The French Geodesic Mission to the Equator (french: Expédition géodésique française en Équateur, also called the French Geodesic Mission to Peru and the Spanish-French Geodesic Mission) was an 18th-century expedition to what is now

Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ' ...

carried out for the purpose of performing an

arc measurement Arc measurement, sometimes degree measurement (german: Gradmessung), is the astrogeodetic technique of determining of the radius of Earth – more specifically, the local Earth radius of curvature of the figure of the Earth – by relating the la ...

, measuring the length of a degree of

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north ...

near the

Equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can also ...

, by which the

Earth radius Earth radius (denoted as ''R''🜨 or R_E) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid, the radius ranges from a maximum of nearly (equatorial radius, den ...

can be inferred. The mission was one of the first

geodesic In geometry, a geodesic () is a curve representing in some sense the shortest path ( arc) between two points in a surface, or more generally in a Riemannian manifold. The term also has meaning in any differentiable manifold with a connecti ...

(or ''geodetic'') missions carried out under modern scientific principles, and the first major international scientific expedition.

Background

In the 18th century, there was significant debate in the scientific community, specifically in the

French Academy of Sciences The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at ...

(''Académie 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 Louis XV (15 February 1710 – 10 May 1774), known as Louis the Beloved (french: le Bien-Aimé), was King of France from 1 September 1715 until his death in 1774. He succeeded his great-grandfather Louis XIV at the age of five. Until he reache ...

, the

King of France France was ruled by monarchs from the establishment of the Kingdom of West Francia in 843 until the end of the Second French Empire in 1870, with several interruptions. Classical French historiography usually regards Clovis I () as the fir ...

and the academy sent two expeditions to determine the answer: one was sent to

Meänmaa (), or sometimes Torne Valley or Torne River Valley ( fi, Tornionlaakso; sv, Tornedalen) lies at the border of Sweden and Finland. It is named after the Torne River flowing through the valley and into the Gulf of Bothnia. Geographically the tow ...

in Lapland, close to the

Arctic Circle The Arctic Circle is one of the two polar circles, and the most northerly of the five major circles of latitude as shown on maps of Earth. Its southern equivalent is the Antarctic Circle. The Arctic Circle marks the southernmost latitude at ...

, under Swedish physicist

Anders Celsius Anders Celsius (; 27 November 170125 April 1744) was a Swedish astronomer, physicist and mathematician. He was professor of astronomy at Uppsala University from 1730 to 1744, but traveled from 1732 to 1735 visiting notable observatories in Germ ...

and French mathematician Pierre Maupertuis. The other mission was sent to Ecuador, at the Equator. Previous accurate measurements had been taken in

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. Si ...

by Cassini and others.

Expedition

The equatorial mission was led by French

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

Charles Marie de La Condamine Charles Marie de La Condamine (28 January 1701 – 4 February 1774) was a French explorer, geographer, and mathematician. He spent ten years in territory which is now Ecuador, measuring the length of a degree of latitude at the equator and p ...

Pierre Bouguer Pierre Bouguer () (16 February 1698, Croisic – 15 August 1758, Paris) was a French mathematician, geophysicist, geodesist, and astronomer. He is also known as "the father of naval architecture". Career Bouguer's father, Jean Bouguer, one ...

Louis Godin Louis Godin (28 February 1704 – 11 September 1760) was a French astronomer and member of the French Academy of Sciences. He worked in Peru, Spain, Portugal and France. Biography Godin was born in Paris; his parents were François Godin and Eli ...

and Spanish

geographer A geographer is a physical scientist, social scientist or humanist whose area of study is geography, the study of Earth's natural environment and human society, including how society and nature interacts. The Greek prefix "geo" means "earth" a ...

s Jorge Juan and

Antonio de Ulloa Antonio de Ulloa y de la Torre-Giralt, FRS, FRSA, KOS (12 January 1716 – 3 July 1795) was a Spanish naval officer, scientist, and administrator. At the age of nineteen, he joined the French Geodesic Mission to what is now the countr ...

. They were accompanied by several assistants, including the naturalist

Joseph de Jussieu Joseph de Jussieu (3 September 1704 – 11 April 1779), was a French botanist and explorer, member of the Jussieu family. He introduced the common garden heliotrope ('' Heliotropium arborescens'') to European gardeners. He was born in Lyon, and ...

and Louis's cousin Jean Godin. La Condamine was joined in his journey down the

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...

by Ecuadoran geographer and

topographer Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sci ...

Pedro Maldonado. (Maldonado later traveled to Europe to continue his scientific work.) The Ecuadoran expedition left

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

in May 1735. They landed on the

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean ...

coast in

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the ...

, sailed to

Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...

where they traveled overland to the Pacific, and continued by sail to Ecuador, then called the ''Territory of Quito'' by Spain. In Ecuador, they split into two groups, traveling overland through rain forests, arriving in

Quito Quito (; qu, Kitu), formally San Francisco de Quito, is the capital and largest city of Ecuador, with an estimated population of 2.8 million in its urban area. It is also the capital of the province of Pichincha. Quito is located in a valley on ...

in June 1736.

established the length of a

pendulum A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward th ...

beating seconds on the Equator at

, near Quito at the top of Pinchincha, and at sea level to determine

gravity of Earth The gravity of Earth, denoted by , is the net acceleration that is imparted to objects due to the combined effect of gravitation (from mass distribution within Earth) and the centrifugal force (from the Earth's rotation). It is a vector quant ...

