Book Review: The Measure of All Things: The Seven Year Odyssey and Hidden Error That Transformed the World, By Ken Alder

Many of us have had to explain our presence to an irate landowner (never a pleasant task under the best of circumstances), but imagine yourself in this situation: You and your crew arrive at the outskirts of a provincial village in what is obviously a government vehicle. Your rig is crammed with personal gear, tripods, and elaborate shipping crates loaded with the very latest in high-tech equipment. As you approach the town, a militia man stops your vehicle. The man examines your identification papers and, finding them somewhat deficient, asks you to explain just what it is you are doing HERE in HIS town and what you mean to do with all of that STUFF.  

Explain Yourself!
Meanwhile the townsfolk, being suspicious of government officials (you're traveling in a government vehicle, remember), begin to take an inordinate interest in your conversation with the militia man. Soon you find yourself at the center of a small crowd and are forced to begin your explanation anew. You speak of geodesy and meridian arcs and of measuring the size of the Earth with triangulation using angles and target signals. You drag out the instruments to explain their purpose-but are immediately accused of being a spy for the despised government regime-after all, the people wonder, what else could one do with such complicated and intricate equipment? Nothing good, certainly! As more villagers arrive, the crowd begins to take on the mood of a mob, and you must begin your explanation again! Post-September 11th Afghanistan? Post-Saddam Iraq? Would you believe, maybe, revolutionary France in 1792?
In June of that year, two astronomers from the Paris Academy of Sciences, Jean-Baptiste-Joeseph Delambre and Pierre-Francois-Andre Mechain, were chosen to lead an ambitious expedition to re-measure the meridian arc from Dunkerque through Paris to Barcelona in order to determine the length of the meter. The Measure of All Things: The Seven Year Odyssey and Hidden Error That Transformed the World by Ken Alder, retraces the footsteps of these two dedicated and skilled scientist-surveyors but, perhaps even more interesting is the book's investigations into the motivations and jealousies, moods and fears, quirks and characters of two very different men who were to undertake the most prestigious scientific mission of their day.

With this book, Alder takes the history-of-science genre popularized by Dava Sobel's Longitude, to new levels of reader accessibility. There is much to like in this very engaging book: The teacher in me was amused by the vivid account of the spur-of-the-moment geodesy lecture that Delambre was forced to deliver repeatedly to a hostile crowd. The surveyor in me was gratified to learn that everyone, even an eminent scientist, has to deal with mundane difficulties like inclement weather, points that have been destroyed, or trees that have grown too tall, obscuring the line of sight. The scope of the book is surprising but not the least bit intimidating. Reading it is like retracing a really good GLO survey wherein you find yourself constantly delighted by just how well the old fellow did his work, so much so that looking for the next corner becomes a treat you anticipate, not a chore to be avoided. In addition to providing wonderful links between geodesy and our everyday world, the story touches upon politics, economics, and most surprisingly and much to my delight, describes the first application of least squares adjustments and the theory of errors and measurement! "The price of precision is continual vigilance," says Alder, and my geeky cup runneth over!

Although they worked at opposite ends of the meridian arc, Mechain in the south, Delambre in the north, Mechain was chosen as the nominal leader of the expedition. While both were highly skill-ed observers, Delambre and Mechain could not have been more different. Delambre was competent, careful, thorough, methodical, and meticulous-excellent traits for a scientist or a surveyor to possess! Moreover, he was more than willing to share some of his responsibilities-and glory-that were part of the mission, with his assistants. Delambre took his assignment seriously-but not too seriously. Alder describes a man I would gladly work with or work for. Where do I sign up?

Burdened by Responsibility
On the other end of the arc, Mechain was a brilliant but mercurial practitioner of his discipline. He was perhaps a bit distrustful of his assistants (he felt that he was solely responsible for the integrity of the observations, thus reserving those duties for himself) and so instead of making good use of his helpers' talents, he alienated himself from them. Curiously, though Mechain held himself solely responsible for the integrity of his data and for the quality of his results, his records were chronically disorganized and one can only assume, difficult for others to follow.
Delambre in contrast, used bound books to record his data and dutifully recorded each observation in ink, in order, noting the observer, date, and other pertinent information. Of the two men, Mechain may have possessed the superior intellect, but my sense is that he'd have been a very difficult man to work for. While Delambre took the rigors and responsibilities of the mission in stride, Mechain was dreadfully burdened by the weight of it all. Eventually the enormous load engendered by his acute sense of personal responsibility for the success of the mission, combined with his perception of his place in history, broke him. Mechain's descent is long and hard and fraught with angst and pain, and reading the story, you can feel it.

The book also describes the many obscure and offbeat proposals to rationalize all human endeavors by imposing the decimal system on every facet of life. Why stop with a decimal system for weights and measures? Why not apply the decimal system to money, the calendar, and to the passage of time itself? Personally, I think that I could have lived with ten 30-day months (with five days a year set aside exclusively for parties), but I'd draw the line at ten-day weeks! And there is more, much more interesting content in this wonderful book, but I digress.

Impeccable Research
I suspect that if he had chosen our profession, Alder would have made a very good surveyor because his research is absolutely impeccable. A professor of history at Northwestern University, a novelist, and an avid cyclist (many of the surveyors I know are cyclists, too), he not only located and examined the original field books, notes, and project records (including Delambre's personal copy of the project report), but also personally retraced the route of the meridian arc by bicycle. His book is a thoroughly engaging journey through 18th century France, but it is no mere travelogue. Alder puts you on the crew, right at the sides of these two men and directly in the thick of a political, scientific, and economic upheaval whose effects we can still feel today. Indeed, but for Mechain and Delambre's work, many aspects of modern life (a money economy for instance), would not have been possible. This book is highly recommended for all readers, but I think it will be especially appreciated by anyone who works in the surveying and mapping and related disciplines, and especially students.


Jon Purnell is a licensed professional land surveyor. Since 1997, he has run a two-year surveying-geomatics degree program for Peninsula College in Port Angeles, Washington. He is also the book reviewer for the magazine.

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