The Shepherd Gate Clock (51°28′41″N 0°00′05″W) is mounted on the wall outside the gate of the Royal Observatory, Greenwich building in Greenwich, Greater London.
The clock, an early example of an electrically connected clock system, was a sympathetic clock mechanism controlled by electric pulses transmitted by a motor clock inside the main building.
The network of 'sympathetic clocks' was constructed and installed by Charles Shepherd in 1852.


A sympathetic clock is a system where one clock (often called the "master clock") transmits time signals to one or more other clocks (called "sympathetic clocks" or "slave clocks"), ensuring they all display the same time. These systems typically use electrical impulses or other mechanisms to synchronize the clocks.
Here's a more detailed explanation:
Master Clock: The central clock that generates the time signals.
Sympathetic/Slave Clock: Clocks that receive the signals from the master clock and adjust their time accordingly.
Synchronization: The master clock sends out signals (e.g., electrical impulses) that cause the sympathetic clocks to either advance or reset their time.