. La Condamine had a marble plaque prepared, with a bronze exemplar ''(varilla metalica)'' of the length of such a pendulum set into it, which he presented to the Jesuit College of San Francisco in Quito in 1742, engraved with an inscription reading: ''Penduli simplicis aequinoctialis, unius minuti secundi temporis medii, in altitudine Soli Quitensis, archetypus (mensurae naturalis exemplar, utinam et universalis)'' Archetype of the equinoctial simple pendulum, of one second of a minute of mean time at the latitude of Quito (a natural and, may it be, a universal model of measure)" The plaque is now in the Observatorio Astronómico in the Parque La Alameda. Bouguer, La Condamine, Godin and their colleagues measured arcs of the Earth's curvature on the Equator from the plains near Quito to the southern city of Cuenca. These measurements enabled the first accurate determination of the shape of the Earth, eventually leading to the establishment of the international

metric system The metric system is a system of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s. The historical development of these systems culminated in the definition of the Intern ...

of measurement. When an International Commission for Weights and Measures was convened in Paris to settle the true length of the

metre The metre ( British spelling) or meter ( American spelling; see spelling differences) (from the French unit , from the Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its pre ...

, it adopted on 22 June 1799 a standard metre based on the length of the half meridian connecting the North Pole with the Equator. The

had commissioned an expedition led by

Jean Baptiste Joseph Delambre Jean Baptiste Joseph, chevalier Delambre (19 September 1749 – 19 August 1822) was a French mathematician, astronomer, historian of astronomy, and geodesist. He was also director of the Paris Observatory, and author of well-known books on t ...

and

Pierre Méchain Pierre François André Méchain (; 16 August 1744 – 20 September 1804) was a French astronomer and surveyor who, with Charles Messier, was a major contributor to the early study of deep-sky objects and comets. Life Pierre Méchain was born i ...

, lasting from 1792 to 1799, which attempted to accurately measure the distance between a belfry in

Dunkerque Dunkirk (french: Dunkerque ; vls, label=French Flemish, Duunkerke; nl, Duinkerke(n) ; , ;) is a Communes of France, commune in the Departments of France, department of Nord (French department), Nord in northern France.

and Montjuïc castle in

Barcelona Barcelona ( , , ) is a city on the coast of northeastern Spain. It is the capital and largest city of the autonomous community of Catalonia, as well as the second most populous municipality of Spain. With a population of 1.6 million within c ...

at the

longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek let ...

of Paris Panthéon. This portion of the

Paris meridian The Paris meridian is a meridian line running through the Paris Observatory in Paris, France – now longitude 2°20′14.02500″ East. It was a long-standing rival to the Greenwich meridian as the prime meridian of the world. The "Paris meri ...

was to serve as the basis for the length of the half meridian connecting the

North Pole The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface. It is called the True North Pole to distinguish from the Ma ...

with the Equator. The metre was defined as the ten-millionth of the half meridian's length extrapolated from an Earth's flattening of 1/334 obtained from the results of the survey by

Delambre Jean Baptiste Joseph, chevalier Delambre (19 September 1749 – 19 August 1822) was a French mathematician, astronomer, historian of astronomy, and geodesist. He was also director of the Paris Observatory, and author of well-known books on t ...

and Méchain combined with those of the Peru

meridian arc In geodesy and navigation, a meridian arc is the curve between two points on the Earth's surface having the same longitude. The term may refer either to a segment of the meridian, or to its length. The purpose of measuring meridian arcs is to ...

as established by La Condamine and his colleagues. They completed their survey measurements by 1739, measuring the length of a

of three degrees at the Equator. They did this in spite of earlier news that the expedition to Lapland led by

Maupertuis Pierre Louis Moreau de Maupertuis (; ; 1698 – 27 July 1759) was a French mathematician, philosopher and man of letters. He became the Director of the Académie des Sciences, and the first President of the Prussian Academy of Science, at the ...

had already finished their work and had proven that the Earth is

oblate In Christianity (especially in the Roman Catholic, Orthodox, Anglican and Methodist traditions), an oblate is a person who is specifically dedicated to God or to God's service. Oblates are individuals, either laypersons or clergy, normally liv ...

; ''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

and then to France. La Condamine, along with Maldonado, returned by way of the

Amazon River The Amazon River (, ; es, Río Amazonas, pt, Rio Amazonas) in South America is the largest river by discharge volume of water in the world, and the disputed longest river system in the world in comparison to the Nile. The headwaters of t ...

. Godin took a position as professor in

Lima Lima ( ; ), originally founded as Ciudad de Los Reyes (City of The Kings) is the capital and the largest city of Peru. It is located in the valleys of the Chillón, Rímac and Lurín Rivers, in the desert zone of the central coastal part of ...

