There is significant debate in the scientific community, specifically in the French Academy of Sciences (Académie des sciences), as to whether the circumference of the Earth is greater around the Equator or around the poles.

French astronomer Jacques Cassini holds to the view that the polar circumference is greater.

Louis XV, the King of France, and the Academy send two expeditions to determine the answer: one is sent to Lapland, close to the North Pole, under Swedish physicist Anders Celsius and French mathematician Pierre Maupertuis.

The other mission is sent to Ecuador, at the Equator.

Previous accurate measurements had been taken in Paris by Cassini and others.

The equatorial mission is led by French astronomers Charles Marie de La Condamine, Pierre Bouguer, Louis Godin and Spanish geographers Jorge Juan and Antonio de Ulloa.

They are accompanied by several assistants, including the naturalist Joseph de Jussieu and Louis's cousin Jean Godin.

La Condamine will be joined in his journey down the Amazon by Ecuadoran geographer and topographer Pedro Maldonado. (Maldonado will later travel to Europe to continue his scientific work.)

The Ecuadoran expedition leaves France in May 1735.