Finding Longitude Read online

  CONTENTS

  Forewords

  Prologue: A WORLD DIVIDED

  Chapter 1: THE PROBLEM

  Chapter 2: THE CONTENDERS

  Chapter 3: ON TRIAL

  Chapter 4: MAKING LONGITUDE WORK

  Chapter 5: WORKING AT SEA

  Chapter 6: COMMERCE AND CREATIVITY

  Chapter 7: DEFINING THE WORLD

  Epilogue

  References

  Bibliography

  Index

  Acknowledgements

  Copyright

  About the Publisher

  FOREWORDS

  Ships, Clocks & Stars: The Quest for Longitude

  Director’s Foreword

  Longitude is central to the stories of navigation and discovery told by the National Maritime Museum since it opened in 1937. It gained even greater importance to us in the 1950s, when we assumed responsibility for the Royal Observatory, itself founded expressly to help solve the ‘longitude problem’. It is most appropriate and a great pleasure, therefore, to be able to commemorate the tercentenary of the first Longitude Act of 1714 with an ambitious exhibition and this new book, both of which tell what is an extraordinary story for twenty-first century audiences.

  The famous Harrison timekeepers are, naturally, central to it and have been a draw for visitors since coming to the Museum in time for its opening in 1937. In thinking about them in this tercentenary year, it has been fascinating to look afresh at the often fraught events that first brought them to Greenwich nearly 250 years ago, and at their broader context as part of the longitude story as a whole.

  I would like to thank the authors for their efforts in researching and writing this book. Their work has been possible thanks to a major research project on the history of the Board of Longitude, run in collaboration with the Department of History and Philosophy of Science at the University of Cambridge and funded by the Arts and Humanities Research Council, to whom we are most grateful. I should also like to thank United Technologies, which has supported the exhibition so generously. Together, the book and exhibition present an extraordinary story of innovation, creativity and competition that changed how we understand our world.

  DR KEVIN FEWSTER AM FRSA

  ROYAL MUSEUMS GREENWICH

  Sponsor Statement

  Innovation is timeless. Yesterday’s ideas form the foundation for today’s inventions, which power tomorrow’s solutions. At United Technologies, we are proud of our long history of pioneering innovation to make modern life possible. We understand the relentless drive of those who sought to solve the longitude problem. It’s the same drive that pushes us to solve today’s global challenges. In this spirit of innovation, we are delighted to sponsor the exhibition Ships, Clocks & Stars: The Quest for Longitude. We hope you are inspired by this great story.

  LOUIS R. CHÊNEVERT

  CHAIRMAN & CEO,

  UNITED TECHNOLOGIES CORPORATION

  Ships, Clocks & Stars: The Quest for Longitude

  Foreword

  The Longitude Act of 1714 was an extraordinary event, an unprecedented moment when natural philosophers put a scientific problem on the political and national agenda. Their success was evident in the speed with which Parliament took up the call to action, and in the large rewards that the Act offered – sums that could be life-changing for the winners. More important, the potential rewards would incentivize energetic and ingenious efforts to meet the challenge, and the measurement of longitude was indeed the number-one technical challenge for a maritime nation.

  The Act was also notable in creating a diverse group of experts, the Commissioners of Longitude, who brought together Britain’s naval, political, academic and scientific interests. The Commissioners constituted what was in effect the first ‘research council’, aimed at rewarding invention and innovation. And although it is best known for the long-delayed recognition of Harrison’s achievements, the Commission remained in existence for more than a century, rewarding other ingenious inventions and explorations.

  The ex-officio members of the Commission included the Astronomer Royal, the President of the Royal Society, and a Cambridge professor. As the fifteenth Astronomer Royal, as well as a former holder of the other offices, I have special historic links with the Commission (‘Astronomer Royal’ is now, however, just an honorary title, without any formal link with Greenwich). I am therefore delighted that the 300th anniversary of the Longitude Act should be marked by a splendid exhibition at the National Maritime Museum. This fine book accompanies the exhibition. It tells the story of the search for practical ways of determining longitude while on a ship at sea, a quest that many considered to be as hopeless as the search for perpetual motion or eternal life. Yet the problem was effectively solved in the eighteenth century, largely by British artisans and philosophers.

