Central Telegraph
The electric telegraph, which had been developed in the early part of the 19th century, was refined by William Fothergill Cooke and Charles Wheatstone and was installed on a short section of the Great Western Railway in 1839. 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. This technology was also used in India to synchronise railway time.