The Measure of All Things

by Ken Alder

  Lavoisier was not only the world’s premier chemist, he was also one of the Ancien Régime’s “tax farmers,” the financiers who collected the king’s taxes—and took a healthy cut for their pains. This position had earned him one of France’s great fortunes, as well as the hatred of millions of ordinary French men and women. Despite the source of his income, however, Lavoisier was committed to the physiocrats’ policies of laissez-faire and the elimination of the Ancien Régime’s many taxes, both visible and invisible. He had thought long and hard about the optimal way to manage a national economy, and his thinking on this point was closely connected to his understanding of chemistry. His lofty principle that “matter is neither created nor destroyed, all it knows is transformation” committed his young science to precision measurement. How else could the chemist know whether matter had been conserved or not? If the chemical equation was to be the new mode of thought about the material world, then the finely tuned balance scale would be the proof that such thinking paid off. Novelty, productivity, and profit all relied on careful bookkeeping. Economic exchange, like chemical transformation, should be measured in universal units so that transactions would be transparent, with buyers and sellers equally informed about the deal they were cutting. Such transactions would also be easier for the centralized state to monitor for fairness and, of course, to tax. Without the decimalization of money, he noted, “the metric system will have been adopted in vain.”

  Condorcet, in addition to his role as Permanent Secretary of the Academy of Sciences, had served as Master of the Royal Mint. Along with his contributions to mathematical social science, he was one of the nation’s premier political economists. For Condorcet, economic progress went hand in hand with political progress. He was history’s greatest optimist. His goal was to reconcile freedom, equality, and material well-being through a program of universal education and a new social science that would match human laws with social needs. That nature’s laws were everywhere the same meant, for Condorcet, that the hodgepodge of human laws must be aligned with universal principles. Reduce the legal code to its essentials and the law would be comprehensible to all literate men and women. This would diminish the unfair advantage that those in authority held over the powerless. Give all citizens equal access to knowledge and they would all have the power to control their own fate. Condorcet had imagined a scheme to classify all knowledge in a decimal system, a forerunner of the Dewey Decimal System. More grandly still, he imagined a language of universal signs to replace all forms of logical thought, much the way algebra expresses mathematics. Such a language would apply to social relations as well as to logical ones. It would “bring to all objects embraced by human intelligence a rigor and precision that would render knowledge of the truth easy, and error almost impossible.”

  Condorcet considered the metric system a first step toward achieving this new universal language for the objects of the material world. In combination with the reform of the French currency, the metric system would bring efficiency to economic relations—and this, in turn, would foster political equality and freedom. “[It] will ensure that in the future all citizens will be self-reliant in all those calculations which bear upon their own interests; because without this independence citizens can neither be equal in rights . . . , nor truly free. . . .”

  As for Prieur de la Côte-d’Or, he had an engineer’s appreciation of optimization, plus an administrator’s preference for clear protocols—which is another way of saying that he embraced the clichés of the day. Prieur was younger than Lavoisier or Condorcet, and nowhere near their intellectual equal. Under the Ancien Régime he had been a run-of-the-mill military engineer: underemployed, a bit shy, lame in one leg, uncomfortable with public speaking, formerly his mother’s darling, in love with a married woman, well trained in mathematics, primed with the ambition to rationalize the world, and not much of an original thinker. But from his new position on the Committee of Public Safety, he had the clout to make things happen.

  Prieur believed that uniform measures would make France a great nation, smoothly administered from the center and united through trade. The metric system would transform France into “a vast market, each part exchanging its surplus.” It would make exchanges “direct, healthy, and rapid,” diminishing the “frictions” which impeded the wheels of commerce. These frictions included anything that masked the true price of an item, such as the variable measures of the Ancien Régime. The price of an item, Prieur argued, necessarily depended on many factors: its scarcity, the work necessary to produce it, the quality of the product. But in the final analysis, price was whatever people agreed it should be. This meant that when people agreed on a price they needed to know what they were getting, not be baffled by secret shifts in the quantity being exchanged. Those who claimed that differences in measures aided commerce were just talking about their personal profits. “The French Republic,” he wrote, “can no longer tolerate men who earn their living by mystery.” Worse, those who profited from the diversity of measures, said Prieur, corrupted those who tried to conduct honest and transparent exchanges by “complicating commerce, spoiling good faith, and sowing error and fraud among the nations.” Until commerce was carried out with complete probity, the common people would doubt the advantages of free trade. Only if price were the sole variable in exchange would these exchanges be based on clear understanding between parties.

  Instruction in this new form of “right thinking” about economic matters would come from the metric weights and measures themselves. The people’s new rulers would be the rulers they used every day. Rational measures would engender a rational citizenry.

  If we want the people to put some order in their acts and subsequently in their ideas, it is necessary that the custom of that order be traced for them by all that surrounds them. . . . We can therefore look upon the metric system as an excellent means of education to be introduced into those social institutions which conjure up the most disorder and confusion. Even the least practiced minds will acquire a taste for this order once they come to know it. It will be reflected by the objects which all citizens have constantly before their eyes and in their hands.

  Today, many of these ideas are taken for granted and hence unexpressed. But like many things that appear ordinary on the surface, they mask a long history of bitter controversy. Making measurement banal proved to be hard work and would take more than a century of struggle and conflict.

  For instance, these reformers all presumed something we are apt to forget: that free trade would have to be fostered by state action. It may be that people everywhere have an innate desire to “truck and barter,” as Adam Smith taught, but the leaders of the new French republic understood that a “free market” was something quite different and required a new set of social institutions. The proponents of the metric system wanted both a powerful state apparatus and a free citizenry empowered to participate in the political and economic life of the nation. To resolve this apparent contradiction, they wished to transform their fellow citizens into a calculating people. The savants, engineers, and administrators of eighteenth-century France were already superb calculators who had earned their posts thanks, in large part, to their mathematical merits. They simply wanted the French people to become more like them.

  The advocates of the metric system, like today’s advocates of globalization, saw their goal as creating at one stroke a new kind of economy and a radical new kind of politics. This is not to say that the savants were innate revolutionaries. The French savants of the eighteenth century had been as fond of their comfortable Ancien Régime lives as the lawyers, financiers, and military men who likewise stepped warily into the new age. They had little cause for complaint. Foreign savants who visited Paris before the Revolution often remarked wistfully on the respect their French colleagues received at the hands of the kingdom’s great nobles and ministers. The savants were appreciated, and they enjoyed their daily routines. Yet their very routines masked a radical premise. Give scientists a chance to
remake the world, and who knows what will be left standing when they are done? What human habit can survive the blade of logic? What social institution can justify its ways to mathematics? What ancient custom can be assayed with precision? The metric system belonged to that radical strain of the French Revolution which sought to destroy all local distinctions to make way for a future in which everything was the same everywhere, much as today’s critics of globalization suggest that the Information Age will level all cultural differences around the world. The metric system was to be the new language of the material world. And just as the Revolutionaries sought, in the name of linguistic unity and rational communication, to eliminate the diversity of France’s various patois—its many regional languages and dialects—substituting French as the sole language of rational communication, so did the savants dream of extending their metric language to all domains of scientific and public life.

  REVOLUTIONARY CALENDAR

  This calendar of 1797 enabled users to convert between Revolutionary and Gregorian dates. The Revolutionary calendar came into existence in October 1793 and began with the year II. It was abolished early in the year XIV in time to start 1806 on January 1. (From the Photothèque des Musées de la Ville de Paris)

  Time was first. The Revolution had marked a new beginning in human history. Where the Gregorian calendar had wed the year’s rhythm to Christian holy days, a secular republic needed a calendar based on nature and reason—although pinpointing the exact moment of rupture proved contentious. Was it January 1, 1789—the beginning of the year which had proved so liberating? Or was it July 14, 1789—the date the Bastille fell? Both moments of origin, and many others, were proposed. Not until 1793 did the mathematician-turned-politician Gilbert Romme—on the advice of his friend, Jérôme Lalande—settle upon a solution. Year I of the new era would be backdated to the founding of the French Republic on September 22, 1792, which happily coincided with the autumn equinox, a most auspicious conjunction of nature and reason. “Thus, the sun illuminated both poles simultaneously, and in succession the entire globe, on the same day that, for the first time, in all its purity, the flame of liberty, which must one day illuminate all humankind, shone on the French nation.” The calendar would contain twelve months of thirty days, each poetically named after its season as experienced in France.

  vendémiaire

  month of the wine harvest

  September/October

  brumaire

  month of fog

  October/November

  frimaire

  month of frost

  November/December

  nivôse

  month of snow

  December/January

  pluviôse

  month of rain

  January/February

  ventôse

  month of wind

  February/March

  germinal

  month of germination

  March/April

  floréal

  month of flowering

  April/May

  prairial

  month of meadows

  May/June

  messidor

  month of the harvest

  June/July

  thermidor

  month of heat

  July/August

  fructidor

  month of fruits

  August/September

  Each month was then divided into three ten-day weeks known as décades; no more Sundays, no more saints’ days. National festivals would commemorate the anniversaries of Revolutionary uprisings, with a climactic festive sans-culottide of five days (six in leap years) to ensure that each year began anew on the autumnal equinox. No creation of the Republic, wrote Lalande, would do more to break the hold of the priests over their superstitious dupes. He did admit, however, that ordinary people might find the ten-day work-week a tad on the longish side, and proposed a midweek holiday, the quintidi, to ensure that the Revolutionary calendar and the Revolution itself would become popular.

  A DECIMAL CLOCK

  In 1794 and 1795 the French government briefly mandated the use of a decimal clock with a day divided into 10 hours of 100 minutes of 100 seconds each. Of all the unpopular changes associated with the metric system, this was the most unpopular. Some forward-thinking individuals, like Laplace, had their Ancien Régime pocket watches modified accordingly. A clock in the Palais des Tuileries still kept decimal time as late as 1801. But decimal time was otherwise ignored. (From the Musée des Arts et Métiers-CNAM, Paris; photograph by Pascal Faligot, Seventh Square)

  And while they were at it, the rationalizers reasoned, why not divide each day into ten hours, and each hour into one hundred minutes? A law of 11 brumaire of the year II (November 1, 1793) so decreed. Master watchmakers designed prototype clocks that pointed to “V o’clock” at midday, and “X o’clock” at midnight. Laplace had the dial of his pocket watch adapted to show decimal time.

  And why stop at time? Why divide circles into 360 degrees just because the ancient Babylonians had done so? A 400-degree circle (with a 100-degree right angle) would not only ease calculation, it would synchronize astronomy and navigation. In a world where the quarter meridian was 10 million meters long, each degree of latitude would then measure 100 kilometers. This would simplify maps and assist sailors. Already, as a pledge of the metric system’s coherence, Etienne Lenoir had ruled his repeating circles for Delambre and Méchain in 400 rather than 360 degrees. The new angular division would require new trigonometric and logarithmic tables. But their production too could be rationalized. By breaking down the complex formulas into a series of simple arithmetical tasks, the savants could portion out the work to semiskilled “calculators,” creating a factory of mathematical results. Condorcet proposed employing the graduates of the deaf-mute schools because they would be less easily distracted from their labors than other people. In the event, the savants employed out-of-work wig-makers, laid off by the Revolutionary assault on aristocratic hairstyles. This collective human computer—inspired by Adam Smith, and the inspiration for Charles Babbage—prefigured our information economy: universal measures, transparent numbers, and the division of mental labor.

  Condorcet and Lavoisier were well placed to press for metric reform, at least at first. As the Permanent Secretary of the Academy of Sciences, Condorcet spoke for that body. He was also an elected representative to the National Assembly, where he became a chief advocate of equality for women, Jews, and blacks. He urged public education for all French children. He believed that virtue and reason were forever conjoined. These views would also garner him enemies, especially when the Jacobin party came to power. Not that the Jacobins disputed those goals exactly, but they despised Condorcet’s voluntarist methods of achieving them. When the Committee of Public Safety condemned Condorcet along with the rest of his political allies, he went into hiding. There he composed his great utopian tract, Sketch for a Historical Picture of the Progress of the Human Mind, which he left unfinished when he killed himself rather than face execution in May 1794.

  Though he lacked a formal political role in the new Republic, Lavoisier had considerable power to promote the metric system. As Treasurer of the Academy of Sciences, he controlled the purse strings of the meridian expedition. As the patron of one of Paris’ finest salons, he hosted dinner parties on the boulevard de la Madeleine where the scientific elite could hash out policy and win political allies. Lavoisier was a man who knew everyone and was everywhere respected. He secured an exemption from the military draft for the savants and instrument-makers working on the metric system, including Delambre, Méchain, and their assistants. He determined the standard for mass, which he defined as the weight of a cubic centimeter of distilled water at the temperature of melting ice. He was just completing these experiments when the Committee of Public Safety incarcerated him, along with the rest of the tax farmers, in the Porte-Libre prison (the “Free-Entry” prison).

  Lavoisier, who had fretted over the fate of the injured Méchain, now fou
nd himself in need of a protector of his own. Borda wrote to the Revolutionary authorities, bravely demanding that Lavoisier be released so that he might resume his labors for the metric system. Where once Lavoisier had cited the ongoing metric reform project as the chief rationale for preserving the Academy of Sciences (to no avail), his colleagues now cited his labor for the metric reform as the chief rationale for preserving his life. The Committee of Public Safety responded by purging Borda—along with Delambre, Laplace, and several others—from the Commission of Weights and Measures. The signature on the order was that of Prieur de la Côte-d’Or.

  For the past few years, Prieur had been a regular guest at Lavoisier’s home, where the nation’s greatest scientific minds had gathered over dinner to thrash out the details of the new metric system. The conversation often turned to politics. Prieur, the youngest person present and no scientific luminary, often found himself alone in defending the Revolutionary government, of which he was a rising member. Conversation became animated; these were men who spoke their minds. At times, Prieur’s views were mocked. It was this personal pique, according to Delambre, that explained Prieur’s vendetta against the senior savants. “As a result he nourished a resentment against Lavoisier and those of his colleagues, such as Borda . . . , who showed themselves to be most ardent, lively, or witty in their disputes.” In his own mind, of course, Prieur had only acted to “regenerate” the Commission of Weights and Measures. He had cancelled the superfluous meridian expedition so that the government might focus on the far more important task of implementing the metric system. The scientific portion of the mission, he wrote, had been “carried to that point of maturation at which the need for reflective thought separates itself from the need for action.” The time for action had come.