Benedetto Castelli

Dom Benedetto Castelli O.S.B.
Born	1578 Brescia, Republic of Venice
Died	9 April 1643 (aged 64–65) Rome, Papal States
Alma mater	University of Padua
Title	abbot
Scientific career
Fields	Mathematician
Workplaces	University of Pisa
Academic advisors	Galileo Galilei
Notable students	Giovanni Alfonso Borelli Evangelista Torricelli Bonaventura Cavalieri Antonio Nardi Raffaello Magiotti

Benedetto Castelli O.S.B. (1578 – 9 April 1643), born Antonio Castelli, was an Italian mathematician. Benedetto was his religious name that he adopted when he entered the Benedictine Order in 1595.

Life

Born in Brescia, Castelli studied at the University of Padua and later became an abbot at the Benedictine monastery in Monte Cassino.

He was a long-time friend and supporter of his teacher, Galileo Galilei, and in turn, he was a teacher to Galileo's son. He assisted Galileo's study of sunspots and participated in the examination of the theories of Nicolaus Copernicus. Castelli was interested in mathematics and hydraulics. He was appointed as a mathematician to the University of Pisa, replacing Galileo, and later at the University of Rome La Sapienza. Castelli introduced Bonaventura Cavalieri to Galileo, leading to extensive correspondence between the latter; Galileo was instrumental in procuring a position for Cavalieri at the University of Bologna in 1629.

Castelli was involved in the discovery of the phases of Venus:

In December 1610, Galileo received a letter from Castelli, asking if the phases of Venus were observable through Galileo's new telescope. Days later, Galileo wrote in a letter to Johannes Kepler saying that he'd observed Venus going through phases, but took complete credit for himself. It is unclear, lacking copies of any earlier correspondence, whether Castelli was telling Galileo of it for the first time, or responding to Galileo having previously informed him of it.

Castelli died in Rome. His students included Giovanni Alfonso Borelli, Raffaello Magiotti, Antonio Nardi, and Evangelista Torricelli, the inventor of the barometer and an early proponent of the air pump. He recommended Gasparo Berti for a chair of mathematics at Sapienza. Berti was to be his successor at the university, but he died before he could take the post.

Works

He published Mensuration of Running Water, an important work on fluids in motion, and then his Geometrical Demonstrations of the Measure of Running Waters in which the publishing notes described him as Abbot of San Benedetto Aloysio and Mathematician to Pope Urban VIII, once a supporter of his mentor, Galileo.

He dedicated both publications to "the most Illustrious, and most Excellent Prince" Taddeo Barberini, a nephew of Pope Urban VIII.

• Benedetto Castelli (1661) [1628]. Della misura delle acque correnti (in Italian). London: William Leybourn.
• Castelli, Benedetto (1669). Alcuni opuscoli filosofici. Brescia.
• Castelli, Benedetto (1639). Discorso sopra la calamita.
• Benedetto Castelli, Galileo Galilei, Archimedes, Giovanni Alfonso Borelli, Evangelista Torricelli, Vincenzo Viviani Opuscoli idraulici, Bologna, Tipografia Marsigli, 1822.
• Risposta alle opposizioni del signor Lodovico delle Colombe e del signor Vincenzio di Grazia, contro al trattato del signor Galileo Galilei, delle cose che stanno su l'acqua, o che in quella si muovono (in Italian). Firenze: Cosimo Giunta. 1615.

See also

• List of Roman Catholic scientist-clerics
• Letter to Benedetto Castelli

From the 1913 Catholic Encyclopedia

Benedetto Castelli — Mathematician and physicist; b. at Perugia, Italy, 1577; d. at Rome, 1644. He was destined by his parents for the service of the Church and entered the Order of St. Benedict, at Monte Cassino. There he became abbot, and in 1640 he was transferred to the Abbey of San Benedetto Aloysio. He was specially interested in the mathematical sciences and their application to hydraulics. Galileo, his teacher, and Toricelli, one of his pupils, speak very highly of his scientific attainments, and both of them frequently asked his advice. In 1623 Urban VIII invited him to Rome and later appointed him chief mathematician to the pope and public professor of mathematics in the University of Rome. In 1625 he was sent with Monsignore Corsini to study the disorders occasioned by the waters of the Romagna, and to propose a remedy. Here he completed his important work on the "Mensuration of Running Water", in which he developed the important relations, that the speed of a current varies inversely as the area of its cross section, and that the discharge from a vessel depends on the depth of the tap below the free surface of the water. He was often consulted in other provinces of Italy in connexion with drainage, water-supply, prevention of floods, and the like.

His chief work is "Della misura dell'acqua corrente" (Rome, 1628; 3rd ed., 1660), translated into English by Salusbury (London, 1661), and into French by Saporta (1664), reprinted (Bologna, 1823) in Cardinali's collection "d'autori italiani che trattano del moto dell'acqua". Another work is "Risposta alle oppositioni del Sig. Lodvico, &c., contro al trattato del Sig. Galileo, Delle cose che stanno sopra acqua" (Bologna, 1655). According to Poggendorf, the invention of the helioscope is ascribed to him.

SALUSBURY, Math. Collections and Translations (London, 1661); La Grande Encycl., s. v.

External links

• Media related to Benedetto Castelli at Wikimedia Commons
• "Galileo Galilei, Letter to Benedetto Castelli (1613)", Religion and Science. (Source of the English translation.)
• The Galileo Correspondence Project at Stanford University Archived 2018-07-19 at the Wayback Machine