The process of surveying is a very repetitive one requiring an almost obsessive attention to detail, a commitment to exacting measurements, and above all a patient disposition. A quite laborious process, often involving measuring miles of territory in small 20 foot segments, it does not strike one as the most suitable subject for an exciting story.
However, Larrie D. Ferreiro's Measure of the Earth: The Enlightenment Expedition that Reshaped our World manages to be such a story. In documenting the first international scientific expedition to measure a degree of latitude at the equator, he recounts not only a scientific adventure filled with eccentric personalities but a mission that intersects with the politics, culture, and intellectual tenor of the time.
A joint Franco-Spanish expedition was tasked with traveling to Peru to measure accurately a degree of latitude at the equator. Comparing it with another measurement of latitude made in France would enable scientists to know the true shape of the world. An unlikely mix of adventurers, officers, and scientists were assembled to complete a task intended to take only three years. Instead, a difficult environment, caused as much by terrain as the personalities involved, extended the mission to a full ten years.
What best unlocks the nature of the book is its subtitle relating to the Enlightenment. Fundamentally, the scientific mission was designed to settle an ongoing academic debate regarding the shape of the world. To one side were the defenders of René Descartes and on the other the acolytes of Isaac Newton.
While Europeans had long known the shape of the earth they had yet to catalog its exact dimensions. Descartes believed the Earth was elongated at the poles giving it an egg-like shape while Newton thought the spin of the earth caused it to bulge at the equator and flatten at the poles. This debate highlighted the changes occurring in Enlightenment Europe both in the belief in human reason to unlock the mysteries of the universe and the growing professionalism of science.
Ferreiro brings us into the very 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 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.
Indeed, the French mission was giving funding and support by Comte de Maurepas Louis XV's minister of the navy and minister of colonies. Maurepas well understood advantages that would come with an accurate measurement of the earth which might give France the scientific advantage necessary to supplant British 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. These connections, between science and the politics of the day, are what the Measure of the Earth helps to illustrate.
Yet, Ferreiro's book is also about the expedition itself and he balances such intellectual issues with an almost intimate look at the members of the expedition. In doing so, he humanizes what might have been presented as a bland mission of cataloging measurements. This is, by far, the most colorful aspect of the narrative with such vignettes as expedition leader Louis Godin who spent 1,000 ecus ($27,000) of the expedition's funds on a diamond for his lover in Saint Dominque, or the expedition's surgeon, Jean Seniergues who, deeply enmeshed in a lover's quarrel, was killed after helping cause a riot at a bullfight in the town of Cuenca. These serve to highlight the quite eccentric cast of characters who were tasked with such an important mission.
Ironically, if there is a weakness to the book as a whole it is the attention to these figures. Having so well established the importance of this mission Ferreiro's cataloging of these misadventures, such as an entire chapter to the aforementioned surgeon, leaves the reader lost at times in terms of the overall expedition. With that said the painstaking nature of the endeavor, for example a full three years devoted to making astronomical observations to account for stellar aberration, meant that a compelling narrative could only be crafted through the personalities assembled for the expedition.
Upon returning the Europe Peirre Bouguer and Charles-Marie de La Condamine, two of the chief scientists on the mission, wrote memoirs recounting the mission. While not indicated the title of the book appears a blending of the titles of both memoirs: Figure of the Earth (Bourger) and Measure of the First Three Degrees of the Meridian (La Condamine). Beyond a potential allusion to these titles Ferreiro's book also straddles the two natures of these authors themselves. Bouguer achieved scientific acclaim and position in the Academy while La Coundamine "won" in public with his more exciting narrative Journal of the Voyage to the Equator becoming "the most recognized story of the Geodesic Mission."
Ferreiro succeeds in blending exciting narrative along with erudite science, including one of the most concise and clear descriptions of triangulation surveying I have encountered, leaving the reader 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, was 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 "meter" or one-ten-millionth of the distance between the North Pole and the Equator, would become the nearly universally adopted metric system.
Thus, the "winner" of the scientific debate fades from the narrative in the same way it did in reality as Measure of the Earth documents the far more interesting intersections of this mission to the science, intellectual ferment, politics, and culture of the times and the legacy of the mission itself.
