THE MEASURE OF THE WORLD

After his fine romp-cum-history-of-mathematics (The Parrot’s Theorem, p. 889), Guedj brings us another science-novel, this one set during the French Revolution and telling how the metric system came to be.

Based on reason (and wild excesses of same), the Revolution occurred in an age that craved the universal, ideal, and absolute. Little wonder, then—when “seven or eight hundred different units of measurement” were in use—that the revolutionists set out not just to end the monarchy but to unify weights and measures once and for all. Nor is it surprising, either, that they based their thinking not on something artificial or made up, but that “they chose the earth itself as the standard—the earth, shared by all men, invariable, and universal.” In short, they would measure the earth’s quarter meridian, divide by ten million, and—presto!—the meter would exist. With scrupulous detail and passionate attentiveness, Guedj follows the two scientists appointed to the huge task of measurement—Pierre Méchain and Jean-Baptiste Delembre—as they go on their individual six-year odysseys, one starting in Barcelona and measuring north, the other in Dunkirk and measuring south. These real-life scientists will indefatigably climb mountains and bell towers to take endless sightings with the newly invented and incredibly accurate “repeating circle”; will be imprisoned, threatened by mobs, struck by injury—and even persecuted by the Terror itself during their 1792–98 labors, all the while discoursing with the likes of Lavoisier, Condorcet, Borda, d’Alembert, and Laplace. Patience can be helpful as the increments of narrative tick by, but rewards are plentiful, too, in seeing the Revolution, for example, from these scientists’ unusual vantage, or in living through the nightmarish possibility that the entire great project might crumble due to a single mismeasurement back at the very beginning.

“Seldom has history been so inextricably intertwined with the history of science,” comments Guedj. And seldom have such interesting books as his come from that union.