Capra, Baldassar or Baldksar

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Capra, Baldassar or Baldksar

(b. Milan. Italy, ca. 1580; d. Milan, 8 May 1626),


Capra was the son of Aurelio Capra and Ippolita Della Croce. Corte states that he was a good philosopher, doctor, and astronomer; Argelati adds that he received his degree in medicine. Both these authors, besides giving a list of his works in Latin, emphasize the nobility of his family, which included Galeazzo Capra (or Capella), who was secretary and historian to Duke Francesco II, the last of the Sforzas of Milan. But Capra is known today only because he was one of the first opponents of Galileo, whom he attacked unjustly in 1605 regarding his observations on the new star which had appeared the year before, and whom he gravely offended two years later by plagiarizing the first book Galileo submitted for publication. He published as his own a brief Latin treatise on the proportional compass, which proved to be scarcely more than a translation of Galileo’s Le operazioni del compasso geometrico e militare, a translation not without defects and, in addition, sprinkled with malevolent insinuations against the real author.

When he was a little more than ten years old, Capra was taken to Padua by his father, who augmented his income by teaching fencing and surgery. Galileo himself, according to letters and the Difesa that he wrote in 1607 “against the calumnies and fraud of the Milanese Baldessar Capra,” had procured for Aurelio Capra a student and a profitable consultation. Yet Capra’s father entrusted his son to Simon Mayr, a teacher from abroad, who Latinized his surname to Marius and, coming from Prague, boasted of having studied under Tycho Brahe and Johannes Kepler (even though he had stayed in that city for less than a year). In Padua, where he arrived at the end of 1601, Mayr attended the course in medicine and, later, Galileo’s classes; and although he had enemies who called him an “unskilled and bad astrologer,” he must have distinguished himself and gained importance, for he was councillor of the German nation in 1604 and in 1605, the year in which he returned to his native land, where he became the court mathematician to the margrave of Brandenburg, who had financed his studies. Mayr’s influence on Capra and on his works is evident not only in the work published in the year of his departure but also in the subsequent ones, which certainly had been begun before he left Italy.

Capra’s first work, published in Padua in 1605 (and reprinted later in the National Edition of Galileo’s Works, vol. II), is entitled Consideratione astronomica circa la nova et portentosa stella the nell’anno 1604 a di 10 ottobre apparse, con un breve giudicio delli suoi significati, di Baldesar Capra, gentil’homo milanese, studioso di astronomia e medicina. Although it is not among the works listed by Corte and Argelati, it is perhaps the one of greatest interest and value. It is written in Italian, for which he apologizes in the dedication to his maternal uncle, Giovanni Antonio Della Croce, stating, “If one considers the material which is dealt with, it should have, for every reason, been described [written entirely] in Latin, which is more excellent and worthy.” This is probably an excuse, for he finds justification in his having to refute the nonsense written, also in Italian, by a Peripatetic (probably Antonio Lorenzini of Montepulciano, in his Discorso intorno alla nuova stella). Galileo had polemized against Lorenzini in his classes and in a popular dialogue, which appeared at the same time under the pseudonym of Cecco de’ Ronchitti.

Capra also maintains, against the Aristotelian thesis, that the new star belongs to the sphere of fixed objects and gives ample and precise information on its position and the variations of its color and its size, demonstrating that he made careful observations. At the end there is an attempt at an astrological interpretation, which should not be surprising, since astrology was still popular—in fact, astrology is also present in the similar booklet by Kepler. In very bad taste, on the other hand, are the frequent taunts at Galileo, on secondary questions and often with an air of pretext, almost as if the author were looking for controversy. For the time being, however, Galileo did not feel it necessary to answer, nor did he wish anyone else to do so.

In 1606, in Padua, Capra published two book lets in Latin, both dedicated to Cardinal Federigo Borromeo and each consisting of fourteen pages. Modest also in their content, they were entitled Tyrocinia astronomica, in which Capra prudently appeals as much to the authority of Tycho Brahe as to that of Ptolemy, and Disputationes duae, una de logica et eius partibus, altera de enthymemate (the enthymeme, the well-known abbreviated syllogism, implies one of the premises).

The work to which he devoted the greatest effort and the most diligence, Usus et fabrica circini cuiusdam proportionis, per quem omnia fere turn Euclidis, turn mathematicorum omnium problemata facili negotio resolvuntur, consisting of fifty-six pages with numerous woodcuts and one copperplate on the title page, was published at the beginning of 1607 but was probably the result of several years of work, even though it shows very little originality. It explains the use and construction of a proportional compass by means of which, with a few simple operations, one can solve almost all the problems of both geometry and mathematics; and the clear engravings on the title page illustrate the use of the proportional compass with the aid of a standard compass. The work is dedicated to Joachim Ernest of Brandenburg, to whose court Simon Mayr had returned after completing his studies. Because of the close analogies with Galileo’s II compasso, which had appeared a few months before, this book was clamorously condemned to sequestration and destruction, but for the same reason it was fully analyzed by Galileo’s students and included in all editions of his works, beginning with the one published at Bologna in 1655.

To all that has been said on this subject, it is possible to add that probably Capra, while his teacher was still in Padua, had set out to give greater authority (by putting them in Latin) to the handwritten instructions on use of the compass that had been publicly dictated by Galileo but generally were circulated in the “adespota” form (anonymously), which meant they were both without author and without owner. This at least explains the imprudent and foolish attempt by Capra, who, if he had only cited his source and renounced the absurd pretext of priority, would have had both fame and advantage, including economic benefit, from that work. That unfortunate attempt was instead his ruin. Having left Padua quite precipitously, he apparently returned to Milan, where he kept in contact with the anti-Galileans, including Horky; but at the end of 1620, when he asked to register at the medical college of Milan, Lodovico Settala energetically opposed him because of his behavior toward Galileo. There is no further news of him until his death, which came shortly after his forty-fifth birthday.


On Capra or his work, see the following (listed chronologically): Bartolomeo Corte, Notizie istoriche intornoa’medici scrittori milanesi… (Milan, 1718); Filippo Arge-lati, Bibliotheca scriptorum Mediolanensium (Milan, 1745); Pietro Riccardi, Biblioteca matematica italiana (Modena,1870–1880); Antonio Favaro, Galileo Galilei e lo Studio di Padova, I (Florence, 1883), 182–192; Scampoli galileiani, CVI, Intorno alla stampa della Difesa contro il Capra (Padua, 1906); Amici e corrispondenti di Galileo, XVII(Venice, 1906); and Per la storia del compasso di proporzione (Venice, 1908); and the Edizione Nazionale of Galileo’s Opere, XX (Florence, 1909), biographical index.

Giorgio Tabarroni