He spent ten years in territory which is now Ecuador, measuring the length of a degree of latitude at the equator and preparing the first map of the Amazon region based on astro-geodetic observations.

In 1729 La Condamine and his friend Voltaire exploited a loophole in the French government’s lottery, which brought them large profits.

After returning to Paris, La Condamine submitted in November 1732 a paper to the Academy entitled Mathematical and Physical Observations made during a Visit of the Levant in 1731 and 1732.

Three years later he joined the French Geodesic Mission to territory which is now Ecuador, which had the aim of testing a hypothesis of Isaac Newton.

After stopovers in Martinique, Saint-Domingue, and Cartagena, they sailed southward through Panama, arriving at the Pacific port of Manta on 10 March 1736.

The expedition was beset by many difficulties, and finally La Condamine split from the rest and made his way to Quito, Ecuador separately,[4] following the Esmeraldas River, becoming the first European to encounter rubber in the process.

The meridian arc whose length La Condamine and his colleagues chose to measure passed through a high valley perpendicular to the equator, stretching from Quito (now the capital of Ecuador) in the north to Cuenca in the south.

Though assisted by two Americans of the region whom I took with me as guides, I was able to collect no more than eight or nine young plants of Quinquina [cinchona] in a proper state for transportation.

I hoped to leave some of the plants at Cayenne [in Guiana] for cultivation and to transport the others to the King's garden in France.He collected valuable seeds, sarsparilla, guaiacum, ipecacuanha, cacao, vanilla and simarouba.

After returning to Quito on 20 June 1737, he found that Godin refused to disclose his results, whereupon La Condamine joined forces with Bouguer.

He did not dare to travel back to France on a French merchant ship because France was at war (the Austrian Succession War of 1740–1748), and he had to wait for five months for a Dutch ship, but made good use of his waiting time by observing and recording physical, biological and ethnological phenomena.

Being the only surviving member, he received most of the credit for the expedition which drew a great deal of attention in France, as he was a gifted writer and popularizer.

On a visit to Rome La Condamine made careful measurements of the ancient buildings with a view to a precise determination of the length of the Roman foot.