Courtesy of the Science Museum Group.

September 2021 9 Min Read

George Margetts - the unknown watchmaker who inspired George Daniels

By Dr. Andrew Hildreth

Many might assume that George Daniels was entirely inspired by the work of Breguet. Afterall, he wrote a book detailing his fascination with the French watchmaker entitled The Art of Breguet, yet Daniels would also look a little closer to home for inspiration as well.

Around the time George Margetts set up his business at No. 12 Ludgate Street in the 1770’s, the question of if a watch could be made accurate enough to determine longitude at sea had been met by Harrison, Arnold and Earnshaw. The problem was the cost. Indeed, the chronometers were still too expensive to provide to all ship’s captains at a time when sea faring vessels were as frequent as London buses. Most relied on either “dead reckoning” – basically an educated guess as to where and how far you had sailed – or the lunar distance method for navigation.

The inner workings of a marine chronometer made by Margetts, courtesy of Sotheby's.

Margetts was unusual for his time as he made contributions to both horology and the more conventional methods of navigation. He was an accomplished mathematician and had a predisposition towards mechanics, which led him to create marine chronometers, simplify lunar distance calculations and to devise a new way of mechanically showing mean lunar and sidereal time. He was not always commercially successful and would sadly succumb to mental illness towards the end of his life, consigning him to a footnote in the annals of horological history.

A lunar cycles chart that Margetts would have likely used, courtesy of Wellcome.

While the memory of his accomplishments might have faded, his work was closely studies by George Daniels and would go on to help inform his work on the two Space Traveller watches. Hence, we thought it worth diving a little deeper into this Englishman’s chequered past and giving some perspective to one of the more imperfect craftsmen that make up this profession’s history.

George Margetts

Born in Woodstock, Oxfordshire in 1748, he would initially apprentice to his brother as a wheelwright before his later horological apprenticeship in London. Margetts set up shop as a clockmaker in London and was made a freeman of the Clockmakers Company in 1779, elected to the Livery 20 years later.

George Margetts had a varied and financially disparate career that spanned the latter part of the 18th century. Despite his talents and initial success, his watchmaking business suffered and on 29th December 1788, the Morning Chronicle noted Margetts’ bankruptcy. With the loss of income from his horological pursuits, George turned to his talents in the mathematical and astronomic sciences.

The complex Horary Tables drawn up by Margetts, courtesy of Google Books and Sotheby's.

Margetts devised and published his own tables and charts that enabled navigators to reduce the calculations involved in finding longitude with the lunar distance method of which the East India Company ordered 82. He was also awarded 50 guineas by the Board of Longitude for his work on corrections to the navigational tables. The Horary tables that Margetts produced, that are still part of the Admiralty Library, were found to be “precise” two centuries after they were published.

“Fine examples of the art of the 18th century English horologist...” 

George Daniels

Some of the earliest works were Margetts’ printed astronomical rotulas that would, as their title suggests, show “the rising & setting of the sun, moon and stars, with the time of new moon and full moons and eclipses for 6000 years before or after any year of the 18th century”. Because of their complexity and fragility (being made of multiple layers of paper) rotulas are very rare. A complete one was offered for sale at Sotheby’s back in 2017. According to Daniels, these rotulas were a more complex form of the underlying calculations for the mechanical dials on Margetts’ astronomical watches.

Astronomical Watches

Margetts made six or seven astronomical watches, which varied in size and scope, over the course of two decades. The watch that belonged to the Royal Institution, No. 311 hallmarked 1783, was stolen (and since recovered), with the latest known watch made in 1802. There was also a watch offered in 2019 by Sotheby’s titled No. 1, 1778.

All of the watches differ in terms of their display of the constellations as well as the amount of information on the dial with regards to the tides and the calendar. However, Margetts knew that the depiction of the night sky on the dials was too basic compared to the complexity of the constellations that were used for navigation purposes.

The intricate dial of an astronomical watch made by Margetts, courtesy of the Science Museum Group.

Most of the innovation within Margetts astronomical watches lies beneath the dials. On examining the Royal Institution watch, George Daniels calls the astronomic gearing “extremely ingenious”. The problem lies in gearing mean solar time and sidereal time (for the astronomic displays) from the same gear train when there is only a small disparity in measuring hours and minutes over the single rotation of the earth. Either you use very large wheels with a high number of teeth, or you increase the number of gear wheels by factorising the number of teeth required.

“Pseudo-scientific instruments that were primarily intended to display mathematically correct astronomical indication…'

Jonathan Betts

Daniels credits Margetts’ importance in producing a watch that was portable and could tell both mean solar and sidereal time. While Margetts favoured wheels and pinions with a high number of teeth to find the correct motions of the dials in his astronomical watches, he nonetheless found a solution that was erudite with a minimum number of cog wheels. Daniels also noted that Breguet tried a solution, but his mathematics was not as advanced as Margetts’ and the difference (error) over the year (between true mean solar and sidereal time) was larger by a factor of 5.

The difference between a mean solar and a sidereal day is the passage of time based on the position of the Sun in the sky, where a mean solar day is 24 hours and a sidereal day is approximately 23 hours, 56 minutes, and 4.0916 seconds. The ratio of a sidereal to a solar day on average is 1:1.002738.

A selection of Margetts' pocket watches, courtesy of Sotheby's and SJX.

