This clock hasn’t moved anywhere in 162 years, although its hands certainly have.
This is the famous (in some circles at least!) Shepherd 24-hour Gate Clock, outside the gate of the Royal Observatory in Greenwich Park, London and just a few feet away from the Greenwich Meridian Line (which marks Longitude 0o).
There are several things worth noting about this clock:
- It is one of the world’s first electrically-driven public clocks
- It shows all 24 hours on the dial, the hour hand moving only once round in a day, unlike almost all other analogue clocks and watches which rotate twice around a 12-hour dial
- It only ever shows Greenwich Mean Time (GMT) - meaning that the photo above was actually taken an hour later than is shown, because the UK is currently on British Summer Time (BST), which is GMT+1
- It is slave clock, controlled by electric pulses originally from a master clock, now a quartz mechanism, inside the main Observatory building
- The face is a modern reproduction of the original, which was damaged beyond repair by a bomb in the Second World War
- The same time signal that drove this clock was used to drive others at the Observatory and one at London Bridge Station, and via that, clocks throughout England. By 1866 the time signal was being transmitted to Harvard University in the United States, via transatlantic cable.
- The same signal also drives the Royal Observatory Time Ball (see photo below), which drops at exactly 1pm every day, originally to enable ships down on the River Thames to check and set their marine chronometers