9 - The XVIth century and beginning of the XVIIth.

With the new century astrology went into decline in Italy and Bologna. In fact the lecturing, which already in 1419 was called Astronomia, in 1521 was taught only on a Sunday, losing a good deal of its importance. The last Italian reprint of the treatise of Alcabizio is the Venice one of 1525; the last edition of Ptolemy’s astrological treatises with Alî ibn Ridwân’s comment is the Venice one of 1519. (52)

In 1563, under pressure from Carlo Borromeo (1538-1584), the then papal legate in Bologna, the old and in many ways declining university began its move to the new and splendid building of the Archiginnasio, built in just three years to provide a dignified home for it.

The old Sunday lecturing in Astronomy came to an end in 1571 with the death of the teacher, Lattanzio Benacci (1499-1572), who had taught for 34 years and compiled the yearly Pronostici. Two years earlier however a new chair called Ad Mathematicam had already been established . The syllabus for this course, at least from 1591, was organized over a three-year period: in the first year Euclid’s geometry was read, in the second Theorica Planetarum, and in the third the Almagest.

This scheme was followed, at least officially, until the end of the XVIIIth century. Naturally the actual syllabus adopted depended to a large extent on the scientific personality of the teacher and the advances of the day (53).

In 1576 the new chair was given to the renowned astronomer and geographer from Perugia Egnazio Danti, whose secular name was Carlo Pellegrino Danti (1536-1586). It was with him that astronomical geography became a regular interest for the Bolognese astronomers, reviving a tradition that went back to the previous century when in 1476 the then lecturer in Astronomy, Girolamo Manfredi (?-1493), had edited, together with Cola Martino and Pietrobono Avogario, the Bolognese edition of Ptolemy’s Cosmographia (54) in which, for the first time, the map of the terrestial globe had been redrawn on the basis of the prescriptions and learning of the great Alexandrian astronomer.

Before being summoned to Bologna, Egnazio Danti had been cosmographer to Cosimo dei Medici, leaving many traces of his work at Florence, like the meridian line in the church of Santa Maria Novella. This was essentially a new astronomical instrument designed to ensure a degree of precision unattainable with the large gnomons used in antiquity for the same purpose. The tip of the shadow cast on the ground by a gnomon - however big it might be and in ancient times even obelisks were used - is in fact of much worse definition than the centre of the spot of light produced on the floor of a big church by sun-rays admitted through a small hole.

One of the first undertakings of Egnazio Danti in Bologna - no longer with us today - was the building of a second meridian line in the church of San Petronio (for which on December 20, 1576, he was paid 60 lire), by means of which he ascertained the epoch of the spring equinox that was held to be important for establishing the rules underpinning the Gregorian reform of the calendar, promulgated on March 3, 1582. (55)

Danti was a member of the Commission set up by pope Gregory XIII to prepare the new calendar and presided over by cardinal Guglielmo Sirleto, together with eight other experts: the Calabrian astronomer Antonio Lilio, brother of the physician proponent of the reform, Luigi Lilio , the Jesuit from Bamberg Christophorus Clavius, the Spaniard Pedro Chacon, the Mathematics teacher at the University of Padua Giuseppe Moleti, the Patriarch of the Syrians Ignatius Nehemet, the Verona humanist Giambattista Gabio, and Vincenzo Lauro and Serafino Olivari acting as consultants on liturgical, religious and legal matters.

The only works of Egnazio Danti that have survived in Bologna are a meridian line and what is left of an anemoscope. The former, built in 1576 and recently restored, is to be found in the Sala dell’Inquisizione (Inquisition Room) at the convent San Domenico and consists of a simple iron strip built into the floor which continues up the wall. The latter is a "horologio per conoscere li venti che giornalmente spirano" (clock for knowing the winds that blow daily), built in the great cloister of the same convent according to a model Danti had borrowed from the Torre dei Venti (Wind Tower) in Athens and then modified; it recorded on a vertical plane information provided by a wind vane anenometer which, as was normal then, spun on a horizontal plane. An outline of the map of the winds can just about be recognized on the wall of the cloister, the rest having been demolished at the end of the XVIIth century, including the six metre turret which supported the wind vane (56).

