The Measure of All Things by Ken Alder

Author:Ken Alder
Language: eng
Format: mobi, epub
Publisher: Free Press
Published: 0101-01-01T00:00:00+00:00

All that remained was to boil down those concatenated results into a single number: the meter. For the next few weeks, each commissioner calculated independently, using his own preferred method. The mathematician Legendre deployed refined calculations using ellipsoid geometry. The Dutch astronomer Jan Hendrik Van Swinden made use of traditional geodetic techniques. Delambre employed improved methods that he had recently published.

Borda was not present for these final calculations. The inventor of the repeating circle and the guiding force behind the meridian project did not live to see the meter become definitive. During Méchain’s final procrastination the old commander, after a long illness, died. In a pounding rain, a cortège of international savants bore his body up a muddy road for burial below Montmartre. His legacy was a conundrum.

As each savant completed his geodetic calculations, it became increasingly clear that the rumors were justified: something was wrong. The meridian results were shocking, unexpected, inexplicable. Against all odds, the meridian expedition had produced something unanticipated: genuine scientific novelty.

This had never been their intention. Delambre and Méchain had not been sent out to unearth new knowledge. They had been sent out to refine to a nicer degree of exactitude what was already known. But the world, they had now discovered, was more eccentric than anyone supposed. Was it a scandal, or a discovery?

According to the data gathered fifty years earlier in Peru and Lapland, and confirmed by Cassini III in France, the eccentricity of the earth was approximately 1/300—which is to say that the earth’s radius at the poles was 1/300 (or 0.3 percent) shorter than its radius at the equator. By contrast, Delambre and Méchain’s data for the arc from Dunkerque to Barcelona suggested that the eccentricity was 1/150, or twice as great. Even more startling, when the Commission plotted the curve tracked by the intervening “superfluous” latitude measures at Dunkerque, Paris, Evaux, Carcassonne, and Barcelona, they discovered that the surface of the earth did not even follow a regular arc, but shifted with every segment. It was a stunning discovery. But what did it mean?

The reversal clearly delighted Méchain. It was a vindication of sorts. His colleagues would now regret their refusal to let him triangulate as far as the Balearic Islands or take additional latitude measures. He took the experimentalist’s perverse joy in baffling his theoretical colleagues—Laplace most of all. He gloated that “the earth has refused to conform to the formulas of my mathematical colleagues, who have insisted until now, with absolute certainty, that it is a perfectly regular spheroid of revolution.” It was perhaps Méchain’s one true moment of joy in the entire expedition. It was also a moment of great discovery, as he wrote to his Carcassonne friends.

Our observations show that the earth’s curve is nearly circular from Dunkerque to Paris, more elliptical from Paris to Evaux, even more elliptical from Evaux to Carcassonne, then returns to the prior ellipticity from Carcassonne to Barcelona. So why did He who molded our globe with his hands not take more care .

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