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The Swiss railways have a slightly similar system of synchronization once per minute, with an interesting nuance:

"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."

(Wikipedia)




In the United States there were a number of private time services one could subscribe to.

One of the largest was operated by Western Union. A telegraph line would be used to send a synchronized signal a short period before the top of the hour, which energized a solenoid in the clock. The minute hand would be pulled to the :00 position and the clock would restart once the signal was released. Commercial telegraph message traffic would be offline until this signal was completed.

https://www.hemmings.com/blog/article/tick-tock-whirrrrrr-th...

There were also thousands of local "master clock" installations in schools and other facilities. Lots of kids from the 70s and 80s probably remember the IBM school clock:

https://www.schoolhouse.com/products/1960s-ibm-standard-issu...


There's also the time error correction that's done to ensure the accuracy of clocks that get their timing signal from the AC electric supply.

https://en.wikipedia.org/wiki/Utility_frequency#Time_error_c...


I'd never considered the school clocks would be a centralized system, but it makes sense. Interesting


NB the school clocks were only "locally" centralized...


Or even with "rolling updates", https://thedailywtf.com/articles/SyncingSunk




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