DANTI, Egnatio

First edition of Egnatio Danti’s translation of Proclus’ ‘Sfera’ and his companion treatise on the use of the sphere, and second edition of Piccolomini’s treatise on the proportions respectively of water and dry land of the Earth. According to Graesse there was a 1540 edition of the latter, but from Ziletti’s dedication a Venetian senator, it is clear that the book was first published in 1558. Houzeau & Lancaster lists a ‘very rare’ 1571 first edition of Danti’s translation and treatise, but it is probably confusing the latter with Danti’s commentary upon the translation of Sacrobosco’s ‘Tractatus de Spaera’ made by his grandfather Pier Vincenzo Rainaldi (called ‘Dante’ after the author of the ‘Divine Comedy’) and first published in 1571. Egnatio Danti (1536-86), referred to as ‘Cosmographer of the Grand Duke of Tuscany’ on these title-pages, was an outstanding scientist who taught at Pisa and Bologna, drew maps for Cosimo de’ Medici, designed a number of astronomical instruments (two of which were set up in Santa Maria Novella, Florence), brought about the reformation of the Gregorian calendar after having detected a 11-day error, wrote the first book to be published in Italy on the astrolabe (1569), and was appointed Papal Cosmographer and Mathematician by Gregory XIII (1580). His translation of Proclus’ ‘Sfera’, dedicated to Isabella de’ Medici, opens with a two-page life of Proclus and contains long and detailed annotations, often flanked by diagrams, for each of the fifteen chapters of the book. It ends with a five-page essay on how to study the stars without using scientific instruments. Proclus (412-485), illustrious Neo-Platonic philosopher from Constantinople, was also a fine astronomer who expounded the division of the celestial sphere with modern accuracy. Danti’s treatise on the use of the sphere is divided into thirty short chapters dealing with, i.a., how to make a sphere, determine the various positions of the sun and stars and the corresponding times of day and night, and study the Zodiac.
The proportions of water and dry land was a much debated topic of the time. Like Aristotle, Leonardo was convinced that the quantity of water exceeded that of the land, and that a great quantity of water was collected in caverns underneath the surface of the Earth. Piccolomini was one of the first scientists to maintain the opposite. In his fifteen-chapter essay he provides detailed explanations of why, from the antiquity, the amount of water on the Earth had been thought to exceed that of the land, followed by the exposition of his own revolutionary theory. Alessandro Piccolomini (1508-1578), a typical Renaissance polymath, wrote poems along with scientific, philosophical and legal works. An important scientific collection in a very attractive contemporary Spanish binding – a charming example of ‘encuadernación plateresca’, most widespread in university town in the C16. Both the Danti and the Piccolomini are also of interest as early Americana.