Biography of Jorge o Jorge Juan Juan y Santacilia (1713-1773)

Mathematician and Spanish physicist born in Novelda (Alicante) January 5, 1713, and died in Madrid in 1773.


He was the son of Juan Bernardo and Canicia and Violante Santacilia. He/She made his first studies in the College of the society of Jesus in Orihuela and Zaragoza. Zaragoza, at the age of twelve, he/she went with his paternal uncle Juan Cipriano and Canicia, Knight of the order of Malta, the island, entering in the order in which soon obtained an encomienda. He/She returned to Spain in 1729, and obtained the carta-orden of guardia-marina, went to Cadiz to enter in his Academy. In it, he/she took part for three years in the campaigns of Italy and Oran, with the degree of subrigradier of marine guards.

Late 1734, being again in Cádiz, he/she was appointed by Felipe V, together with Antonio de Ulloa, to form part of the famous the Peru expedition organized by the Académie des Sciences de Paris, to measure the arc of the terrestrial meridian, and whose main objective was the contrast different theories proposed about the shape of the Earth, especially those of Newton.

Promoted to Lieutenant de navio, Jorge Juan and Antonio Ulloa embarked for America, arriving in July 1735 at Cartagena de Indias, where were to meet with French scientists Louis Godin, Charles de La Condamine and Pierre Bouguer, Joseph de Jussieu, the latter as a naturalist. The French arrived in November, and once all together, moved to Quito to begin observations that were to last new years.

From these, Jorge Juan resumed, in 1744, the trip to Spain, before passing through Paris, where reported some scientific issues and, in particular, in basin by the stellar aberration and Louis Godin. In Paris was elected member of the Académie des Sciences, correspondent Charles de la Condamine. On his return to Spain planned, in 1746, the publication of astronomical observations and phisicas made of order of S. Mag. in the reynos of the Peru together with the historical relation of the voyage written by Antonio Ulloa. In court, initially, met with official indifference, though, to the end, Zenón de Somodevilla and Bengoechea, Marquis of Ensenada, interested by the topic, supported the publication of the works, which were printed to actual expense.

But not here ended the difficulties, since the decidedly Copernican character of the observations raised to Jorge Juan inquisitorial censorship problems. The Inquisitor general Francisco Pérez de Prado demanded that, alluding to the theories of Newton and Huygens, based on the movement of the Earth, he/she added: "system with dignity condemned by the Church". After a series of steps, which intervened in support of Jorge Juan, the Jesuit Andrés Marcos Burriel (who, in addition, prepared a comprehensive and detailed report of the relationship... and participated in the final drafting of the work, as well as the historical introduction of the observations) and Gregorio Mayáns and Císcar, was a compromise solution. Was this when Jorge Juan, exposing the theories of Christian Huygens and Newton about the shape of the Earth based on the movement of the same and the effects of centrifugal force, had to add: "... but even if this hypothesis is false, the reason for the balance always tested against the perfect esfereidad of the Earth, once supported the observation that bodies according to the experiences of the pendulums '", they exert less heaviness in the vicinity of the Ecuador, than at higher latitudes" (comments, p. XVI). However, any attentive reader could warn the character of imposing foreign to the author of the "Although this hypothesis is false". Years later, the own Jorge Juan would write a formidable argument in favor of copernicanism and Newtonian science entitled State of astronomy in Europe, which was published, already died its author in the second edition of the observations.

Delays in shipbuilding in Spain and a lack of suitable staff moved to the Marquis Cove think Jorge Juan for a trip to England, along with José Solano and Pedro de Mora, it takes place in a Committee in 1748, in order to acquire information and capture some builders, engineers and teachers. In England he/she made various reports, acquired instruments and hired several of the best builders of English ships: William Rooth, Matthew Mullan and Eduardo Bryant. Returning to Spain, he/she organized the general plan of the "arrangement for the construction of vessels and other factories of this branch, also that the draft direction of arsenals and their works". Carried out, in addition, other technical services, and promoted to captain, won the leadership of the Academy of marine guards of Cadiz, taking possession of it in 1752. In Cádiz Jorge Juan surrounded himself with professors like Louis Godin (who offered the leadership of the Academy), Joseph Carbonell Fogassa and Bonfigli, Vicente Tofiño Vandewalle and José Díaz Infante, among others, that organized a literary friendly Assembly. This wasn't a shadowing of the Royal Society of Sciences of Madrid to the Marquis of the Ensenada projected to create and for what Jorge Juan, Louis Godin and José Carbonell Fogassa had developed a detailed Plan of 50 ordinances (with the initial help of Antonio de Ulloa). The project collapsed with the fall of the mentioned Marquis. Was also carried out, many trips as Royal Commissioner to different points of Spain, especially El Ferrol, Cartagena and Almaden.

In Cadiz, Jorge Juan organized an astronomical observatory and was devoted, in addition, to the theoretical and experimental study of shipbuilding and ships maneuver, making trials in the Bay of Cádiz with models built specifically. Bound for teaching at Guardia-marinas Academy, published a compendium of navigation which includes theory and practice of piloting, the help of compass and rule variations to see them and correct them, construction and use of flat and spherical charts, etc.

In 1766 he/she settled again in court. In November of the same year he/she was appointed Ambassador extraordinary to the Court of the Emperor of Morocco, together with Sidi A. the Gazel, who had come to Spain. It was six and a half months in Morocco. Back in Madrid, in 1770, was entrusted the Organization and preparation of the curricula of the Royal Seminary of Nobles, whose address was, suggesting the King Carlos III Foundation of an astronomical observatory in Madrid, idea, although it was well received by the monarch, did not materialize until many then.

