Jerome Girolamo Cardano (Cardan), an Italian scholar and physician, born at Pavia, or according to some authorities at Milan, Sept. 24, 1501, died in Rome, Sept. 21, 1576. He was the illegitimate son of a distinguished scholar of Milan, Facio Cardano. At the age of 22 he acquired no little distinction by lectures on mathematics and metaphysics, and by his remarkable attainments in the study of the sciences. He resided alternately in Milan, Venice, and Padua till 1533, when he was appointed professor of mathematics in Milan, and a few years later of medicine in Pavia. Difficulties with regard to his salary soon caused him to return to Milan, where he enjoyed at this period a considerable fame. Shortly after his return he published his mathematical treatise, Ars Magna, and in 1550 his De Subtilitate, both adding greatly to his reputation, which was thus far grounded on actual desert. The king of Denmark made him an offer of a large annuity if he would reside at his court, but Cardan refused, and continued to lecture and practise medicine, rendering valuable services to the cause of science, and enjoying a popularity which was apparently rapidly increasing.
But he now began that extraordinary career of vice, eccentricity, and quackery with which his name is connected, and which is principally known to us through his own works. In 1552 he was called to Scotland by John Hamilton, archbishop of St. Andrews, to attend him for an illness with which he had been long afflicted. He succeeded, though apparently by mere good fortune, in effecting a cure, and was largely rewarded. In returning he drew the horoscope of Edward VI., prophesying for him a long life; but Edward died the year after, and Cardan found himself everywhere ridiculed, in spite of his attempted explanations. After travelling for ten months through the principal countries of Europe, he returned to Milan, where he lived a life of debauchery and extravagance that soon reduced him to absolute penury, in spite of his efforts to repair his fortunes by gambling. His two sons followed the example of his vices; the elder was executed for the murder of his wife; the younger led a life which compelled even his father to abandon him. The various quackeries which Cardan practised during this period are innumerable; among them were magic and astrology, with pretended methods of cure, which, however, brought him few advantages.
He took the greatest pride in his many eccentricities, and in considering himself different in constitution and composition from other men. He pretended that he was accompanied by a familiar spirit, and ruled by peculiar fates. In spite of his manner of life, he was called to Pavia in 1560, and in 1562 to Bologna, through the influence of friends, and was a professor in the latter city from 1562 to 1570; but he continued in his former habits, and involved himself in many difficulties from which he escaped by going to Rome, where he ended his life as a pensioner of Pope Gregory XIII. - Cardan's works present that singular mingling of learning and absurdity which might be expected from the history of his life. He is said to have written 222 separate treatises besides his autobiography (Be Vita Propria). The chief of these are the works already named, his mathematical essays, and his Be Rerum Varietate, a supplement to the treatise Be Subtilitate. The best edition of Cardan's complete works is that of Lyons, Hieronymi Car-dani Mediolanensis Philosophi ac Medici cele-berrimi Opera omnia, Cur a Car. Sponii (10 vols, fol., 1663).