Skip to Content

This cache has been archived.

Morton: As I said in my previous log, I'd been planning to replace the missing cache this month. However, another geocacher has kindly warned me that the area containing the final is "closed until further notice due to health & safety" - and the powers that be clearly really mean it, since there are notices posted on all the gates.

With regret then, I've decided to call it a day. The final spot has been getting harder and harder to access and there's no way of knowing how long the current closure is going to last. Maybe at some future point it'll make sense to bring it back, but that time is not now.

In the meantime, thanks to everyone who's found the cache, and to everyone else who's shown interest in it! I enjoyed doing the research and planning the route, and I enjoyed reading all the logs as well. I have other ideas for historical caches, so watch this space [:)]


The One O'Clock Gun

A cache by Morton, with thanks to Haggis Hunter Send Message to Owner Message this owner
Hidden : 02/04/2015
2.5 out of 5
2.5 out of 5

Size: Size: small (small)

Join now to view geocache location details. It's free!


How Geocaching Works

Please note Use of services is subject to the terms and conditions in our disclaimer.

Geocache Description:

You’ve probably heard of the One O’Clock Gun. You probably know it’s at Edinburgh Castle. So what are we doing here, on the summit of Calton Hill? Follow the trail through the city, and learn the history and science behind a celebrated civic icon: a tale of sailing-ships in peril, of Victorian innovation, and of the button on this hill-top which fired a cannon in Dundee.

This historical multi-cache will take you on a walk through Edinburgh city centre, starting at Calton Hill to the east of Princes Street and ending near Edinburgh Castle. The total distance is about a mile, with a couple of short but steep hills to climb along the way.

Including time to find the clues and read the back-story, you can expect the whole tour to take 60 to 90 minutes. As well as finding the cache, you’ll get to enjoy some great views of Edinburgh – and if you time your visit right, you’ll witness a 150-year-old ritual, too.

IMPORTANT: The final location is accessible from 8am to 4:30pm all year round, or 8am to 6pm from April to September. You cannot sign the logbook outside these times. Make sure you allow plenty of time to complete your visit, or you might get locked in!

Additionally, Calton Hill (where the trail begins) has a reputation for anti-social activities at night. Don’t let this put you off a daytime visit – you’ll be perfectly safe, and surrounded by tourists – but it’s best not to climb the hill after dark unless you’re confident looking after yourself.

Ready to begin? Then let’s travel through time…

Calton Hill in 1820

Waypoint 1: Calton Hill

N 55 57.275, W 3 10.983 (the published coordinates)

The year is 1820. Scotland, like all of Europe, is struggling to recover from a generation-long war. Just five years after Napoleon’s ultimate defeat, the names of the battles are fresh in everybody’s minds: Copenhagen, Trafalgar, Waterloo. And looming over the city of Edinburgh, Calton Hill has become a kind of national shrine, a fitting home for a striking field of monuments to the 300,000 British fallen.

Already, there’s the tall tower of the Nelson Monument – shaped like an upturned telescope, evoking the battle of Trafalgar. Plans are afoot for a National Monument in front of you, an ambitious replica of the Parthenon. (Some express doubt it’ll ever be complete.) But to your left, a quite different structure is emerging... not a memorial to the dead, but a living place of learning.

Clue A. Not far from here, there’s a lengthy inscription in Latin. How many words are there in the longest line?

Waypoint 2: The Gothic Tower

N 55 57.274, W 003 11.064

The year is 1831. The hilltop is still changing; the fine monument you’re standing beside wasn’t here a year ago. But one thing’s been the same as long as anyone can remember. At the corner of the walls above you stands a fortified house, former home of the celebrated telescope-maker Thomas Short.

For years, Short’s gothic tower stood alone. But now it’s been absorbed into a grand new observatory – designed by none other than William Playfair, one of the greatest architects of his time. And despite the rigors of economic depression, the Government has found the funds to fit brand new telescopes inside. Why invest such effort in watching the stars? The answer lies just around the corner.

Clue B. Very close to you, there’s a name carved in stone. How many letters are there in the surname?

Waypoint 3: The view to Leith

N 55 57.334, W 003 10.935

The year is 1840. The view in front of you is different from today – but not completely different. There are still neat rows of houses; there are still factory chimneys. And there in the distance, there’s the busy port of Leith, opening onto the River Forth and the sea.

