The Pneumatic Clocks of Paris

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:&#x2F;&#x2F;hackaday.com&#x2F;2019&#x2F;09&#x2F;25&#x2F;100-year-old-atomic-clock&#x2F;" rel="nofollow">https:&#x2F;&#x2F;hackaday.com&#x2F;2019&#x2F;09&#x2F;25&#x2F;100-year-old-atomic-clock&#x2F;</a><p>And, since this is HN, it&#x27;s worth mentioning that this was a <i>subscription</i> service.

This was not just for clocks. There were pneumatic network in Paris &quot;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.&quot; 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:&#x2F;&#x2F;www.nature.com&#x2F;articles&#x2F;022226a0" rel="nofollow">https:&#x2F;&#x2F;www.nature.com&#x2F;articles&#x2F;022226a0</a>

Another interesting illustration of innovation displacing a successful and widespread infrastructure. It wasn&#x27;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&#x2F;tech &quot;expos&quot; 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 Nowadays they&#x27;re less important because they&#x27;ve been replaced by conferences (which are the same idea dialed up to 11, I&#x27;d argue, and no less important in driving innovation). Maybe I&#x27;m going completely off here, but would be interesting to read an analysis.

&gt; &quot;...<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>...&quot;<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&#x2F;GPS&#x2F;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&#x2F;speed up until the top of the hour is reached. Then there&#x27;s a daily pulse that tells them to wait&#x2F;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&#x2F;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 &#x27;tick&#x27; the other clocks.<p>And if the clocks ever got out of sync for any reason, there doesn&#x27;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 &#x27;suck&#x27; for a minute before midnight, and use a mechanical system which would fast-forward all clocks to midnight at that point.

&gt; 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>&gt; 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:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;R%C3%A9seau_Express_R%C3%A9gional" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;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

&gt; 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&#x27;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:&#x2F;&#x2F;www.coned.com&#x2F;en&#x2F;commercial-industrial&#x2F;steam" rel="nofollow">https:&#x2F;&#x2F;www.coned.com&#x2F;en&#x2F;commercial-industrial&#x2F;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 &#x27;reset&#x27; the clocks remotely, for example to send a 60 second burst of air that resets all the clocks to 12:00.

do the clock still exist?

OMG I misread the title.