It was not long before a few other makers had their own engines, some copying, others altering Ramsden’s design. They too put their own marks on the scales they divided as a guarantee of their quality. By 1789, Jesper Bidstrup, a Danish instrument maker and industrial spy, was reporting that:
Fig. 15 – Models of a scoring machine and a mortising machine, by Marc Isambard Brunel and Henry Maudslay, c.1803. The full-sized machines were used to mechanize the production of wooden pulley blocks at Portsmouth dockyard
{National Maritime Museum, Greenwich, London}
The division of instruments here is no longer free hand, unless their radius is 2 feet or more; everything is done on machines ... The owners of these machines will not permit anyone to see these machines, fearing lest others should get similar machines, by which they might lose their share of the advantage they have by dividing.11
The introduction of the dividing engine revolutionized the production of octants and sextants, making them smaller, cheaper and more widely available: Ramsden’s firm, for example, had made at least 1450 sextants by the end of the century and divided countless scales for others. It was not long before these instruments were sufficiently common among mariners to become emblematic of the naval officer. A midshipman holding his sextant or octant (Fig. 14) was an instantly recognizable shop sign by the nineteenth century, with Charles Dickens in Dombey and Sons in 1848 describing these ‘little timber midshipmen in obsolete naval uniforms, eternally employed outside the shop-doors of nautical instrument-makers in taking observations of the hackney coaches.’12
In contrast to chronometer makers like Arnold and Earnshaw, Ramsden brought his workers under one roof at his Piccadilly factory in London. This allowed him to control the production of the instruments that bore his name more closely than would be possible with the usual network of artisans working in their own workshops or houses. Ramsden’s set-up was unique in instrument manufacture for this period and can be seen as part of the gradual move towards factory-style production, although his workers were still specialized in the same ways as those working in their own premises. Nonetheless, it was a sign of things to come.
The limits of machines
Mechanization was neither inevitable nor straightforward. A less successful attempt to mechanize the production of the tools of astronomical navigation came in the work of the Cambridge mathematician and scientific reformer Charles Babbage (1791–1871). ‘One of the most singular advantages we derive from machinery’, Babbage wrote, ‘is in the check which it affords against the inattention, the idleness, or the knavery of human agents.’13 With this in mind, he sought to improve the Nautical Almanac and other published tables by replacing human computers with mechanical ones.
Babbage had in fact applied to be a computer for the Royal Observatory after leaving Cambridge in 1814, but his friend John Herschel dissuaded him from what he was sure would be a thankless task. Later, on coming to appreciate the number of errors in the existing tables, Babbage is said to have exclaimed that, ‘I wish to God these calculations had been executed by steam!’14 Around the same time, the Nautical Almanac was coming under attack from many quarters, including the astronomer and actuary Francis Baily, who bemoaned the errors he claimed had crept in since Nevil Maskelyne’s death. So it was that, in the summer of 1822, Babbage launched a project to build a machine, which he called a ‘Difference Engine’, that could automatically perform logarithmic calculations and print sets of tables. In a stroke, he claimed, it would eliminate errors and reduce losses at sea. For, as Herschel later wrote, ‘An undetected error in a logarithmic table is like a sunken rock at sea yet undiscovered, upon which it is impossible to say what wrecks may have taken place.’15
Babbage’s vision was of a machine that could perform complex calculations by reducing them to a sequence of additions, carried out by linked series of mechanical gears. It was an idea that emulated the latest innovations in automated manufacture, exemplified by the block-making machines introduced at Portsmouth dockyard (Fig. 15). Devised by Henry Maudslay and Marc Isambard Brunel (father of Isambard Kingdom Brunel) and installed between 1802 and 1807, the Portsmouth machines made the wooden pulley-blocks that the Navy needed in vast numbers – 100,000 a year by 1800. Operating as a production line, they could turn out 1420 blocks a day, allowing ten men to do as much as 110 by hand alone. This meant that fewer and less-skilled workers were needed, which led to a reduction in wages for those remaining. Resistance was inevitable but in the end futile.