  This book takes a broad view of the subject, tracing the history from the attempts of the sixteenth and seventeenth centuries, some of which seemed genuinely promising, to the mid-nineteenth century, by which time new techniques for measuring longitude at sea had been embedded in naval routines. These advances helped create a better understanding of the world through improved charting, in which British surveyors and ships were a major force.

  The story is also about problem-solving – the process of identifying a problem, exploring different options to overcome it, and then bringing workable solutions to a state where they can be used by all. Clock- and watchmakers including John Harrison, John Arnold and Thomas Earnshaw, and astronomers including Edmond Halley and Nevil Maskelyne, all feature prominently. But it is also a story that shows that the most difficult technical problems are not solved instantaneously: they usually require huge efforts over a long time to become a part of everyday life, often necessitating what we would now call ‘public/private partnership’ whereby the state offers support to inventors and entrepreneurs. Thanks to the priority given to the longitude challenge, London became a crucial centre for the development and discussion of ideas, instruments and techniques that would underpin major changes in seafaring, which was Britain’s lifeblood.

  MARTIN REES, ASTRONOMER ROYAL

  A WORLD DIVIDED

  it is well known by all that are acquainted with the Art of Navigation, That nothing is so much wanted and desired at Sea, as the Discovery of the Longitude, for the Safety and Quickness of Voyages, the Preservation of ships, and the Lives of Men.

  ‘An Act for providing a Publick Reward for such Person or Persons as shall discover the Longitude at Sea’ (1714)

  In 1494, Spain and Portugal partitioned the world. Under the Treaty of Tordesillas, signed that year, a line 370 leagues west of the Cape Verde and Azores islands split the globe from pole to pole. Lands discovered to the west of the line would belong to Spain, those to the east to Portugal. East–west position – longitude – had become territorial. Yet the treaty did not explain which of the islands was to be used to determine the line’s position, or how to translate leagues (roughly three miles) into degrees and so decide whether new discoveries lay to east or west. Portugal also assigned more leagues to a degree of longitude than did Spain, placing more territory under its domain. Moreover, the Treaty had effect only in the Atlantic hemisphere and things became even more difficult when both nations reached the East Indies. Within a few years, matters came to a head there over possession of the Moluccas, the ‘Spice Islands’. The struggle for the control of the lucrative spice trade was intense, and the conflict between Spain and Portugal was only resolved in 1529 by the Treaty of Saragossa, which specified an equivalent dividing line in the East. Global positioning was, even then, a serious political matter.

  This book is an account of how the determination of longitude at sea became feasible, and of how
global positions could be agreed and the world known with greater clarity. On the one hand, it is a tale of seafaring, time and astronomy; on the other, it concerns commerce, competition and conflict, exploration and empire. The ‘longitude problem’, as it has become known, was a technical challenge that taxed the minds of many of the great thinkers of the Renaissance and Enlightenment. Galileo Galilei, Christiaan Huygens and Isaac Newton all grappled with it as a puzzle that seemed insoluble. Finding the longitude became a ridiculous quest only to be undertaken by the deluded, until the simultaneous development in the late eighteenth century of two practicable, complementary means of fixing a ship’s position changed everything. These methods gradually came into use, both for routine navigation and for creating better charts of the world’s oceans and coastlines, mapping the Earth in ways that had been inconceivable in 1494.

  The quest for longitude is an international story, and this account touches on important work in the Netherlands, France and other countries from the late fifteenth century onwards. However, the main focus is on events in Britain from the early eighteenth century to the middle of the nineteenth. It was in Britain that the rewards offered under the Longitude Act of 1714, and the creation of an administrative structure to support promising ideas, led to the testing and development of the two methods that would eventually come into standard use at sea.

