Thursday, April 18, 2024

The Expedition

The French Academy of Sciences sent a 10-member expedition to the Viceroyalty of Peru in 1735, which was the first scientific expedition to the New World. The French mapmakers went to measure a degree of latitude at the equator in order to answer questions about the exact size and shape of the earth. But as they were the first foreigners that Spain had allowed to travel widely in Peru,  the French scientists were also eager to explore the flora and fauna of this “new world,” and in many ways, their expedition to South America was similar in kind to the exploration of the American northwest by Lewis and Clark.

The illustrations here are from works published by Charles Marie de La Condamine and Pierre Bouguer, and two Spanish naval officers who accompanied the expedition, Jorge Juan and Antonio de Ulloa.


La Condamine’s map of his 10-year journey to South America

A map of Cartagena by Ulloa and Juan

A drawing by Ulloa and Juan depicting daily life near Cartagena.

From Cartagena, the expedition sailed to Porto Bello, a port located on the Atlantic side of the Panamanian isthmus. They arrived here on November 29, 1735.


The expedition travels up the Chagres River, on its way across Panama.


After sailing down the coast of South America, the expedition landed in Manta on March 8, 1736. The group split up there. While La Condamine and Pierre Bouguer stayed behind, Ulloa, Juan and the others headed south to Guayaquil. This drawing depicts a balsa raft in the Bay of Guayaquil.

Ulloa, Juan and the others left Guayaquil for Quito on May 3, 1736, traveling up the Guayaquil River.

The expedition members rode mules as they ascended the western cordillera of the Andes. The hazardous journey, Juan and Ulloa wrote, filled their “minds with terror.”

A map by Ulloa and Juan of Quito, where they arrived on May 29, 1736.

La Condamine and Pieere Bouguer stayed behind in Manta and then headed north together, where La Condamine located the equator as it crossed the coastline. To mark the spot, La Condamine wrote: “I carved on the most prominent boulder an inscription for the benefit of Sailors.”

La Condamine’s drawing of Quito.

A drawing by Juan and Ulloa of the dress of the inhabitants of Quito.

The French expedition had traveled to Quito to measure the distance of one degree of latitude at the equator. As a first step, they measured a baseline nearly eight miles in length by placing measuring rods end to end.

La Condamine’s drawing of the baseline measured in the plains north of Quito.

After measuring the baseline, the French scientists had to measure a distance of about 200 miles south through the Andes, which they did by plotting a series of triangles. Here, one of the scientists uses a quadrant to determine an angle to a distant point on a mountain.

A drawing by Bouguer detailing the use of a quadrant to measure angles.

As they moved south through the Andes, the expedition members observed a volcanic eruption.

A drawing by Juan and Ulloa of bridges used in the Andes.

La Condamine’s depiction of their use of the zenith sector.

Bouguer’s map of their triangulation scheme in Peru.

To commemorate their work, the French scientists erected pyramids at the two ends of their initial baseline near Quito. This is La Condamine’s blueprint for the pyramids.

La Condamine returned to France via the Amazon. He was the first scientist to travel this route, and his was the first accurate map of this region.


During their time in Peru, Ulloa and Juan traveled widely throughout the viceroyalty. This is their depiction of tropical regions near the Andes.

Ulloa and Juan returned to Europe by traveling south to Lima. They sailed from the port of Callao on Oct. 22, 1744. This drawing depicts the animals and inhabitants they encountered in and around Lima.

The title page of La Condamine’s 1751 account of the expedition.