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"Measure of the Earth: The Enlightenment Expedition That Reshaped Our
World," Larrie D. Ferreiro, Basic Books, 2011.

"In the early eighteenth century, at the peak of the Enlightenment, an
unlikely team of European scientists and naval officers set out on the
world's first international, cooperative scientific expedition. Intent
on making precise astronomical measurements at the Equator, they were
poised to resolve one of mankind's oldest mysteries: the true shape of
the Earth.

"France and Spain organized a joint expedition to colonial Peru, Spain's
wealthiest kingdom. Armed with the most advanced surveying and
astronomical equipment, they would measure a degree of latitude at the
Equator, which when compared with other measurements would reveal the
shape of the world. But what seemed to be a straightforward scientific
exercise was almost immediately marred by a series of unforeseen
catastrophes, as the voyagers found their mission threatened by
treacherous terrain, a deeply suspicious populace, and their own hubris."

Among the "other measurements" was the expedition to Lapland where
surveyors determined the length of a degree in the Arctic. A chapter of
"The Mapmakers" (John Noble Wilford, 1981) tells the stories of both
expeditions. The work in Lapland was made miserable by intense cold in
winter and swarms of biting flies in summer. They (the surveyors, not
the flies) proceeded by triangulation, measuring a base line with wood
rods 10 meters long. The year after departure, chief of party Maupertuis
reported to the Royal Academy in Paris that the length of a degree was
definitely longer in the Arctic than in France, consistent with an
oblate (not prolate) Earth.

Conditions for the equatorial expedition were even worse. They had
departed from France in 1735, but it was not until 1744 that party
co-chief Pierre Bouguer stood before the Academy. By then, he and the
other chief, La Condamine, would not speak to each other. To make it
worse, after years of work the group in Peru learned that the Lapland
results had settled the prolate vs. oblate question. The disheartened
team nevertheless finished their survey. But we now know there was
significant error in the Lapland results. Had it been in the other
direction, the question may have remained open, to be settled by the
Peru expedition.

That's how Wilford tells the story. I just started the Ferreiro book.

   

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