As an early example of mass production in action, Maudslay and Brunel’s machines exemplified precisely the sort of automated production line Babbage had in mind for his Difference Engine. It was no coincidence, therefore, that it was they who introduced Babbage to Joseph Clement, a skilled toolmaker and draughtsman, who would oversee the project. Its scale was breathtaking. The Difference Engine would need around 25,000 high-precision parts and weigh many tons but, with the completion of a small experimental version in 1822, Babbage was able to get the Royal Society’s support and financial backing from the British government. Production of a full-sized engine began in earnest two years later. But the work took years and, with costs soaring, was brought to a standstill by financial disputes. Clement had nevertheless successfully assembled a working demonstration piece (Fig. 16), which Babbage proudly showed to all and sundry. Invited to witness the machine’s workings after church one day, the American academician George Ticknor recalled that ‘during an explanation which lasted between two and three hours, given by himself with great spirit, the wonder at its incomprehensible powers grew upon us every moment.’16
The halting of production was a major blow, although Babbage continued to seek government and public support, as well as devising new and improved designs including his ‘Analytical Engine’, a programmable computing machine that has led to him being called the father of the modern computer. Yet, despite his impassioned lobbying, experts were uncertain about the possibility and benefits of producing mathematical tables mechanically, particularly given that the government had already spent almost £17,500 on Babbage’s incomplete machine by 1834. When consulted by the Treasury, George Airy (1801–92), Astronomer Royal since 1835, was in no doubt: Babbage’s engine was ‘useless’.17 State backing was killed off in 1842 during a period of financial uncertainty when the government was looking to make substantial cuts.
Fig. 16 – The working demonstration piece of Babbage’s Difference Engine, from Harper’s New Monthly Magazine, 1865
{National Maritime Museum, Greenwich, London, Courtesy of Richard Dunn}
Fig. 17 – Four of the twenty-one volumes of Babbage’s Specimen of Logarithmic Tables (London, 1831)
{UK ATC, Royal Observatory, Edinburgh}
Babbage was also a connoisseur of mathematical tables and had a personal collection of 300 or more volumes. He appreciated that a further source of error, in addition to calculation and printing errors, lay in users misreading the tables. Just one look at the printed masses of numbers is enough for one to appreciate how easy it would be to copy the wrong figure while in the middle of a lengthy calculation on a pitching and rolling ship. Babbage therefore looked into ways of making printed tables easier to read. Seeking out every colour of paper and ink available, he had sample tables printed in all combinations to see which would be the most effective (Fig. 17). He could not be faulted for his thoroughness: he even tried illegible pairings such as black on black. In the end these experiments also came to nothing.
The quest goes on
While the 1760s had seen the development of the lunar-distance and timekeeper methods for finding longitude at sea, the search for other methods and for advances in existing ones did not end. New legislation in 1774 extended the Board of Longitude’s remit to include more general improvements in navigation, making them ‘the Scientific Protectors of the British Navigation, as Castor and Pollux were of the old Ships of Greece and Rome’.18 Other opportunities for would-be inventors also began to appear. From
1755, the recently founded Society for the Encouragement of Arts, Manufactures and Commerce offered premiums in mechanics, in particular for practical applications such as navigation, with a number of proposals for instruments and timekeepers being rewarded. Patenting offered a further means of trying to turn a profit from an idea. The marketplace did not want for new inventions – a few succeeded but many failed.
The Board of Longitude now found itself assessing increasing numbers of applications, which by the end of the century had to be sifted ahead of Board meetings. Joseph Banks warned one correspondent that the Commissioners would only respond to ideas they thought worth pursuing. Finally they decided that no proposal would be considered unless it had a supporting certificate from someone with authority. Many applicants got no response.
Most proposals sought to improve or extend the three existing longitude methods: dead reckoning, lunar distances and timekeepers. Among the ideas for dead reckoning, which was still used on every ship, the Board considered many for improved speed measurement and depth sounding. As one correspondent pointed out, dead reckoning was essential around the British coast, given the preponderance of ‘cloudy weather, accompanied by dense fogs’.19 His mechanical speed log failed to impress the Board but others were considered more seriously. Edward Massey, for instance, had a lengthy correspondence about his mechanical log, which became a commercial success (Fig. 18). The Board also awarded him £200 for a depth-sounding machine and suggested the Navy buy 500 of them.
Fig. 18 – Mechanical log, by Edward Massey, London, c.1830
{National Maritime Museum, Greenwich, London}
Fig. 19 – William Chavasse’s proposed observing platform, submitted in 1813
{Cambridge University Library}
Fig. 20 – Samuel Parlour’s shoulder-mounted apparatus for observing Jupiter’s satellites, submitted in 1824
{Cambridge University Library}
Other proposals looked to the ideas that were still proving impossible at sea, including observation of Jupiter’s satellites. Although the failure of Irwin’s marine chair had led Nevil Maskelyne to warn that managing a telescope on a ship was likely to remain a pipe dream, many applicants explored the idea. Joseph Senhouse of Arkleby Hall near Cockermouth wrote that he had trialled a model chair on a voyage to China by placing a wine glass filled with water on it. Not a drop was spilled, he said, and his full-sized chair worked perfectly. In 1813, Lieutenant William Chavasse of the 6th Madras Regiment sent a beautiful watercolour illustration (Fig. 19) of an observing platform but his scheme was not thought worthy of the Board’s attention. Others imagined devices that sat on the body, like Samuel Parlour’s shoulder-mounted arrangement (Fig. 20). Parlour had already tested it and the Board was interested enough to arrange further sea trials, but it proved unwieldy in strong winds.
The Board also considered proposals about magnetic variation. One of the more successful came from the engineer Ralph Walker (1749–1824, Fig. 21), a Scotsman who had settled as a planter in Jamaica. His compass (Fig. 22) had a sundial attachment to find true north from the Sun. Comparing this with the needle’s direction gave the magnetic variation and thus, in theory, longitude. Walker had already impressed the Governor of Jamaica and Captain Bligh but Maskelyne was not convinced: it was neither innovative nor useful, he said. Nevertheless, the Board met Walker and sent the compass for trials. In the end, it was not felt to be a viable longitude solution but Walker received £200 for his improved compass design. The Navy also bought several, although some officers found them tricky to use.
Fig. 21 – Ralph Walker, published by James Asperne, 1803 (detail)
{National Maritime Museum, Greenwich, London}
Fig. 22 – Azimuth compass, designed by Ralph Walker, London, c.1793
{National Maritime Museum, Greenwich, London}
Fig. 23 – Mercury log glass, designed by Henry Constantine Jennings, made by William and Thomas Gilbert, London, c.1817
{National Maritime Museum, Greenwich, London}
Walker dealt with the Board well. Not so Henry Constantine Jennings, a chemist and inventor who, among other things, campaigned against the waste of stationery in the House of Commons. Jennings suggested several devices, including a mercury-filled log glass for measuring speed (Fig. 23) and an ‘insulating compass’ (Fig. 24). This, he said, always pointed due north, allowing mariners to determine latitude and longitude. Its secret was the addition of curved pieces of iron beneath the card. These were covered with specially prepared iron filings to protect the needle from magnetic deviation (deflections caused by iron in the ship), with more iron filings lining the compass bowl.
Although the Board of Longitude was sceptical, Jennings got the Admiralty and the East India Company to test his compasses. Captain John Ross took one on his 1818 expedition in search of a North-West Passage and found that it ‘answered the purpose for which it was intended, and completely obviated the effect of local attraction; but ... ceased to act when the variation was great’.20 Jennings took this as an endorsement and later claimed the support of no less than 2711 mariners. Sadly, he lacked diplomacy, blustering in one letter that, ‘it requires only Common Sense to judge of the case; & I am sorry the Board of Admiralty have proved themselves so deficient in that necessary quality’.21 His failure to gain any lasting support comes as little surprise.
