Man of the Hour
















If he’s remembered at all, Charles Piazzi Smyth, born in Naples on 3 January 1819, is either the astronomer who first showed the increased clarity from mountain-top stargazing, or the mystical pyramidologist with bizarre theories about the Great Pyramid of Giza.

However, in Edinburgh – his “own adopted town” for 40 years – Piazzi Smyth is now largely forgotten. This is despite arguably his most audible legacy, one that can be heard every day, bar Sundays—the One O’Clock Gun, which has been fired regularly from the Castle ramparts since 1861.

Piazzi Smyth was among the last great “amateur” stargazers, most obviously during his 40 years as the second Astronomer Royal for Scotland and Professor of Practical Astronomy at the University of Edinburgh. This was despite his own “academic” schooling ending at the age of 16, after which he took up the role of assistant to Thomas Maclear, then King William IV’s Astronomer at the Royal Observatory, Cape of Good Hope, in South Africa.

During a near-10 year stay in South Africa, Piazzi Smyth’s duties had included the operation of an accurate time signal – a falling ball – installed for the benefit of shipping in Table Bay. Given that, back then, the accuracy of a ship’s chronometer was vital for effective navigation, Piazzi Smyth was unsurprised to learn that the creation of a similar time-signal – for the benefit of ships in the nearby Port of Leith – had been added to his list of priorities once settled in Edinburgh.

Piazzi Smyth undoubtedly believed that a publicly-funded institution such as the Observatory had a duty to provide what public good it could, and he had from the start recognised the need for a better alternative – for those Edinburgh citizens wishing to accurately adjust their watches – to climbing up Calton Hill to check the Observatory’s own astronomically-calibrated clock.

It was Piazzi Smyth who suggested the time-ball should be placed on top of the nearby Nelson Monument, erected on Calton Hill in 1807 and instantly recognisable from much of the city thanks to its “upturned telescope” design. The project was speedily approved by the Observatory’s own watchdogs, its “Board of Visitors”, and the Town Council which owned the tower. Alas, the British Government was somewhat slower in providing the £200 needed to pay for it; the time-ball wouldn’t begin operation until 1852, six years after Piazzi Smyth arrived in Edinburgh.

The time-ball mechanism was connected to the nearby Observatory’s most accurate clock by a wire, and triggered – with an accuracy down to a fraction of a second – by an electrical signal at the agreed time of 1pm. Its original wooden ball was replaced, after just three years, with a more sturdy metal one.

Admittedly, the new time-signal was not an unqualified success. Piazzi Smyth’s journals regularly list when the ball release mechanism jammed, the Observatory’s acid batteries failed to provide a sufficient charge, and when the ball had to be dropped manually or at a later agreed hour. To add to his frustration, Edinburgh’s unpredictable weather meant that, even when the time-ball dropped perfectly, it wasn’t always clearly visible.

No wonder, then, that some people suggested adding an audible signal. Chief among these was local businessman John Hewat. Back in 1846, he had visited Paris and, while walking in the gardens of the Palais-Royal, “heard the report of a cannon” (as later explained by The Scotsman newspaper) and “observed other visitors and promenaders in the gardens mechanically referring to their watches”. This, he subsequently learned, was the city’s mid-day time-gun, ignited by the sun’s rays acting through a precisely positioned magnifying glass.

On his return, Hewat had argued for something similar in Edinburgh, but it was only in 1858, when elected a Director of the city’s Chamber of Commerce, that he was finally in a position to do something about it. However, his original idea was quickly vetoed by Piazzi Smyth, on the grounds that firing any cannon from Calton Hill would upset the Observatory’s delicate equipment.

The Royal Astronomer’s alternative was for a gun safely fired from the ramparts of Edinburgh Castle, with the two linked by an electrical cable. For as early as 1852, Greenwich had been transmitting signals simultaneously to an electric clock on The Strand in London and to the Admiralty dockyards. Piazzi Smyth, meanwhile, had experimented with transmitting signals over Britain’s rapidly expanding telegraph system; in 1855, he had successfully demonstrated how the Royal Observatory in Edinburgh could trigger a time-ball at the University of Glasgow.

From the early hours of 22nd April 1861, Leith sailors hoisted and connected a cable more than 1,200 metres (4,000 feet) long between Edinburgh Castle and the Nelson Monument – maintained at a minimum height of 73 metres (240 feet) above the ground. This didn’t, however, carry the signal which fired the gun; instead it carried signals from a carefully secured master clock in the Observatory which regulated a second clock installed at the Castle—that in turn triggered the gun.

The inauguration of Edinburgh’s new time-gun was set for 5 June 1861, coinciding with the annual meeting of the Observatory’s Board of Visitors. Unfortunately, while the nearby time-ball fell, no gun fired from the Castle, and the celebratory wine – as Piazzi Smyth later noted in his journal – “remained untouched.” It proved to be a simple technical fault with the gun; it fired perfectly the following day, and a succession of artillery has continued to do so with remarkable consistency ever since.

Notwithstanding a few complaints in local newspapers about the noise, and the nuisance of the cable (which, if in place today, would necessarily pass through the city’s iconic Balmoral Hotel), Piazzi Smyth was soon extending the reach of his time-signal to Newcastle upon Tyne, Dundee, and even an experimental gun in Glasgow. For little more than a year, Edinburgh’s Royal Observatory was, with the assistance of the Universal Private Telegraph Company, giving accurate time to the world, or at least that within a hundred miles of Calton Hill.

It didn’t last; Piazza Smyth failed to anticipate how some Glaswegians might be offended by the use of an Edinburgh-based time signal. Indeed, Robert Grant, then director of the public observatory at the University of Glasgow, said that “it would be a reproach to Glasgow to go to Edinburgh for the time,” and set about providing accurate time-keeping from his own observatory to various clocks installed around the city. When the Glasgow time-gun’s operator ended up in a local Police Court, it was clearly meant – if you pardon the pun – as a shot across Piazzi Smyth’s expansionist bows.

By 1864, all the time-guns outside Edinburgh had fallen silent, partly as the rival Electric and International Telegraph Company began to distribute Greenwich time throughout Britain’s growing railway network. With accurate clocks appearing in every train station, time-guns were quickly viewed as superfluous.

Only the original – Edinburgh’s One O’Clock Gun – has survived. It no longer needs kilometre-long cables, or even the involvement of astronomers. Yet Piazzi Smyth’s legacy is assured—and on hearing the One O’Clock, the good folk of Edinburgh now automatically check their watches!

First published by The Scots Magazine, #January 2019.