The Time Ball

on the Nelson Monument


One o'Clock Gun

at Edinburgh Castle

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.

Time Ball in raised position

Photographed at 12.59pm -  2 October 2006

The Nelson Monument on Calton Hill.  The time ball photographed at 11.59pm on October 2, 2006  -  waiting to be lowered at 1pm


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.

The time ball mechanism was designed by the Edinburgh clockmaker, Frederick James Ritchie.

Detail from an advert in the Edinburgh & Leith Post Office Directory  -   1867  -  Ritchie & Son, with a view from Calton Hill ©

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 on the ships in the Firth of Forth could check their clocks and chronometers.

Mons Meg at Edinburgh Castle

This is not the canon that is used for the one o'clock gun!

    Mons Meg  -  The C15 siege gun at Edinburgh Castle ©

In 1861, a master clock on Calton Hill was linked by an overhead electric cable to a clock at Edinburgh Castle.  This enabled the one o'clock gun at the castle to be fired automatically at exactly one o'clock.

Equipment used for the observations at Calton Hill can still be seen in the Observatory on the hill.  The clock used to time the firing of the cannon at the castle is now on display in a case in the Café at the castle beside the one o'clock gun.

The electric cable linking the castle and Calton Hill was 1,225 meters long.  It passed passed over Waverley Valley, without any support, at the height of 73 meters.

The gun could be heard from far afield.  The falling of the time ball at the top of the Nelson Monument could be seen immediately,  but it took several seconds for the sound of the gun to travel even the two miles from Edinburgh Castle to the ships in Leith Harbour.

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.

Edinburgh Time-Gun Map  -  1861  -  The whole map ©

Connection between

Time Ball


One o'Clock Gun



I read, some time ago, that there used to be a cable, strung across the  Waverley Valley, connecting the One o'Clock gun at Edinburgh Castle to the Nelson Monument on Calton Hill.

I've been trying to find out more about this cable and how long it survived for.


Nineteenth Century

Thank you to George Robinson for telling me more about this cable.

George wrote:

"The cable was hung in one single span, three quarters of a mile long, between the Castle and the Nelson Monument in April 1861 by a squad of  sailors from Leith.

In 1873,  due to the strain on the Nelson Monument caused by the the weight of the cable, it was attached to the Old Post Office, the New Post Office, St. Giles and the steeple of the Highland Tolbooth Church.

In 1896, the time began to be sent from the Royal Observatory on the Blackford Hill to the One o'Clock Gun, along the GPO's cable."

George Robinson:   One o'Clock Gun & Time Ball Association:  August 21+25, 2011


In the 1990s, while working on a personal project to photograph people at work in Edinburgh, I accompanied the Edinburgh Clock Winder on a few occasions.  He was one of the employees of clockmaker, Ritchie who created the original time ball in 1861.

One of his daily duties was to climb the steps of Nelson Monument and wind a handle to raise the time ball a few minutes before 1pm.  He then watched the gun at Edinburgh Castle until he saw a puff of smoke from it, and immediately released the time ball.

The sound of the gun firing reached Calton Hill about 4 seconds later, and reached the shipping in Leith Docks about 11 seconds later.

Time Gun Map

Please click on the thumbnail image below to see an extract from the 1861 Time Gun Map, and discover how long it takes sound from the gun to travel across Edinburgh.

    Edinburgh Time-Gun Map  -  1861  -  Edinburgh to Leith  -  without key ©