Fig. 24 – Insulating compass, by Jennings and Company, London, c.1818
{National Maritime Museum, Greenwich, London}
Any scientist today would dismiss Jennings’s ideas as nonsense but in the early nineteenth century they had some plausibility. The same could not be said for every letter to the Board of Longitude. As the only government-funded body with a scientific remit able to give out money for new ideas, the Board found that it was presented with an extraordinary array of miscellaneous schemes. Lieutenant John Couch sent a stream of ideas between 1818 and 1823. Some concerned longitude methods, including the improvement of lunar tables. Others were more general: better ways of communicating between ship and shore; replacing the hay for cattle with dried parsnips and carrots to prevent shipboard fires; and a ‘Calitsa’ for carrying troops through surf (Fig. 25).22
Fig. 25 – John Couch’s ‘Calitsa’ for riding through surf, 1819
{Cambridge University Library}
Some proposals were more esoteric. John Bradley wrote with an impenetrable account of how he had found out the ‘londdetude’, offering to present it in person if the Commissioners would send a ‘small Bill’ to pay his way from Birmingham to London, ‘for I am not able to walk so far’.23 In 1819–20 the Board considered letters, diagrams and tables from Henry Croaker, beginning with his discovery of longitude from the ‘perpetual motion’ of the shadow on a sundial.24 The Board did not respond. The more astute at least tried to link their ideas to finding longitude; perpetual motion machines, for example, might keep perfect time on a moving ship. The Board disagreed: perpetual motion lay far beyond its interests, as did squaring the circle and other impossibilities. Yet, as one correspondent observed, they were in danger of becoming ‘the Grand National Tribunal for such difficult and obstruse undertakings’.25
When the Board of Longitude was finally disbanded in 1828, the political rhetoric played up the extent of these ‘wild ravings of madmen, who fancied they had discovered perpetual motion and such like chimeras’,26 although the reasons for its demise had more to do with government cuts and Admiralty moves to create a smaller advisory body on scientific matters. In truth, most of the ideas the Board had been assessing were legitimate attempts to solve the problems of position finding at sea. Far from being over, the quest for longitude lived on. How it was to be encouraged and judged, however, was changing.
Britain’s pride in its manufacturing expertise was in the ascendant in the last decades of the eighteenth century and would soon be justified in British global economic domination. Advances in the development of instruments for determining longitude were a conspicuous part of this, with British makers
acknowledged as world leaders. The new devices could even become vehicles of imperial diplomacy, as happened during British attempts to woo the Chinese court in the hope of developing trade.
It was well known that the Chinese Emperor was fascinated by scientific instruments, so when Charles Cathcart led a mission for the East India Company in 1787, he took £488 worth of instruments (over a quarter of the value of all the gifts carried), including chronometers valued at £175. Cathcart died en route and the mission was aborted. It was revived five years later under George, Lord Macartney, with additional funding from the British government. Macartney’s lavish gifts were mostly scientific equipment, including astronomical, surveying and navigational instruments by Ramsden and Dollond, and a chronometer by Josiah Emery. Yet the mission failed. The Chinese saw the gifts as tribute from a lesser nation, luxurious novelties akin to the automata and instruments already common in court circles.
Nevertheless, there was every reason for pride in the skills of artisans who had made evident advances in the design and manufacture of horological and navigational instruments for finding longitude. This progress was bound up with broader changes in British industries, although the introduction of fully mechanized, factory-style processes remained a long way off. By the beginning of the nineteenth century, standardized instruments, and the texts and mathematical tables to go with them, were being produced in numbers large enough for their increasingly widespread use in naval and merchant vessels the world over. This did not end the quest for new or improved techniques but it did pave the way for the regular use of more certain navigational techniques, based on the longitude methods first recognized as practicable half a century earlier.
Finding Longitude Page 15
