The Measure of All Things: The Seven-Year Odyssey and Hidden Error That Transformed the World [Deckle Edge] [Hardcover]

Prof. Alder's achievement in writing this book is considerable. Firstly, like any good historian, he brings to life a story (of the creation of the metre) that is familiar to few. In doing so, he also brings to our attention the two individuals charged with performing the measurements -- the metre was to be 1/40000000 of the "Paris Meridian" -- and the times in which they worked. Because those times happen to coincide with the demise of the Ancien Regime and the French Revolution, there is excitement and action aplenty, no minor thing for a history of science. That he also managed to unearth the undiscovered letters of Mechain and Delambre in the Paris Observatory to flesh out his understanding of the two principals makes this book an important academic work as well as a popular account of history.

Secondly, he tells a story that grips the reader. His book will naturally draw comparisons to Dava Sobel's "Longitude," but in my estimation Alder's story is the more compelling of the two. In fact, there is an additional similarity I would draw to Thomas Pynchon's fictional "Mason and Dixon," which likewise tells the story of two geographers traveling across perilous country to perform a measurement (or, in the case of Mason and Dixon, to draw boundaries). Of the two works, "The Measure of All Things" is the more readable account and no less poignant a story than that of Mason and Dixon.

Thirdly, from my perspective as a practicing scientist, Alder achieves yet more with this book. The tragic story of Mechain's horror regarding his perceived errors of measurement leads neatly into Alder's coda regarding the nature of error in measurement. Error analysis, now the staple of all science, was completely unknown in the time of Mechain, and consequently he was unable to perceive of the limitations of his own instrumentation and methods as the ultimate source of error. Instead, tormented by his sense of personal failure, Mechain drove himself to death in a misguided attempt to correct his mistakes. The pathos of this subplot transforms "The Measure of All Things" from a dry work of scholarship into the stunning work of literature that it is.

Anyone with an interest in science and history should find this book to be something special.

The author brings a day-to-day familiarity to the mission, filling in the historical details without the story becoming a dusty history lesson. Not being one particulary interested in European history, I was nonetheless pulled into the tale and thoroughly enjoyed it. The tale was entertaining, and it also introduces one to the concept of "precision" versus "accuracy".

Set against the upheaval in the aftermath of the French Revolution, Jean-Baptiste-Joseph Delambre and Pierre-Francois-André Méchain journeyed to measure the meridian of Paris from Dunkerque to Barcelona in 1792, little realising the time it would take. If like me, you do not understand the science of geodesy, this is still a very good read, and although the technical details of, for example, Borda's circle are given, this revolutionary (pun intended) piece of equipment can be appreciated from afar. The journeying enabled the metre to be defined, this being one ten-millionth of the distance from the North Pole to the equator, as extrapolated from the measurements of the meridian through France and into Spain. An unforeseen consequence was that the knowledge of the shape of the earth was changed forever by the measurements taken. Hitherto, it had been seen as a uniform, if oblate (fatter at the equator) sphere, if measured at the equator.

A reading of this work may raise lots of questions, for example about theories of measurement and error compensation (after all, geodesaic triangulation has to compensate for the curvature of the earth; the sum of the angles of a triangle may not equal 180º). It also speaks about the nature of science, and whether it is better to 'published and be damned', or to work and rework calculations ad infinitum. Of the two measurers, Méchain was haunted by his seemingly inconsistent results, and he wasted much time, and only published his results under duress. However, the everlasting legacy of their journey is the metre as defined by results. The fact that the measurement is now seen as "incorrect" is almost an incidental fact. (The metre is not as accurate as the 'provisional metre', adopted as an interim measure whilst the astronomers triangulated their way through France). More recent definitions of the metre keep the established and erroneous distance, redefining this special distance with respect to other basic units (now the distance that light can travel through a vacuum in a very small, precisely defined unit of time). Science can be based upon 'wrong' results, but it can still be very useful.

Measuring everything against a basic unit derived from nature was a laudable aim, probably a child of the enlightenment times. This coverage of the historical journey is very well researched, and shows that neither the intellectual nor the geographical journey was a straight line. You can travel with the author to discover more than just a story. It is more of a journey of how we journey. For serious students, there are ample source references to explore the subject further. Sources are often in French, but located in scientific or university libraries on both sides of the Atlantic.

Peter Morgan, Bath UK (morganp@supanet.com)