◀ ▲ ▶History / 16th-century / Person: Danti, Egnatio Pellegrino Rainaldi

Person: Danti, Egnatio Pellegrino Rainaldi

Egnatio Danti was an Italian Dominican who made contributions to architecture, geography and astronomy.

Mathematical Profile (Excerpt):

• As we mention below, Pier Vincenzo Rainaldi was an outstanding scholar and his friends gave him the nickname Dante (or Danti) after the brilliant author of the Divine Comedy.
• For simplicity, we shall use the name Egnatio Danti throughout this article.
• Egnatio also had an aunt named Teodora who had written a work on Euclid's Elements and also books on art.
• At the age of 18, on 7 March 1555, Egnatio Danti entered the Dominican Order having already attended courses at the University of Perugia.
• In 1566 Pope Pius V requested that Danti use his architect's skills to design Santa Croce, the church of the Dominican monastery at Bosco Marengo near Alessandria.
• Pius V had been born at Bosco Marengo so it was a project of great importance to him and, as well as the church, he asked Danti to design the monastery at Bosco Marengo.
• Danti designed the church as a Latin cross with a dome over the crossing.
• Danti's design of the monastery cloisters was particularly fine.
• Cosimo became first grand duke of Tuscany in 1569 and he appointed Danti to be professor of mathematics at Pisa.
• In 1571 he made a request of the Dominican Order that Danti be allowed to live at the convent of the Santa Maria Novella in Florence.
• The reason for this request was that Cosimo wanted his sons Francis and Ferdinand, and the sons of other important families, to be given a good mathematical education, and what better person to undertake such a teaching role than Danti.
• Francis, Cosimo's eldest son, was 30 years old at the time and certainly did not appreciate the mathematical lessons Danti gave at the Medici Palace.
• Soon he decided to rid himself of his former mathematics teacher and in 1575 Danti was told he had 24 hours to leave Tuscany.
• Danti had been working on a major project at the time of Cosimo's death, being he was in charge of the construction of canals to join Florence to both the Mediterranean Sea and the Adriatic Sea.
• When Danti was forced to leave Florence this project, which was still at the planning stage, was abandoned.
• During his time in Tuscany Danti had continued his interest in astronomy and in particular he had designed a number of astronomical instruments.
• In order to calibrate the astronomical year Danti had to calculate accurately the height of the noon sun, which he achieved by making a small hole in the round window of the church to act as a camera obscura.
• In 1574, using his various instruments, Danti detected the 11 day error in the calendar when he calculated the vernal equinox to have fallen on 11 March rather than on 22 March as it should for the calendar to be in step with the seasons.
• From that time on Danti became a leading figure in pressing for calendar reform and although his name is not associated with the final decisions on the Gregorian calendar, he was one of the most important people to bring it about.
• After leaving Tuscany, as Francis required, Danti moved to Bologna in 1575.
• From 1577 Danti accepted a commission from Ghisilieri, the Governor of his native city of Perugia, to map the area around Perugia but this only took him away from Bologna for short periods and during this period he continued with his duties at the University of Bologna.
• While he lived in Bologna, Danti continued his interest in astronomical instruments and he built a gnomon at the cathedral.
• The first edition of Trattato dell' Uso, e della fabbrica dell' astrolabio con l'aggiunta del planisfero il Planisferio del Roias was published by Danti in 1569, while the second edition appeared 1578.
• Among Danti's mathematical publications are editions of some of Euclid's works, in particular he published an Italian translation of Euclid's optical treatise under the title La prospettiva di Euclide tradotta e annotata in 1573.
• The next work by Danti we mention is Usus et tractatio gnomonis magni, quem Bononiae ipse in Divi Petroni templo conferit anno domini 1576 which was published in Bologna but contains no date of publication.
• Danti's description of a machine he made to measure the wind appears in Anemographia.
• One of Danti's most interesting publications was Le due regole della prospettiva pratica di m.
• Finally, among Danti's publications, we mention Trattato del radio latino (1586) which is Danti's work describing his surveying instrument.
• This book appeared in the year in which Danti died.
• The obelisk had been brought to Rome in the 1st century AD and Danti and Fontana erected it in 1586 where it now stands in the centre of St Peter's Square in the Vatican.
• After his return from this trip to Rome, Danti contracted pneumonia from which he died.

Born April 1536, Perugia (now Italy). Died 19 October 1586, Alatri (now Italy).

View full biography at MacTutor

Tags relevant for this person:

Astronomy, Geometry, Origin Italy

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@J-J-O'Connor

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References

Adapted from other CC BY-SA 4.0 Sources:

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