**Paolo Frisi** was an Italian mathematician who wrote on geometry, mechanics and cosmology.

- Frisi entered the Barnabite Arcimbolde school in Milan in or before 1741.
- Pietro Verri (1728-1797) was the same age as Frisi and they studied together at the Arcimbolde school.
- He remembered that in 1741-42 Frisi, who was at that time his companion in the Arcimbolde, stood out for his reliability and attendance at the Ambrosiana Library.
- Frisi joined the Barnabite Order and on 11 July 1743 he was admitted to the novitiate of the church of Santa Maria of Carrobiolo in Monza.
- Verri certainly felt that Frisi did not exhibit deep religious feelings and was following this religious path more because it offered him a quality education from learned men and also gave him the opportunity to study without having to worry about his material needs.
- Paolo Onofrio Branda (1710-1776) was a scholar who wrote Della lingua toscana Ⓣ(On the Tuscan language) (1759).
- After studying the philosophy courses at the Arcimbolde, Frisi went on to study mathematics on his own.
- In 1747 Frisi went to Pavia where he studied theology in the Ordine School.
- Rampinelli supervised Frisi's mathematical studies and had him read his unpublished work 'Institutiones mechanicae ac staticae'.
- While in Pavia Frisi also read the 'Treatise of fluxions' of Colin Maclaurin, the 'Instituzioni analitiche' of Agnesi, and some writings of Leonard Euler.
- By the time he left Pavia at the end of 1749, Frisi had completed his theological studies and, in addition to the mathematical texts mentioned above, had also studied works of the French school up to Alexis Claude Clairaut and Jean Le Rond d'Alembert.
- Leaving Pavia, Frisi was sent to teach philosophy in the College of San Giovanni alle Vigne in Lodi.
- Frisi, having started printing without the permission of the Barnabite Order, was told to stop, but nevertheless publication went ahead.
- Appointed by the Savoy government, Frisi taught philosophy at Casale from November 1751.
- While at the College of Casale, Frisi wrote his first work on pure mathematics, De methodo fluxionum geometricarum et eius usu in investigandis praecipuis curvarum affectionibus Ⓣ(The geometric method of fluxions and its application in the investigation of principal geometric curves) which was published in Milan in 1753.
- The Barnabite Order was unhappy with Frisi's dedication to science and his neglect of religion and, in 1752, they asked the Savoy government to remove him from his chair at Casale.
- The Barnabite Order wanted him to go to their house of penance but, in November 1752, Frisi managed to postpone the decision citing health reasons.
- Perelli, in particular, had a large influence on Frisi who often made the relatively short journey to Florence where Galileo's influence was strong.
- Frisi was able to publish works on celestial mechanics after 1757 since Pope Benedict XIV had promoted scientific learning and instructed those drawing up the Index of Forbidden Books to act with restraint.
- Frisi published Memorie sopra la fisica e l'istoria naturale Ⓣ(Memoir on physical and natural history) (1757), De aberratione lucis opusculum Ⓣ(Work on the refraction of light) (1757), and De atmosphaera caelestium corporum dissertatio physico-mathematica Ⓣ(Physical and mathematical dissertation on the atmosphere of heavenly bodies) (1759).
- Between June and autumn 1760, Frisi made a journey to Rome and Naples.
- This was not something that Frisi had looked at before but he quickly immersed himself in the vast literature on the subject and drew up a plan.
- After holding the post in Pisa for eight years, Frisi returned to Milan becoming professor of mathematics at the Scuola Palatina in April 1764.
- Frisi discussed the three body problem with French mathematicians, visited science museums and observatories of Paris and Greenwich, and attended meetings of the Royal Society of London and the Paris Academy of Sciences.
- Frisi returned to Milan in April 1767.
- Joseph, who was a highly intelligent man, was keen to discuss with Frisi the latest developments in science, particularly in electricity, and since he had lost two wives to smallpox, he was naturally keen to discuss developments in inoculation.
- We have already indicated many contributions that Frisi made to mathematics, physics and astronomy.
- The work on this canal was not undertaken in Frisi's lifetime, but in 1819, thirty-five years after Frisi's death, the canal was built to his plan.
- In the paper De problematis quibusdam isoperimetricis Ⓣ(Some isoperimetric problems) of 1761 Frisi discussed isoperimetric problems.
- Frisi looked at problems involving both maximising and minimising.
- Frisi also wrote on the contributions of Galileo: Elogio del Galileo Ⓣ(In praise of Galileo) (1775), Cavalieri: Elogio di Bonaventura Cavalieri Ⓣ(In praise of Bonaventura Cavalieri) (1778) Newton: Elogio del cavaliere Isacco Newton Ⓣ(In praise of Sir Isaac Newton) (1778), and d'Alembert: Elogio del signor d'Alembert Ⓣ(In praise of d'Alembert) (1786), and brought their ideas to a wide audience.
- These major works include Algebra e geometrica analitica Ⓣ(Algebra and analytic geometry) (1782), Meccanica Ⓣ(Mechanics) (1783), and Cosmografia Ⓣ(Cosmography) (1785) which contain much of Frisi's earlier work, but written up in a polished form.
- Frisi was also editor of the newspaper Il caffè.
- After this, the Scuola Palatina, where Frisi was professor of mathematics, was moved to the Palazzo Brera, which had been a Jesuit College until the suppression.
- In August 1778 Frisi made a third trip abroad, going to Switzerland.
- Frisi was honoured by election to many academies; we have indicted when he was elected to several of these academies above.
- Streets named after Frisi include: the Via Paolo Frisi, Milan; the Via Paolo Frisi, Melegnano; the Via Paolo Frisi, Lissone; the Via Paolo Frisi, Pavia; the Via Paolo Frisi, Rome; and the Via Paolo Frisi, Bologna.

Born 13 April 1728, Milan, Austrian Habsburg (now Italy). Died 22 November 1784, Milan, Austrian Habsburg (now Italy).

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Astronomy, Origin Italy

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive