Book Review: Measure of the Earth

I picked this book up in Ireland a few years ago, at Charlie Byrne’s used bookshop in Galway. I read it then, and I reread it recently – mostly because it’s a rollicking good read, but also because it is such an astonishing academic achievement. An American, author Larrie Ferreiro completed his Ph.D. at Imperial College London in 2004.

Since ancient times, intellectuals had known that the planet was essentially spherical. However, in the 18th century debate began to rage over whether it might bulge at the equator or be somewhat elongated at the poles. There were two possibilities. One was that the world was like an exercise ball with someone sitting on it. The other was that the planet was a bit like an egg standing upright in its carton.

While Europeans had long known the shape of the earth, they had yet to catalog its exact dimensions. Also, there were disputes about its shape. That is the reality of the book’s full title: Measure of the Earth: The Enlightenment Expedition that Reshaped the World. Fundamentally, this work is about an Enlightenment-era scientific mission designed to settle an academic debate regarding the shape of the world. On one side were the defenders of René Descartes; on the other, those of Isaac Newton. Descartes believed the Earth was elongated at the poles, giving it an egg-like shape. Newton thought the spin of the earth caused it to bulge at the equator and flatten at the poles.

Isaac Newton had argued for a bulging equator – an idea consistent with his revolutionary theories about gravitation. From today’s perspective, the controversy may seem trivial or even nationalistic: just another quarrel among philosophers and scientists over a trifle, or one of the endless quarrels between France and Britain over almost anything.

Yet without knowing the shape of the Earth in some detail, you couldn’t reliably determine geographical location. Navies couldn’t navigate with precision, land surveyors would be inaccurate in their calculations, and explorers might go astray.

Ferreiro takes us into the halls of the French Academy of Sciences where careers were made, and lost, over this debate. But, this was not merely a dry academic question. While the men of letters at the French Academy and the British Royal Society could overlook political differences in the name of science, government and military officials were well aware that the shape of the earth was of grave importance – so much so that the French mission was giving funding and support by Comte de Maurepas, King Louis XV’s minister of the navy and minister of colonies.

Maurepas well understood the advantages that would come with an accurate measurement of Earth: It might give France the scientific advantage necessary to unseat Britain’s sea power. It is no surprise that at the same time the British were offering £20,000 to whoever could claim the “Longitude Prize” and enable an accurate measurement of longitude at sea. Measure of the Earth helps to illustrate these and other connections between science and the politics of the day.

To resolve matters, the French and Spanish joined forces in the first international scientific expedition. A team sympathetic to Newton’s view would measure the exact length of a degree of latitude near the equator. This would then be compared with the same measurement taken in France. If A longer measurement at the equator would prove Newton right.

Ferreiro has produced an astonishingly detailed account of the so-called Geodesic Mission and its importance. He has mined all the sources, visited the key sites, balanced conflicting historical documents and memoires, and produced a book that is gripping, authoritative and balanced. He describes this expedition — despite the frequent foolishness and ineptitude of its members — as one of the great scientific adventure stories of the 18th and early 19th centuries.

It “inaugurated a spate of large-scale international scientific expeditions that rewrote our understanding of the planet,” he writes. “It gave us the concept of South America as a unique place, separate from its mother country of Spain, which would eventually give birth to the new nations of Latin America.” His footnotes reference works in French, Spanish and English. To write the book, the author went to every place visited by the original team members – both in France and Spain and in Latin America.

The 1735 Geodesic Mission to the equator mainly consisted of three mismatched French savants and a pair of Spanish naval officers. Gathering together everything that can be known about the mission, Ferreiro shows how the ideals of science may even be realized by flawed human beings – in this case, a team that took nearly a decade to complete a project that shouldn’t have needed more than three years.

The mission leader was the ambitious Louis Godin, who lacked every possible management skill. He was arrogant and absolutist, kept crucial information to himself, and spent the expedition’s government money with abandon – a good deal of it on a prostitute with whom he’d grown infatuated. (Godin spent the equivalent of US$27,000 of the expedition’s funds on a diamond for his lover.) These serve to highlight the quite eccentric cast of characters who were tasked with such an important mission.

Another Frenchman was the polar opposite. Charles-Marie de La Condamine was a worldly and wealthy friend of Voltaire, as much an adventurer as a scientist and one of those men whose actions regularly combined “curiosity, bravery, and sheer idiocy.” Because of Godin’s squandering, La Condamine ended up using his personal wealth to fund much of the expedition. A third Frenchman, Pierre Bouguer, had not really wanted to join the expedition in the first place. Eventually, he became its de facto chief.

After months of difficulties and delays on the island of Santa Domingo, the French group was joined by two Spanish naval officers: Jorge Juan y Santacilia and Antonio de Ulloa y de la Torre-Guiral. Ferreiro clearly admires these young men for their quiet professionalism. They were capable engineers, expert swordsmen, deeply sympathetic to the native peoples and openly outraged by colonial atrocities. The two friends would eventually go on to distinguished maritime and diplomatic careers, and are still venerated by the Spanish navy. Since 1851, Spain has named three pairs of warships after them.

Eventually, the full team reached its destination, the city of Quito. Following further squabbles and reversals, the scientists, along with their servants and slaves, finally began their measurements. They first created a baseline, “an absolutely straight path, seven miles long and just eighteen inches wide.” Then, on the slopes of the nearby mountains and volcanoes of the Andes, they erected “large pyramids of timber, straw, and fabric, whitewashed with lime and lye, to make signals that could be clearly seen through a telescope, even at thirty miles’ distance.” Using these pyramids — and sometimes just their large tents — as focal points, they gradually calculated the dimensions of a chain of gigantic interlocking triangles running south along the Andes. This triangulation reached slightly more than 200 miles to the city of Cuenca.

