It’s All Relative: Marine Timekeeping and Searching for Longitude
Every January, the first-year fellows of the Winterthur Program and several students in MA and PhD programs from the University of Delaware take part in British Design History: a three-week course on design and material culture with one week at Winterthur and a two-week field study in Great Britain. Traveling to cities including London, Stoke-on-Trent, and Bath, the students have an opportunity to study American Material Culture within a greater global context. Students’ posts in this section are centered on their experiences in England or working with British objects in the Winterthur collection.
The highlight of the 2018 British Design History field study for me was undoubtedly our visit to the Royal Observatory at Greenwich. The long-time home and office of Great Britain’s royally appointed astronomers, today it is both a museum about the Astronomers Royal and one of England’s most significant collections of clocks and marine chronometers. Curator of Horology, Rory McEvoy, walked us through the collection and introduced us to the 17th-19th century Astronomers Royal and the museum’s collection of incredible timepieces and scientific instruments.
Today in our world of constant digital timekeeping and communication, it’s difficult to imagine a time when sailing across the Atlantic Ocean was one of the most dangerous and isolated jobs. Until the early 18th century, sailors navigated by the North Star and dead reckoning – approximating one’s location based on the sun’s known movements – to determine where they were in relation to both departure and destination. These methods were risky at best; an accident in 1707, wherein four British Royal Navy ships perished off the Isles of Scilly, was blamed on navigators’ inability to accurately determine the ships’ proximity to the rocks upon which they perished. Had the navigators properly understood their longitudinal position, the crews might have survived.
This accident led to the Longitude Act of 1714. The new Board of Longitude provided financial incentive for inventors to develop a simple, accurate method to determine location on long voyages. John Harrison, a cabinet- and clockmaker, acquainted himself with then-Astronomer Royal Edmond Halley and quickly rose to fame through his innovative ideas regarding how to balance such a delicate instrument as a clock on a ship at sea.
The concept was relatively simple. Astronomers Royal had used the stars to keep British timepieces accurately ticking for centuries, but clocks and watches were incredibly vulnerable to motion and changes in temperature and pressure. Harrison realized that if he could create a clock stable enough to resist these factors while onboard ship, mariners could minimize their risk by more accurately determining both their local time and their longitudinal relationship to Greenwich. In 1730 Harrison presented his first design to Edmond Halley and secured funding to build his first model. Its first live test in 1736 was successful on the return voyage from Lisbon, and Harrison spent the next thirty years developing subsequent designs to improve accuracy and meet the Board’s demands for a transatlantic voyage.
John Harrison’s first, second, and third designs made in reality: H1, H2, and H3. Images courtesy of the Royal Museums Greenwich.
If you have ever seen a 21st-century marine chronometer, it looks nothing like Harrison’s first designs. To account for unfixable errors in his first three models, Harrison changed his designs in the 1750s to more closely resemble a watch. H4, or Harrison’s first “Sea watch,” was his most accurate creation. Even King George III deemed it a success!
John Harrison was neither the first nor the last to attempt making a chronometer, but he is credited with the most significant breakthroughs in timekeeping and marine navigation in modern history. His designs inspired future inventors and mariners to create increasingly accurate instruments, many of which are still used by navies worldwide. A smart backup if your digital equipment fails!
A special thank you to Rory McEvoy for his thought-provoking, technical, and understandable explanation of these incredible instruments and the role of the Astronomers Royal!
By Katie Fitzgerald, WPAMC Class of 2019