, 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 Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a German polymath, geographer, naturalist, explorer, and proponent of Romantic philosophy and science. He was the younger brother of the Prussian minister ...

and others. La Condamine tried in vain to promote the length of the

seconds pendulum A seconds pendulum is a pendulum whose period is precisely two seconds; one second for a swing in one direction and one second for the return swing, a frequency of 0.5 Hz. Pendulum A pendulum is a weight suspended from a pivot so that ...

measured at the Equator as a universal measure of length. He was more successful with his proposal to adopt the geodetic standard used in Peru as the official standard of the

toise A toise (; symbol: T) is a unit of measure for length, area and volume originating in pre-revolutionary France. In North America, it was used in colonial French establishments in early New France, French Louisiana (''Louisiane''), Acadia (''Acadi ...

of Paris. The toise of Peru became the royal standard of the

in 1766 under the name ''Toise de l'Académie''.

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 Cotopaxi () is an active stratovolcano in the Andes Mountains, located in Latacunga city of Cotopaxi Province, about south of Quito, and northeast of the city of Latacunga, Ecuador. It is the second highest summit in Ecuador, reaching a h ...

volcano in 1743 and 1744. * Expedition members, through talking to local inhabitants, became the first Europeans to discover and scientifically document

rubber tapping Rubber tapping is the process by which latex is collected from a rubber tree. The latex is harvested by slicing a groove into the bark of the tree at a depth of with a hooked knife and peeling back the bark. Trees must be approximately six years ...

(and thus

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and ...

), and identify the correct type of

cinchona ''Cinchona'' (pronounced or ) is a genus of flowering plants in the family Rubiaceae containing at least 23 species of trees and shrubs. All are native to the tropical Andean forests of western South America. A few species are reportedly nat ...

tree that produces the active form of

quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to '' Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...

(an important anti-malarial agent). * Charles Marie de La Condamine developed the concept of the

as a universal unit of measure based on the dimensions of the Earth (rather than local standards that differed and hindered trade).

Subsequent mission

In the late 19th century, the Academy of Sciences sent another mission to Ecuador at the behest of the

International Association of Geodesy ) , merged = , successor = , formation = , founder = , founding_location = , extinction = , merger = , type = scholarly society , tax_id ...

to confirm the results of the First Geodesic Mission and commemorate the relationship between the two republics. This second mission was led by Captain E. Maurain and several other military personnel during its tenure in Ecuador from 1901 to 1906. The only two members of the French mission to spend the entire time in Ecuador were Lieutenant (later General) Georges Perrier and medical officer

Paul Rivet Paul Rivet (7 May 1876, Wasigny, Ardennes – 21 March 1958) was a French ethnologist known for founding the Musée de l'Homme in 1937. In his professional work, Rivet is known for his theory that South America was originally populated in pa ...

, later an important

anthropologist An anthropologist is a person engaged in the practice of anthropology. Anthropology is the study of aspects of humans within past and present societies. Social anthropology, cultural anthropology and philosophical anthropology study the norms an ...

and founder of the

Musée de l'Homme The Musée de l'Homme (French, "Museum of Mankind" or "Museum of Humanity") is an anthropology museum in Paris, France. It was established in 1937 by Paul Rivet for the 1937 ''Exposition Internationale des Arts et Techniques dans la Vie Moderne ...

in Paris.

Monument

A reproduction of the pyramids that marked the baseline for measurement at Yaruqui (which was destroyed by Quito authorities in the 1740s) was erected in 1836, the centennial of the expedition, by the Rocafuerte administration of the nascent republic of Ecuador. This monument fell into disrepair over the next century but was rebuilt in 1936, minus its original French inscription, for the bicentennial of the first geodesic expedition, along with a second pyramid at San Antonio de Pichincha on the Equator. These monuments still exist today. The new Quito International Airport opened in the Yaruqui Valley. Though talks of having a mural celebrating the Geodesic Mission took place during planning stages, no acknowledgement of the scientific importance of this site currently exists. In 1936, the French American Committee of Ecuador sponsored 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 10-meter-high

monument A monument is a type of structure that was explicitly created to commemorate a person or event, or which has become relevant to a social group as a part of their remembrance of historic times or cultural heritage, due to its artistic, hist ...

at Ciudad Mitad del Mundo in San Antonio de Pichincha, in

Pichincha Province Pichincha () is a province of Ecuador located in the northern Sierra region; its capital and largest city is Quito. It is bordered by Imbabura and Esmeraldas to the north, Cotopaxi and Santo Domingo de los Tsáchilas to the south, Napo and ...

of Ecuador. However, there is no record that the Mission ever visited the area. There is a project to build a new pyramid exactly on the Equator, to be designed by famed architect Rafael Viñoly.

Publications

*''Relación histórica del viaje a la América meridional'', Jorge Juan and Ulloa, 1748 *''Figure de la terre determine'', Bouguer, 1749 *''Journal du voyage'', La Condamine, 1751 *''Le procès des étoiles'', 1735–1771, ,

Background

Expedition

Observations during the mission

Subsequent mission

Monument

Publications

See also

Footnotes

References

Further reading