Nothing went smoothly. Frequent cloud cover impaired accuracy during key sightings. The group suffered from altitude sickness, dysentery and malaria (the latter cured by quinine from the cinchona tree, which the scientists studied), hostile colonial administrators, lack of funding, and internal strife. At one point, a riot erupted at a local bullfight. The expedition’s surgeon, Jean Seniergues, also became involved in a lover’s quarrel. He was beaten and stabbed after helping cause a riot at a bullfight in the town of Cuenca, and died of his wounds.

After war broke out between England and Spain, and British naval forces ravaged the nearby seaports, the two Spaniards were ordered to provide military leadership and assistance. Despite such complications, the team eventually completed its setup and, using an instrument called a sector, made a series of simultaneous celestial observations and calculations. These determined that the length of a degree of latitude at the equator was 68.7 miles. This, Ferreiro says, is “within fifty yards of the modern accepted value.” The result proved that “the length of a degree of latitude shortened considerably toward the equator, as a result of its bulging out from the axis.” The expedition had confirmed that the planet was an “oblate spheroid,” and that Newton was right.

You may have wondered why, when we fly from Western Canada to London, say, the flight goes to higher latitudes, and we can usually look down into Greenland. The reason is that the planet is an oblate spheroid. Because that is so, the flight is shorter if we take a northerly route.

When the pair eventually returned to France, both were fêted by their scientific colleagues. La Condamine’s action-packed Abridged Relation of a Voyage Made in the Interior of South America soon became an international bestseller. Bouguer read his memoirs of the expedition to the French Academy of Sciences and to other audiences over the next seven months. This account – it was a bit “self-serving,” Ferreiro notes, “a narrative of arduous toil under grueling conditions in the noble cause of science” – essentially became the official account of the Geodesic Mission.

“By publishing less scientific, more popular accounts of the Geodesic Mission’s exploits,” Ferreiro writes, “La Condamine was also pulling back the curtain on the previously veiled kingdom of Peru, which in those days was a generic name for much of Spanish South America. Plays, operas, ballets and novels featuring Aztec and Peruvian themes began sprouting up….At the same time that he was transforming the expedition’s travels into a thrilling narrative adventure, he devoted considerable effort to producing a comprehensive atlas of the audience you of Quito….The finished Atlas was released to public acclaim, coming at a time when European society was transfixed by all things Peruvian.”

La Condamine’s published works were so successful, I think, because he was a born writer. Ferreiro illustrates by quoting this passage from his field notes.

The higher I climbed the more the jungle cleared; soon I saw only sand, and higher up naked and calcified boulders which bordered the northern edge of the volcano of Pichincha. Having reached the highest point of the edge I was seized by a sense of wonder mixed with admiration, and the appearance of a large valley five to six leagues wide, interspersed with streams which joined together: I saw, as far as my eye could see, cultivated lands, divided between planes and prairies, green spaces, villages, and towns surrounded by hedges and gardens: the city of Quito, far-off, was at the end of this beautiful view. I felt as if I had been transported to the most beautiful of provinces in France, and as I descended I felt the imperceptible change in climate going from extreme cold to the temperature of the most useful days in May. Each instance I added to my surprise; I saw, for the first time, flowers, and send fruit in the middle of the countryside on all of the trees. I saw people planting, laboring and harvesting all on the same date and in the same place. I have let myself become carried away by the memory of the first impression I had, quite forgetting that this [Journal] is only a place for recounting our academic work.

Godin – the man who invested so much of the mission’s money on a prostitute – knew he had ruined his career in France, so stayed behind when the rest of the mission began heading home. Later, after a huge earthquake and an accompanying tsunami, he partially redeemed himself by overseeing the reconstruction of Lima. In this work, he greatly benefited from his experience as a surveyor. According to Ferreiro, under his guidance “Lima was transformed into one of the most gracious cities in South America.… The city’s architecture also became more modern and secular, with churches and monasteries giving way to civic buildings like theaters, and with prayer rooms in private homes being converted to French-style salons. “

Ferreiro combines exciting narrative with good science, including clear descriptions of the use of triangulation in surveying. Personally, I felt both educated and entertained. While the debate had largely pitted French and English scholars against one another, it was a sign of the growth of a scientific mindset how readily the findings of the mission, which proved Newton correct, were readily accepted. The Geodesic mission to Peru was just the beginning of greater cooperation among scientists to form a more accurate measure of the earth. The end result of this process would be a command from the French National Constituent Assembly to form a new set of measurements to replace those used by the old regime. What they decided, based around a “metre” or one-ten-millionth of the distance between the North Pole and the Equator, would become the basis of the metric system.

Thus, the “winner” of the scientific debate fades from the narrative in the same way it did in reality. Besides recounting the legacy of this extraordinary mission, Measure of the Earth documents the intersections between this mission and the science, intellectual ferment, politics, and culture of the Enlightenment itself.

To sum up, Measure of the Earth documents the first international scientific expedition to measure a degree of latitude at the equator. In doing, it recounts not only a scientific adventure filled with eccentric personalities, but a mission that intersects with the politics, culture, and intellectual mood of the time. One of the outcomes of this work is ironic. So famous was this scientific expedition that, after its rebellion against Spain and nearly a century of ultimately successful nation building, the country named itself República del Ecuador, which translates as “Republic of the Equator.”