Mechanization and standardization were key features of the Industrial Revolution, but their spread was neither uniform nor rapid. Clock-, watch- and instrument making largely remained craft industries. In some other areas, too, attempts to displace humans with machines failed. Likewise, while standardized parts began to be developed for instruments, their introduction did not automatically lead to mass production, since the market for navigational equipment, though sizeable, was not so large that it was immediately essential.
Fig. 2 – Thomas Mudge, by Nathaniel Dance, c.1772
{Science Museum / Science & Society Picture Library}
Making the chronometer
John Harrison had shown that he could make a watch that kept good time at sea. As those who had seen him take H4 apart, and others who tried to make sense of the published account of it, realized, it was ingenious, extraordinarily complex and fiendishly difficult to copy. Timekeepers of equal accuracy were needed but had to be reproducible and affordable. Unfortunately, it was not immediately obvious how this might be achieved. One approach, unsuccessful as it turned out, was to build timekeepers based on Harrison’s beautiful but complex machines. It was an approach taken by Thomas Mudge (c.1715–94, Fig. 2), one of the finest watchmakers of the period.
Fig. 3 – Marine timekeeper ‘Green’, by Thomas Mudge, 1777
{Dr John C. Taylor}
Fig. 4 – Mudge-type marine timekeeper no. 4, by Howells and Pennington, London, c.1794, in a later box
{National Maritime Museum, Greenwich, London, Ministry of Defence Art Collection}
As a former apprentice of George Graham, Mudge had almost certainly met Harrison in the 1730s. Even if he had not, he was clearly impressed by Harrison’s craftsmanship and by the early 1770s had turned his attention to the design of marine timekeepers, hoping that he could gain similar rewards from the Board of Longitude. He was, of course, already well known to the Board as one of the expert witnesses to the ‘discovery’ of H4, and as the man Ferdinand Berthoud had talked to about Harrison’s secrets. His horological expertise was evident in his watches, which set the standard for quality in the second half of the eighteenth century.
Mudge’s first marine timekeeper was completed in 1774, two years before Harrison’s death. It tested well when sent to Thomas Hornsby, Professor of Astronomy at Oxford, yet stopped twice after being put on trial at Greenwich. Mudge blamed poor handling, so it was tried again from late 1776 to early 1778 and performed exceptionally at first, but then accelerated and stopped. Nonetheless, its performance convinced the Board of Longitude to award Mudge £500, although he was already unhappy that a new Longitude Act had limited the rewards on offer for timekeepers to £10,000, and introduced the requirement that two timekeepers be tested.
Undeterred, Mudge set about making two almost identical timekeepers, known by the colour of their cases as ‘Blue’ and ‘Green’ (Fig. 3). These were extraordinary pieces of mechanism, every bit as complex as Harrison’s, but with a number of differences, notably in the escapement. The two were tested at Greenwich in the 1780s but did not perform well enough for the Board to approve either a reward or further trials. Mudge responded, through his son (a lawyer), by challenging the Board’s decision and accusing Maskelyne and his staff of incompetence. Perhaps remembering the resolution of Harrison’s dealings with the Board, the Mudges took the matter to Parliament and published a long account of the affair. Uncharacteristically, this led to a published rebuttal by Maskelyne and, less surprisingly, a counter-response by Mudge junior.
Fig. 5 – John Arnold and family, by Robert Davy, c.1783
{Science Museum / Science & Society Picture Library}
Fig. 6 – Pocket chronometer no. 36, by John Arnold, London, 1778
{National Maritime Museum, Greenwich, London}
Meanwhile, a Select Committee of MPs heard evidence from all concerned, while members of the Board of Longitude voiced their opposition to Mudge’s petition. Joseph Banks lobbied particularly hard in print and behind the scenes, writing personally to the Committee members. Rewarding Mudge, he argued, would be to reward ‘an inferior artist, manifestly to the injury & discouragement of those who are superior to him in the Same Line’. If they were to rule in Mudge’s favour, he added, the Board would be ‘sorely humiliated’.4 To his horror, the Select Committee did just that and awarded Mudge a further £2500, a testament to his son’s successful lobbying.
In the light of Parliament’s decision, Mudge junior decided to market the designs and set up a dedicated factory under two London watchmakers, William Howells and Robert Pennington. The new venture failed, however, and, by 1796, Howells had formed a rival partnership. This failed as well; Mudge’s designs were just too complex. In the end, the factory produced only twenty-seven timekeepers (Fig. 4), and Howells’s breakaway firm no more than about seven.
With the benefit of hindsight, one can see the wisdom in the Board of Longitude’s emphasis on modifying and simplifying Harrison’s work to create a design that could be reproduced in large numbers. This was largely achieved through the work of two watchmakers: John Arnold, whose timekeepers were being trialled on Cook’s second voyage, and Thomas Earnshaw. By combining essential elements from Harrison’s designs and the concept of the detached escapement, almost certainly derived from the work of Pierre Le Roy in France, they were responsible for creating the marine chronometer as we know it.
Fig. 7 – Thomas Earnshaw, by Martin Archer Schee, c.1808
{National Maritime Museum, Greenwich, London}
Arnold and Earnshaw were very different characters. Arnold, as his family portrait suggests (Fig. 5), was a man with aspirations, who knew how to develop and exploit social and commercial networks. His manner was not to everyone’s taste. Thomas Mouat, a Shetlander who met him in 1775, found his talk ‘animated, blustering and much adorned with oaths’.5 Nonetheless, Arnold’s easy self-promotion was already clear in 1764 when he presented a miniature watch to George III, thus securing royal patronage that would help him build a lucrative business. Alongside productive dealings with the Board of Longitude, Arnold got to know Alexander Dalrymple and through him gained access to the East India Company. With Dalrymple’s encouragement, Company captains purchased Arnold’s timekeepers and commented enthusiastically on their performance.
He was an innovator too, whose commercial success arose in part from his technical improvements. In 1775, he patented the helical (or coil) balance spring, which was more isochronous than a flat spiral spring, and the compensation balance, which adjusted the shape of the balance to accommodate changes in temperature. The balance was incorporated into his watch no. 36 (Fig. 6), which performed so well in trials at the Royal Observatory that Arnold proudly published the results in 1780. He also noted that the name ‘chronometer’ had been suggested for the watch by Dalrymple and Banks. Dalrymple was also using the term in his own publications on the use of the new marine timekeepers in navigation and charting. This marked the adoption of the term in its modern sense. The watch’s results impressed many others too, including the mathematician William Ludlam, who confessed his changed opinion of Arnold:
I once thought he was one of those who talk much and do little ... But since the account of the going of his watch ... and since I have seen what he has actually done, I have far different thoughts. His contrivances are far simpler and easier than those of Mr Harrison’s, or any I have seen, and full as likely as any to answer the end proposed.6
In 1782, Arnold took out a patent for a spring-detent escapement, a new type of detached escapement, which required no problematic lubrication. It was this patent that would cause a bitter and long-running dispute with the younger watchmaker Thomas Earnshaw (Fig. 7). Earnshaw was more of a maverick, blunt in his public statements, quick of temper and prone to accusation. As a businessman, he was less skilful than Arnold, already having spent time in the Fleet debtors’ prison by the mid-1770s, but he was the finer craftsman and quickly gained a reputation for quality among London’s wa
tchmakers.
Fig. 8 – Marine chronometer, by John Arnold, London, c.1784
{National Maritime Museum, Greenwich, London}
Fig. 9 – Marine chronometers nos. 512 (top) and 524 (bottom), by Thomas Earnshaw, London, c.1800
{National Maritime Museum, Greenwich, London}
Fig. 10 – Escapement model, made by Thomas Earnshaw for the Board of Longitude, 1804
{National Maritime Museum, Greenwich, London, Ministry of Defence Art Collection}
Fig. 11 – Jesse Ramsden, by Robert Home, c.1791
{The Royal Society}
Earnshaw seems to have turned his attention to marine timekeepers around 1780. In contrast to Arnold’s ever-changing approach to their design (compare Fig. 12 of Chapter 4 and Fig. 8 here), Earnshaw quickly settled on an arrangement that he stuck to and which would become standard for all marine chronometers (Fig. 9). He had simplified Harrison’s complex designs to such an extent that his timekeepers had just 128 parts (plus the box). Like Arnold’s, they included a spring-detent escapement, which Earnshaw said he had invented a year before his rival patented the device (Earnshaw did take out a patent, but not until 1783). Earnshaw had boasted of his invention to other watchmakers and maintained that Arnold must have learned about the new escapement from them. It was an accusation Arnold never denied, lending plausibility to Earnshaw’s grievance, which he pursued aggressively for the rest of his life, even after Arnold’s death in 1799.