Out on the featureless ocean, it’s vital for sailors to keep track of where they are. With the stars and a sextant, they can work out their latitude – but to figure out their longitude, they need reliable clocks as well. If they get the time just one minute wrong, they’ll be fifteen miles off-course. That’s not much in the middle of the Atlantic, but it’s the difference between life and death near a rocky shoreline in the fog.

Clue C. Look around you now, and you’ll find the letters OS BM S. After the S comes a number. What’s the first digit of the number (immediately after the S)?

The observatory’s meridian passes due north and south through the eastern wing of the building. The transit telescope is still there, but inaccessible to the public.
Imagery: Google, Infoterra Ltd, Bluesky.

Waypoint 4: The observatory gates

N 55 57.284, W 003 11.015

The year is 1850. Within living memory, sea-going “chronometers” were rare and precious things; but by now, they’re affordable enough for every sailing-ship to carry one. Yet even the best chronometer is only as good at the clock that you set it from. And so today, like every day, there’s a column of officers tramping up the hill, checking the time on the observatory’s clock before they set out to sea.

They call it the “politician’s clock”, because it has two faces. One face looks out for the sailors to read; the other looks in, so the astronomers can set the time. But how do the astronomers know the time? It’s all down to the meticulous construction of this building, set foursquare around a north-south axis called the “meridian line”. Using a special “transit telescope”, they record the exact moment each star crosses the meridian – and when the Sun itself passes over the line, it’s noon.

Clue D. There are several benches along the wall outside the gate, many of them with plaques marking someone’s passing. But one of the plaques has a happier purpose: to celebrate a “loving wife’s” birthday. Which month was she born in? January = 1, February = 2 and so on.

Waypoint 5: The time ball

N 55 57.266, W 003 10.947

The year is 1853, and the steady stream of seafarers has gone. As you stand here, at the base of the Nelson Monument, you can see the reason why: there’s a brand new “time ball” at the top of the tower, just below the compass rose. The Astronomer Royal, Charles Piazzi Smyth, campaigned dauntlessly to install it here – putting Edinburgh on a par with English cities like Portsmouth, where the idea of the time ball was invented some twenty years ago.

It’s a simple but brilliant device. Each day at noon, the astronomers complete their measurements and correct their clock. Fifty-five minutes later, they wind the ball up to the top of the pole; and when the clock reads one o’clock, they let it drop back down again. Watching through their telescopes from the port of Leith, sea-captains use the signal to set their chronometers – with no need for anyone to climb any hills, or even to step on dry land.

Clue E. Above the entrance to the monument, there’s a date in Roman numerals. Not counting “A.D.”, how many letters are there in the date?

The time ball is still raised at 12:55pm and dropped at 1:00pm, every day except Sunday. If you’re on the hill at the right time, the benches at the previous waypoint make a good place to sit and watch.

Optional Step! You can climb to the top of the Nelson Monument – and while you don’t need to do that to finish this cache, it’s worth taking the time. The views from the top may well be the best in Edinburgh, and offer unique perspectives on the observatory and its immediate surrounds. There’s also a small exhibition on Edinburgh’s maritime history. Admission is £4 and opening times vary throughout the year, so check this web page if you particularly want to make the climb.

Waypoint 6: The road to the Castle

N 55 57.262, W 003 11.087

The year is 1860. Piazzi Smyth’s time ball has been more successful than even he’d imagined – but there’s just one flaw in his plan. If you live in Edinburgh, you’ll know it’s a foggy city; when mists roll in off the sea, Calton Hill is often hidden from view. So why not, Smyth argues, add an audible signal too? Shouldn’t the one o’clock ball be joined by a One O’Clock Gun?

Not everyone likes the idea. The astronomers at the observatory are worried about their telescopes; would the shock waves from a cannon disturb the delicate balance of their tools? So Piazzi Smyth gets his gun, but there’s a complication. It’ll be based at Edinburgh Castle – three-quarters of a mile from the clock here on Calton Hill.

Clue F. Look around you carefully. Nearby, you can see the letters GNR, followed by two digits. What’s the last of the digits?

Checkpoint as you return to the street: the digits A to F should add to 30.

