The Underground Clocks of Paris

Who doesn’t love a little obscure clock history? This video from Primal Space on YouTube details Paris’ pneumatic clock system, which engineer Victor Popp developed and put in place in the late 19th century.

British engineer Douglas Self also has a nice overview of the system on his personal website:

In 1877 Carl Albert Mayrhofer set up a pneumatic clock network in Vienna; he was granted US patent 215,381 in May 1879, assigning it to the Austrian engineer Viktor Antoine Popp and his co-worker Resch. In 1879 Popp & Resch demonstrated the system of pneumatic clock synchronisation in the Austro-Hungarian section of the Universal Exposition. The Paris city council granted Popp’s Compagnie des Horloges Pneumatiques (CGHP) authorization to install a compressed air network to drive both public and private clocks. It was not a power distribution network but a time distribution network, which synchronised a large number public clocks, in particular those of railway stations, by sending a pulse of air every minute. The pipes ran through the sewers of the city, and the tunnels of the Metro and the RER. (The RER is a commuter rail network serving Paris and its suburbs) Each Popp clock contained a metal bellows which advanced a 60-tooth wheel by one tooth per minute. Operation began in 1880; it is interesting to note that this was a long time after the Paris pneumatic post had opened in 1866.

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