Antonio de Ulloa y de la Torre-Guiral (12 January 1716 – 3 July 1795) was a Spanish Navy officer. He spent much of his career in the Americas, where he carried out important scientific work that earned him a reputation as one of the major figures of the Enlightenment in Spain. As a military officer, Ulloa achieved the rank of vice admiral. He also served the Spanish Empire as an administrator in the Viceroyalty of Peru and as governor of Spanish Louisiana.
At the age of nineteen, Ulloa joined the French Geodesic Mission to the Equator, which established that the shape of the Earth is an oblate spheroid, flattened at the poles, as predicted by Isaac Newton. The mission took more than eight years to complete, during which time Ulloa, in close collaboration with his fellow naval officer Jorge Juan, made many astronomical, natural, and social observations in South America. Ulloa and Juan also helped to organize the defense of the Peruvian coast against the English squadron of Commodore Anson, after the outbreak of the War of Jenkins' Ear in 1739.
The reports of Ulloa's scientific findings during his time in South America earned him an international reputation. Notably, Ulloa published the first detailed observations of platinum, later identified as a new chemical element. Ulloa returned to Europe in 1745. He was elected as a fellow of the Royal Society of London in 1746, and as a foreign member of the Royal Swedish Academy of Sciences in 1751.
From 1758 to 1764, Ulloa served as governor of Huancavelica, in Peru, and as superintendent of the mercury mines of the region. There, he fought unsuccessfully against the corruption of the local administration. Following the Seven Years' War, Ulloa became the first governor of Spanish Louisiana in 1766. His rule was strongly resisted by the French Creoles of New Orleans, who expelled him from the city during the Rebellion of 1768. Despite some controversies, Ulloa continued to serve in the Spanish Navy and ended his career as its chief of operations.
Family background and education
Antonio de Ulloa was born in Seville, Spain, into a socially prominent and intellectually distinguished family. His father, Bernardo de Ulloa y Sousa, was noted for his writings on economics. His brother Fernando would become an engineer and the chief of works of the Canal de Castilla. Another brother, Martín, became a jurist, historian, and member of the Royal Spanish Academy.
The young Antonio was tutored in grammar and science by a priest and learned mathematics at the Colegio de Santo Tomás in Seville. At the age of thirteen he embarked from Cádiz on the galleon San Luis, bound for the port of Cartagena de Indias (in present-day Colombia). After returning to Cádiz, Antonio entered the Real Compañía de Guardias Marinas (the Spanish Naval Academy) in 1733. Soon thereafter he sailed to Italy, where the Spanish navy was fighting to wrest control of Naples and Sicily from the Habsburg monarchy.
At that time, the French Academy of Sciences was organizing a major scientific expedition to Quito, in present-day Ecuador, to measure the length of a degree of meridian arc (i.e., latitude) near the equator. This was part of an effort to determine in the precise figure of the Earth to settle the scientific debate between the defenders of René Descartes's physics and those who advocated the newer Newtonian mechanics. By comparing the length of a meridian arc at two very different latitudes, scientists would be able to determined whether the Earth is a prolate spheroid (i.e, flattened around the equator), as the Cartesians claimed, or whether it is instead an oblate spheroid (i.e, flattened at the poles), as predicted by Newtonian theory. The determination of the precise figure of the Earth was also regarded as being of practical importance for navigation.
When Ulloa returned from Naples to the Cádiz naval academy in 1734, he learned that a recent graduate of the academy, Juan García del Postigo, and one of his fellow cadets, Jorge Juan, had been chosen by the Spanish Crown to accompany the French geodesic mission to Quito. However, García was soon dispatched to Naples in the context of the War of the Polish Succession and therefore had to withdraw from the geodesic expedition. Perhaps through the influence of his father, Ulloa (who was only nineteen years old) was then chosen to replace García. This was a sensitive assignment, both politically and scientifically. Juan and Ulloa were selected on the strength of the recommendations of the king's chief minister, José Patiño.
The early work of the geodesic mission, led by Charles Marie de La Condamine, was delayed and hindered by a lack of cooperation from the local Spanish authorities. Indeed, in 1737, a personal dispute between Ulloa and the president of the Real Audiencia de Quito, Joseph de Araujo y Río, reached such a pitch that Araujo ordered the arrest of Ulloa and Juan, announcing his intention to have them killed. Juan and Ulloa took refuge in a church and Ulloa then escaped through the cordon of Araujo's men, reaching Lima and obtaining the protection of the Viceroy of Peru, the Marquis of Villagarcía. When war between Spain and Great Britain broke out in 1739, Juan and Ulloa, as naval officers, actively participated in the defense of Peru.
Ulloa traveled throughout the territories of the Viceroyalty of Peru from 1736 to 1744, making many astronomic, natural, and social observations. In one of his reports he described, for the first time in the European scientific literature, some of the properties of a metal that he called platina ("little silver") and which he encountered during his inspection the gold panning operations in the Chocó region of what is now Colombia. This metal would later be identified as a new chemical element, now known as platinum. Ulloa is therefore often credited as the discoverer of this metal.
Both Ulloa and another member of the French Geodesic Mission, Pierre Bouguer, reported that while walking near the summit of Mount Pambamarca they saw their shadows projected on a lower-lying cloud, with a circular "halo or glory" around the shadow of the observer's head. Ulloa noted that
The most surprising thing was that, of the six or seven people that were present, each one saw the phenomenon only around the shadow of his own head, and saw nothing around other people's heads.
This has been called "Ulloa's halo" or "Bouguer's halo". It is similar to the phenomenon that later came be known as the "Brocken spectre" after the Brocken, the highest peak in the Harz mountains in central Germany. Ulloa reported that the glories were surrounded by a larger ring of white light, which would today be called a fog bow. On other occasions, he observed arches of white light formed by reflected moonlight, whose explanation is unknown but which may have been related to ice-crystal halos.
The final results of French Geodesic Mission, published by La Condamine in 1745, combined with the measurements of French Geodesic Mission to Lapland that had been published in 1738 by Pierre Louis Maupertuis, decisively vindicated the predictions first made by Newton in Book III of his Principia Mathematica of 1687. These results greatly contributed to the triumph of Newtonianism over Cartesianism among Continental European savants.
In 1745, having finished their scientific labours in South America, Ulloa and Jorge Juan prepared to return to Spain. They agreed to travel each on different ships and each carried their own copies of all the important samples and records, so as to minimize the risk of their work being lost during the dangerous ocean crossing. The ship upon which Ulloa was travelling was captured by the British Royal Navy, and he was taken to England as a prisoner of war. There, he was soon befriended by leading British scientists and was elected as a fellow of the Royal Society in December 1746. Thanks in part to the intervention of Martin Folkes, the president of the Royal Society, Ulloa was released from British custody and allowed to return to Spain.