Ritchie’s firing mechanism in 1863

Waypoint 7: Frederick James Ritchie

N 55 57.209, W 003 11.350

The year is 1861. The garrison at the Castle has provided a cannon, but at such a distance from the observatory, how can it be fired? Sending a runner is out of the question; the timing is too critical to trust to human frailties. A new technology is needed, and Edinburgh clock-maker Frederick James Ritchie has proved the man for the task.

It takes four men at the castle to load the cannon with gunpowder, but it’s Ritchie’s invention which sets it alight. His mechanism relies on electricity to carry a signal from Calton Hill; when the current stops, a weight drops, using friction to set off the charge. There was amusement in the newspapers when the gun didn’t fire on its inauguration day. But two days later, and every day after that, it went off on cue.

Clue G. Close to where you’re standing, there’s a clock bearing Ritchie’s name. (You’ll learn more about this clock later in the tour.) There’s an address on the clockface: 5G Broughton Street. G should be a single digit.

Waypoint 8: The thousand-metre wire

N 55 57.154, W 003 11.563

If there is an event in Princes Street Gardens you may not be able to access this exact spot, but don't worry - you can answer the question from outside the railings.

The year is 1870. Take a look back the way you came, and you’ll see the monuments on Calton Hill; turn around, and you’re facing towards the Castle. And far above the Victorian-era street, unsupported by props or pylons, there’s a 4,000-foot electrical cable strung straight between the two.

It’s this cable which bears Ritchie’s signal – the all-important electric trigger, which fires the gun precisely on time. It sways in the wind; it sags in the snow; there are even worries its weight might pull the Nelson Monument down. But for now, it hangs impossibly high above the valley, an unmistakeable symbol of the importance of time to this growing mercantile city.

Clue H. You’re standing next to a statue. There’s just one word written on its plinth: there are 1H letters in the word. H should be a single digit.

Princes Street and Waverley Station in 1875

Waypoint 9: The rise of the railway

N 55 57.090, W 003 11.495

The year is 1880. The overhead cable is gone now, re-routed across the roofs of the Royal Mile; and time itself is changing too. Half a century ago – before the railways came – each city set its clocks by “local noon”, the moment when the sun was highest in the sky. But local noon changes as you move east or west, so when it’s local noon in Edinburgh, it’s just 11:56 in Glasgow.

Back when it took days to travel between cities, and the only clocks were on churches, the time gap mattered little to anybody. But now there are fast trains, and affordable watches; it seems silly that a timepiece from Edinburgh is four minutes fast on the banks of the Clyde. So the law has changed, unifying the whole of Great Britain in a single common time zone. The observatory still checks the stars, and the One O’Clock Gun still fires, but now they mark the time in London… Greenwich Mean Time.

Clue I. You're standing at the modern-day entrance to Edinburgh Waverley railway station. On Mondays to Saturdays, the station closes to the public at 00:45. At what hour does it re-open? I should be a single digit.

Waypoint 10: Time by telegraph

N 55 57.004 W 003 11.574

The year is 1883, and Frederick James Ritchie, who designed the firing mechanism for the gun, has made another breakthrough. He’s patented a method of synchronising clocks across telegraph lines – providing a time check not just at one o’clock, but 24 hours a day. What’s more, he’s created the “Edinburgh Time Circuit” to showcase his invention; Ritchie’s clocks, precise to the second, have been springing up at public buildings across the city.

Is there a clock at the Bank of Scotland, where you’re standing now? Well, maybe. The plans for the Time Circuit are long lost, and nobody’s quite sure where all his stations were. But there was definitely one at City Chambers – a short walk up the High Street – and then, as now, the Bank of Scotland’s green-domed headquarters was a truly iconic building. It’s easy to imagine one of Ritchie’s handsome timepieces in pride of place here.

You saw one of Ritchie’s clocks back at Stage 7 (the one with an address on the dial).

Clue J. Look up! How many white thistles are there below the shield?

Waypoint 11: The speed of sound

N 55 56.933, W 003 11.732

The year is 1890, and the heyday of the One O’Clock Gun is almost over. With synchronised clocks on display across the city, the signal will soon be an old-fashioned curiosity – a tradition to please tourists, not an essential tool. But people still listen for the gun, and everyone knows how long it takes the sound to reach their home. Right now, you’re standing 340 metres from the muzzle; right here, when you hear the bang, it’s one second past one.

