Interesting that by 1855, they had a sort of "Network Time Protocol" running over telegraph lines: > By 1852 a telegraph link had been constructed between a ne

Interesting that by 1855, they had a sort of "Network Time Protocol" running over telegraph lines: > By 1852 a telegraph link had been constructed between a new electro-magnetic clock at Greenwich and initially Lewisham, and shortly after this London Bridge stations. It also connected via the Central Telegraph Station of the Electric Time Company in the City of London, which enabled the transmission of a time signal along the railway telegraphic network to other stations. By 1855 time signals from Greenwich could be sent through wires alongside the railway lines across the length and breadth of Britain.[1] By the late 19th Century, they had invented "master clocks": > Between the late 1800s and the availability of Internet time services, many large institutions that depended on accurate timekeeping such as schools, offices, railway networks, telephone exchanges, and factories used master/slave clock networks. These consisted of multiple slave clocks and other timing devices, connected through wires to a master clock which kept them synchronized by electrical signals. The master clock was usually a precision pendulum clock with a seconds pendulum and a robust mechanism. It generated periodic timing signals by electrical contacts attached to the mechanism, transmitted to the controlled equipment through pairs of wires.[2] [1] https://en.wikipedia.org/wiki/Railway_time#Influence_of_the_electric_telegraph https://en.wikipedia.org/wiki/Railway_time#Influence_of_the_... [2] https://en.wikipedia.org/wiki/Master_clock#History https://en.wikipedia.org/wiki/Master_clock#History