  Why it should have been in Britain that the problem was solved is one of the issues this book addresses. The answer has much to do with the relationships operating between government, commerce and science at the time. Longitude solutions were encouraged by the British state through the 1714 Act, as had happened elsewhere; but, crucially, the new incentives addressed a British audience of skilled, commercially driven artisans working in a context of public discussion of new ideas. The Act therefore played to the strengths of Britain’s metropolitan culture of craft skill and open intellectual debate.

  Longitude mattered greatly at sea, but much of the story of how it was found and then deployed took place in cities on land, among academics and artisans. Crucially, the Commissioners of Longitude named in the 1714 Act eventually took on the role of encouraging promising work over many years, and of fostering the means by which the new techniques could be used on all ships, not just Britain’s alone. It was not simply a matter of paying a reward; good ideas needed to be turned into reliable tools. Once they had been, Britain’s existing maritime dominance allowed its navy to lead efforts to deploy the new methods for finding longitude in order to chart the world with certainty. As a result, a new line, now passing through the Royal Observatory at Greenwich, would come to divide the globe and define every ship’s longitude.

  A map of the world, by Paolo Forlani, published by Fernando Bertelli, 1565

  {National Maritime Museum, Greenwich, London}

  CHAPTER 1

  THE PROBLEM

  Nowe some there be that be very inquisitive to have a way to get the longitude, but that is to tedious.

  William Bourne, A Regiment for the Sea (1574)1

  Seafarers have always needed to know where they are to avoid danger and ensure a successful voyage. First and foremost, this was about safety, although they appreciated that more precise navigation could increase speed and efficiency. To most, this meant pinpointing the ship’s latitude and longitude on a reliable chart. Latitude was fairly straightforward to measure from a ship. Longitude was the problem and good charts could only be produced when both could be measured.

  As European vessels made longer and longer voyages from the fifteenth century onwards, navigation, including the determination of longitude, began to matter more. Long-distance trade, in particular, drove the desire for speed and reliability, and with it navigational certainty, to make voyages safer and more profitable. As international trading networks developed, and with them the need for stronger navies, navigational knowledge and training became more important to those with commercial and political power. Yet, despite this growing interest, the problem of determining longitude at sea would challenge seafarers, artisans and men of science for centuries before being solved, in principle at least, in the mid-eighteenth century. In the meantime, and, indeed, for long afterwards, seafarers relied on knowledge and techniques that had been developed over generations. Many voyages were successful, some ended in disaster.

  * * *

  ... some difference arose between them about Latitude and Longitude; Mr. Kempthorne alledging that there was no such word as Longitude; after that, further angry words arose

  * * *

  Evidence at the trial of John Glendon, convicted of the manslaughter of Rupert Kempthorne at the Ship Tavern in Temple Bar, London in October 16922

  Fig. 1 Carte universelle du commerce, by Pierre Du-Val, Paris, 1686, showing French and Spanish trade routes to the West and East Indies. Note that longitudes are shown from a meridian through the Canary Islands

  {National Maritime Museum, Greenwich, London}

  Why longitude mattered

  The importance of being able to measure longitude at sea was inextricably linked with wider issues of marine navigation and safety. For many seafarers, the main concern was not simply a matter of getting from place to place, since by the seventeenth century it was possible to sail to many parts of the world with some confidence of return. Rather, it was whether this could be done more predictably, more quickly and with less risk; in other words, could it be done more profitably?

  Broadly speaking, the further people wished to sail, the greater the risks, whether along well-travelled routes with known hazards or into relatively unknown waters. The determination of longitude and other potential advances were of most interest, therefore, to nations investing in long-distance trade and outposts and settlements overseas (Fig. 2). Having opened up trade routes to the Pacific and Indian oceans, Spain and Portugal were the maritime superpowers of the sixteenth century. By the end of the seventeenth, the Netherlands, France and England were coming to dominate the oceans. It is no coincidence that the chronology of rewards for longitude solutions mirrored this sequence of maritime activity.

