Experimentation and radical solutions Tucked quietly away on a country estate in Lincolnshire is an extraordinary 300-year-old turret clock. Since it was made around 1722 by a young, local, (probably) self-taught clockmaker by the name of John Harrison, it has been running continuously, resolutely keeping time.[1] This is the Brocklesby Turret Clock. Its making played a crucial role in Harrison’s development as a clockmaker, because it gave him the opportunity to experiment, push boundaries, upend standards and innovate upon the limitations of existing horological technology. Eventually, Harrison would go on to become one of the most important figures in horological history, paving the way for modern-day inventions, like GPS (Global Positioning System). A commission for a clockmaking carpenter Around 1720, the Tory politician, Sir Charles Pelham (b. around 1679, d. 6 February 1763) had just finished renovating the stable complex on his Brocklesby Park Estate. On the heels of this project, he decided to install a turret (or tower) clock on the premises and commissioned Harrison, then a local clockmaker, to manufacture his new clock.[2] Harrison was from the village of Foulby in Yorkshire, England, where he was born in 1693. From the time of his youth, he cultivated an early interest in mechanics and music, and even learned how to conduct land surveys, for which purpose he made his own instruments, a plane table and compass.[3] When Pelham commissioned him, Harrison was 33 years old and living and working full-time as a joiner in Barrow upon Humber in North Lincolnshire. He was not a clockmaker by trade. Where or indeed whether Harrison received any training as a clockmaker is a mystery. It is certainly possible that he was an autodidact (self-taught) clockmaker, which could go towards explaining his unorthodox approaches to problem-solving when designing and constructing clocks. Harrison came to Pelham’s attention because, in his spare time, he had managed to produce three interesting clocks, thus establishing a reputation as a promising and technically gifted young clockmaker.[4] It is clear that Harrison's interest in horology took root early in his life because he managed to complete the first of these clocks in 1713 at the age of 20. This clock was made almost entirely from wood,[5] which was unheard of at the time in Britain.[6] Harrison’s intimate knowledge of wood and its properties, and the degree of precision to which he could manipulate this material to solve problems and realise his designs, surely owes a great debt to his father, Henry Harrison (b. 1665, d. 1728). Henry was a carpenter who worked in Barrow upon Humber and trained his sons in the family joinery and woodworking business. Harrison used the same methods for the manufacture of all his early wooden clocks, three of which have survived (as mentioned above).[7] Each of these was designed and completed by the young clockmaker while he was living and working full-time as a joiner in Barrow-upon Humber, making clocks on the side, with only the help of his brother, James. For the Brocklesby project, he continued to experiment with wood in the same vein. The Brocklesby project The Brocklesby Turret Clock was the first major clockmaking project undertaken by Harrison. Yet again, he enlisted the help of his brother James.[8] Work began around 1720 and would take around two years to complete. While working on the project, Harrison struggled with achieving a design that could withstand the weather. An early iteration of the clock needed constant maintenance and lubrication to run, because its mechanism jarred whenever the temperature changed. This was because the clock oil would dry out in the summer and freeze in the winter. These set backs forced the newly minted clockmaker to confront the limitations of clock oils first hand. Harrison's experience of clock oils was not unusual. During the 1700s, clock oils were typically derived from animal and vegetable sources. These were (and still are) difficult to work with because they are prone to thickening, becoming acidic, and even evaporating with age. They also, over time, tend to spread away from where they are needed. All these properties can wreak havoc with the smooth running of a clock, meaning that their mechanisms required frequent cleaning and re-oiling. Clockmakers tried to find ways around these problems and were constantly at pains to improve the quality of the clock oils used to grease the mechanism. Unfortunately, however, their efforts achieved only limited success. Harrison took a radical approach. Instead of attempting to improve clock oils, he set about designing a clock that did not need oil. In essence, he turned the usual approach to solving the problem on its head! He did so by experimenting with different woods for the turret clock’s movement, trying to find one that could provide an effective oil-free bearing surface. After having achieved some success with boxwood, he found the definitive solution in a wood called lignum vitae, the name of which literally translates to ‘tree of life’ in Latin. Lignum vitae: the tree of life Lignum vitae is a hard oily wood