Finding Longitude Read online

  Almost forty years later, John Wood used eclipses of the Moon for on-the-spot longitude determinations when he was master’s mate on John Narbrough’s 1669–71 expedition to the Pacific, which was instructed to bring back geographical information and lay the foundations for future trade in South America. Observations at sea of a partial eclipse on 26 March 1670 gave the longitude of Cape Blanco (Cabo Blanco in southern Argentina) as 69° 16' W, while today’s value is 65° 45' W. Another observation a little further south on 18 September placed Port Desire (Puerto Deseado) at 73° W, the correct longitude being 65° 54' W. Wood also measured the position of the harbour of St Julian (Puerto San Julián, also in Argentina) from a conjunction of the Moon and Mars, calculating a longitude of 75° W, compared with a modern value of 67° 43' W. The observations showed significant errors by modern reckoning, not surprising given the instruments and data available, but they did demonstrate that determinations of longitude could be made while on expedition. While the infrequency of eclipses meant that they would never be routinely useful, other observations of the Moon had the potential to be used on a more regular basis and, as discussed in Chapter 2, some attempts to try them out were made in this early period.

  Error and loss

  Shipwrecks had many causes, just as they do today. Storms were a persistent problem but human error, including navigational mistakes, was also common. In many cases this was not simply about longitude determination but arose from a range of factors causing uncertainty as to a ship’s position and surroundings. Without proper charts, no amount of position fixing could prevent disaster.

  Fig. 15 – Sir Cloudisly Shovel in the Association with the Eagle, Rumney and the Firebrand, Lost on the Rocks of Scilly, October 22, 1707

  {National Maritime Museum, Greenwich, London}

  Problems could easily arise in relatively unfamiliar parts of the world, and might be compounded by hostile weather and unknown currents. This was something that William Dampier, the first person to circumnavigate the world on three separate occasions, discovered repeatedly in a turbulent seafaring life. Dampier ventured into the Pacific for the second time in 1703 in command of the St George, as part of an ill-fated privateering party with the Cinque Ports. As the ships rounded Cape Horn, storms hit with their expected venom. The St George attempted to crawl its way around the Cape but its position was soon uncertain as the winds took it wherever they wished. What happened next depends on whose account one believes. According to William Funnell, an officer whom Dampier later accused of desertion, Dampier ordered the ship north once he believed they were to the west of Cape Horn but two days later it turned out, ‘contrary to all our expectations’, that they were still five leagues east of Tierra del Fuego.11 Dampier saw it differently. While he conceded that there was some uncertainty about their east–west position, sighting Tierra del Fuego was not so unexpected:

  for it is well known the Evening before, I told them we should see Land the next Morning, that of Terra del Fuego, the South Part of it: Now I look upon that to be a greater Mistake, to take one side of the Land for the other, than ’tis to be mistaken that we were Westward of the whole Island, and miss his Longitude ...12

  In any case, they were forced to brave the Horn once more.

  Their troubles did not end there. Having separated from the Cinque Ports, the St George headed north towards the Juan Fernandez archipelago, off the coast of Chile, which was a regular rendezvous and watering spot for ships entering the Pacific. The typical approach to Juan Fernandez was to run down the latitude from the coast of Chile but, according to Funnell, the St George sailed right past because Dampier failed to recognize the islands. They finally returned after three days without sight of land, only to find the Cinque Ports safely anchored there. Dampier’s information and memory had led him astray. Incidentally, one of the sailors on board the Cinque Ports was Alexander Selkirk, the inspiration for Daniel Defoe’s Robinson Crusoe, who decided he would rather be abandoned alone on an uninhabited island in the archipelago than remain on the unseaworthy Cinque Ports. Despite the privations of life on the island, it proved to be wise decision as the Cinque Ports foundered later in its journey.

  Mariners feared Cape Horn with reason, and the same was true of the western coast of Australia, which is littered with offshore reefs and islands that saw the demise of many ships plying their trade between Europe and Asia. The most notorious incident followed the loss of the VOC ship Batavia on its maiden voyage. Batavia sailed from the Netherlands in October 1628 and was in the southern Indian Ocean eight months later, heading along the recommended route eastwards before turning north for Java once it reached the correct longitude. By 4 June, it was approaching the Houtman Abrolhos, a known hazard off the west coast of Australia named ten years earlier by Frederik de Houtman, from the Portuguese abre os olhos, meaning ‘open your eyes’. The Batavia’s pilot knew he was approaching the reefs but seems to have ignored the danger signs and the ship struck. Of 322 on board, forty drowned during the shipwreck, and more than 110 men, women and children were killed as they awaited rescue in a tale of mutiny and murder that made for sensationalist reading back in Europe.

  Remote, unknown waters presented obvious dangers but there were plenty closer to home as well. Indeed, the Royal Navy’s worst maritime disaster of this period occurred not hundreds or thousands of miles away, but off the Isles of Scilly. Having concluded naval operations in the Mediterranean, a fleet under the command of Admiral Sir Cloudesley Shovell set sail for England at the end of September 1707. It should have been a routine voyage in well-known waters, even though they hit gales as they headed home. Just over three weeks in, the Admiral ordered his ships to heave to and check their position, concluding that they were safely in the English Channel. On the evening of 22 October, however, five ships struck the outlying rocks of Scilly (Fig. 15). Within hours four had sunk and at least 1600 men, including Shovell, were dead. It was a national tragedy.

