The One o'Clock Gun

Time Ball on Calton Hill

In 1852, Edinburgh installed a time ball at the top of the Nelson Monument on Calton Hill, to enable the sailors in Leith Docks and the Firth of Forth to check and adjust their chronometers.

The Edinburgh time ball was devised by the photographer and Astronomer Royal for Scotland, Charles Piazzi Smyth, who had worked previously as assistant astronomer at the Cape of Good Hope Observatory, which had its own time ball. 

It was designed by the Edinburgh clockmaker, Frederick James Ritchie.

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Ritchie of Edinburgh still have the contract for maintaining the time ball and several of Edinburgh's public clocks, including the Floral Clock in Princes Street Gardens.

Observations of the stars were made, using the telescope on Calton Hill.  This enabled the precise time to be known.

On the Nelson Monument, the time ball was raised shortly before one o'clock every day, then lowered at one o'clock so that the people of Edinburgh and the ships in the Firth of Forth could check their clocks and chronometers.

One o'clock Gun at Edinburgh Castle

In 1861, the time ball was linked by an overhead electric cable, 4,200 ft long, stretching across the valley from Calton Hill to Edinburgh Castle on Castle Rock, to enable a canon to be automatically fired at one o'clock.  The gun could be heard from far afield, but it took several seconds for the sound to travel even the two miles from Edinburgh Castle to Leith.

Time-Gun maps were published in the Edinburgh & Leith Post Office Directories in 1861 and 1862.  These maps showed the time taken for the sound of the gunfire to travel across Edinburgh.