Meanwhile, in the USA, Western Union used their telegraph network to build out a system of synchronized clocks. A long pulse on the line at the top of the hour engaged a solenoid in the clock that pulled the minute hand back to :00.<p><a href="https://hackaday.com/2019/09/25/100-year-old-atomic-clock/" rel="nofollow">https://hackaday.com/2019/09/25/100-year-old-atomic-clock/</a><p>And, since this is HN, it's worth mentioning that this was a <i>subscription</i> service.
This was not just for clocks. There were pneumatic network in Paris "distributing compressed air at a relatively low pressure of 5-6 bar over a network of (eventually) more than 900 km of mains, serving more than 10,000 customers." That run the industry and lasted over 100 years until 1994.
Apparently, they even had subscribers that paid half a penny a day for a timepiece.<p><a href="https://www.nature.com/articles/022226a0" rel="nofollow">https://www.nature.com/articles/022226a0</a>
Another interesting illustration of innovation displacing a successful and widespread infrastructure. It wasn't better pipes or a better gas in the pipes, it was technology from a different source that displaced these compressed air clocks and obsoleted the hundreds of miles of pipe needed to transport it.
I wonder what the human side of maintaining the clock network was like. Did dedicated civic employees walk the clocks each day looking for telltale time differences that would indicate a break in the lines, and then debug with maps? I bet those maps would be interesting too. And how did they keep problems in one section from propagating through the whole system? Buffers and interlocks I suppose.
My impression is that those trade/tech "expos" in the 19th century were really a massive acceleration force of innovation and industrialization. To the point that I could imagine that the lack of such expositions might be an explaining factor why the Roman empire never experienced an industrial revolution. Nowadays they're less important because they've been replaced by conferences (which are the same idea dialed up to 11, I'd argue, and no less important in driving innovation). Maybe I'm going completely off here, but would be interesting to read an analysis.
> "...<i>However, the system was repaired and pneumatic clocks continued to work until 1927, when the invention of accurate mechanical and electric clocks made the need for a central synchronization clock obsolete</i>..."<p>This is not really true, in that you may remember from your elementary or high school days that many places <i>still</i> have centrally synchronized clocks.<p>When there are about 100 clocks distributed around a building, and not yet migrated to individually-kept radio/GPS/network time, the only staff-sanity preserving method of keeping them together is to use a central electronic pulse transmitted over the power lines (which the clocks are plugged into).<p>If I recall right, there is an hourly pulse that tells the clocks to wait/speed up until the top of the hour is reached. Then there's a daily pulse that tells them to wait/speed up to reset to midnight!
I would have loved to see how the world’s technology would be like if electricity was discovered much later and there had been no major wars. Probably closer to Steampunk/Gearpunk.
I wonder what reliability was like... With just one pipe accidentally cut, the pressure across the pipe network might not rise high enough to 'tick' the other clocks.<p>And if the clocks ever got out of sync for any reason, there doesn't seem to be any way to get them back in sync - for example they could have used a vacuum on the same pipes to 'suck' for a minute before midnight, and use a mechanical system which would fast-forward all clocks to midnight at that point.
> The pipes ran through the sewers of the city, and the tunnels of the Metro and the RER, a commuter rail network serving Paris and its suburbs.<p>> However, the system was repaired and pneumatic clocks continued to work until 1927.<p>Considering that the RER started to operate in 1977 [0], I find that hard to believe.<p>[0]: <a href="https://en.wikipedia.org/wiki/R%C3%A9seau_Express_R%C3%A9gional" rel="nofollow">https://en.wikipedia.org/wiki/R%C3%A9seau_Express_R%C3%A9gio...</a>
I do wonder if there was an (unmentioned in article) synchronization system like a special midnight pulse to get the clocks all back in sync in case there was drift.. or it was all handled by periodic inspections
> when the invention of accurate mechanical and electric clocks made the need for a central synchronization clock obsolete, and the service was discontinued<p>Most accurate clocks in factories and railway stations are controlled by a central timekeeping source, so it's not quite correct that such a source is obsolete.<p>(edit: wording)
incidentally conedison still operates commercial steam delivery in manhattan to this day.<p><a href="https://www.coned.com/en/commercial-industrial/steam" rel="nofollow">https://www.coned.com/en/commercial-industrial/steam</a><p>pneumatic signaling is cute. it makes me imagine the french mob, running around with black strap eyemasks, stripey shirts, bicycle pumps and hand-drills jacking into the system and running the clocks forward for nefarious purposes.
I wonder if there was a way to 'reset' the clocks remotely, for example to send a 60 second burst of air that resets all the clocks to 12:00.