Finding Longitude
Page 18
Despite all the brand-new technologies at their disposal, the old enemies of weather and treacherous coasts remained a danger, especially when rounding the Horn. FitzRoy wrote, ‘I assure you that this last cruise has rendered me an implicit believer in all that is said in Lord Anson’s Voyage, and previously I considered that account exaggerated’.24 Such shores and weather made surveying particularly challenging and, before any day’s observations could begin, they had to find safe harbour. Only then could ‘observations for Latitude, time, and true bearings, on the Tides and Magnetisation’ be attempted, and plans drawn up. These plans were based on triangulation, which involved measuring the angles made between significant features of the landscape and a base line connecting two temporary observatories or hill-top stations.25
Fig. 16 – The Victoria River on Australia’s north-western coast, surveyed by John Lort Stokes in 1839; published 1845
{National Maritime Museum, Greenwich, London}
Fig. 17 – Theodolite by J. Dollond & Son, c.1840, and sextant by Worthington & Allen, c.1831. Both belonged to John Lort Stokes, the latter being presented by Robert FitzRoy
{National Maritime Museum, Greenwich, London}
‘Many leagues of exposed and difficult coast’, FitzRoy wrote, ‘were looked down upon in this manner, and at the least their exact bearings from one fixed spot ascertained.’ Ideally, the length of the base line used in the triangulation would be determined by one of four methods. In descending order of value, they were, ‘deduced from good Astronomical or Chronometrical observations’; ‘deduced from angular measurements of small spaces exactly known’; ‘obtained by actual measurement with a chain, with rods or with a line’; or, ‘obtained by sound’, that is, rockets.26
FitzRoy emphasized accuracy but also made clear that hair-splitting levels of precision, would not make a difference to the detail available on a chart, which could be sacrificed for efficiency. He concluded:
By multiplying bases, which with such easy methods is soon effected; and by a frequent use of the sextant, artificial Horizon and Chronometer, material errors may be kept out of the work of a practical surveyor. With a Sextant, Horizon, and Chronometer (in a sheltered spot), a micrometer ... a Theodolite, and intelligent Assistants, much work may be done in a short time.27
Fig. 18 – Marine chronometer no. 294, by John Roger Arnold, c.1807, used on the Beagle and later converted into a travel clock
{National Maritime Museum, Greenwich, London}
Fig. 19 – ‘Chart of the World, showing Tracks followed by Sailing and Low Powered Steam Vessels’, 1888
{National Maritime Museum, Greenwich, London}
The Beagle’s and other surveys of the nineteenth century were extraordinary, dangerous and painstaking endeavours. They achieved new levels of precision in an ever-increasing series of charts and added to the stock of data and specimens in a whole range of scientific fields. They helped underpin the nation’s trade and enabled further exploitation of the resources of a growing empire. Even where the current value of particular territories was as yet unclear, there was confidence that increased knowledge would render them profitable. As Stokes wrote of Australia’s unpromising northern territory,
no one who reflects on the power of trade to knit together even more distant points of the earth, will think it visionary to suppose that Victoria [Settlement] must one day – insignificant as may be the value of the districts in its immediate neighbourhood – be the centre of a vast system of commerce ...28
Stokes was wrong about the potential of the recently founded Port Essington (Victoria Settlement), which he imagined as ‘the emporium ... where will take place the exchange of the products of the Indian Archipelago for those of the vast plains of Australia’, for it was abandoned in 1849. However, his comments speak for the sentiments that lay behind much of the scientific effort of the British Admiralty and the Royal Navy.29
Fig. 20 – Visualization of international shipping routes, based on the Climatological Database for the World’s Oceans 1800–1850 (CLIWOC)
{CollinsBartholomew Ltd 2014}
In 1836, the Hydrographer of the Navy, Francis Beaufort, wrote of how,
Every day, intelligence arrives of the discovery of new rocks and shoals, or of more correct limits being assigned to those already known. Improved means of observation are constantly yielding more accurate positions in lat.de and long.de. The time and height of Harbour Tides, the set and velocity of sea currents, the altitudes of conspicuous headlands, descriptions of foreign ports, with the modes of obtaining water, wood and refreshments are scattered in expensive books. Lighthouses are springing up in various parts of the world, and at home continual changes are making in the places of buoys and beacons. And new charts and sailing directions are frequently published as well as gradual improvements in the practice of navigation ...30
This was a world that was, in many ways, shrinking and increasingly coming under the surveillance and control of metropolitan elites. Scientific methods and institutions were at the heart of this. Observatories were aiding the use of chronometers and providing ‘a local centre of reference’ for navigation, cartography and territorial administration. Each was, said the astronomer John Herschel, in his presidential address to the British Association for the Advancement of Science, ‘a nucleus for the formation around it of a school of exact practice’, almost synonymous with civilization itself.31 Nothing before the late twentieth century defined a position or the local time more exactly than an observatory.
