First Scientific Exploration of the Amazon River Led by Charles-Marie de La Condamine
First Scientific Exploration of the Amazon River Led by Charles-Marie de La Condamine
In an expedition intended to take the most accurate measurements ever of Earth, a team of French scientists were given permission as the first foreigners to be allowed into the New World territories of the Spanish Empire for the purpose of conducting scientific research. At the end of years of work the expedition's leader, Charles-Marie de La Condamine (1701-1774), undertook the first scientific expedition down the length of the Amazon River from its headwaters in the Andes Mountains to its mouth on the Atlantic Ocean. Previous explorers to the area were military or government agents acting on behalf of the Spanish or Portuguese authority in the New World or clergy accompanying them. La Condamine's exploration, which occurred over the course of 4 months in 1743, focused on observing the river and its environment. The expedition would turn out to be the main achievement of the original mission.
In the first half of the eighteenth century physicists, geographers, and astronomers had come to the conclusion that the various forces acting on Earth as it spun on its axis changed its shape from the perfect sphere it was long assumed to be. Two conflicting theories arose as to how that shape was imperfect. English physicist Sir Isaac Newton (1642-1727) calculated that the planet flattened out at the poles and bulged at the equator. A conflicting theory was put forward by two French astronomers, Giovanni Domenico Cassini (1625-1712) and his son Jacques (1677-1756), who made measurements demonstrating that Earth was elongated at the poles and drew in at the equator. The French Academy of Sciences decided to settle the matter by sending two expeditions out to make the same measurements where they would show the greatest difference. One team was sent to northern Scandinavia to make the measurements close to the North Pole. The other team, led by the mathematician Charles-Marie de La Condamine, would go to northern Peru, where the equator passed through the Andes Mountains in South America. Each expedition would take accurate measurements of the distance covered by one degree of latitude and compare the measurements back at the Academy of Sciences in Paris.
La Condamine's team was given unprecedented permission from the Spanish Crown to travel into its South American territories to conduct their research. In May 1735 they sailed from France to what is now Colombia, and from there traveled to the Isthmus of Panama, where they crossed overland to the Pacific Ocean. From there they sailed to the northern portion of the Peru Territory (now Ecuador) and ascended the mountains to the city of Quito, where they would make their measurements. Delays plagued the expedition: accusations of espionage, meddling colonial officials, disputes over the participation of Spanish scientists, and death threats. In the middle of all their delays word arrived from France that the Arctic expedition had returned, and their data confirmed Newton's theory that Earth flattened at the poles. La Condamine's team continued its work, and in 1743 they made their last measurements. The expedition split up with only La Condamine making an immediate return to France.
La Condamine chose to make his way back to France by embarking on a mapping expedition down the Amazon River. He chose a route that began at the furthest navigable reaches of the Marañón river and proceeded through the dangerous pass at Pongo of Manseriche for the expressed purpose of seeing the pass. In June 1743 La Condamine and his native Andean guides left from the river port of Jáen in what is now northern Peru, about 100 miles (160.9 km) from the Pacific coast of South America. Traveling on a raft built by his guides, La Condamine had several close calls with not only his life but also the eight years of research and scientific instruments he was transporting back to France. However, during the expedition's arrival in South America La Condamine had been introduced to latex made from the sap of the rubber tree. Early on in the trip he was able to make rubber-treated sheets of cloth into waterproof bags that he used to protect his scientific instruments from the tropical moisture. After passing through the Pongo of Manseriche, where the river narrowed from 1,500 to 150 feet (457 to 45.7 m) across, La Condamine again almost lost his raft and work before emerging out of the mountains and onto the flat plain of the Amazon basin.
The raft arrived at a settlement on the river at Borja, where a priest provided him with a map of the area and accompanied him for the next portion of the voyage. At Borja the expedition changed from rafts to two large canoes, each 44 feet (13.4 m) long and 3 feet (0.9 m) across. Safer in the new canoes and with rowers paddling day and night, La Condamine took up the task of mapping and measuring the river. In late July the team reached the place where the large Ucayali River meets the Amazon and observed the Omaguas, a tribe first encountered by the missionary Padre Fritz years before. La Condamine noted the Omagua practice of placing the heads of newborn babies between wooden boards to squeeze them into a rounder shape and their cultivation of hallucinogenic seeds for ritual uses. By early August the expedition had entered Portuguese territory and the mission of São Paulo, where European influences were strong and La Condamine saw brick buildings and women wearing clothing imported from England. From there they continued downstream with more than 1,200 miles (1,931 km) ahead of them to the Atlantic. Below where the Rio Negro meets the Amazon, La Condamine observed the influences of the Atlantic tide on the river. The tides coming in from the ocean, still 700 miles (1,126 km) downriver, created two currents on the river, one at the surface and another in the opposite direction below. Along with the movements of the river, La Condamine recorded the animals he saw living along the river, including crocodiles, monkeys, vampire bats, anacondas, parrots, and frogs used by the river's inhabitants for their deadly poison.
On September 19, 1743, almost four months since setting out on the river, La Condamine reached the city of Grão Pará, now called Belém, near the mouth of the river. After several months in Grão Pará, La Condamine continued on to Cayenne, in what is now French Guyana, by way of the mouth of the river. He took another canoe with 22 rowers to explore Marajó Island at the very end of the river. Beyond the island the canoe crossed the river at it's widest point and reached the flatlands of Macapá, which he observed was at 3° north latitude and would have served just as well for the French Academy's expedition as the Peruvian Andes while being far more accessible. From Cayenne La Condamine was able to get a ship back to Europe, where he arrived at the French Academy of Sciences on February 23, 1745, almost 10 years after he had left.
La Condamine's voyage did not help settle the dispute over the shape of Earth. In the end he was in disagreement with members of the Academy over the meaning of his data. His precise calculations and mathematical corrections of the existing maps and measurements in South America improved navigation, and his explorations of the river's tributaries and islands made important corrections to the imperfect maps of the day. As a mathematician, his expedition down the Amazon ushered in a new era of scientific endeavor in the New World and helped to stimulate the scientific explorations of the nineteenth century.
Not least of La Condamine's observations of the natural life in the Amazon was his ingenious application of rubber as a waterproofing treatment for textiles. This would be the first of many applications of rubber that would provide a booming economy and great changes throughout the Amazon basin La Condamine observed. Some of his observations of the natural and cultural life of the region are still accurate today, but they are also notable as a record of what has changed in the last 250 years in what is now a threatened and contested part of the world. In 1743 he already observed the loss of native languages and beliefs to Spanish and Portuguese incursions into the indigenous culture. He noted insufficient efforts to protect the native Amazonians from the same European diseases that pose a threat to the few tribes that still avoid outside contact even today.
Smith, Anthony. Explorers of the Amazon. New York: Viking, 1990.