The Measure of All Things
The Seven-Year Odyssey and Hidden Error that Transformed the Worldby Ken Alder
Hardcover: New York: The Free Press, 2002. ISBN 0-7432-1675-X
Paperback: New York: The Free Press, 2003. ISBN 0-7432-1676-8
What a shocker this book would've been in the 1970s, when the United States last tried to metrify. As highway crews added kilometers to signs and grocery stores handed out pamphlets, metric advocates championed the natural basis of the new measurements — one kilogram to the liter, 100 degrees to boil water, even 40 million meters to go around the world. Imagine what the metric opponents could've done with a book like The Measure of All Things, which exposes the basis of the entire metric system as a fraud!
To be more specific, Ken Alder follows the expedition dispatched to survey the length of the meridian from Dunkirk to Barcelona. During that epic seven-year journey, Pierre-François-André Méchain and Jean-Baptiste-Joseph Delambre would face many difficulties. Attacked by peasants, trapped behind enemy lines in a war, and beset by malaria, they slogged on while revolutions and counterrevolutions roiled Paris. That the undertaking was completed under such circumstances is remarkable, but the results are less so. Alder, digging through original correspondence and Delambre's published account of the expedition, discovers that Méchain had made errors, then altered data to cover them up. Ever mindful of his partner's seniority, Delambre papered over the errors and preserved Méchain's reputation. Yet Delambre, having been so meticulous with his own data, nonetheless recorded the discrepancies for posterity.
Shocking? Hardly. The earth's circumference is not 40 million meters exactly, and the strength of the metric system lies in its universality, not its basis in the natural world. Arbitrary and customary units can be standards when well-defined and broadly accepted: computer publishing has 72 points to the inch, aviation gives altitudes in hundreds of feet, and the international merchant marine measures speed in knots. The meter itself has changed, first etched on a bar of platinum, later defined in terms of krypton state transitions and the speed of light. None of the latter two definitions are particularly round numbers, but they are repeatable, each more precise than the last. Considering the errors that Méchain and Delambre must've failed to discover, the ones that they did discover seem rather irrelevant today.
And so, when Alder writes in the prologue that "a secret error lies at the heart of the metric system" (p.5), a theme repeated sporadically and played up by the jacket copy, it seems to be much ado about, well, very little. Ultimately, he develops the theme into an exposition on the nature of error and the progress of science. Where once savants regarded measurements as their prerogative to perfect, the later scientifiques (scientists) understood Gaussian distributions and least-squares error. And he eventually alludes to the arbitrary nature of measurements when he covers later metric conferences, where the delegates decided to enshrine the then-current values for all time. But unfortunately, this theme is developed in fits and starts, a couple of pages at a time amidst the more interesting narrative of the two men's journeys. It feels like one of those television shows where every 12-minute segment is followed by a teaser for the big finale, which comes at last after two hours and falls far short of expectations.
As a professor of history who focuses on science and technology, Alder also appears light on the technical details. Often he launches into several awkwardly-phrased paragraphs of prose to explain a concept much better presented with a few equations or a nice figure. The one time that he uses a figure to explain the use of the repeating circle to eliminate angular error, the figure used is a period illustration and much more confusing than a modern illustration would be. Indeed, he himself apparently gets confused by it, reiterating several times that the instrument can "double" measurements to reduce error, when the instrument shown actually adds measurements to yield multiples. He gives the first three terms of such a doubling of successive measurements: 1, 2, 4, etc., confirming a conceptual error rather than a simple wording mistake, and somehow fails to deduce from the exponentiation that the user would eventually have to measure an angle greater than 360 degrees on the repeating circle (what would he sight on, and why?). This is actually an important point, since an instrument that progressively doubles would require fewer measurements for a given error tolerance, and plays down the scope of the task faced by the two surveyors for each and every angle measurement they made.
This technical shallowness also carries across to more incidental anecdotes. He trumpets Eratosthenes' estimation of the earth's circumference, except that this accomplishment is often disputed due to uncertainties about the actual length of a stade. He also gives the simplistic explanation for the loss of the Mars Climate Orbiter, when it was the more serious process issues that allowed the discrepancy in units to remain undetected. It's a bit like picking up a business book and reading about the failure of the Ford Nova in the Latin American market — a "fact" that everyone knows to be true.