Egnazio Danti was also the author of the big mural map of Italy that can be seen in today’s loggia of the Vatican Museums. Of his successors Magini was also a well known cartographer, leaving behind a large 61 plate atlas of Italy which was then printed by his son (57).

Closely tied to this interest with geography was the long series of ephemerides that began with those covering the period 1554-1569, calculated by the then lecturer in astronomy, Nicolò Simi (1530-1564) (58), followed by those of Magini for the period 1581-1620 (59) and then, later, the Ephemerides Bononiensis Motuum Coelestium begun by Eustachio Manfredi and published uninterruptedly from 1715 to 1844.

The work of Copernicus was certainly well known to Magini, the lecturer we have already mentioned and who held a chair in Bologna from 1589 to 1617.

Among the candidates for the chair vacated by Danti, who had been appointed bishop of Alatri, was the 23 year-old Galileo (1564-1642). The Bolognese Senate, however, went for the older and better known Giovanni Antonio Magini from Padua who, while not being Copernican, corresponded with Tycho Brahe (1546-1601), Kepler (1571-1630) and Galileo himself. Magini had based his ephemerides on the work of Copernicus and was probably one of the first scholars to appreciate the work of Kepler, the astronomer rightly considered the continuator of Copernicus.

It was indeed a disciple of Magini, Giovanni Antonio Roffeni, then Rector of the University, who invited Kepler to move to Bologna upon the death of Magini to take up the chair that had become vacant (60). Magini and Kepler must have held each other in mutual esteem, given the fact that in 1610 Kepler had asked Magini to join him in Prague to share with him the responsibility of compiling new ephemerides (61). The National Museum of Science and Technology in Stockholm has a brass quadrant with a radius of 38.3 cm, built in Bologna in 1595 by Arnoldum Scherpenselensem for Io. Antonius Maginus in Bon. Gymmnasio Mathematicarum Professor.

  1. - L'ultima ristampa italiana del trattato di Alcabizio è quella di Venezia del 1525, l'ultima edizione dei trattati astrologici di Tolomeo con il commento di Alì ibn Ridwân è quella di Venezia del 1519.
  2. - G. Vernazza: 1961, La crisi barocca nei programmi didattici dello Studio bolognese, in Studi e Memorie per la Storia dell'Università di Bologna, Nuova Serie, II, p. 95.
  3. - L. Sighinolfi: 1908, I mappamondi di Taddeo Crivelli e la stampa bolognese della cosmografia di Tolomeo, La Bibliografia, X, p. 241.
  4. - E. Danti: 1577, Usus et tractatio gnomonis magni, Bononiae. Vedi anche: L. Ximenes: 1757, Del vecchio e del nuovo gnomone fiorentino, Firenze, p. 112.
  5. - G. Zucchini: 1936, Gli avanzi di un anemoscopio di Ignazio Danti, Coelum, VI, p. 105.
  6. - F. Magini: 1620, Italia, Bologna.
  7. - N. Simi: 1544, Ephemerides ad annos XV incipientes ab anno Christi MDLIIII usq; ad annum MDLXVIIII, Venetiis.
  8. - G. A. Magini: 1582, Ephemerides coelestium motum ... ad annos XL, Venetiis.
  9. - Kepleri epistolae, 1 martii 1616: 1718, Lipsia.
  10. - A. Favaro: 1886, Carteggio inedito di Ticone Brahe, Giovanni Keplero ed altri con Giovanni Antonio Magini, Zanichelli, Bologna, p.337.
    Presso il National Museum of Science and Technology di Stoccolma si trova un quadrante in ottone, da 38,3 cm di raggio, costruito a Bologna nel 1595 da Arnoldum Scherpenselensem, per Io. Antonius Maginus in Bon. Gymnasio Mathematicarum Professor.