from trees of the genus Guaiacum, which are indigenous to the Caribbean and the northern coast of South America. It had been exported to Europe since the early 1500s. It was the expansion of trade routes, as well as the exploitation of exotic resources by colonial powers, that made Harrison’s access to this type of wood possible. Harrison homed in on lignum vitae as his wood of choice because of its properties: it is an oily olive green wood, famous for its resistance to rot and is also widely regarded as being the heaviest and hardest wood in the world. Harrison used lignum vitae not only for the movement but also for the turret clock’s escapement, replacing its original anchor escapement. In so doing, he entirely rethought and streamlined the design of the anchor escapement to reduce friction. Harrison’s new kind of escapement became known as the ‘grasshopper escapement’ because the movement of its pallets resembled the movement of the hind legs of a grasshopper.[9] While other escapements moved with a sliding action, Harrison’s wooden grasshopper escapement ‘jumps’ after each impulse. This makes the movement virtually frictionless, so no oiling is required! Horologist and expert on Harrison, Jonathan Betts perfectly sums up the elegant simplicity of Harrison’s solution: ‘Harrison’s victory over the problem of lubrication by eliminating the problem itself was ingenious...’[10] For the making of the turret clock’s gears, Harrison used oak, inventing what science writer Dava Sobel describes as ‘a whole new kind of wheel’. She compares his design to ‘a child’s drawing of the sun, with the lines of the wood grain radiating from the center of the wheel to the tips of the teeth as though drawn there with pencil and ruler.’ [11] To avoid the possibility of rust in damp conditions, Harrison decided not to use iron or steel anywhere in the mechanism. Instead, he used brass wherever metal was required. Yet again, rather than searching for a solution to reduce the impact of the problem, Harrison simply eradicated it altogether. Once completed, the Brocklesby project was a huge success for Harrison. It is also a testament to the integrity of his design that, roughly 300 years later, the Brocklesby Turret Clock is still running and keeping time in its original setting at Brocklesby Park without need of lubrication.[12] Lessons learned and confidence gained As stated above, the Brocklesby project played a crucial role in Harrison’s development as a clockmaker. At a practical level, the solutions that he discovered clearly informed the design of his next projects. However, speaking to the bigger picture, the knowledge and experience that he gained from the Brocklesby project ultimately gave him the confidence to turn his mind to finding a solution to the greatest scientific problem of his day: the problem of determining longitude at sea. Through his work on the Brocklesby project, Harrison had come to believe that he could design a sea clock accurate enough to reliably calculate longitude at sea – a scientific fete that would bring him riches and fame. However, he knew that this would not be possible without an accurate land clock against which he could test his sea clocks, and that the existence of such a land clock required an entirely new design. Thus, in 1725, he set to work on making a revolutionary new kind of pendulum land clock, again with the help of his brother James.[13] In 1726 the Harrison brothers produced and successfully calibrated an identical pair of precision wooden regulators. From a design perspective, these were basically smaller, longcase versions of the Brocklesby Turret Clock.[14] True to form, Harrison engineered and manufactured these in his home in Yorkshire and in relative isolation. Innovations that appeared in the Brocklesby turret clock, such as the use of lignum vitae, anti-friction rollers and the grasshopper escapement, appear as refined later iterations in Harrison’s wooden regulators. To achieve this design, he also expanded upon his experimentation with the properties of metals, identifying the expansion rates of steel vs. brass. The results culminated in his invention of the grid iron pendulum – an entirely new kind of temperature compensated pendulum that also represented the first use of bi-metals in any mechanism ever. One of Harrison’s precision wooden regulators survives in its full form and is exhibited here on Clocktime. Its story illuminates the creative genius of Harrison and details the enormity of the challenge that he took on in making it, his experimental methods and resourcefulness (for instance, he made his own astronomical instruments!) and his bull-headed drive to push the limits of his design vision. In 1726, when Harrison successfully calibrated his twin wooden regulators, they became the most accurate clocks in the world for the next 150 years. The rest, as they say, is history. Within just a few years, in 1730, Harrison completed the design of his first sea clock, H1. Soon after, in 1736, he moved to London to secure financing for the further development of his sea clocks. Over the next 23 years, he produced two more sea clocks, H2 and H3. Then, in 1759, his quest to find a horological solution to determining longitude at sea was finally realised with the production of his H4 chronometer, which represented a radical rethink and improvement upon his earlier designs. It was not until 1773 that Harrison, by then an old man, was finally given his due and awarded the Longitude Prize.