  The expansion of global trade was linked to a progressive rise in the numbers and activities of chartered companies. Britain’s Muscovy Company (chartered in 1555), East India Company (1600), Royal Africa Company (1660) and Hudson’s Bay Company (1670) competed with similar institutions from other European countries, notably the Vereenigde Oost-Indische Compagnie or VOC (Dutch East India Company, 1602) and the Compagnie Française pour le Commerce des Indes Orientales (French East India Company, 1664). Subject to state supervision, each was granted the right to colonize, sign treaties, make and enforce laws, and hold a trade monopoly for specific territories overseas. The companies were largely free to do as they pleased but could draw on naval support and possibly, in times of crisis, government aid.

  Fig. 2 – A busy Dutch East Indies factory port, possibly Surat, by Ludolf Backhuysen, 1670. Dutch and English ships can be identified by their flags, testament to the commercial interest that both countries had in Asia

  {National Maritime Museum, Greenwich, London}

  This was big business. In 1636–37, an inspection of the Spanish Manila galleons heading from the Spanish East Indies (Philippines) to New Spain (Mexico) valued their cargo at one million pesos (equivalent to £200,000 at the time and over £17 million today), while, in 1685, a French observer claimed that Dutch and English trade with Asia was making profits of between twelve and fifteen million livres (around £10,000,000, or more than £870 million today). This was exaggerated but English imports of tea, coffee, spices, textiles, chinaware and other commodities from Asia have been valued at just under £600,000 for that year, while the loss of five East India Company ships to privateers in 1695 cost the company £1,500,000. (Privateers were privately owned ships that had state permission to attack ships of enemy countries – and to keep the plunder.)

  Privateers were just one of the risks. A ship’s high-value cargo was also in danger from natural hazards, suc
h as storms, throughout a voyage, as were the lives of its crew. Between 1550 and 1650, one in five ships was lost between Portugal and India, and crews had a one in ten chance of dying during the voyages. It is no surprise that the safe arrival of a trading vessel at remote outposts was a cause for celebration, or that sailors looked to protective measures such as amulets to keep them from harm.

  Fig. 3 – ‘A description of the old town & the port of realejo’ (El Viejo, Nicaragua), from ‘A Waggoner of the South Sea’, by William Hack, 1685, based on Spanish sea charts captured in 1680

  {National Maritime Museum, Greenwich, London}

  Each of the main trade routes – between Europe and America across the Atlantic; between Europe and Asia around the Cape of Good Hope; and between the Philippines and Mexico across the Pacific – presented its own challenges. Stormy passages in the Strait of Madagascar plagued Portuguese and Dutch vessels between Europe and Asia. The Dutch established an alternative route in the seventeenth century, sailing eastwards from the Cape of Good Hope until reaching the correct longitude and then turning north towards the trading posts of Indonesia. If they sailed too far east, however, they were likely to fall foul of the reefs of Australia’s western coast. It was a route on which knowing longitude really mattered.

  Trading companies and the navies that supported them clearly had a vested interest in better charts and improved understanding of sea routes. As the famous diarist and naval administrator Samuel Pepys noted in 1683 in his Tangier Papers:

  the East Indies masters are the most knowing men in their navigations, as being from the consideration of their rich cargoes, and the length of their sailing, more careful than others ...3

  The companies encouraged their officers to gather data about weather patterns, currents, coastlines and sailing directions. It could be sensitive information. In the sixteenth century the Spanish monarchy prohibited the circulation of maps and descriptions of the Indies to protect their outposts in the Pacific. So it was a major coup when a British privateer took a book of sea charts and sailing directions from a captured Spanish ship. The charts were soon copied and made available by William Hack, a London chart maker, who presented a set to James II in 1685 (Fig. 3). By then, systematic chart provision had begun elsewhere in Europe, initially with impetus from the Dutch and French trading companies rather than their navies, while commercial chart makers like Hack led the way in England. The possibility of finding better ways to determine longitude was bound up with this interest, as the poet John Dryden suggested in his historical poem Annus Mirabilis in 1667: