 This is the great room at the Royal Society of Arts in December 1852. The same room where just the previous year in 1851 it was arranged for a rather famous exhibition to be staged in a completely enormous building made out of glass. I want you to imagine you're there just a few months after this event. Listening with some hostility to a guest speaker talk about the stuff of fairy tales. Regulating the most precision timepieces, chronometers, using ballad springs made entirely of glass. On Monday 30th May 1853 the post-talk discussion at the second extraordinary meeting of the Society of Arts got more than usually nasty. Marine engineer Francis Herbert Wenham had just set out his paper on constructing glass ballad springs for timekeepers. A methodology he had developed in the late 1840s where window glass heated by a blowpipe and drawn into a thread was wound onto a conical mandrel to form a spring then dropped onto a hot iron bulb. On contact the conical spring would collapse into a flat spiral. Wenham would later note up to the time my paper was read I had not the slightest acquaintance with any chronometer maker. Poor Mr Wenham. Before he could even begin to consider the advantages of glass over metal springs, less sensitive to temperature, corrosion and magnetic influence, and as has been shown in the late 1820s, capable of more perfect elasticity than the best steel. He came under a retubative attack from that notoriously meticulous bunch, not least Mr Willamie and the Frotten Brothers, Charles and George, just a few of the Emily Potbakers in the audience. Wenham found his first foray into the Society of Parologists, characterally denounced as one of the puffs of the trade. Glass springs, said the Frotions, were ingenious but useless, and not to be mentioned in comparison with those of steel. If glass was on trial, then the experiment should be to make the main spring of glass, that's the power source, not a ballad spring that acts as a case maker. But why bother? Thousands of chronometers have been made successfully with steel springs, and the late great John Roger Arnold had always repudiated any practical utility in using lats. So saying, Charles Frotten took one from his pocket and showed the assembly this beautiful thing. A flat spiral ballad spring, now in the British Museum, made in 1828 by Glasgow watchmaker James Springer, passed to the great Arnold by Springer in late 1841 and inherited by Frotten along with Arnold's business in 1843. Lawyer Cambridge Wrangler and clock designer Edward Edmund Beckett Dennis rose to the bait. In 1833 the celebrated chronometer maker Edward John Dent and his future stepson Frederick Ruppon had used glass to produce a helical ballad spring fitted in a chronometer, now going 20 years and showing a remarkable result. The backstory is well known. Arnold and Dent were then in business together, but the celebrated partnership came to an acrimonious end in 1840, and three years on, when Arnold died, Dent and Frotten fought over who would take on his works and contracts. Following the 1840 dissolution of the partnership, Dent had become involved with Demerson and with the construction of big public clocks, not least the clock for the Royal Exchange. And in 1852 he won the contract for the construction of the Westminster clock, Big Ben, that was designed by Dent. Dent died in March 1853 while Big Ben was under construction and his stepson and collaborator in glass springs, Frederick Ruppon, took on his name and the Westminster contract. When Denison argued with Frotten at the Society of Arts less than two months on from Dent's death, he addressed the meeting as the executor to the will that reached a deceased chronometer maker. Denison spoke on behalf of Dent. He didn't have a glass spring in his pocket like Frotten, but pointed instead to the Great Exhibition of 1851, where Dent's glass ballad spring chronometer had been on display in that massive palace of glass. So this is the Great Exhibition in the Crystal Palace and apparently in the corner there, that's the horological section. There's a lot like dresses to me, but I'm not a horologist. The debate is now explicitly focused on Dent's work and the audience divided. On the one hand clockmakers ranged against Dent's glass ballad springs and on the other designers who spoke for them. The Frotten brothers and Denison's respective conclusions stand out and I want to highlight them here because they set out the questions this talk needs to answer. Mr George Frotten said that if Mr Dent's experiment had proved successful, it was quite certain he would have made more than one chronometer with the glass spring. If Dent's glass springs performed so well, why was there only one of them? By contrast, Mr Denison, on behalf of Mr Dent, said the reason glass springs have not been brought into the more general views was that they could not get the work from them to use them. The springs worked, but the men wouldn't. I'd like to ask you to keep these two points in mind. Why only one and why would the workmen work with glass? This talk looks to show they are central to understanding glass springs in context and the significance of Dent's glass for innovation, calibration and standards in the age of reform. Since that 1853 