[15] The problems that Harrison faced during construction of the Brocklesby Turret Clock and the solutions that he devised to overcome these problems confirmed his ability to innovate and invent. This also gave him the confidence to continue to do so. What is even more impressive is that he did all this in relative isolation, away from the collective knowledge, the resources, and hustle and bustle of London, then the clockmaking capital of the world. To great effect, Harrison drew on the lessons learned from the Brocklesby project for the rest of his life. You can learn more about Harrison’s inventive genius here on Clocktime, by visiting the John Harrison Wooden Regulator exhibit and other Harrison-related exhibits. Dr Kristin Leith, Curator of Clocktime September 2025 End Notes [1] Betts 2023, 40–42; Sobel 68–70 and 109. [2] Sir Charles Pelham was also a Tory politician. He served as the elected Member of Parliament in the House of Commons from 1722 to 1754. [3] Betts 2023, 34–35. [4] In his book John Harrison and the Quest for Longitude, Betts (2023, 36–39) details the design of three surviving early wooden clocks by Harrison. Also see King forthcoming. [5] The movement of Harrison’s first clock is on display at the Science Museum, London, as part of the Worshipful Company of Clockmakers Collection (Object Number L2015-3435). Also see Carter 2021, 218. [6] Betts (2023, 36) suggests that Harrison may have seen ‘continental precedents’ for wooden clocks, because there were a few coming out of southern Germany at the time, and ‘one or two characteristics of Harrison’s early work suggest the influence of Continental clockwork’. Horologist and collector Dr John C Taylor expands upon this possibility and suggests that Harrison could have seen examples of these wooden German clocks as they arrived in shipments at the Humber ports. [7] Supra no. 4. [8] Betts 2023, 40–42; Garnier and Hollis 2018, 381, Catalogue No. 119; Sobel 2011, 68–70, 109. [9] Betts 2023, 40–42; Quill 1971. [10] Betts 2023, 44; Garnier and Hollis 2018, 381, Catalogue No. 119. [11] Sobel 2011, 69. [12] Sobel (2011, 68) points out that the only time the clock was not running was during a brief period in 1884, when workers stopped the clock for refurbishment. [13] When Harrison began work on his precision Wooden Regulator Longcase in 1725, a lauded astronomer by the name of Nevil Maskelyne occupied the prestigious post of Astronomer Royal at the Royal Observatory in Greenwich. Maskelyne, the fifth Astronomer Royal, adamantly adhered to his predecessors’ belief that the solution to the problem of longitude would be an astronomical one and particularly favoured a solution using the lunar distance method. Maskelyne was also on the Board of Longitude. The astronomer did not support Harrison’s approach and used his position and influence to undermine the clockmaker’s efforts. You can read a full account of Harrison and Maskelyne’s feud in Sobel 2011. [14] Betts 2023, 43–45; Garnier and Hollis 2018, 381, Catalogue No. 119; Taylor et al. 2020, 1; Matthew King forthcoming. [15] Harrison's quest to solve the problem of determining longitude at sea is also well documented. You can read more about his designs, trials and tribulations in Longitude: The true story of a lone genius who solved the greatest scientific problem of his time by Dava Sobel; John Harrison and the Quest for Longitude by Jonathan Betts; and John Harrison: The man who found longitude by Humphrey Quill (1966). References Betts, J. 2023. John Harrison and the Quest for Longitude (2nd edition). Greenwich, London: National Maritime Museum. Carter, J. 2021. The John C Taylor Collection: Part II (Selling Exhibition Catalogue, Carter Marsh & Co.). Winchester: Carter Marsh & Co. Garnier, R. and L. Hollis. 2018. Innovation & Collaboration: The early development of the pendulum clock in London. Isle of Man: Fromanteel Ltd. King, M. Forthcoming. Clocking on with John Harrison [working title]. Quill, H. 1966. John Harrison: The man who found longitude. New York, NY: Humanities Press. Sobel, D. 2011. Longitude: The true story of a lone genius who solved the greatest scientific problem of his time. London: Harper Perennial. Further Reading Andrews, W. (editor). The Quest for Longitude (Proceedings of the Harvard University Longitude Conference of 1993). Cambridge, MA: Harvard University Press. Betts, J. 2006. Time Restored. Oxford/Greenwich, London: Oxford University Press/National Maritime Museum. Quill, H. 1971. ‘The grasshopper escapement’ in AHJ VII/4: 288–296. Roberts, D. 2003. Precision Pendulum Clocks: The question for accurate timekeeping in England. West Chester, PA: Schiffer Publishing. Taylor, J. C. and K. Leith (with contributions from T. Phillipson and K. Neate). 2020. The Luxury of Time: Clocks from 1500–1800. Isle of Man: Fromanteel Ltd.
