Background
Castiglione was born on January 15, 1708, in Castiglione della Pescaia, Italy, the son of Giuseppe Salvemini and Maria Mad- dalena Lucia Braccesi.
Lungarno Antonio Pacinotti, 43, 56126 Pisa PI, Italy
Salvemini studied mathematics and law at the University of Pisa, where he received a doctorate in jurisprudence in 1729.
Astronomer mathematician scientist
Castiglione was born on January 15, 1708, in Castiglione della Pescaia, Italy, the son of Giuseppe Salvemini and Maria Mad- dalena Lucia Braccesi.
Salvemini studied mathematics and law at the University of Pisa, where he received a doctorate in jurisprudence in 1729.
Shortly afterwards his graduation, Salvemini 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 1745 he took a teaching position in Lausanne.
From 1749 to 1751 Castillon taught in both Lausanne and Bern. In the summer of 1751 he received offers of positions in 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 Gottingen 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, which occurred on October 11, 1791.
In 1745 Castillon married Elisabeth du Fresne, with whom he had three children, the only surviving child was Maximilian Friedrich Gustav Adolf Salvemini. His first wife died in 1757, and he married Madeleine Ravene in 1759.