  Many causes have been cited: weather; tides and currents; compass error; even longitude. What the surviving log-books show is that variable navigational abilities and unreliable data were the main culprits. The officers’ latitude determinations from backstaff observations, for instance, had an average spread of 25.5 nautical miles (47.2 km), those by dead reckoning a spread of 73 nautical miles (135.2 km). More dangerously, their geographical data was flawed. Most of the fleet took Cape Spartel at the entrance to the Strait of Gibraltar as their point of departure. Its latitude and longitude were listed in manuals such as Colson’s New Seaman’s Kalendar and Seller’s Practical Navigation, but their figures varied widely. Combined with inaccurate charts (see Fig. 11) and generally moderate navigational skills, poor data landed the fleet in its perilous position.

  The drive to improve navigational knowledge

  The known hazards of the sea and the resulting losses were a spur to improve all aspects of seafaring, including navigation. Among Europe’s maritime states, possible improvements were of obvious interest to those wielding commercial and political power as they sought to strengthen naval and trading operations. As will be seen in Chapter 2, the various rewards offered for longitude solutions from the sixteenth century onwards, and the foundation of state observatories in the seventeenth, arose within this context.

  Identical motives lay behind initiatives to improve navigational training. State-backed schools to train and license navigators and pilots engaged in long-distance trade were founded in Spain and Portugal in the fifteenth and sixteenth centuries, and these inspired a number of French navigation schools in the second half of the seventeenth century. Britain was not far behind its rivals when, in 1672, Samuel Pepys, by then Clerk of the Acts of the Navy, led moves to create ‘a Nursery ... of Children to be educated in Mathematicks for the particular Use and Service of Navigacon’.13 Granted a charter by Charles II, the Royal Mathematical School at Christ’s Hospital took in forty boys each year, from 1673, to study mathematics and navigation to prepare them for life in the merchant service o
r Royal Navy.

  Significantly, the school had the support of Isaac Newton (1642–1727) and the astronomers John Flamsteed and Edmond Halley (1656–1742), who saw this as a way in which their work could have tangible public benefit. Flamsteed, who taught some of the boys at the Royal Observatory, wrote to Pepys of the school’s value, foreseeing a time when trained seamen would fix longitudes from astronomical observations, ‘whereby the faults of our present Mapps and Sea Charts ... will be corrected and a halfe the Business of navigation perfected’.14 Another school initiated in 1712 as part of Greenwich Hospital for Seamen followed similar lines, with pupils first taught (from 1715) by Thomas Weston, assistant to the Astronomer Royal.

  Pepys continued his campaign to improve standards after becoming Secretary of the Admiralty. Having observed naval navigation in action, his assessment was scathing:

  it is most plain from the confusion all these people are to be in how to make good their accounts (even each man’s with itself) and the nonsensical arguments they would make use of to do it, and disorder they are in about it ... that it is by God Almighty’s providence and great chance and the wideness of the sea that there are not a great many [more] misfortunes and ill chances in Navigation ...15

  The school solution had been one way to address the problem. Pepys anticipated that, with concerted state support and the help of astronomers and mathematicians, the painful situation he described might be alleviated to the benefit of the nation.

  Up until the eighteenth century, longitude determination at sea was one of a number of challenges that faced naval and merchant fleets worldwide. As different nations became the dominant players in maritime affairs, so their political and commercial leaders were willing to give encouragement to anyone offering to solve any of the myriad problems that diminished profits and put lives in danger.

  In Britain, the drive to improve navigational knowledge gained impetus as a result of the loss of Admiral Sir Cloudesley Shovell and his men. As an experienced and high-ranking naval officer who knew the dangers only too well, Shovell had had an interest in navigational improvements; for instance, he had met with Isaac Newton in 1699 to examine a proposal for finding longitude put forward by a Monsieur Burden. His death in 1707 alongside so many of his men was a national disaster and, though not solely (if at all) attributable to problems in determining longitude, would be cited in lobbying for a Longitude Act seven years later.

  Since there were techniques allowing mariners to navigate with some confidence, one could argue that the measurement of longitude was not an insurmountable problem for them. Nonetheless, it was a practical issue whose solution was felt by some to be within reach and of obvious benefit. For mathematicians, astronomers and cartographers, in particular, it was an intellectual challenge and a practical conundrum in which the peculiarities of being at sea merely hindered elegant mathematical and astronomical solutions. To their way of thinking, here was an arena in which their skills might be called upon in the service of humanity, perhaps earning them fame, fortune and influence in the process. Longitude was a problem for which they believed they might have the answer, and it was they who would put it on the political agenda.

  CHAPTER 2

  THE CONTENDERS

  in the Judgment of Able Mathematicians and Navigators, several Methods have already been Discovered, true in Theory, though very Difficult in Practice ...