In the meantime, gaining an introduction to Nevil Maskelyne in 1789 improved Earnshaw’s fortunes. His work impressed the Astronomer Royal, who became a key supporter in later years. By the early 1790s, Earnshaw was in regular contact with the Board of Longitude, sending timekeepers for trial at the Royal Observatory and supplying them to numerous ships and expeditions. Their quality was often noted. Returning from the Cape in 1803, for example, John Crosley reported that the squadron’s commander was using an Earnshaw timekeeper, which was ‘the only timekeeper in the fleet to be depended upon’.7
Fig. 12 – Ramsden’s second dividing engine, from Description of an Engine for Dividing Mathematical Instruments (London, 1777)
{National Maritime Museum, Greenwich, London}
Never one for the soft approach, Earnshaw was soon petitioning the Board for rewards, often in startlingly blunt terms. Eventually this paid off: in 1804 the Board decided to grant him £3000 if he would reveal his secrets, but they also decided that Arnold’s years of work should be equally rewarded. This enraged Earnshaw, still embittered at Arnold’s theft of his invention. So began a protracted dispute between the Board, Earnshaw and Arnold’s son, John Roger (the boy in Fig. 5), who had taken over his late father’s business. It was a contest that would rapidly embroil London’s watchmaking community and expose divisions within the Board of Longitude, notably between Joseph Banks in support of Arnold and Nevil Maskelyne fighting Earnshaw’s corner.
To resolve matters, the Board proposed that Earnshaw and Arnold junior produce models of the disputed escapements (Fig. 10), as well as written descriptions of their respective mechanisms, which were printed and circulated to other watchmakers for comment. The Board also interviewed London’s watchmakers about the competing claims of Arnold and Earnshaw and about the manufacture of chronometers more generally, seeking to understand the trade and assess how near they were to their goal of having reliable chronometers produced in large numbers.
Earnshaw did himself few favours. His explanation, which was unfortunately printed without being vetted, was littered with further accusations against Arnold and with more generally scurrilous comments. ‘Mr Arnold was a pompous man’, he wrote, ‘and because he made large Machines it must be right, and the fools followed him in his Blunders.’ Arnold’s machines were of an ‘absurd size’, Earnshaw went on, because they needed a large, powerful mainspring ‘to drag the Works on through all Impediments of oil and dirt’.8 His own, of course, were free of such flaws.
The book had to be pulped and a sanitized version reissued. Nonetheless, Earnshaw received only lukewarm support from his peers and the Board duly decided that both watchmakers should receive the rewards originally suggested. Earnshaw, still furious, then made matters worse by publishing a broadsheet and newspaper articles that, among other things, accused the ‘malicious and envious Watchmakers’, with Joseph Banks at their head, of ‘extraordinary exertions’ against him.9 Banks considered Earnshaw’s attack libellous enough to sue but the Board, perhaps with Maskelyne’s encouragement, refused to take up the case. Unsatisfied with this lacklustre response, Banks threatened to pursue it personally, but eventually let it drop. Unsurprisingly, later petitions from Earnshaw failed to gain the Board’s support. Banks, meanwhile, attended no further Board meetings until after Maskelyne’s death.
