The Swiss railways have a slightly similar system of synchronization once per minute, with an interesting nuance:<p>"The station clocks in Switzerland are synchronized by receiving an electrical impulse from a central master clock at each full minute, advancing the minute hand by one minute. The second hand is driven by an electrical motor independent of the master clock. It requires only about 58.5 seconds to circle the face, then the hand pauses briefly at the top of the clock. It starts a new rotation as soon as it receives the next minute impulse from the master clock.[4] This movement is emulated in some of the licensed timepieces made by Mondaine."<p>(Wikipedia)
The whole site for this is great. I really like the multitude of variations they had in early steam/IC engines[0]; it reminds me a lot of the expirementing we have in the software ecosystem today<p>[0a]<a href="http://www.douglas-self.com/MUSEUM/POWER/unusualICeng/unusualICeng.htm" rel="nofollow">http://www.douglas-self.com/MUSEUM/POWER/unusualICeng/unusua...</a><p>[0b]<a href="http://www.douglas-self.com/MUSEUM/POWER/unusualsteameng/unusualsteameng.htm" rel="nofollow">http://www.douglas-self.com/MUSEUM/POWER/unusualsteameng/unu...</a>
It was almost certainly related to the "télégraphe pneumatique" messaging system, that allowed to send mail and small objects extremely rapidly across Paris in air-filled tubes:
<a href="http://www.cix.co.uk/~mhayhurst/jdhayhurst/pneumatic/book1.html" rel="nofollow">http://www.cix.co.uk/~mhayhurst/jdhayhurst/pneumatic/book1.h...</a><p>They had the compressed air generation available already! And this service was available until 1984 (the last line was closed in 2004!).<p>More details on the French Wikipedia:
<a href="https://fr.wikipedia.org/wiki/Tube_pneumatique" rel="nofollow">https://fr.wikipedia.org/wiki/Tube_pneumatique</a>
> <i>The pipes ran through the sewers of the city, and the tunnels of the Metro and the RER. (...) Operation began in 1880...</i><p>The Paris Metro was inaugurated in 1900, and the RER in 1977, so this is unlikely. (It would be possible to run pipes through tunnels before the inauguration, but works on the Metro started no earlier than 1898).<p><a href="https://fr.wikipedia.org/wiki/Histoire_du_m%C3%A9tro_de_Paris" rel="nofollow">https://fr.wikipedia.org/wiki/Histoire_du_m%C3%A9tro_de_Pari...</a><p><a href="https://fr.wikipedia.org/wiki/R%C3%A9seau_express_r%C3%A9gional_d%27%C3%8Ele-de-France" rel="nofollow">https://fr.wikipedia.org/wiki/R%C3%A9seau_express_r%C3%A9gio...</a>
I liked the "explode all clocks" lever, which puts 73 PSI of pressure into the lines designed for just 10 PSI.<p>> Note that there is a provision for connecting the high pressure air directly to the low-pressure reservoir, by means of valve f. Why you would want to do this I do not know, because as mentioned above I would have thought it would have caused all the clocks to explode.
I wonder if any equipment from the system survives today... a quick Internet search doesn't turn up anything but the old drawings and photos shown here. Like a lot of other obsolete technology, it's one thing to read about it, but I'd be very interested in seeing a (modern) photo.
It's true the whole site is full of gems!<p>I wonder why Elon hasn't tried to go prop with high speed locos!
<a href="http://www.douglas-self.com/MUSEUM/LOCOLOCO/proprail/proprail.htm" rel="nofollow">http://www.douglas-self.com/MUSEUM/LOCOLOCO/proprail/proprai...</a>