Timeline is the title of a sound installation by the artist Susan Philipsz which took place in Edinburgh, Scotland, from the Second of August, 2012 to the Second of September, 2012. A brief descending choral exultation occurred at 1 pm every day emitting from speakers set at points from Edinburgh Castle to Calton Hill, aurally marking the amount of time the sound of a cannon shooting at the castle travels between those two points.

The cannon, known as The One O'clock Gun, fires at this time six days a week, skipping Sundays and a couple holidays, and has been doing so for over 150 years to note time for ships unable to see the time ball installed at Calton Hill. Nowadays, of course, this is just a tradition, there being easier and more accurate ways for ships to know the time, and mainly serves as a way to differentiate between the tourists and the residents by who reacts to it. Yet if this tradition stopped, it would be severely noticed and seem like a breakdown in society, as if this daily (except kipping in day) event pins the city down, keeping the old town old, the castle its symbol of security, the clocks on church and hotel buildings honest, and the ships anchored.

During its time in existence, I 'watched' the installation once, taking a bus from the other side of town to the Old Calton Cemetery. I stood by the remains of David Hume, and next to a memorial to those fallen in the American Civil War (the only one outside of the United States, and sporting a statue of Lincoln standing above what could now seem a dodgy statue of a supplicating freed slave) and checked the time along with two other suits who'd also arrived. I looked up to Nelson's Monument up on the Hill, which has the appearance of an ancient lighthouse and has a time ball installed. It was one of those almost raining days we often get here in the spring with raindrops spitting down and stopping so that you don't know whether to open an umbrella or not. I could see the speakers the sound would come from, set up on the pseudo-castle crenelated Governor's House. They were in the shape of siren speakers, an obvious homage to its inventor, the physicist John Robison, whose original use was as a musical instrument for pipe organs.

Suddenly, a shot rang out. The ball dropped, and in between was the sound of a lowering 'ah', almost like a sample from Queen's Flash Gordon. And that was that. The two suits and I smiled briefly, said 'Well...' adjusted our hats or ruffled our umbrellas, and headed back to work.

A short simple siren call that echoed back in history, Philipsz' work gave me a small bit of pleasure, exactly as it should have. It reverberated throughout the month, while I stopped at other art installed in the city during its mad Festival month, finding other works with links to other parts of the city, a sort of psycho-geography forming.

The next time I heard the One O'clock Gun I checked the time on my phone and nodded, as if all was well.

More on this work, including a video, here