To a reader with a scientific or engineering background, the book is thus infuriating at points. Yet it also makes some excellent points about the meaning of metric reform, and deftly ties in the personalities and attitudes of the period. Alder is a historian, after all, and he has a solid understanding of the context in which the expedition took place. He describes the Republican calendar, the decimalization of currency, the proposed base-12 counting system, and alternative proposals to define the meter using a pendulum rather than a survey. He also explains the difference between the ancien régime concept of measurement, based on just price, and the modern understanding, based on accuracy. A similar clash of value and precision would take place in modern standardization movements, from shoppers inadvertently paying more for cloth in square yards, to the current Italian lament that they earn money in lira and spend it in euros.
Such thoroughness is Alder's strength, and they carry over to his account of the voyage itself. We read about freezing nights on mountain slopes, pervasive fog blocking sight lines, primitive accomodations far from major cities, and an overall determination to get the job done. There are more pages on Méchain than on Delambre, but it was Méchain, after all, who covered the southern leg of the journey, found himself behind enemy lines in Spain, made the much-ballyhooed mistakes, and had the nervous breakdown. M&echain ultimately dies of malaria, and in the fine spirit of technological history, Alder points out that the cinchona extract used to treat him actually contains quinine.
There are similarly interesting asides throughout the book. Just as we are beginning to get bored with a lengthy description of the surveyors' mentor Joseph-Jérôme Lalande, Alder tells us that he ate caterpillars. Those aristocrats of the ancien régime sure had the luxury to cultivate highly interesting quirks! Colorful details mix with vivid descriptions of Revolutionary tumult to set the scene. There is a mixture of dread and wonder when the Bourbons are removed from their resting places in the Basilica of Saint-Denis and the popular king Henry IV is found "perfectly preserved, his face black as pitch" (p.36) after over a century. We get a good sense of how the Revolution affected people's lives by learning the social particularities of the scientific establishment, and we follow the personal story by following Madame Méchain's as she moves from dwelling to dwelling while her husband's fortunes rise and fall with each change of government. The French Revolution was just as bloody and vicious a revolution as more modern ones, a fact that is often obscured by lists of the guillotined. Alder's chronicle of quotidian happenings disabuses us of any revolutionary romanticism.
It's easy to see why the jacket copywriter chose to focus on the "secret error," though. Such fascinating anecdotes are difficult to summarize into book-selling copy, even though they form the backbone of the book. Unfortunate, for the book is very readable and brings many specifics to the cut-and-dry history that one learns in European History classes. Alder, a devout Francophile (in the acknowledgments: "I thank my parents for first introducing me to matters scientific and French"), has biked across the surveyors' entire route, and his geographical settings have the verisimilitude of personal presence. His immersion in the culture also enables him to make unanticipated links, between villagers pulling down Méchain's geodetic signals, for example, and the activist José Bové, who arrived at the 1999 Seattle WTO protests bearing a package of the banned Roquefort cheese and bulldozed a local McDonald's for its standardized food (p.228: "since rebuilt, [it] is the world's most famous, and certainly the most charming ... with ... a soothing view over a bucolic valley").
And so, even if Alder's own book is, as he quotes Gauss on the subject of Delambre's textbooks, "mathematically simplistic," (p.314), he steers clear from the the other half of Gauss' assessment: "dull and craftsman-like." The book is engaging, chock-full of the facts that bring life to a long-past, little-remembered expedition. Those with a technical background will gulp occasionally at the errors, but will find continued reading rewarding. The Measure of All things is also handsomely-designed by Dana Sloan, with well-chosen illustrations and an elegantly readable typeface that fits well into the era. Read the book not to learn about the "secret error," for it has long been forgotten, and the unsealed correspondence lay largely unread for most of the twentieth century before Ken Alder picked it up. Rather, read it to get a glimpse of how science was conducted in the era of savants rather than scientifiques, to marvel at the fortuitous political maneuverings which somehow managed to leave the mission alive, to respect the determination that got the mission finished.
