jonathan.rawle.org

One o'clock gun

The gun is fired at 13:00 hours every day of the week except Sunday. It was originally a signal that allowed sailors in the Firth of Forth to set their chronometers, and was intended to complement the time ball on top of Nelson's Monument on Calton Hill, which could not be seen in adverse weather.

The castle guide, a Scotsman, joked that the gun is fired at 1pm rather than noon as the Scots would not wish to pay for 12 charges each day. I wonder whether the true reason is that it was necessary for astronomers to observe the sun at midday to set the clocks accurately, ready for the signal at 1pm, which is the reason for the time ball at Greenwich dropping at one o'clock.

This photo was taken approximately a second after the gun fired. The explosion still comes as a shock to onlookers, even though everyone is expecting it! The gunner himself, however, does not even flinch.