FRISI, PAOLO, a distinguished Italian mathematician, was born rat Milan, April 13, 1723, of a family which came originally from Strasbourg; and at fifteen yearn of age he was placed iu a monastery of the Barnabites, of whose order he became a member. At this time apparently the cultivation of the sciences formed no part of the dis cipline of the institution ; Frisi acquired however some notion of geography from a number of old maps which lined the walls of the corridors, and he made considerable progress in the study of mathe matics, with almost no other aid than that of a few books of which he obtained possession.
From Milan lie was sent to the University of Pavia, where he studied theology; and at intervals of leisure he greatly extended his knowledge of mathematics. He was afterwards appointed to give instruction in philosophy at Lodi ; and while at this place he composed a treatise entitled `Disquisitio Mathematica in Caussam Physicam Figurm et Magnitudinis Telluris nostraa,' which his friend Donato Silva, at his own expense, caused to be published at Milan in 1751. In this work proof is given, agreeably to the Newtonian system, that the earth has the form of an oblate spheroid ; and its merit procured for the author an invitation from the king of Sardinia to deliver lectures in philosophy at Ca.al. Friel accepted the invitation ; but the Academie des Sciences of Paris having in 1753 nominated him one of its foreign correspondents, the honour thus conferred upon him seems to have induced the prin cipals of his order at Milan to give him the appointment of professor of philosophy in the college of St. Alexander in that city. His dissertation on the figure of the earth was about that time criticised by an ill-informed person, a Jesuit, who asserted that the arguments were inconclusive, and who reproached the author with attempting to obscure the glory of Italian science by the adoption of English ideas. Such an adversary was easily silenced, but the attack produced in the mind of Frisi a rooted dislike to the Jesuits in general. In answer to the objections made to some of the propositions he wrote a work called Estratto del Capo Quarto del Quinto Volume della Storia Literaria d'Italia,' &a, which was published at Milan in 1755.
In the same year he published at Lugano a tract entitled Seggio della Morale Filosofia,' &c. ; and, at Milan, his work De Existentia et Motu tEtheris, seu de Theoria Electricitatis,' &c. About the same time be took occasion to oppose in public the belief in witchcraft and magic, which then existed in Italy ; and this boldness, together with a certain freedom in his manner of living, appears to have raised up against him many enemies : fearing their machinations, he wished to withdraw from Milan, and he gladly accepted an appointment in the University of Pisa, which was conferred upon him in 1756 by the grand-duke Leopold. While holding this post he published, in Latin
(Lucca, 1757), select dissertations on the subject of electricity, which two years before had been written by Euler, Resaud, and himself, for the prize proposed by the Academy of Sciences at St. Petersburg ; and a tract entitled De Motu Diurno Term' (Pisa, 1758), which had obtained the prize proposed by the Royal Academy of Berlin. He also published Dissertationce Variaa' in two volumes ; of which the first (Lucca, 1760) contains a tract entitled De Atmosphxra Ccelestium Corporum,' and the second (Lucca, 1761) two others, entitled Do • Inmqualitatibus Motus Planetarum omnium in Orbitis Circularibus atque Ellipticis' (in two books), and De Mcthodo Fluxionum Geometricarum.' In 1760 Friel made a journey to Rome and Naples in consequence of a commission which he received from the pope, Clement XIII., to examine and report upon a subject in dispute between the people of Ferrara and Bologna respecting the navigation of certain rivers : he also assisted with his advice the commissioners appointed by the Venetians to repair the damages caused by the overflowing of the Brenta; and for theso services, though he appears to have excited the jealousy of the engineers of the country, and to have made enemies of many persons whose estates were affected by the measures which were taken in consequence of his reports, he was liberally remunerated both by the pope and the Venetians. In 1761 he published, at Lucca, a tract entitled ' Piano de' Lavori da farsi per liberare e aseicurare dells Acque lo Provincie di Bologna, di Ferrara, di Ravenna,' &c.; and, in the following year, one in three books, entitled Del Mode di rego lare i Fiumi e Torrenti principalmente del Bolognese a della Romagna.' Of this there have been four editions. He returned to Milan in 1764, having been appointed professor of mathematics in that city, and, except occasional absences, he continued to reside there till his death. In the year 1766 he made a visit to France, and thence he came to London, where, as well as in Paris, he received great attentions from the learned : the Portuguese ambassador in the latter city proposed to him an appointment in Lisbon, but this he declined, being unwilling entirely to leave his country. Two years afterwards he went to Vienna, where also he was well received, and where he was consulted on the subject of the disputes between the pope and the emperor.