meeting, historians and therologists have understood Dent's glass springs as an isolated curiosity, a one-off that didn't work out. It's only in the last year or so, thanks to the amazing generosity of the Antwerlont Parological Society, that unresearch archival material has been brought together with Dent's original springs in the British Museum. One unused unical spring at the bottom there, labelled B, looking very neat with its own original stand made of edli and ivory. The other labelled A, attached to a glass-balanced spring, showing some of the effects of the wear and tear from being trialled in a working monopter. One of the exciting outcomes of this project is how it developed into a collaboration, enabling the first technical analysis of the composition of the springs by British Museum adventurous material scientists, Andrew Mead, using variable pressure scan, electron microscopy, digital microscopy and X-ray fluorescence. So these are from the digital microscopy of the two Dent's springs. I'm showing you really just a teaser of the kind of amazing things Andrew has been doing. On this side, A, we have the child spring and on this side the unused one. And thanks to Andrew, you can see that they're actually in a very different shape, with the child spring flat and thick while B, the unused one, is finer than rounder, something I'd like to come back to at the end of the talk. My background is as a doctoral candidate on a collaborative award between University of Cambridge and Greenwich National Maritime Museum researching precision instrumentation in the study of magnetism. I am not a horologist, but I was privileged to update and contribute to the most comprehensive survey we have of the networks that brought knowledge of glass working to the running track by a meeting programme. I'm going to come back to the springs, but some brief discussion of the history of glass making in Brooklyn is important here. The glass springs need to be understood in the wider history of industrial organisation and economic and technical innovation at the height of the industrial revolution. A time when questions on free trade, whether in corn or glass, iron or labour, were central to the policy of industry and the business state. To understand how and why glass springs might seem singular and workmen unwilling to deal with these materials, we need to understand the problem of the glass exercise and its relation to the regulation of labour and trade. There are three aspects to emphasise. First, from its earliest introduction in Britain, glass making was heavily regulated by the state. Regulation that was achieved by constant surveillance, quantification of the raw materials of glass manufacture and restricting the movements and rights of an immigrant workforce, trafficked into the country and ghettoed in the glass springs. This gives us the second point. The history of the regulation of glass in Brooklyn is the history of social regulation. Since the introduction of the window tax at the end of the 17th century, glass not only became a means to extend state control into private domestic spaces, but it imported tax. By the 18th century, glass was not only the most heavily and punitively regulated industry in Britain, but, and this gives us the third and final point, glass warrants tax. 1820s and 1830s Britain was in the middle of the glass crisis. Foreign imports and quality glass increasingly threatened Britain's market leadership. For those vocally lobbying free trade, the glass industry was understood as like the porn market, strangled by regulations. Introduced in 1746 and intensified in 1812, the glass excise discriminated between common bottle glass with a low rate of tax and other glass subject to higher rates. A glass with a significant importional lead was one of the most heavily taxed, four times the rate imposed on common bottle. From the late 16th century, the state had used restrictions and privileges to push the ship from wood to coal burning production. Lead glass was developed as a response to the appalling conditions of the coal burning furnaces. The heat of these furnaces was such that it maimed the workers tasked with the constant stirring essential to produce homogenous glass. With lead as a flux, the working temperature was lowered and the properties of the material transformed. The tax divided glass into strict classes that enforced severe hierarchies of skill and divisions of labour between different sectors of the trade, hammering innovation and blocking skill transfer. Also it was argued by leaders of the scientific community in the 1820s and 30s who were striding lobbyists in calling for excise appeal. When celebrated chemist Michael Faraday began on behalf of the Joint Board of Longitude and Royal Society Committee to attempt to reverse engineer fine German glass in 1824, he was frustrated by the geography and organisation of this trade. I'll come back to the slide in a moment at the renovation. In thinking about that geography and culture, a couple of episodes from early modern Britain's glass making capital for coal-based city of Newcastle are particularly illustrative and set up an important idea in this talk in considering the relationship between glass, tax and innovation. From the 14th century, Newcastle was run by an effective oligarchy of merchant guilds whose dignitaries occupied all the civic roads. By the early 17th century, this merchant elite lived in glass-fronted houses serving the dual purpose of displaying their wares as well as their wealth and power. This power was consolidated with great quasi-religious processions through the town where the merchant aldermen would parade in all their official trackings and their households assembled in the fronts of the houses to spectate through the glass. Glass was the medium through which power relations were represented. This is a detail of a frieze that is in the cordoners room of a trade hall, cordoners for shoemakers. The whole thing is about 11 foot long and in true British tradition it was started in 1787 by a house painter, Alex Meddler, and not completed until 1825 by a different house painter, Harry Barlow. In early November of 1789, the cordoners of Newcastle, according to annual custom, made a grand procession to the streets of Newcastle and Gateshead in honour of King Crispin. That's the patriarchal saint of cordoners and you can see that's been with the crown to them. Just a week later, and in direct response, the glass makers of Newcastle were also possessed, but rather than the formal show of power by the elected elite, the march of the glass makers satirised the cordoners with the most irresistible comic humor. It was carnival, the subversion of the social order through the performance of the grotesque, and it got so up to hand, so unruly and outrageous, that processions were discontinued for over three decades. That is, until 1823, when for the first time since the 1789 outranges, the cordoners marched once again through Newcastle. The glass makers again responded, but a carefully ordered affair this time, with the masters of the glass houses inviting their men to march with their best and most curious pieces of workmanship. The men responded by making the trappings of the cordoners' march, the swords, pupils, feathers, cats and badges of office entirely out of gloves. Even the cannons fired to mark the intervals of the procession were glass cannon. That's one of the original pupils. Many of the items from the processions still exist in the National Museum of Scotland, though not the cannon sadly, presumably destroyed through overuse as a metaphor. Glass was taxed, a medium of power and of social regulation, but it was also a medium of social comment through distortion of the existing order. To quote the master of subversive caricature, Jonathan Swift, sat up as a form of glass. Swift referred to the reflection of a mirror, but whether through reflection or refraction, this glass mediated observation of the existing order. In the case of the Newcastle glass makers, it was precisely the drive to satire that led to glass being deployed in such extraordinary, innovative ways, completely counter to its usual classification. On 31 December 1833, just months after Arnold and Dent first announced that they had successfully applied to the chronometer a balance frame made of glass, the partners wrote to complain to the then astronomer of John Park. Wrath o'r maker, John Sweetman Beattybyn, had deposited two chronometers at the trial of the Royal Observatory, which, instead of the speculated numbers, carried the names of the glass fiddle and the strand and harlot. Writing from their premises on the strand, just a few hundred yards from the most popular pantomime of the season, Harlequin and Cinderella called the glass snipper, There could be no doubt, said Arnold and Dent, of the contempt intended towards us. Like the Newcastle glass makers, Evee saw innovation in glass as the start of satire and the screams as a part of such a terrible fit. Bibliometric analyses have shown that the origin of Cinderella's glass slipper lies in a 17th century mixup over the medieval French for heraldic reason flow. I resisted the urge to put up a slide for reason for things of my time. But the same vast analyses also show that the Cinderella story underwent a dramatic shift between 1830 and 1850. Early in the 1830s, the slipper that was simply glass or weasel became elastic glass. In the exhibition halls of London, waistcoats and shoes of glass cloth were displayed as the workmanship of Cinderella's crystal. They were made from threads of elastic glass drawn and wound just as Dent did in the manufacture of this precision chronometer spread. Here's an excerpt from a caricatures and book illustrator George Crochang Cinderella. Her shoes made in elastic material and covered in spun wheels. You can see Cinderella having a bad time and hanging over the public cloth. I really want you to forget about all the Maria Prince Cinderella stuff and see this as a story about poor time management and exploitation in the work place. Because by the early decades of the 19th century and above all in Croochang's hands, that's precisely what it was. In Croochang's social commentary, public clocks oversaw the regulation and exploitation of labour. His work reflected the contemporary preoccupation of labour relations, often riotous and always fraught in the public extension of time discipline. Croochang's close friend Charles Dickens was infuriated by what he saw as Croochang's tendency to ruin classic fairytales with undue moralising. In response he made a satire of Croochang Cinderella, with a fairy godmother who first changed mice into horses free from the obnoxious and oppressive post-war's duty. Then a rat into a steak coachman not amenable to the iniquitous success to taxes before turning the wizards into six footmen each with a petition in favour of the early closing movement. The godmother's final act to put on Cinderella's feet a pair of shoes made of glass was carried out observing that but for the abolition of the duty on that article, glass never could have been demoted to such purpose. The effect of all such taxes being to cramp invention and embarrass the producer to the manifest injury of the customer. The Croochang used the glass slipper to focus labour concerns quite general to Victorian society and that Dickens read the glass slipper and heard satire and tax is fundamental to understanding the powerful equivocation in the glass. Armour from Denmark were prompted to glass research by concern over the imperfect state of balance frames. The material that the balance frame affected going rate. Use hardened steel and the chronometer would gain rate. Use a soft material like gold or soft steel and it would lose. The problem was reduced by using hardened tempered steel of a couple of years use so the tension structure worked out. However steel came with other issues highly susceptible to magnetism and rust. Further to this, and this is the really important one, Armour from Denmark noted that even the best chronometers when exposed to extremes in temperature would lose at the maximum and minimum. The 1833 announcement was not only the public debut of Denmark's glass springs but also the first statement of middle temperature era to appear in print. The firm substitution of glass began as an attempt to do away with the material floor and it is compensation for middle temperature era that ultimately explains what happened in the springs. In July 1833 within months of the first announcement Armour from Denmark deposited a glass spring chronometer number 616 at the Royal Observatory of the Triangle. It is worthy to remark, noted Denmark, that the improvement of the balance has followed that of the spring. This chronometer had a glass balance as well as its balance frame. We now know the glass of the spring was manufactured by Armour from Denmark themselves and from purified synthetic intervals quite distinct from the common window glass at the time. So the spring of our flat spiral is the yellow trace and you can see significant levels of silica, that's the SI, lime, that's the CA calcium and potash is the K potassium and no lead, no P lead. Further analyses also found particularly high strontium levels indicative of a seaweed base like kelp. Basically the spring of flat spiral is indeed common window glass. It makes a useful comparison of the dense springs, the red and blue traces. The red is the spring of the child and the blue is the one that was just displayed and you can see they are of an entirely different composition to the yellow trace. Though both dense springs are almost identical to one another, you can see a potassium spike on the blue trace of the untrialled spring, not present on the red. The significance of this will come back at the end of the talk but that's a surface reading from the handling and sweaty things. The dense springs are made from extremely pure, synthetically produced raw materials, salt, peter, quartz and significantly really high lead. In fact, the composition of the dense springs is very close to the octal glass produced by Faraday and the 1820s glass commission, the most vocal lobby for the reveal of the glass. There's was a lead glass, like dense, loaded with one of the heaviest tax rates, two to three times that window glass. Lead at the point of production, rather than say it, this particular tax pattern involved the most intensive and relentless surveillance and intervention by the state, crippling even the manufacture of such tiny objects as these. Dare to make direct reference to Faraday's glass commission and the scientific lobby in lamenting the great expense of his lead glass research. Now this is the really important bit I need you to remember as we're going to come back to it. The glass balances shown by the green trace is a completely different composition again. It does not have that lead spike. It is closer, in fact, to the yellow spring word trace. High in strontium, it's another kelp of glass. It's that crucial detail I really want you to remember. It has no lead. In March 1836, three years on from the glass spring conometer, first being deposited at the observatory, hydrographer to the Admiralty of Francis Beaufort wrote to the new astronomer royal George Biddle Airy, noting that dent had applied to continue the rating of the glass spring conometer. But as far as they had gone, the experiments were highly interesting and added, I wish you would turn your powerful mind for a few minutes of the subject, for it is evidently in the balanced and balanced spring that we must now look for essential improvement in all conometers. Over the next few months, the results of the glass spring's performance came under post scrutiny because of which it came to light that it was formally not usual to register the temperature of the conometer room except during the annual public trial. The results, prompted by the spring's regular temperature observations in the conometer room were introduced, when each time became a function of temperature measurement and its constant surveillance. Despite Beaufort's request, airyndent became absorbed with projects of design rather than material, most significantly a conometer with a concealed telltale, an idea carried over from the ruthless techniques of labour discipline in factories. In a private correspondence with Beaufort, Airy noted, now it cannot be denied that the thing it concealed is of the nature of a spine, but in the first place it has none of the envy, hatred and bad or selfish passions of a human spine, and in the next place it might be employed in the first instance simply to collect evidence. There is my chasmistry for you. Chronometry and factory discipline were united in Airy's moral science. Interest in the glass spring has almost seemed to have run down, that is, until 1840, when the partnership between Ireland and Dent had a rather new broken. The change in Dent's circumstances is crucial to understanding the fate of the glass springs. Just as the 1820s glass crisis was all about regulation of trade and control of foreign imports, so was Dent's decision to centralise all his capital in a single manufacturing. Following the split with Arnold, Dent acquired a factory at Somerset Wharf and concentrated the separate branches of the pot making trade under one roof and one management his own. No longer a partner in a firm, he was now an owner of factories and an industrialist with an intense ambition to have the best, and I believe only, complete manufacturing of chronometers in London, and I may almost say the world. In 1833, as a member of the pot makers company, Dent had lobbied government demanding heavier import duties on foreign watches, principally made in Switzerland, a country exempt from taxes, rates and times, without court laws to force up the value of labour. But in the early 1840s following the dissolution of his partnership with Ireland, Dent's approach changed. He called instead for corn law repeal, demogulation that would justify a drop in wages. He noted since splitting with Arnold and heading up his own words, he had made more English watches than at any prior period, and consequently had paid more for labour. For Dent, his time he was to outcompete foreign manufacturers, specifically because they were painstakingly compensated for variable temperature, and so was the superior, but this compensation took a great sacrifice in time and additional labour of the artisan. Dent gave lectures at prestigious societies on his research, but also on the construction of watches in London. In these he would take one of his watches and pull it apart, examining each piece before the audience, dividing them into groups and showing the range of operations the raw materials had undergone to reach the finished piece, and listing the number of different trades for each required, 43. As he did so, he listed the necessary parts and divisions of his total factory. The watch became a factory of miniature. In the audience of one such lecture given in 1837, eminent American mathematics professor Joseph Henry noted in his diary that Dent illustrates the great division of labour which is required to produce cheap and good articles where the labour-saving machine is not used or cannot at present be applied. When Dent acquired the factory at Somerset Wharf three years later, he brought all the divisions under one roof around such enormous labour-saving machines. In private, Dent noted to Henry that his glass springs worked exceptionally well, but that different materials take different times to acquire permanent elasticity. The glass springs took too long, and in that time good capital was locked up in the manufacturer. For Dent, it was only the level of the wage raised by the high price of pork which prevented English watches and chronometers from dominating home and international markets, and it was about all the exquisite temperature compensation of his chronometers that would enable British manufacturers to dominate without protections. Joining the clamour of industrialists, he argued for free trade and the repeal of the poor laws. Just a few months on, in early February of 1842, Dent wrote to Henry with a tentative proposal for improved solutions for temperature problem, which he turned secondary continuous compensation. This would move the ordinary compensation awaits on a change of temperature in a direction near the concentric of the centre of motion, and so minimise variations in the isochronism of the system. He described a constant sliding-scale approach to temperature fluctuations. The problem was a complicated one because of the marked difference between the effects of temperature change on the inertia of balance and the tension of the spring. It's just too many variables. Dent reckoned if he could remove the variable that the balance is changing inertia, a result of its expansion, then he could make the action of balance and spring in all life. And he reckoned he could remove this variable by the substitution of metal with glass in the balance, and the assumption that any expansion in the glass was negligible and so could be safely ignored. In 1754, concerned with the building of temperature-compensated pendulums for precision clocks, civil engineer John Smeeter published a description of a new pyrometer to establish precise coefficients for different materials expansion. One of the findings of Smeeter's research was the minimal expansion of glass tubes. Thirty years on, as William Roy, head of the Ordnance Survey, laid out the baseline for the Survey of England using steel chains constructed on the principle of a watch chain and subjected to constant temperature measures, a captain in the horse light directed him to Smeeter's measurements. And Roy chose to calibrate the watch chain survey length with standardised glass tubes made in the Fleet Street glass walls. The bottom half of this plate is concerned with how the cases of the glass tubes are joined together. It's the top half that's interesting here. The cases containing the tubes are set on their stands and the central case is open to reveal the glass tube inside. The cupboards either side show the horizontal stems of thermometers, whose bulbs run up inside most of the tubes. Each of which is about 20-foot long. This was a new standard of precision measurement. Roy's surveys set the pattern. Survey lengths were typically calibrated against glass tubes. British surveys based their authority on Smeeter's pendulum organisation measurements. And it worked both ways, as shown by astronomer and stockbroker Francis Bailey's work on the material compensation pension published in 1823. The table is dominated by the results of precision expansion measurements by Smeeter's and those engaged in the review of standards for surveys, both in France and Britain. The precedence mattered to Dent. He wrote to Aerry explaining that, for his secondary compensation research, I refer for all the divotations to Mr Bailey's table. We know, thanks to the British Museum's analysis, that Dent's spring is contained with a mark in high-level content, while the balance does not. For the expansion of the high-level spring, Dent preferred to the results of Le Poitiers and Le Plats, thermometry advanced in the review of French standard measures for surveys. But Dent's glass balance is the really interesting mark. Remember it's kelp glass, with no lead, entirely unlike the spring. The expansion of Dent's glass balance was defined using Roy's 1785 survey results. Dent's glass balance was calibrated against the baseline of the Ordnance Survey of Britain, intended to be the basis for the commutation of times. The relation with these surveys of standards was timely. In the wake of the 1934 fire that destroyed the houses of parliament and the national standards of length, standard measures were under intense scrutiny, not eased by air. The problem was whether those hallowed and singular parliamentary standards that had been the embodiment of national metrology, now destroyed, could ever be recovered. Just as he applied mechanisms of factory discipline in the construction of his plot mechanisms, Dent's patron, Aery, saw these questions of standards, maintenance and mechanical measures as applicable and general throughout the national economy. And he was far from alone. The age of reforms saw a drive to growing factory at little economies in his correspondence, and standards and tax of the principle means to his end. Survey measures and national politics have not just connected the reasons of patriotism, they were the means of this correspondence. In 1832 Aery had acted as adviser to parliament and Ordnance Survey on the mathematics of the division of counties for the commutation of times. The transmutation of the traditional work of farmland into hard cash mobilised vast surveys that would make land evaluation possible and credible. Surveys based on lengths calibrated against the expansion of bloods. For industrialists, the closely linked appeal of the Cornwall's regulations which not only set the value of commuting times, but kept the price of bread artificially high by having duty on imports, justified a reduction in the wages of factory workers, wages that were dent to particular concern of the manufacturing and mechanical territory compensation in his own factories. I think these half-pelling tokens produced around the corner from Dent's factory and workshops are really eloquent on the connection between wage labour and Cornwall's. Since the 1780s Britain had suffered from a small crisis and small change, there just wasn't enough in circulation to pay the rapidly increasing proportion of the population on fitable factory wages. In response, industrialists began producing their own trade tokens, often with moral and political slogans. The promise of the free trade industrialists was that the Cornwall people, bread here symbolised by the wheat, would be cheap and plentiful. Their motivation was the further reduction of Britain's wages. The connections between the regulation of clocks and of the national market were explicit. In February 1842, Arian Dent corresponded more than daily on the design of Dent's proposed mechanical system of secondary continuous temperature compensation, founded on his calibration against the material compensation of glance. In the middle of this flurry of correspondence, Arian wrote to the editor of political weekly the exam, proposing a solution to the problem of the Cornwall laws. Significantly, Arian described the great machine of the Cornwall kid as a chronometer, gaining and losing in rate with temperature, arguing with the uniformity of movement of any machine that is to be secured, not by accelerating it when moving most slowly and retarding it when moving most quickly, but by accelerating it when losing speed and retarding it when gaining speed, that the motion is when more uniform than it would be without interference. The solution Arian proposed to the problem of the Cornwall laws was to take a fixed duty based on an average price, the primary compensation, and add or subtract from this sum based on the past two averages price, the secondary compensation. The result, a continuous sliding scale. Arian proposed the solution of Dent's secondary temperature compensation to the Cornwall law. Characteristically there, and indeed of Dent, the solution he preferred was a mechanical one. A mechanical solution might perhaps obviate the fundamental fear of the two managers, over dependence on skilled labour. Their correspondence was carpet with references to the problem of depending on the talent and ability of the workman, and removing this reliance on human care was the principle criteria in their assessment of mechanisms. With Dent going so far as to write to Arian in September 1842, while I consider the principle perfect and capable of being made by a careful worker, still I am of the opinion that it must more or less depend on his practical care and experience, of which I have a great threat. In the summer of 1842, just a few months on from Arian's letter to the examiner, and following their correspondence on temperature compensation, Dent began to consider its application in the construction of a new clock for the Royal Exchange. This building was the edifice of commutation. Its clock was to be a finely compensated pendulum, rated against an exquisite chronometer. On its completion in 1845, and in consideration of the construction of a new clock for the Houses of Parliament, Arian wrote, I should state without hesitation that I believe the popular construct of the Royal Exchange to be the best in the world, as regards accuracy of going and striking, and that I consider you the most proper person to be entrusted with the construction of another clock of similar pretensions. The Factory Act of June 7, 1844 stated, the hours of work indicated by the factory clock must be regulated by a public clock. As the most accurate public clock in the world, where that accuracy was a function of Dent's secondary compensation, calibrated against the expansion of the last thousands, Dent's exchange clock regulated factory hours. These hours were the constant struggle between the worker and the capitalist, the factory manager, who, by nibbling and crippling at minutes and seconds, stole from the wage value of the labour expenditure. Crookshaith famously satirised how industrialists exploited the factory acts and time discipline to lower wages yet further, wasting bodies to the virtue of competitive prices. This image shows the sweating system, where if the output of the worker fell below the average rent, she or he would be scrapped. Dent's work on the Royal Exchange clock coincided with his finalisation of the pattern for his secondary compensation, and he wrote to Arian noting that this would be the last public scientific work he would engage in, as my future life would be devoted to the practical introduction of my improvements. The concentration of capital in larger manufacturers, as in the case of Dent, went along with the work of standardisation. Dent could not have made a more extensive introduction in his improvements than in the construction of the Royal Exchange and subsequently the Westminster clock, like Ben. The most public of state standards which set the standard for working hours in Britain. In future years, the going rate of the Westminster clock would be further regulated by the adding or taking away of proper points, literal penny weights, the great clock to the tax to be regulated. At the beginning of this talk, I asked you to keep two questions in mind. The fraudulent argument, if Dent's last springs performed so well, why was there only one of them? And the Dent is an argument that, according to Dent, the springs did indeed work exceptionally well, but the work would have not. I want to propose some answers. First, Dent's last was not singular because it was a failure. It was singular because standards functioned by the comparison of one against many. Dent's last was an embodied standard, as much as the parliamentary standard yard enclosed in a glass case and embedded in the Masonry of Westminster. Dent's last, like the parliamentary standards, was authoritative precisely for removal from circulation. Such embodied standards set masters apart from workmen by judging workmanship of many against the singular material form. Second, Dent's initial substitution of glass to remove the troublesome variable of