Recently, a new book in the Royal Society library caught my eye. Ships, Clocks & Stars: The Quest for Longitude (also known as Finding Longitude) offers a thorough, yet fresh and engaging narrative of what was perhaps one of the greatest scientific and technical problems of all time.

We’ve previously featured a very eclectic list of things Robert Boyle wished to achieve through science. Amongst such fantastical things as ‘emulating fish’, one of his desires was ‘The practicable and certain way of finding Longitudes’. He was certainly not the only one. As far back as Eratosthenes in 225 BC, scientists have been attempting to solve the problem of longitude.

The consequences of inaccurately calculating longitude at sea were very real: between 1550 and 1650, a fifth of all ships sailing the south Atlantic were lost. Disasters such as the grounding of four ships off the Isles of Scilly in 1707 have been blamed on the consequences of not knowing exact position, but the 1628 wreck of the Batavia is attributed specifically to the inability to find longitude. The ‘longitude problem’ was not just a matter of safety, but also political and economic. As international trade blossomed, so did the need for efficient and reliable voyages. Identifying a need for a solution, Queen Anne established the Longitude Act in 1714, and appointed a 24-strong committee to award a substantial prize to anyone who could find a proven and accurate way of determining longitude at sea.

There were several proposed ways of determining longitude, each with its own drawbacks. Using the eclipses of Jupiter’s moons was one, but observing them at sea was impossible. Navigators were already using the Moon to determine longitude, but that method was only accurate to 2-3 degrees. The other method was through keeping exact time. Eratosthenes was the first to propose that longitude could be calculated through measurement of time. To the modern mind, this solution would seem simple enough, but ways of measuring time accurately on land were not useful at sea. The accuracy of land clocks had improved in the 17th century with the inclusion of the pendulum, but pendulums were jostled out of place in rough seas. Watches did exist at the time, but they were much less accurate than pendulum clocks and their performance was heavily affected by variations in temperature, moisture and atmospheric pressure.

In the late 17th century, Christian Huygens made great strides in developing a sea-worthy clock, but died before anything suitable had been produced. Many others picked up where he left off, each making incremental progress towards a working solution. Lothar Zumbach de Koesfelt (and his son Conrad) made the first ‘sea clocks’ with mechanisms to control temperature. Henry Sully addressed size, temperature and gravity, but his design fell foul of the often violent motion of ships at sea. Enter John Harrison, a British clockmaker.


Engraving of John Harrison by Philippe-Joseph Tassaert


Harrison began following in his father’s footsteps as a carpenter, but moved on to design clocks. His early timepieces addressed many of the mechanical problems that cursed clockmakers, removing the need for oil in mechanisms and solving the temperature-related inaccuracies of metal pendulums. He heard of the reward being offered for a solution to the longitude problem, and set out to design a clock to solve that too. In 1728, he met George Graham in London to present his ideas for sea clocks. Graham was taken with Harrison’s ideas and gave him money to develop them further.

Harrison’s first model, known as H1, was tested in 1736. The success of this trial garnered him £500 to work on refining his design. Harrison soon produced H2 but, before it went to trial, he discovered mechanical flaws which he set out to correct with H3. Harrison laboured over the H3 model for nearly two decades, and then began to move towards making a sea watch. H4, pictured below, was a beautiful marvel of mechanical engineering, but was not tested at sea until 1761. By this time, competing theories and friction with the commissioners of the longitude reward began to hinder Harrison’s progress. The ensuing events are too detailed to try and cover in a short blog post, but Ships, Clocks & Stars chronicles them well.


John Harrison’s H4 chronometer


The quest for longitude is a complex and multifaceted thing. There was no singular winner of the challenge; longitude measurement was refined over hundreds of years via the input of many individuals and several different complementary solutions. Advances in timekeeping and the method of lunar distances proceeded simultaneously, and together formed a workable solution. The Longitude Act was more than just an effort to find longitude. It transformed the relationship between government and science and between the public and science, the two now inextricably linked in ways unimaginable before the 18th century. It also changed the relationship between innovation and the public. Challenge prizes have proliferated, offering motivation and reward to tackle great problems, spurring innovative ideas and inspiring the ‘everyman’.

In recognition of the tercentenary of the Longitude Act, NESTA launched the Longitude Prize 2014 earlier this year, with antibiotic resistance winning the public vote as the challenge to be addressed. In similar ways to longitude, antibiotic resistance can also be considered a political and economic problem. I look forward to seeing the outcomes of this challenge, and finding how it can inspire innovation and public awareness. Will there be a clear winner? Or will this challenge take after its namesake, and result in a collection of complementary advancements in science and technology?

If, like me, you are fascinated by the history of longitude and the legacy it has created in science policy and innovation, I would encourage you to come to Longitude: back and forth across the years at the National Maritime Museum on 25 September, which will be followed by a book signing of Ships, Clocks & Stars: The Quest for Longitude.

The Ships, Clocks & Stars exhibition at the National Maritime Museum continues until 4 January 2015. There you can find more about the quest for longitude and see a variety of artefacts, including items on loan from the Royal Society: several examples from our fine collection of oil paintings, including portraits of Nevil Maskelyne and Jesse Ramsden, our first edition of Newton’s Principia Mathematica (John Flamsteed’s own copy), and our Shelton regulator.


Benjamin Palmer is an Events Officer in the Royal Society’s Public Engagement team.

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