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Danti, Egnatio [Egnazio, Ignazio]

1. Dates
Born: Perugio. Baptised on 29 April 1536.
Died: Alatri (c. 80km straight east of Rome), 19 Oct. 1586
Dateinfo: Dates Certain
Lifespan: 50
2. Father
Occupation: Artisan
It is difficult to categorize the father, Guilio Danti, with assurance. DBI asserts that the family was noble. In its article on Giulio, however, DBI describes a goldsmith-- one who made artistic objects such as statuettes of gold. Palmesi describes him as an architect and a maker of astronomical instruments. Egnatio Danti himself described a surveying instrument developed and used by his father.
No explicit information on their financial status.
3. Nationality
Birth: Italian
Career: Italian
Death: Italian
4. Education
Schooling: Perugia
One source states that Danti established a reputation as a scholar in science and the arts. Palmesi says that he attended the University of Perugia before joining the Dominicans. No mention of a degree.
5. Religion
Affiliation: Catholic
As stated above, he was a Dominican.
6. Scientific Disciplines
Primary: Astronomy, Mathematics, Cartography
Subordinate: Instrumentation, Optics, Geography
In 1574 he determined by observation that the equinox was eleven days earlier than the calendar. Danti continued to pursue this issue, and was one of the more important figures in the reform of the calendar.
He published his grandfather's translation of Sacrobosco's Sphere with his own commentary on it. He also published other astronomical work and mathematical works (as for example an edition of some of Euclid).
Danti prepared huge mural maps in Florence (in the Palazzo Vecchio) and later in the Vatican, and he published a work on a surveying instrument that he improved upon.
Danti published the Perspective of Euclid together with that of Eliodoro Larisseo.
He translated Ptolemy's Geography.
7. Means of Support
Primary: Church Life, Patronage, Academia
Secondary: Schoolmastering
Danti became a Dominican in 1555 as he was nearing the age of nineteen. In 1562 (when he was about 26) Cosimo I de' Medici heard of his reputation, perhaps through Danti's brother who was a sculptor at the court. Cosimo ordered him to prepare maps for his collection, large mural maps for the garda robbia in the Palazzo vecchio, and a large terrestrial globe.
In 1566 he designed a monastery for Pius V.
In 1571 Cosimo requested of the general of the Dominicans that Danti be allowed to reside in the palace. It appears that Danti instructed the princes in mathematics (not to the pleasure of Francesco, the heir), and he also gave lessons in mathematics to aristocratic youths.
Cosimo had him appointed professor of mathematics in Pisa with a salary of 36 scudi, which Cosimo made available by cancelling the appointment of a professor of theology.
With the death of Cosimo, Danti, who was hardly in favor with Francesco, was in effect ordered to leave Tuscany-- within twenty-four hours. He moved to Bologna, where from 1576 to 1583 he was a professor of mathematics in the university.
Having fulfilled a commission to map the territory of Perugia, Danti was commissioned by Gregory XIII to map the papal states and to work at reforming the calendar. In 1580 he was appointed cosmographer and mathematician to Gregory.
In 1583 Gregory appointed him bishop of Alatri.
8. Patronage
Types: Court Official, Eccesiastic Official, Aristrocrat, City Magistrate
Cosimo was his first patron. When Danti was attacked by other envious Dominicans, Cosimo defended him vigorously in a letter to the general of the order in Rome.
Pius V commissioned Danti to plan a church in 1566.
Ghisilieri, the Governor of Perugia, employed him to map the region in 1577, leading on to the papal mapping commission.
In Bologna he was under the protection of Card. Paleotii, who commissioned some of the instruments that Danti built there.
In Bologna, Count Giovanni Pepoli built (i.e., financed) the gnomon for him. The Senate of Bologna chose him to be professor of mathematics one year after he arrived in the city.
He built anemoscopes (instruments to show the direction of the wind) for a number of aristocrats in Florence and Bologna.
He dedicated a work on the astrolabe to Card. Ferdinando de' Medici (later Ferdinando I).
He dedicated his publication of his grandfather's Sphere of Sacrobosco to the Marquise of Castiglione.
He dedicated his publication of Euclid's Perspective to the Cardinal of Lorraine. (Recall that Christina of Lorraine was the wife of Ferdinando.)
He dedicated Le due regole della prospective practica to the Duke Jacomo Buoncompagni.
He dedicated a translation of the Sphere of Proclus to Isabella Orsini, the daugher of Cosimo I.
9. Technological Involvement
Types: Architecture, Instruments, Cartography, Civil Engineering, Hydraulics, Military Engineering
Danti constructed an astronomical quadrant and an equinoctial armillary mounted on the facade of Santa Maria Novella for observations meant to determine the true equinox in order to correct the calendar. He later built a gnomon in Santa Maria Novella for that purpose, and after he moved to Bologna the more famous gnomon in the cathedral there. He published extensively on astronomical instruments.
He build anemoscopes (to indicate the direction of the wind) in Florence and in Bologna.
He mapped the region embracing Perugia and later the papal states. He perfected the rado latino, a surveying instrument.
In 1566 Danti designed a church for Pius V and later a chapel in Bologna. Near the end of his life he was summoned to Rome to help Fontana raise the obelisk.
He planned a canal across Italy through Florence to link the two seas and to make Florence a commercial hub.
Danti left behind a manuscript on fortification. I hesitate with this, but end up including it.
10. Scientific Societies
Memberships: None
Danti was a member of the Accademia del Disegno in Perugia and later in the Accademia of Santa Luca in Rome.
He was familiar with the leading intellectual of Florence of his day.
Ferrato has published many of his letters. Unfortunately my information on this publication is not more precise.
  1. Jodoco Del Badia, Egnazio Danti cosmografo e matematico e le sue opere in Firenze. Memoria storica, (Florence, 1881).
  2. V. Palmesi, "Ignazio Danti," Bollettino della R. deputazione di storia patria per l'Umbira, 5 (1899), 81-125.
  3. Dizionario biografico degli italiani, 32, 659-62.
Not Available and Not Consulted
  1. G.B. Vermiglioli, "Elogio di Ignazio Danti detto in Perugia nel giorno 26 Dicembre 1819," Opuscoli letterari di Bologna, 3 (Bologna, 1820), 1.
  2. "Ignatio Danti," in Biografie degli scrittori perugini e notizie delle opere loro, (Perugia, 1829), 366-70.
  3. R. Almagia, Monumenta italiae cartographica, (Firenze, 1929), pp. 41-9, 525.
Compiled by:
Richard S. Westfall
Department of History and Philosophy of Science
Indiana University

Note: the creators of the Galileo Project and this catalogue cannot answer email on geneological questions.

1995 Al Van Helden
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