This demand for precision, as well as the worldwide use of charts and tables based on the observations made at the Royal Observatory, Greenwich, ultimately led to the Greenwich meridian serving as the International Prime Meridian. It had slowly become the standard reference point by which to determine longitude, a fact recognised by its proposal as the world’s common starting place for measuring time and longitude by the delegates at the International Meridian Conference held in Washington D.C. in 1884. Over the course of the nineteenth century, chronometers, backed by astronomical methods and served by observatories, likewise became the standard means of keeping track of longitudinal position at sea and a key tool for surveys. The legacy of the search for longitude methods, and their application, together with innovations such as steam power and the electric telegraph, remains in the mapping of the world and in the patterns that were formed, connecting trade, empires and people (Figs 19 and 20).
EPILOGUE
O’er the glad waters of the dark blue sea, Our thoughts as boundless, and our souls as free, Far as the breeze can bear, the billows foam, Survey our empire, and behold our home!
Byron, The Corsair, Canto I1
This story of the search for a way to find longitude at sea has taken us through several centuries and around the world. Monarchs, mathematicians, artisans, businessmen, politicians and mariners have all played their roles in defining the problem, looking for solutions and slowly making them part of life at sea. Many of the risks of sea travel remained but keeping track of, or finding, a ship’s longitude became possible for any well-supplied vessel with a trained crew. Crucially, this position could be tracked on reliable charts, which themselves had been made possible by the infrastructure that had supported the longitude solutions – a thriving instrument trade and government investment in astronomical observatories and specialist skills.
These milieus revealed the abilities and dedicated effort of some remarkable individuals. Many well-known figures in the history of science – Galileo, Huygens, Newton, Halley – helped explore possible avenues of research, but others, from all walks of life, had to enter the story to turn theory into practice. Some names have, of course, loomed larger than others in the preceding pages. John Harrison’s remarkable abilities, for example, led to a career unique in eighteenth-century Britain: by receiving government support he was able to focus on just one problem over three decades. However, the time was ripe for such inventions. Other clock- and watchmakers, in Britain and in France, were also
developing the necessary skills, materials and processes. It was their combined efforts that developed the marine chronometer.
Astronomy, always the closest ally of horology, was an even more international affair. Newton’s theories were improved by French mathematicians and applied by the Hanoverian Tobias Mayer to tame the complex theory of the Moon’s motions sufficiently to meet the purposes of navigators. While the French showed how these numbers could be processed to aid their use at sea, it was the head of the Royal Observatory, backed by a government board, who established a system that made the production of such tables a matter of ongoing routine. Nevil Maskelyne’s Nautical Almanac was widely copied and put to use around the world, supporting all methods of navigation. Maskelyne himself did much to ensure the development and use of marine timekeepers, and his successors as Astronomer Royal added supervision of the Royal Navy’s chronometers and time signals to their daily business.
By the nineteenth century, the tools existed to allow naval officers and other travellers to chart their courses accurately and to carry out detailed surveys. The world slowly became better mapped and defined. This was for good and ill. While improved navigation and charts helped reduce the risk of sea voyages, they also supported military and imperial endeavour, and the exploitation of many people and resources for the profit of a few.
It was not until the twentieth-century advent of, first, wireless radio signals and, later, positioning systems including satellite navigation, that these nineteenth-century methods became obsolete. On 1 November 1968, it was decreed that ships of the Royal Navy should cease to carry marine chronometers, although sextants, almanacs and, of course, dead reckoning remained as a back-up to electronic devices. Given the potential vulnerability of a military-backed system like the Global Positioning System (GPS), it is worth remembering that, should a ship in open water lose communication and its longitude, it is only by astronomy that the latter can be re-established.
It is more than likely that the new longitude techniques would have been developed without the passing of the Longitude Act of 1714, for other rewards or the possibility of developing a profitable business were reason enough to invest in potential solutions. The Act did, however, help cement a lasting alliance between the scientific academy, comprising Oxford and Cambridge universities and the Royal Society, and government. Today, government investment in science and technology, while often appearing under threat, has grown beyond anything that could have been imagined at the start of the nineteenth century. This has not stopped a revival of interest in the idea of retrospectively rewarding those who solve defined problems. Challenge prizes have proliferated since the creation of the XPRIZE Foundation, which sets up competitions and offers large prizes to the winners. The first X Prize was offered to the first non-governmental organization that could launch a manned spacecraft twice within two weeks. It was won in 2004, with the $10 million prize having inspired an estimated total investment of $100 million by the twenty-six competing teams.
This year, 2014, will see the launch of a new prize that is partly funded by the British government. At the time of writing it is being promoted as a new Longitude Prize, although the issues it will attempt to tackle are yet to be decided. Unlike the original backers of the 1714 Longitude Act, the organizers also hope to gauge public opinion on what questions might be answered, although ultimately the range of possible problems and potential solutions will be defined by scientists and politicians. Our story here has shown that, whatever the topic, it will be necessary to outline the terms of the prize with care and to develop the infrastructure required to put new ideas into regular practice.
The effort to map and understand our world – to measure it, its resources and populations – was begun in earnest in the nineteenth century and continues today. It is an inherently political process but, as well as revealing opportunities to gain power and profit, it should also help us to identify and perhaps solve some of the problems that we face on a planet both seemingly smaller and undoubtedly more stressed than it was in 1714.