heat was motivated by the supposition that glass might do away with the lengthy and costly skilled labour of temperature optimization. Finding this was not the case when Dent noted the workmen would not work for glass. He was recalling less their recalcitrance than his own confessed dread of dependiveness on sealed work. To recap, the Cornwall separated factory wages and they separated tides commuted into cash. When Dent became a factory owner, he joined free trade industrialists in fighting the appeal of the Cornwalls. But while he argued for the removal of one set of regulations, his last work placed Dent and his conymetry at the heart of the new emerging world. Remember how the glass balance differed from the high-led content spring? It was a kelp glass with no lead in it at all. It shared the composition of the glass rods used by William Roy to measure the baseline of the great trigonometric survey of England and by ordinary surveys that came after Roy. Dent's glass balance was calibrated against the glass rods from the great surveys that were themselves used to calculate the tides. His precision compensated timekeepers were calibrated to get the glass balance and in turn these timekeepers calibrated the great blocks which gave the standard for British factory time. And one of the spring, with its remarkably high lead content, reflected the highest duty of the most heavily regulated manufacture. Remember there were two in the British Museum collection, one fitted to a balance of child, the other perfect and unused. Remember the high magnification images? The child's spring thicker and flatter, the unused spring, rounded and fine. When Dent spoke of the springs to Joseph Henry, he noticed they were not like steel springs, but thicker and flatter. The purpose of the unused spring was never to be a demonstration model of those on trial. Its purpose was to look exactly like a steel spring, but perfectly rendered in a luminous glass. Its purpose was social and symbolic, a 19th century attribute of innovative art. XRF showed the two springs shared the same composition, except the surface of this display piece is coated in potassium from the fingers that have held out to be admired. It played the greatest role of all in the corn market chronometer. On 14 February 1845, while Dent applied for the commission to manufacture Big Ben, Prime Minister Sir Robert Peel addressed the House of Commons on the subject for appeal of glass duty. It's hard to express just how important this address was. This financial statement was the direct precedent for the appeal of the Cornwalls the following year in 1846. Peel's words are worth reading. If you permit this article to be free of duty, it is difficult to foresee in the first place to what perfection this beautiful fabric may not be bought. And secondly, it is impossible to say what new purposes glass manufactured by our own skill at capital may not be applied. I hold in my hand the valid spring of a chronometer made of glass, instead of the ordinary material of steel. I understand that it possesses a greater degree of elasticity, and that it has a greater power of resisting the alternations of heat and cold. The manufacture is so expensive and requires such skill on the part of the world, that I do not believe under the present system of restrictions that this exquisite discovery can be generated by it. I noticed earlier in this talk that glass manufacturing in Britain was heavily regulated. That the history of the regulation of glass in Britain was a history of social regulation, and that glass itself was taxed. When Peel held out the glass balance frame and called for the withdrawal of the duty, he drew on each of these points. But Swift's quotation in full is useful here. Satire is a sort of glass wherein beholders do generally discover everybody's face but their own, which is the cheap reason for that kind reception it meets within the world, and that so very few are offended with it. Glass was a medium of social comment through distortion of the existing order. For all the calls for free trade, orders to be caused with deregulation, the reality was, like airy solution to the repeal of the cord rules, an extreme increase in the intensity and extent to other regulatory practices. Regulations calibrated against dense glass balance. Final slide. This is Peitsch's depiction of Peel in the House of Commodals after its financial statement, when he held out dense glass frame to successfully call for the repeal of the glass tax, impressed with the 1846 repeal of the cord laws, and here the song punch wrote in tribute to Peel's performance. Much more than a prop in this political theatre, the specific glass and the complex history of label relations it embodied was a powerful tool immobilised in the design and architecture of the former record. Try to recite just a few lines of Peitsch's verse, and it's hard to resist the Newcastle accent. Here's to each Tory and Radical too, but obviously my accent's not Newcastle right. Just only my income tax passports, and you'll see how completely John Ball I shall do by taking the duty of passports. Let the law pass, John's such an axe, a warrant he'll find an excuse in the glass. Hard to resist the riotous history of labour in Wales.