Noon Gun - Time Signalling

Time Signalling

In addition to the aforementioned signalling duties, the guns have had the task of firing a time signal since 1806. According to local tradition, the initial purpose of the gun was to allow ships in port to check the accuracy of their marine chronometers (a precision instrument used aboard ships to help calculate longitude). The gun report might be too inaccurate for ships several kilometers away if they did not correctly compensate for the relatively slow speed of sound.

The invention of the more accurate time ball in 1818 soon made time guns redundant for mariners wishing to set their chronometers. The time ball on Signal Hill was used to relay time from the Cape Town Observatory, whose time ball was not visible from all parts of the bay. At precisely 1:30pm Cape Mean Time, the ball would be dropped at the Observatory – an observer on Signal Hill would then drop that more prominent ball too. When setting their chronometers, mariners adjusted their observation of the time ball on Signal Hill by a second to allow for the relay from the observatory.

After the advent of the galvanic telegraph, it became possible to trigger a gun remotely and since 1864 the Noon Gun has been fired from the master clock of the oldest timekeeper in the country, the South African Astronomical Observatory. One day in June 1895 the gun fired at 10:30 rather than 12:00 when a spider interfered with the relay used to remotely fire the gun.

The original guns – 18-pounder, smoothbore muzzle-loaders – are still in use today. The ritual represents one of Cape Town's oldest living traditions. These are the oldest guns in daily use in the world. They fire every day at 12 noon sharp, except Sundays and public holidays, and are maintained by the South African Navy. There have been few remarkable incidents involving the guns over the centuries. Perhaps the most notable one occurred many decades ago, in the days when horse-drawn traffic was commonplace. The rammer used to tamp the charge into the muzzle was inadvertently left in the bore of the cannon and when the gun fired the rammer flew down into the city and killed a horse. On Friday January 7, 2005, both the main gun and backup gun failed to fire owing to a technical difficulty. This was the first time in 200 years that the noon gun had not fired as scheduled.