Mitad del Mundo, Ecuador
Bust of Jorge Juan y Santacilia in Mitad del Mundo, Ecuador.
https://www.amazon.com/Relacion-Historica-Viage-America-Meridion%C3%A0l/dp/0270411577/?tag=2022091-20
1748
https://www.amazon.com/Historique-Lam%C3%A9rique-M%C3%A9ridionale-Mauvillon-L%C3%A9lecteur/dp/1175360392/?tag=2022091-20
1752
https://www.amazon.com/Observaciones-Astronomicas-Phisicas-Hechas-Spanish/dp/1271961679/?tag=2022091-20
1773
https://www.amazon.com/Discourse-Political-Reflections-Kingdoms-Peru/dp/0806114827/?tag=2022091-20
1978
https://www.amazon.com/Trascendencia-cient%C3%ADfica-Jorge-Juan-Santacilia/dp/8499484689/?tag=2022091-20
engineer explorer mathematician military scientist Soldier
Jorge Juan y Santacilia was born on January 5, 1713, in Novelda, Alicante, Spain. His parents, Bernardo Juan y Cancia and Violante Santacilla y Soler, were hidalgos, the lower aristocracy. Both of his parents were widowed and remarried. They lived in their house on the Plaza del Mar in Alicante and only vacationed in Novelda.
Santacilia orphaned at the age of three, and his two uncles took care of him and his education.
Santacilia grew under the care of the Jesuits of the Jesuit school in Alicante. His uncle don Antonio Juan, a Canon at the Collegiate Church took charge of young Jorge and continued his education. Later another uncle, don Cipriano Juan, a Knight of the Order of Malta, took charge of his education and sent him to Zaragoza. At the age of twelve, he went to Malta where he joined the Knights of Malta with the rank of commander of Gracia de Aliaga.
In 1729, when he was 16, he returned to Spain and applied for entry to the Royal Company of Marine Guards, the Spanish military school for naval officers. He entered the academy in 1730 and studied modern technical and scientific studies subjects such as geometry, trigonometry, astronomy, navigation, hydrography, and cartography. He also completed his education in the humanities with classes in drawing, music, and dancing. He finished his studies at the academy in 1734.
As an officer Santacilia took part in various privateering campaigns against the Moors and in the expedition against Oran.
After Cassini’s measurements of the meridians seemed to show that the earth was a spheroid elongated at the poles, in clear opposition to Newton’s theory, the French Academy of Sciences proposed that two series of measurements of one degree of an arc of meridian should be made, one near the North Pole, the other near the equator. Louis XV designated a Hispano-French commission for the measurement at the equator, in which, by appointment of Philip V, Juan and Antonio de Ulloa would participate, on behalf of Spain, with La Condamine, Godin, Bouguer, and Joseph de Jussieu.
In 1736 the commission’s expedition began its work, principally in the regions of Quito and Guayaquil. Complementary scientific observations were made of the speed of sound and of various aspects of astronomy, physics, geography, biology, and geology. Great effort went into achieving precision and accuracy for the measurements of the Peruvian meridian. The measurement made by the French members of the expedition gave a longitude of 56,750 toises, while that of the Spaniards gave 56,758; that is, a minor difference on the order of 14:100,000. These measurements confirmed the Newtonian theory of the shape of the earth and were extraordinary for their precision.
In 1745, nine years after the inception of the expedition, Juan and his colleague Ulloa returned to Spain, each taking a different route as a precaution for safe arrival of the data.
Juan subsequently designed and directed the shipyards at El Ferrol and La Carraca, took part in the improvement of the working and development of the mines of Almaden, founded the astronomical observatory of Cadiz, and carried out several diplomatic and special missions. He was squadron commander of the Royal Armada and director, at the age of fifty-seven, of the Royal Seminary of Nobles. During his captaincy of the company of midshipmen of Cadiz he established, in his house there, the Friendly Literary Society, which is considered the forerunner of the Royal Society of Sciences of Madrid. For several years this group met each Thursday to consider questions of mathematics, physics, geography, hygiene, history, and archaeology.
In 1757, he founded the Royal Astronomical Observatory of Madrid.
His most important book is Examen marítimo; it is a valuable application of mechanics to naval science.
Jorge Juan y Santacilia went down in history as a noted Spanish officer and mathematician. The combination of theoretical learning and practical experience enabled him to provide a considerable base for the improvement of naval science, to refute several empirical theories of navigation, and to establish the fundamental principles of naval architecture.
For his work and discoveries, Santacilia was elected a Fellow of the Royal Society in 1749.
A Churruca-class destroyer of the Spanish Navy, the Jorge Juan, was named after him.
Among the societies in which Santacilia held membership were the Royal Society, the French Academy of Sciences, the Royal Academy of Sciences of Berlin, and the Spanish Academy of San Fernando.
Santacilia's comrades nicknamed him "Euclid" because of his aptitude for the exact sciences.
Santacilia never married.