Earnshaw’s more positive legacy was the adoption of a procedure for the large-scale production of chronometers that endured until after the First World War. Arnold and others in the eighteenth century appear to have thought of their marine timekeepers as small clocks, each one a unique piece, and had all the parts made in London. Earnshaw, by contrast, thought of his as large watches, and followed long-established watchmaking practices – standardized rough movements were made in Lancashire and then sent to London, where the mainspring, dial and other parts were added, and the chronometers were finished, adjusted and cased. Finally, the retailer’s name and number were added just before sale. The whole process typically involved more than forty specialist artisans but produced work of the highest quality.
Earnshaw’s method, though large scale, still followed a pre-industrial system in which work was subcontracted to individual artisans, with central control lying in the standardization of the design. This was not the same as true mass production, as was being used for the manufacture of other, simpler items, such as buttons and snuffboxes. Traditional techniques were more suited to the existing market for marine chronometers, and Arnold and Earnshaw made more than 2000 box and pocket chronometers between them. This met more than half of Britain’s naval and merchant shipping needs up to the 1820s. By comparison, French production in the same period was in the low hundreds. An 1819 encyclopedia article on chronometers could therefore reasonably hope that ‘the spirit of competition for public fame will continue to entitle our English manufacturers to that preference among naval officers, which the excellence of their workmanship entitles them to expect.’10
Engines and scales
Changes were afoot in the manufacture of observing instruments as well. As early users of octants and sextants came to appreciate, hand-held instruments were limited by the accuracy of their degree scales and their size, both of which were determined by production methods. Until the 1770s, scales were divided by hand using a beam compass, an engraving instrument for marking large circles. This was a highly skilled and laborious art, in which makers like George Graham and John Bird were acknowledged experts. Indeed, Bird’s skills were so valued that the Board of Longitude paid him to describe his methods in print. The question of size was directly related, since the smaller the scale, the harder it was to divide accurately by hand. Observing instruments of the mid-eighteenth century tended, therefore, to be fairly large (see Chapter 3, Fig. 26).
Fig. 13 – Mark on the scale of a sextant by Nathaniel Worthington, London, c.1840; the scale was presumably divided on the second engine made by Jesse Ramsden
{National Maritime Museum, Greenwich, London}
Fig. 14 – ‘Little Midshipman’ trade sign, late eighteenth century
{National Maritime Museum, Greenwich, London}
This changed from the 1770s with the introduction of a mechanical scale division instrument known as a dividing engine. Its development was thanks above all to Jesse Ramsden (1735–1800), one of London’s leading instrument makers, who had begun trying to devise a dividing engine in the 1760s. He produced his first in 1768, although this proved unsatisfactory, and six years later he completed a successful second engine; he sits proudly next to it in his p
ortrait by Robert Home (Fig. 11). The first one was then sold to Jean-Baptiste Gaspard Bochart de Saron, President of the Paris Parliament, who had to hide it in some furniture to transport it secretly between the two countries, which were then at war. It was subsequently confiscated during the French Revolution and passed to the instrument maker Étienne Lenoir, who converted it to the Republic’s metric scale (with 400 divisions of the circle instead of the usual 360 degrees) and used it to train younger craftsmen.
The second dividing engine consisted of a horizontal wheel with 2160 teeth incised around its rim (Fig. 12). These engaged on a precision screw, which was turned to rotate the wheel through predetermined angles. The instrument was clamped onto the wheel and, by alternately depressing the treadle and moving a cutter, the operator could divide its scale in thirty minutes with as much accuracy as a master divider could have done by hand in as many hours. Most importantly, the engine could graduate scales down to eight inches in radius, allowing smaller, more easily manageable instruments to be made.
The Board of Longitude recognized the value of mechanical division and published Ramsden’s description in 1777, rewarding him for the invention itself and for turning it over to public use. Developing the approach it had taken with John Harrison, the Board increasingly felt that its role included offering rewards to makers if they disclosed their production methods, passed them on to other artisans and relinquished all rights to the public. As part of the deal with Ramsden, therefore, he had to teach up to ten instrument makers to build their own engines, and divide octant and sextant scales for other makers on his own engine (for a fee). These scales can often be identified from a special mark – in Ramsden’s case, an anchor with his initials either side (Fig. 13).
Finding Longitude Page 14