The Great Western riding a tidal wave, 11 December 1844’, by Joseph Walter, 1845
{National Maritime Museum, Greenwich, London}
REFERENCES
CHAPTER 1
Fig. 1
Carte universelle du commerce, by Pierre Du-Val, Paris, 1686 (NMM G201:1/32)
Fig. 2
A busy Dutch East Indies factory port, possibly Surat, by Ludolf Backhuysen, 1670 (NMM BHC1933)
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 (NMM P/33)
Fig. 4
Longitude lines
Fig. 5
Latitude lines
Fig. 6
Time and longitude
Fig. 7
A mariner’s compass made by Jonathan Eade in London, c.1750 (NMM NAV0378)
Fig. 8
Log of the Orford, by Lieutenant Lochard, October 1707 (NMM ADM/L/O/22)
Fig. 9
A backstaff, by Will Garner, London, 1734 (NMM NAV0041)
Fig. 10
A seaman with a lead and line, from The Great and Newly Enlarged Sea Atlas or Waterworld, by Johannes van Keulen (Amsterdam, 1682) (NMM PBD8037)
Fig. 11
‘The Islands of Scilly’, from Great Britain’s Coasting Pilot, by Greenvile Collins (London, 1693) (NMM PBD8205)
Fig. 12
The Indian Ocean, from The Great and Newly Enlarged Sea Atlas (Amsterdam, 1682) (NMM PBD8037)
Fig. 13
Practical Navigation, by John Seller (London, 1672) (NMM PBC1327)
Fig. 14
Two English ships wrecked in a storm on a rocky coast, by Willem van de Velde the Younger, c.1700 (NMM BHC0907)
Fig. 15
Sir Cloudisly Shovel in the Association with the Eagle, Rumney and the Firebrand, Lost on the Rocks of Scilly, October 22, 1707 (NMM PAH0710)
1 William Bourne, A Regiment for the Sea (London, 1574), p. 42v.
2 Old Bailey Proceedings Online, December 1692, trial of John Glendon (t16921207-7)
3 E. Chappell (ed.), The Tangier Papers of Samuel Pepys (London, 1935), pp. 127–28.
4 John Flamsteed to Samuel Pepys, 21 April 1697, BL Add MS 30221, p. 187, quoted in W. E. May, A History of Marine Navigation (Henley, 1973), p. 29.
5 John Dryden, Annus Mirabilis (London, 1667), p. 42 verse 163.
6 Chappell, Tangier Papers, p. 130.
7 Quoted in John Gascoigne, Captain Cook: Voyager Between Worlds (London, 2007), pp. 53–54.
8 Benjamin Franklin, ‘Journal of Occurrences in My Voyage to Philadelphia’, 1726, quoted in Jonathan Raban (ed.), The Oxford Book of the Sea (Oxford, 1992), p. 105.
9 William Dampier, A New Voyage Round the World, 5th edn (London, 1703), p. 100.
10 Quoted in S. E. Morison, Admiral of the Ocean Sea: A Life of Christopher Columbus (Boston, 1992), p. 196.
11 William Funnell, A Voyage Round the World. Containing an Account of Captain Dampier’s Expedition into the South-Seas (London, 1707), p. 14.
12 William Dampier, Capt. Dampier’s Vindication of his Voyage to the South-Seas (London, 1707), p. 3.
13 Magdalene College, Cambridge, Pepys MS 2612, p. 104, quoted in N. Plumley, ‘The Royal Mathematical School within Christ’s Hospital: The Early Years – Its Aims and Achievements’, Vistas in Astronomy, 20 (1976), 51–59 (p. 52).
14 Ibid., p. 56.
15 Chappell, Tangier Papers, p. 129.
CHAPTER 2
Fig. 1
‘An Act for Providing a Publick Reward for such Person or Persons as shall Discover the Longitude at Sea’ (the Longitude Act, 1714)(Parliamentary Archives HL/PO/PU/1/1713/13An35)
Fig. 2
Isaac Newton, by Charles Jervas, 1717 (The Royal Society P/0095)
Fig. 3
William Whiston, by an unknown artist, c.1690 (C
lare College, Cambridge)
Fig. 4
William Whiston’s The Longitude Discovered (London, 1738) (NMM PBA2144)
Fig. 5
A terrella (or ‘little earth’), c.1600 (NMM ACO1368)
Fig. 6
An amplitude compass, made by Ferreira, Lisbon, 1780 (NMM NAV0462)
Fig. 7
Edmond Halley, by Thomas Murray, c.1690 (The Royal Society P/0059)
Fig. 8
Edmond Halley’s world sea chart on two sheets, showing lines of equal magnetic variation, 1702 (NMM G201:1/1A-B)
Fig. 9
Galileo Galilei, attributed to Francesco Apollodoro, c.1602–07 (NMM BHC2699)
Fig. 10
Galileo’s journal of the observations of Jupiter and its satellites, 1610 (Biblioteca Nazionale Centrale, Florence MS Gal. 48, f. 30r)