Sunday 21st February

Sunday 21st February marks the 110th anniversary of the death of Professor Charles Piazzi Smyth who worked with Frederick James Ritchie and Chief Master Gunner Findlay to set up of the One o’ Clock Gun.

Following experiments at Edinburgh Castle early in 1861, it was decided to place the time gun on the Half Moon Battery. The professor and his assistants travelled all over Edinburgh and down to Leith Docks to find out how well the sound of the gun could be heard throughout the city. Although mariners on ships lying in the Firth of Forth required binoculars to spot the time ball falling at one, in addition to hearing the sound of the gun, it was possible to see the white puff of smoke.

The Jones clock adapted by Frederick James Ritchie to fire the One o’ Clock Gun was supplied by James Ritchie & Son at the company’s expense. This was a shrewd move which led to international recognition for the firm as the company received orders from observatories in Russia and the United States.

The photograph taken by Professor Piazzi Smyth in 1876 shows the One o’ Clock Gun firing from the Half Moon Battery. Judging by the angle of the photograph, the professor must have stood on top of the wall surrounding the observatory when taking the shot.

The photograph is reproduced by permission of the Royal Society of Edinburgh (The RSE’s Piazzi Smyth Bequest is held on deposit at the Royal Observatory, Edinburgh).