which can keep a reference time to compare with local solar time. The obvious challenges include motion of the ship and huge ranges of temperature encountered on global voyages. Britain invented the best maritime clocks by encouraging open competition for a large prize. https://en.wikipedia.org/wiki/Longitude_rewards https://en.wikipedia.org/wiki/Longitude_rewards See the book Longitude by Dava Sobel. You can see John Harrison's chronometers at the Royal Observatory in Greenwich - on the top of a small hill in a park in south-east London. It really is amazing how the original desktop clock monsters were shrunk down to a pocket watch that had better accuracy. Greenwich was the prime meridian because Britain invented the best clocks.
- perilunar 3y ago
  > Measuring longitude requires an accurate clock Not 'requires' — there are other ways to determine longitude. I've read the book and seen the clocks. They are amazing. > Greenwich was the prime meridian because Britain invented the best clocks. I think that's backwards though. They would have ruled the waves regardless, and Greenwich would have still been the prime meridian.
  - mikhailfranco 3y ago
    Trafalgar 1805. Waterloo 1815. International Meridian Congress (Washington) 1884. France waits until they can adopt a name that does not mention Greenwich ... 1978. The French are very tenacious in their (to put it politely) arrogant obstructionist individualism. Shrug. https://en.wikipedia.org/wiki/International_Meridian_Conference https://en.wikipedia.org/wiki/International_Meridian_Confere... Resolution 2, fixing the meridian at Greenwich, was passed 22–1 (San Domingo, now the Dominican Republic, voted against); France and Brazil abstained. The French did not adopt the Greenwich meridian as the beginning of the universal day until 1911. Even then it refused to use the name "Greenwich", instead using the term "Paris mean time, retarded by 9 minutes and 21 seconds". France finally replaced this phrase with "Coordinated Universal Time" (UTC) in 1978.

jgrahamc 3y ago

GMT became the standard just because they did it first. Sort of. Lots of countries used a local meridian as their 0 degrees reference for longitude. Then in 1884 there as the International Meridian Conference (https://en.wikipedia.org/wiki/International_Meridian_Conference https://en.wikipedia.org/wiki/International_Meridian_Confere...) which chose Greenwich as the reference line. The same conference also voted to have midnight be the start of the day for astronomical and nautical purposes (instead of noon). The French objected to using Greenwich and hung on to the Paris meridian until into the 20th century. But the practicality of lots of maps using Greenwich (because of Britain's naval power) swayed people to have Greenwich as the Prime Meridian.