At one o'clock each
afternoon, a disk known as a Time Ball, mounted at the top of the
Nelson Monument on Calton Hill is lowered.
This was a signal intended to be seen by the shipping at Leith and in
the Firth of Forth, about three miles to the North.
Charles Piazzi Smyth was
responsible for installing this time ball.
In 1861, this time ball was
augmented by the One 'Clock
Gun, a cannon is fired from the ramparts
of Edinburgh Castle, to signal the time to the citizens of Edinburgh.
For many years a signal was sent by electronic wire, stretching to
Edinburgh Castle, and this automatically fired the cannon. Charles
Piazzi Smyth and Master Gunner Findlay, together, installed the One
Today both the time ball and the
One o'Clock Gun still operate, but the two are not linked. The gun
is fired daily, except Sundays.