But if sound takes time to travel, the telegraph works at the speed of light, and the observatory’s network now spreads far beyond the city. Glasgow, ever proud, has rejected Edinburgh’s signal: “I would blush to think that our city, superior both in population and wealth to Edinburgh, should bow so humbly as to accept,” one letter-writer complained. But Newcastle in England takes its time from Calton Hill. And most strikingly of all, the system now includes a second One O’Clock Gun – fired by telegraph from Edinburgh, but stationed sixty miles north in Dundee.

Clue K. Near here is a plaque celebrating a meeting between James Boswell and Samuel Johnson. How many different years are mentioned on the plaque?

The Royal Observatory, Backford Hill

Waypoint 12: The times are changing

N 55 56.912, W 003 11.801

The year is 1896. The century, and the Victorian age, are drawing to a close. And something else is closing too: the observatory on Calton Hill, bedevilled now by light from the city, and the increasing age of its telescopes.

For a while, it seemed that Edinburgh might lose its cherished time service. But salvation came from an unexpected direction: the Dunecht observatory in Aberdeenshire, which donated its instruments and sacrificed its own future to endow a new building in the capital. Look across to the hilltops, and you can see it now: the Royal Observatory on Blackford Hill – a new arbiter of time for Edinburgh.

Clue L. In the foreground of the view from here, there are two red phone boxes. Next to the phone boxes are some green cabinets. How many cabinets are there?

Optional Step! To see the One O’Clock Gun being fired, you’ll need to go into Edinburgh Castle. Admission to the Castle is extremely expensive, but if you’re going to be visiting anyway, it makes sense to plan your visit to be there at 1pm. The gun’s now fired by hand, not machine – but it’s still an enjoyable and iconic spectacle. Allow at least 15 minutes to get your ticket and find the right spot inside, and remember that the gun is not fired on Sundays.

Final waypoint: The One O'Clock Gun!

N 55 56.960, W 003 12.000

Sometimes the gate which leads directly to this area is locked, for no obvious reason. In that case, there's an alternative access point at N 55° 57.018' W 3° 11.761'. If that gate is locked as well, then sorry, the area around the final is closed and you won't be able to log the cache today.

The year is 2018. Time signals are everywhere now: on the radio, on the Internet, even beamed from space. Each GPS satellite carries two atomic clocks, accurate to a single second in 32,000 years. And latitude and longitude – though no less crucial for navigators – also form the basis of a popular outdoor game.

The final cache is at the stated coordinates, but you’ll need to have found the clues before you can sign the logbook. You must sign the logbook to claim the cache!

To avoid causing damage to this potentially sensitive site, there’s a clear hint, and a spoiler photo in the gallery. Please use them sooner rather than later.

Firing the One O'Clock Gun (viewed from inside the Castle – admission fee must be paid to watch from this angle).
Photo credit: Steve Collis (info and licence)

If you walk on a few metres from the cache site and look up at the Castle, you’ll see the muzzle of the One O’Clock Gun peeking through the battlements. The original cannon was replaced long ago; this particular gun is just the latest in a series, installed in 2001. It’s not the oldest, sturdiest or prettiest of the artillery on display. But of all the heavy weapons which ring the Castle’s walls… it’s the only one which actually can fire.

The gun is fired every day, except Sundays, at 1pm. Standing here, you’re as close to the bang as it’s possible to get (even closer than you’d be inside the Castle!) When you see the gun winched up, it’s about to fire; it’ll go off without further warning one to two minutes later.

That’s the end of your journey; if you want to, you can continue down the hill to cross the railway and return to Princes Street. I hope you’ve enjoyed this geocache. Special thanks to Haggis Hunter for securing permission to use the site, and to Original A1 for testing that the numbers add up.

Additional Hints (Decrypt)

Va n avpur ng gur onpx bs gur evtug-unaq fvqr bs gur ebpxl bhgpebc. Gurer vf n fcbvyre cubgb va gur tnyyrel: sbyybj gur qbgf, naq ybbx jurer gur neebj cbvagf.

Decryption Key


(letter above equals below, and vice versa)

Return to the Top of the Page

Reviewer notes

Use this space to describe your geocache location, container, and how it's hidden to your reviewer. If you've made changes, tell the reviewer what changes you made. The more they know, the easier it is for them to publish your geocache. This note will not be visible to the public when your geocache is published.