Excerpt from The Measure of All Things by Ken Alder, plus links to reviews, author biography & more

According to today's satellite surveys, the length of the meridian from the pole to the equator equals 10,002,290 meters. In other words, the meter calculated by Delambre and Méchain falls roughly 0.2 millimeters short, or about the thickness of two pages of this book. It may not seem like much, but it is enough to feel with your fingers, enough to matter in high-precision science, and in that slender difference lies a tale of two men sent out in opposite directions on a Herculean task -- a mission to measure the world -- who discovered that integrity could carry them in directions as contrary as their carriages. Both were men in their mid-forties, men of humble origins from the French provinces who had risen to prominence on the basis of talent and a mind-numbing capacity for work. Both had been trained by the same astronomer, Jérôme Lalande, and elected to the Academy of Sciences in time for the Revolution to hand them the career opportunity of a lifetime: the chance to sign their names to the world's measure. But during their seven years of travels, the two men came to have a different understanding of their metric mission and the allegiance it commanded. That difference would decide their fates.

This then is a tale of error and its meaning: how people strive for utopian perfection -- in their works and in their lives -- and how they come to terms with the inevitable shortcomings. What does it feel like to make a mistake, and in a matter of such supreme importance? Yet even in failure, Delambre and Méchain succeeded, for by their labor they rewrote not only our knowledge of the shape of the earth, but our knowledge of error as well. In the process, scientific error was transformed from a moral failing into a social problem, forever altering what it meant to be a practicing scientist. And the consequences of their labor resonated far outside the realm of science. We can trace the impact of their work in the globalization of economic exchange, and in the way ordinary people have come to understand their own best interest. In the end, even the French countryside they traversed has been transformed.

To come to terms with this history, I set out to retrace their journey. In the year 2000, at a time when France was celebrating the millennium along the Meridienne Verte -- a six-hundred-mile row of evergreen trees which was meant to mark out the national meridian, but which was somehow never planted -- I set out on the zigzag trail of Delambre and Méchain. I climbed the cathedral towers and mountain peaks from which they conducted their survey, and combed the provincial archives for traces of their passage. It was my own Tour de France. Delambre and Méchain had demonstrated that the judicious application of scientific knowledge might, as Archimedes once boasted, move the world. Where they traveled by carriage and on foot, I substituted a bicycle. After all, what is a bicycle but a lever on wheels? -- a lever which allows the cyclist to move along the surface of the world, or, which is much the same thing, move the world.

Copyright © 2002 by Ken Alder.