  ‘An Act for Providing a Publick Reward for such Person or Persons as shall Discover the Longitude at Sea’ (1714)1

  Longitude, as a definable problem that could be separated out from the myriad risks and uncertainties of maritime travel, was of interest to theorists as well as practical navigators. It was, in fact, an issue that advocates of natural and experimental philosophy – what we today call science – latched onto as one for which their approach might be particularly successful. It was clear that finding a solution would be a propaganda coup for the new scientific institutions. It would be irrefutable proof that experimental, observational and mathematical methods, overseen by gentleman philosophers, could be applied to practical issues of importance to national interests.

  Within Britain, maritime matters had been a significant focus for the Royal Society of London. That these included tackling longitude was a matter for satire, as in this anonymous poem, ‘In praise of the Choyce company of Philosophers and witts who meet on Wednesdays weekley, at Gresham Colledge’, written in 1661:

  The Colledge will the whole world measure,

  Which most impossible conclude,

  And Navigation make a pleasure

  By finding out the longitude.

  Every Tarpalling shall then with ease

  Sayle any ships to th’ Antipodes.2

  Fellows of the Royal Society were to play a significant role in the passing of the Longitude Act by the British Parliament in 1714, which was itself to transform the relationship between scientific expertise and the state. It was, however, just the latest in a long line of initiatives to reward anyone able to arrive at workable solutions to the problem.

  Longitude rewards

  Rulers and states with maritime ambitions who were convinced that the longitude problem could be solved looked for ways to hasten solutions. Their conviction was, it seems, more often the result of lobbying by those likely to gain from financial incentives than a response to calls for assistance from practical seamen. The first such incentive scheme was established in Spain, the leading maritime power of the sixteenth century, by Philip II in 1567. This was followed in 1598 by Philip III’s offer of a reward of 6000 ducats, plus 2000 a year for life – some sixty times the annual income of a labourer – and 1000 towards expenses. The large reward was never paid out but several promising inventions were recognized by the repayment of expenses.

  The life-changing size of the rewards on offer, and the fact that workable and complete solutions to the problem were clearly not appearing, led to the whole enterprise being satirized. Cervantes, author of Don Quixote, was one among many over the centuries to mock those who were mad enough to attempt such an impossible task, or who drove themselves mad in its pursuit. He wrote in 1613 of a mathematician who found fixing the longitude like chasing a will-o’-the-wisp:

  Two and twenty years I have been employed in finding out the longitude ... and imagining oftentimes, that I have found it, and that it cannot possibly escape me, when I do not in the least suspect it, I find myself as far to seek as ever, which fills me with surprise and astonishment: it is the same with the square of the circle, which I have come so nigh finding out, that I know not, nor can imagine why I have it not at this time in my pocket ...3

  Finding the longitude – like squaring the circle, creating perpetual motion or predicting the future – was often presented as a fool’s errand. Yet the solutions were, in theory, well understood. What they needed were technical responses to the various challenges thrown up by imperfect astronomical tables and conditions at sea. The answer might, therefore, have seemed tantalizingly close. To nudge them forward, the States General and States of Holland and, less officially, a number of other governments and individuals followed the Spanish example by offering rewards for meeting these challenges. Serious and important ideas were submitted, trials were made and some money paid out.

  The Dutch scheme began in 1600 and established a range of rewards, with large one-off sums, annuities and smaller sums for those with promising ideas ready for trial. The top rewards increased over time, with the States of Holland offering 3000 guilders in 1601 and 50,000 in 1738. These sums were sufficiently alluring to attract a steady flow of ideas. There were forty-six submissions between 1600 and 1775, judged by ad hoc committees of theoretical and practical experts, including surveyors, teachers of navigation and university professors. The Dutch East India Company took an interest in the process, reflecting the particular risks and rewards of their trade routes. As with the Spanish reward, a whole range of ideas and solutions was offered, and a number underwent sea trial.

  Eng
land and France came relatively late to longitude research but their arrival coincided with a period of significant advances in astronomy and instrument-making. Government and royal interest in finding longitude solutions led in both nations to the patronage of individuals with plausible methods, to the theme being taken up by the learned academies – the Royal Society of London and French Académie des Sciences, founded in 1660 and 1666 respectively – and to the establishment of observatories in Paris in 1667 and at Greenwich in 1675.

  In terms of both the legislation and the work it was meant to encourage, the passing of the British Longitude Act of 1714 was more a case of continuity than of change. It did, however, come at a time when key successes and initiatives relating to navigation and longitude determination were bearing fruit: several areas of research, with long and sometimes distinguished track records, were earmarked as most likely to lead to success. Given advances in these areas over the preceding decades, there was probably some confidence that at least partial success could be achieved in the not-too-distant future.

  The Longitude Act of 1714

  If legislators believed that success was imminent, they were encouraged in that view by lobbyists and scientific experts. Their call for a British scheme to echo the Spanish and Dutch was answered on 9 July 1714, when Parliament passed ‘An Act for Providing a Publick Reward for such Person or Persons as shall Discover the Longitude at Sea’. It provided