Jorge Juan was a member of the Royal Society of London, Royal Academy of Sciences of Berlin, correspondent in Paris and Chaplain of the San Fernando.

Scientific work

The most mature work of Jorge Juan as a scientist is the maritime review, a treatise of mechanics applied to navigation. In it he/she knew to take advantage of his vast knowledge on the subject, incorporating the results of the experiences in the Bay of Cadiz. The work appeared posted in two thick volumes:

-The first opens with a prologue in which the author revises the studies carried out by various authors about the movement of ships and the fluids resistance to the movement of a solid, by highlighting the shortcomings of the proposed theories to contrast them with the experience. It is volume I properly said, that it is a treatise of mechanics, with definitions and axioms of the movement, centres of gravity, rotation of a system, pendulums, theory of shock, simple machines, balance and movement of fluids, resistance to the movement of a solid in their various cases, two appendages on the "theory of comets flying by children" and "the implementation of the new theoria of resistance of fluids to the experiences of Mr. J. Smeaton".

-Volume II is an application of the above in volume I to the dynamics of the ship. Jorge Juan considers the characteristics of waves, height, length and period, and its influence on the movements of the ship, balance and bridles, as well as efforts to the rigging is subject. It is also the structural strength, establishing formulas for measuring this in ships. It assumes that a vessel can be considered a beam and uses the curves of weights and thrusts, similarly to the reality, for the calculation of the solid structure of the ship. The work was translated into French in 1783 by Pierre Leveque, who points out that "none of the theories presented here has provided results as conforming with the experience" at the dedication.

His writings include:

Travel order of S. M. ship lieutenants have egecutado don Jorge Juan and Santacilla and don Antonio de Ulloa to the city of Cartagena de Indias in order to merge it with... Parisian scientists going with Royal permission to the kingdoms of Peru and his company make observations to egecutaren. Voyage made to Lima from Quito don Jorge Juan i don Antonio de Ulloa the year 1740. Historical and political relationship of the current state of the Reynos de Peru by regard to the Navy. Made by ship captains don Jorge Juan and don Antonio de Ulloa. (1748). description or diary of the most memorable thing that happened on the trip made from Cadiz to Tetuan... and to the imperial court of Morocco (...)1767]. diario de viage de don Jorge Juan at the Court of Morocco, 1767.




Together with Antonio de Ulloa:

Historical relation of the voyage to South America S. M. order made to measure some terrestrial meridian degrees up and down them in knowledge of the true figure and magnitude of the land, with several astronomical observations and phisicas. 4 vols. (Madrid; A. Marin, 1748). Astronomical observations and phisicas made of order of S. Mag. in the reynos de Peru. (Madrid; J. Zúñiga, 1748). Historical dissertation and geographica on the meridian line of demarcation between the dominions of Spain and Portugal... (Madrid; A. Marin, 1749). Secret news from America on the naval, military, and political state of the Reynos de Peru and provinces of Quito, coast of New Granada and Chile: Government and private regime of indigenous towns: cruel oppression and extortion of the Corregidores and cures: scandalous abuses introduced by missionaries among these people: their root causes and reasons for its continuation for the space of three centuries. Faithfully written according to the instructions of the excmo. Mr. Marqués de la Ensenada, first Secretary of State and presented in secret report to S.M.C. Mr don Fernando VI, by Jorge Juan and Antonio de Ulloa... Brought to light for true knowledge of Government of the Spanish of South America, by don David Barry. (London; R. Taylor, 1826).

Works of Jorge Juan:

Compendium of navigation. (Cádiz; IMP. guards marine, 1757). Maritime review, 2 vols. (Madrid;F. Manuel of Ulena, 1771). Journal of the trip made by Jorge Juan at the Court of Morocco. (Madrid, 1816). ""Reflections on factory and use the quarter circle", in the Depósito Hidrográfico, 1st memory. (1809)."Method of lift and direct map or general level of Spain", in memory deposit hydrographic. (1809).""Opinion of don Jorge Juan on the relox or chronometer invented by Juan Harrison", 1765, report reproduced by FERNANDEZ DURO, Cesareo nautical digressions, 6 vols. (Madrid; Oribau y CIA., 1876-1881).


"Measurement of the terrestrial arc. The history of the Platinum", in Journal of archives, libraries and museums, no. 27 (1912).GUILLÉN TATO, July. The lieutenants of ship Jorge Juan and Santacilia and Antonio Ulloa, Tower-Guiral and the measure of the degree of Meridian. (Madrid, 1936)--"Juan and Ulloa and the precedents of the 18th of the Royal Academy of Sciences of Madrid", in Journal of the Real Academia de Ciencias Exactas, Físicas y Naturales, no. 24 (1940).TODHUNJER, I. Arc of the meridian measured in Peru, A history of the theories of attraction and the mathematical figure of the earth. Vol. I (New York; Dover, 1962).Garcia FRANCO, Salvador. "Bicentennial of a nautical book", in Revista General de Marina, no. 93 (1957). 0' O'DOGHERTY, Pascual. "Jorge Juan and Spanish naval science in the eighteenth century", in Revista General de Marina, no. 184 (1973).PESET LLORCA, Vicente. "About the dissemination of the Copernican system in Spain", in proceedings of the second Congress Spanish for the history of medicine, vol. I (Salamanca, 1965).NAVARRO BROTONS, V. "Contribution to the history of copernicanism in Spain", in Hispanic American notebooks, no. 283 (1974).MAYANS and CÍSCAR, Gregorio. Correspondence. II. Mayans and Burriel. (Valencia, 1972).