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French Geodesic Mission

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The French Geodesic Mission was an 18th-century expedition to Ecuador carried out for the purpose of measuring the roundness of the Earth and measuring the length of a degree of longitude at the Equator. The mission was one of the first geodesic (or geodetic) missions carried out under modern scientific principles, and the first major international scientific expedition.


In the 18th century, there was significant debate in the scientific community, specifically in the French Academy of Sciences (Academie des sciences), as to whether the circumference of the Earth was greater around the Equator or around the poles. French astronomer Jacques Cassini held to the view that the polar circumference was greater. Louis XV, the King of France and the Academy sent two expeditions to determine the answer: one was sent to Lapland, close to the North Pole, under Swedish physicist Anders Celsius and French mathematician Pierre Maupertuis. The other mission was sent to Ecuador, at the Equator. Previous accurate measurements had been taken in Paris by Cassini and others.


The equatorial mission was led by French astronomers Charles Marie de La Condamine, Pierre Bouguer, Louis Godin and Spanish geographers Jorge Juan and Antonio de Ulloa. They were accompanied by several assistants, including the naturalist Joseph de Jussieu and Louis's cousin Jean Godin. They were joined in Ecuador by Ecuadoran geographer and topographer Pedro Maldonado. (Maldonado later traveled to Europe to continue his scientific work.)

Note: In the 18th century the nation of Ecuador did not yet exist. The area was under Spanish control and was called the Territory of Quito after the city of Quito. The fame brought to the region by the French Geodesic Mission appears to have influenced the adoption of the name, Republic of Ecuador when the country gained independence in 1830.

The Ecuadoran expedition left France in May 1735. They landed on the Caribbean coast in Colombia and traveled overland to Panama, then sailed to Ecuador. In Ecuador they split into three groups, traveling overland through rainforests, arriving in Quito, Ecuador, in June, 1736.

Bouguer, La Condamine, Godin and their colleagues measured arcs of the Earths curvature on the Equator from the plains near Quito to the southern city of Cuenca. These measurements enabled the first accurate determination of the size of the Earth and led to the establishment of the international metric system of measurement.

They completed their survey measurements by 1739, measuring the length of an arc of three degrees at the Equator. They did this in spite of earlier news that the expedition to Lapland led by Maupertuis had already finished their work and had proven that the Earth is oblate, i.e., flattened at the poles. However, problems with astronomical observations kept them in Ecuador several more years.

Bouguer returned first from the expedition, going overland to the Caribbean and then to France. La Condamine, along with Maldonado, returned by way of the Amazon River. Godin took a position as professor in Lima, where he helped rebuild the city after the devastating 1746 earthquake, and returned to Europe in 1751. Bouguer, La Condamine and the Spanish officers each wrote separate accounts of the expedition, which opened up European eyes to the exotic landscapes, flora and fauna of South America, and led directly to the great naturalist expeditions by Alexander von Humboldt and others.

Observations during the mission

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. Ulloa made a drawing of the ruins. [*]

The scientists witnessed two eruptions of the Cotopaxi volcano in 1743 and 1744. [*]

Expedition members first came across rubber tapping (and thus rubber), the discovery of the active form of quinine (anti-malarial agent) and the development of what became the Metric System for units of measure.

Subsequent Mission

In the late 19th century, the Academy of Sciences sent another mission to Ecuador to confirm the results of the First Geodesic Mission. This second mission was led by General Charles Perrier.


Relacion historica del viaje a la America meridional, Jorge Juan and Ulloa, 1748

Figure de la terre determine, Bouguer, 1749

Journal du voyage, La Condamine, 1751


Two reproductions of the pyramids that marked the baseline for meaurement at Yaruqui (which had been destroyed in the 1740s) were erected in 1836, the centennial of the expedition. Newer monuments went up in 1986. The new Quito international airport will open on the site in 2009, and will contain a museum that will display information on the Gedoesic Mission.

In 1936, the French American Committee of Ecuador sponsored the idea of the Ecuadoran geographer Dr. Luis Tufino and raised a monument commemorating the bicentennial of the arrival of the First Geodesic Mission. They raised a 10-meter-high monument at Mitad del Mundo in San Antonio de Pichincha, in Pichincha Province of Ecuador. However, there is no record that the Mission ever visited the area.

See also


History of geodesy


Mitad del Mundo Half of the World: First Geodesic Mission

Geography, by David A. Neill

Jacques Cassini

Jacques Cassini

History of San Agustin de Callo

Historic Cultural and Scientific Expeditions to Equator and Ecuador...

Historical Brief Description of the Middle of the World and Its Monument

BBC Video. Voyages of Discovery: Figure of the Earth. (Part 1 of 2)

BBC Video. Voyages of Discovery: Figure of the Earth. (Part 2 of 2)

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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article French Geodesic Mission