Daniels describes Margetts’ astronomical watches as beautifully made; “fine examples of the art of the 18th century English horologist.” The problem for the timekeeping of the watches was the use of the cylinder escapement; a frictional rest escapement where the escape wheel teeth are in contact with the cylinder causing excessive wear and requiring constant maintenance. One solution was to use a ruby cylinder. The Royal Institution watch was the only one known to have incorporated this innovation.

The question remains, given the rudimentary nature of the star charts, and the inherent timekeeping of the watch, whether this was a scientific instrument for navigation purposes. There is some belief that the astronomical watches were designed as adornment for the officers of the East India Company. Daniels conjectures that they were likely made for gentlemen who had the income and an interest in the scientific questions of the age. Nonetheless, he notes that “they remain a complicated, attractive, and extremely clever monument to Margetts’ remarkable talents.” Jonathan Betts, the Curator Emeritus of the Royal Observatory at Greenwich described them as “pseudo-scientific instruments that were primarily intended to display mathematically correct astronomical indication… While Margetts astronomical watches were not timekeepers in the same way as the chronometers being produced by his pioneering contemporaries, they were nevertheless precision instruments.”


Around the 1790’s Margetts moved into marine chronometer design and manufacture. Betts described the ordinary marine chronometers, that Margetts petitioned the Board of Longitude for funds, as “not particularly well made” and “distinctive instruments that display a character that still reflects the quirky nature of their creator”. Daniels was a little more scathing. To his mind, the ordinary marine watches and clocks that Margetts built were implemented almost with disdain for the scientific and manufacturing principles of clockmaking of the day. He further notes that the Board of Longitude did not recommend a single one for navigational purposes.

After a lifetime of mathematical and navigational pursuits, financial success and bankruptcy, partial blindness (cataracts) that involved a rather grisly operation to remove, Margetts fell mentally ill. His obituary describes that in June, 1804, “Suddenly, an apprehension of insanity flashed upon his mind and he exclaimed: ‘Good God, is it then to end in madness!’ and bursting into tears continued to weep with his family, whose affliction may easier be imagined than described. Dr. Willis entertained no hope of his recovery... It was thought advisable to send him to St. Luke’s, where he would be prevented from committing any violent act.”

A contemporary drawing of St. Luke's which has since been demolished, courtesy of The Wellcome Trust.

St. Luke’s Lunatic Asylum, Old Street, Islington, was founded in 1750, and was London’s second mental hospital after St. Mary’s Bethlem (“Bedlam”). Regardless of how such institutions might be viewed in modern times, they were the best available treatment centres in the early 19th century, and it is obvious that Margetts did not lack patrons or friends who helped. He died at home in December 1804 and was buried in a non-conformist grave in Bunhill Fields, Moorgate.

Margetts' Legacy

Margetts is, to some extent, a forgotten name in the history of horology. Navigational tables are no longer necessary, and his marine chronometers were not rated against his contemporaries such as Earnshaw and Arnold; his astronomical watches were not the scientific instruments he had perhaps hoped they would be. Nonetheless, his ideas have re-emerged over the centuries since.

The volume of Antiquarian Horology where Daniels wrote in-depth about Margetts' work.

First, his depiction and rendering of the night sky into two dimensions was to prove the model for watches up to this day. The problem is to take what is essentially a three-dimensional dome of the night sky over the observer’s head and render the view into a flat surface. The same design of dial was used by J. Player & Son of Coventry in their commissioned watch for banker J. P. Morgan in 1909. Likewise, any modern watch with a sidereal time night sky dial and display aperture for the stars and constellations in view, from the Packard and Graves Patek Philippe Supercomplications to now, are using the same idea as Margetts.

The astronomical watch made by J. Player & Son for banker J.P. Morgan that uses the same chart for the night's sky as designed by Margetts, courtesy of AWCI.

Second, and perhaps more telling, it was George Daniel’s knowledge of watches that worked off both sidereal and solar time, which started from his research on Margetts, and that led him to the Space Traveller series. Daniels’ work on the Margetts watch was to prove informative to the gear train design of the Space Traveller watches. In terms of the ratio between mean solar and sidereal time, Margetts’ watch was accurate to within 1.8 seconds a day, and George reckoned with some maths he could improve on that. The first Space Traveller watch had increased the accuracy of the ratio to 1.27 seconds.

George Daniels' Space Traveller I.

By the time George Daniels moved onto designing the Space Traveller II, he was corresponding with Professor Henry Daniels at the Statistical Laboratory and Kings College, University of Cambridge. Correspondence between the two men notes that Margetts was a decent starting point, but in considering near ratios between the mean solar and sidereal time, greater accuracy could be found in prime factor gearing and escape wheels with a different number of teeth rather than Margetts’ use of a minimal number of wheels with a large number of teeth.

Any watch that today indicates both mean solar time and sidereal time, such as the IWC Portugieser Sidérale Scafusia and Patek Philippe Celestial ref. 6102, have refined the problem. Obviously aided by computer algorithms in reducing the prime factor, gearing has seen improved accuracy and the IWC’s difference in mean solar time and sidereal time is to within 11.5 seconds a year. They are, nonetheless, descendants of Margetts astronomical clocks.

I am greatly indebted to Richard Stenning, Jonathan Betts, and Roger Smith for their assistance and support. If this article has piqued your interest in George Margetts, I might note that Jonathan Betts is currently preparing a series of longer articles on his clocks and watches that will be published in Antiquarian Horology in the near future. Equally, my thanks to the staff of the Guildhall Library for access to the George Daniels archive. All errors remain my own.