Castillon, Johann (Giovanni Francesco Melchiore Salvemini)

(b. Castiglione, Tuscany, Italy, 15 January 1704; d. Berlin, Germany, 11 October 1791),

mathematics.

The son of Giuseppe Salvemini and Maria Maddalena Lucia Braccesi, Castillon studied mathematics and law at the University of Pisa, where he received a doctorate in jurisprudence in 1729. Shortly afterward he went to Switzerland, where for some unknown reason he changed his name to Johann Castillon, after his birthplace. In 1737 he became the director of a humanistic school in Vevey, and in 1745he took a teaching position in Lausanne. In that year he married Elisabeth du Frèsne, who died in 1757. He married Madeleine Ravène in 1759. From 1749 to 1751 Castillon taught in both Lausanne and Bern. In the summer of 1751 he received offers of positionin St. Petersburg and Utrecht; in December 1751, after much thought, he accepted the invitation of the prince of Orange to lecture on mathematics and astronomy at the University of Utrecht, where he acquired a doctorate in philosophy in 1754 and rose to professor of philosophy in 1755 and rector in 1758. In 1764 he traveled to Berlin to accept a position in the Mathematics Section of the Academy of Sciences there. In the following year he became the royal astronomer at the Berlin Observatory.

During his lifetime Castillon was known as an able geometer and a general philosopher. His work in mathematics, however, did not go far beyond elementary considerations. His first two mathematical papers dealt with the cardioid curve, which he named. He also studied conic sections, cubic equations, and artillery problems. After publishing the letters of Leibniz and Johann I Bernoulli in 1745, he edited Euler’s Introductio in analysin infinitorum in 1748. In 1761 he published his useful commentary on Newton’s Arithmetica universalis. Throughout his mathematical work there is a preference for synthetic, as opposed to analytic, geometry, which is perhaps a reflection of his preoccupation with Newton’s mathematics. In addition to this mathematical research, Castillon delved into the study of philosophy. In general he opposed Rousseau and his supporters and leaned toward the thinkers of the English Enlightenment. He translated Locke’s Elements of Natural Philosophy into French.

Castillon became a member of the Royal Society of London and the Göttingen Academy in 1753 and a foreign member of the Berlin Academy of Sciences in 1755; he was elected to full membership in the Berlin Academy in 1764, upon the personal recommendation of Frederick the Great. In 1787 he succeeded Lagrange as director of the Mathematics Section of the Berlin Academy, a post he held until his death.

BIBLIOGRAPHY

Castillon wrote Discours sur l’origine de l’inégalité parmi les hommes… (Amsterdam, 1756); and Observations sur le livre intitulé Système de la nature (Berlin, 1771). He edited the following: Isaaci Newtoni, equitis aurati, opuscula mathematica, philosophica & philologica, 3 vols. (Lausanne, 1744); Virorum celeberr. Got. Gul. Leibnitii & Johan. Bernoullii commercium philosophicum & mathematicum(Lausanne, 1745); and Euler’s Introductio in analysin infinitorum (Lausanne, 1748). He translated Locke’s Elements of Natural Philosophy as Abrégé de physique (Amsterdam, 1761); George Campbell’s A Dissertation on Miracles: Containing an Examination of the Principles Advanced by David Hume, Esq; in an Essay on Miracles as Dissertation sur les miracles, con tenant 1’examen des principes posés par M. David Hume dans son Essai sur les miracles (Utrecht, 1765); and Francesco Algarotti’s Opere varie del Conte Francesco Algarotti as Mémoires concernant la vie & les écrits du comte François Algarotti (Berlin, 1772).

Castillon’s articles include “De curva cardiode,” in Philosophical Transactions of the Royal Society, 41 , no. 461 (1741). 778–781; “De polynomia,” ibid., 42 , no. 464 (1742),91–98: “Deux descriptions de cette espèce d’hommes, qu’on appelle negresblans,” in Histoire de l’Académie royale des sciences et des belles lettres de Berlin (avec mémoires), 18 (1762), 99–105; “Descartes et Locke conciliés,” ibid. (1770), 277–282; “Mémoire sur les équations résolues par M. de Moivre, avec quelques réflexions sur ces équations et sur les cas irréductibles,” ibid (1771), 254–272; “Sur une nouvelle propriété des sections coniques,” ibid. (1776), 284–311; “Sur un globe mouvant qui représente les mouvements de la Terre,” ibid. (1779), 301–306; “Sur la division des instruments de géométrie et d’astronomie,” ibid. (1780), 310–348; “Rapport sur une lettre italienne de M. le Professeur Moscati, concernant une végétation électrique nouvellement deéouverte,” ibid. (1781), 22–23; “Mémoire sur la règle de Cardan, et sur les équations cubiques, avec quelques remarques sur les équations en général,” ibid (1783),244–265; “Premier mémoire sur les parallèles d’Euclide,” ibid, 43 (1786–1787) and “Second mémoire…,” 44 (1788–1789), 171–203; “Recherches sur la liberté de l’homme.” ibid., 43 (1786–1787), 517–533; “Examen philosophique de quelques principes de l’algébre” (two memoirs), ibid, 45 (1790–1791), 331–363; and “Essai d’une théorie métaphysico-mathématique de l’expérience,” ibid., 364–390.

An obituary is Friedrich von Castillon, “Éloge de M. de Castillon, père,” in Histoire de l’Académie royale des sciences et des belles lettres de Berlin (avec mémoires), 46 (1792–1793), 38–60.

Ronald S. Calinger