The French Geodesic Mission to the Equator
On one visit to Ecuador, I crossed the Equator six times in one trip, and that does not count flying over it. This imaginary line that circles the Earth at 0 degrees latitude, divides it into the Northern and Southern hemispheres. This line is important for navigation and climate, and we take it for granted today. Back in the early 1,700’s is the fascinating story of the French Geodesic Mission to the Equator. This was a groundbreaking 18th-century expedition that combined scientific curiosity, international collaboration, and daring exploration.
The Quest for Earth’s Shape
In the age of enlightenment, the scientific community grappled with a fundamental question: Was the Earth’s circumference greater around the Equator or the poles? French astronomer Jacques Cassini championed the view that the polar circumference was larger. To settle this debate, Louis XV of France and the French Academy of Sciences dispatched two expeditions—one to the Arctic Circle in Lapland and the other to South America, right at the Equator.
The Equatorial Mission
Led by French astronomers Charles Marie de La Condamine, Pierre Bouguer, and Louis Godin, along with Spanish geographers Jorge Juan and Antonio de Ulloa, the French Geodesic Mission set sail from France in May 1735. Their destination: the mountainous landscapes of Ecuador, then known as the Territory of Quito under Spanish rule. La Condamine afterwards travelled down the Amazon together with Ecuadoran geographer and topographer Pedro Maldonado.
The Journey
After landing on the Caribbean coast in Colombia, the team sailed to Panama. From there, they embarked on an overland journey to the Pacific coast. Splitting into two groups, they trekked through dense rainforests, encountering exotic flora and fauna. Their arrival in Quito in June 1736 marked a pivotal moment in scientific exploration.
Scientific Endeavours
Arc Measurement: The primary objective was to measure an arc of the Earth’s surface near the Equator. By determining the length of a degree of latitude, they could infer the Earth’s radius. This mission laid the groundwork for modern geodesy. Their measurements enabled the first accurate determination of the shape of the Earth, eventually leading to the establishment of the international metric system of measurement. They also proved that the earth is oblate, i.e. flattened at the poles.
Pendulum Length: Pierre Bouguer meticulously established the length of a pendulum beating seconds at various altitudes: at sea level, atop the Pichincha Mountain near Quito, and precisely on the Equator. These measurements helped determine the local gravity.
Marble Plaque: La Condamine commemorated their achievements with a marble plaque. Embedded within it was a bronze exemplar of the pendulum’s length. The plaque, presented to the Jesuit College of San Francisco in Quito.
Other observations: Ulloa and Juan visited the architectural Inca complex in San Agustin de Callo and subsequently wrote a descriptive document of what they observed at the ruins. Today a hacienda and small hotel can be visited here. The scientists witnessed two eruptions of the Cotopaxi volcano in 1743 and 1744. By talking to local inhabitants, expedition members became the first Europeans to discover and scientifically document rubber tapping and identify the correct type of cinchona tree that produces the active form of quinine (an important anti-malarial drug). They opened European eyes to the exotic landscapes, flora and fauna of South America and led to the great naturalist expeditions by Alexander von Humboldt and others.
Problems encountered: From the start things went wrong. The locals regarded them with suspicion. They were stoned by an angry mob near Quito, their doctor was murdered after a disagreement over a woman, their botanist had mental health issues, even a senior member Godin, ran off with a young girl. Others died of fever and other ills. The mountainous geography, instead of giving them clear sights was often shrouded in mist. La Condamine and Bouguer were tenacious and after ten years completed the task. However, they no longer spoke to each other and returned separately to France.
Legacy and Impact
The French Geodesic Mission to the Equator remains a milestone in scientific history. It not only resolved the Earth’s shape debate but also exemplified international cooperation. The courage of these explorers, their meticulous measurements, and their enduring legacy continue to inspire scientists and adventurers alike. The fame brought to the region by the French Geodesic Mission influenced the adoption of the name Republic of Ecuador when the country gained independence in 1830.
In 1936, the French American Committee of Ecuador took the idea of the Ecuadoran geographer Dr. Luis Tufiño and raised a monument commemorating the bicentennial of the arrival of the First Geodesic Mission. They raised a monument at Ciudad Mitad del Mundo in San Antonio de Pichincha, in Pichincha Province. However, there is no record that the Mission ever visited the area. Today many tourists flock to this monument daily, taking photographs astride the Equator line. Recent GPS data shows line is about 200 metres away. Another tourist attraction Inti-Ñan has been created by locals, allegedly closer to the real spot. Here they perform experiments to show the effects of gravity on the equator, such as balancing an egg on a nail. These are entertaining, but hardly scientific.
You can visit both these attractions on any tour to Quito with Select Latin America.