**Giovanni Magini** was an Italian scientist who worked in astronomy and had a version of an earth-centred Solar system.

- Magini completed his education at the University of Bologna, receiving a doctorate in philosophy in 1579.
- Magini competed for the chair as did, among others, Galileo.
- One might think that there would be no competition once Galileo applied for a chair but Magini was nine years older than Galileo and seen as a much safer appointment; he was appointed in 1588 and held the position for the rest of his life.
- Galileo had revolutionary ideas while Magini's ideas were original but based on the established world-view.
- In Novae coelestium orbium theoricae congruentes cum observationibus N Copernici (Venice, 1589), Magini writes about "absurd hypotheses, such as Copernicus imagined".
- The book does contain, however, Magini's own version of an Earth-centred theory which was seen at the time as an impressive development.
- In 1592 Magini published De Planis Triangulis which explains the use of quadrants in astronomy and in surveying, in particular describing details of calculations and measurements which could be performed with a quadrant.
- Several quadrants have survived with an inscription involving Magini's name.
- Two quadrants exit, one with the inscription "Giovanni Antonio Magini of Padua designed this in Bologna in the year 1592", the other is dated 1595 and inscribed "Giovanni Antonio Magini Professor of Mathematics in the University of Bologna had this made".
- The chair of mathematics at Bologna saw Magini receive a salary of 1000 lire which was doubled to 2000 lire in 1597.
- As well as teaching the boys mathematics, Magini was astrologer to the Duke.
- In 1611-12 a one-sided part survives of what must have been a quite regular correspondence, demonstrating that Ferdinando was engaged on alchemical experiments under Magini's direction.
- Magini sent particulars of an experiment to him at Mantua in April 1611, and wrote that he had transcribed many more notes for him, but that a German (Martin Horkey), whom he had sent away on Galileo's insistence, had taken them.
- Ferdinando was evidently well equipped with laboratory apparatus, for Magini asked to be lent some of his glass vessels or instruments.
- In June the same year, when the Cardinal was at Florence and unwell, Magini wrote to cheer him up with the news that he had found at Venice some new books on the subject, including Philip Müller, 'Miracula Chymica et Mysteria Medica' (first edition, Wittenberg 1611) which he urged Ferdinando also to buy.
- In February 1612, when Ferdinando was in Paris, Magini wrote of an even more exciting find, some rare books by the thirteenth-century hermeticist Ramon Llull; even Magini dropped an admission that the attribution to Llull might be false, nevertheless he confidently quoted a passage in his letter and asked Ferdinando to check whether an image of Christ and a cross allegedly made from alchemical gold were still in Notre-Dame.
- Magini urged him to persevere in an exercise to extract the 'menstruo vegetabile' from red wine, which could be very well done in Rome, since the wines there were darker and stronger.
- In another letter, promising more transcripts from the pseudo-Llullian text, Magini insisted on the value of this experiment to distil 'solfere vegetabile' from wine; for it would equip Ferdinando with the key to carrying out still greater transmutations.
- This seems the appropriate place to say a little more about Magini's contributions to astrology.
- In 1606 Magini published an extremely accurate set of trigonometric tables.
- This mathematical work is typical of all of Magini's mathematical contributions which are all highly practical; they include treatises on the geometry of the sphere, on applications of trigonometry, and on calculating devices of his own invention.
- Many in Bologna, including Magini, were sceptical of Galileo's discoveries, and therefore an opportunity presented itself for a demonstration.
- Magini was also interested in mirrors, both in their theory, publishing a treatise on the theory of concave spherical mirrors, and in their practical manufacture.
- We have not yet mentioned the work for which Magini is best known namely his map of Italy.
- It was indeed a long time before Magini's work was superseded.

Born 13 June 1555, Padua, Venetian States (now Italy). Died 11 February 1617, Bologna, Papal States (now Italy).

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Astronomy, Origin Italy

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