Usus Fabrica Circini Cuiusdam Proportionis & Difesa di Galileo Galilei

Bologna: Heirs of Dozza, 1655. Second. Fine.

Baldessare Capra, Usus Et Fabrica Circini Cuiusdam Proportionis, Per Quem Omnia Fere Tum Euclidis, Tum Mathematicorum Omnium Problemata Facili Negotio Resolvuntur, (in Latin) Bologna, heirs of Dozza, 1655 title page, 6 pp of prefaces and 80 pp of text

Galileo Galilei, Difesa di Galileo Galilei Contro alle calunie & imposture di Baldessar Capra, (in Italian) Bologna, heirs of Dozza, 1655, title page and extracted text paginated 83-160

Both volumes contain multiple woodcut decorations to titles, woodcut initials, head-pieces and diagrams Both have been rebound in uniform, very attractive modern blind-stamped calf, and preserved in custom drop-back boxes, [Tomash & Williams C24 & G7], 4to

These are extracts from the first volume of the 1655-1656 Dozza (2nd) edition of Galileo's work The original edition was published in 1607

As described below, these scarce, paired works together document an important controversy of scientific history; Capra's work on the use and construction of proportional compasses and his plagiarism claims against Galileo and Galileo's successful refutation of those claims

Provenance: Both volumes are from the collection of the prestigious Erwin Tomash Library of the History of Computing and bear the library's labels on the inside front covers (see photos) (As an aside, tkhe contents of the library were sold at auction in 2018 Its copy of the first edition of Galileo's Difesa contro alle Calunnie et Imposture di Baldessar Capra Milanese (1607), with a handwritten inscription by Galileo, sold for £466,000 (US$616,378))

From Wikipedia:

Baldassarre Capra (1580âˆ'1626) was an Italian scientist who disputed Galileo's claim to priority of the discovery of Kepler's Supernova and also claimed to have invented the proportional compass, accusing Galileo of plagiarism

Plagiarism accusation against Galileo

Capra's second confrontation with Galileo was sufficiently serious for Galileo to decide he needed to confront it openly In 1602 Capra and his father had asked Galileo to let them observe how his proportional compass worked â€" although Galileo had not invented the instrument, he had made it much easier to use and had devised new applications for it In 1605 the Capras had borrowed a Galilean compass for a time from their friend Giacomo Alvise Cornaro, and they spent time at the workshop of Marc'Antonio Mazzoleni, the craftsman who made Galileo's instruments for him By these means they were able to learn how the compass was made

In 1607 Baldassarre Capra published the tract Usus et fabrica circini cuiusdam proportionis, per quem omnia fere tum Euclidis, tum mathematicorum omnium problemata facile negotio resolvitur, which was more or less a translation into Latin of Galileo's 1606 work Le operazioni del compasso geometrico et militare Capra dedicated the work to Cornaro and used it to claim that he had invented the proportional compass himself Galileo had successfully defended himself against a previous charge of plagiarism fought against him in 1602 by a Flemish mathematician, so he could not afford to take Capra's claims lightly He therefore asked for the matter to be adjudicated by the rectors of the university

The hearing

During the hearing, Galileo was able to demonstrate not only that he had not copied Capra's work, but that Capra had copied his work, and where he had introduced original material of his own, he had introduced errors The testimony of Galileo's friend Paolo Sarpi was crucial to the hearing, and he declared that Galileo had given him a compass as early as 1597

In the face of this, Capra stated that he was willing to apologize for his unfounded allegation of plagiarism by publishing a book in which he would acknowledge the offense caused to Galileo Galileo refused however, wanting to give the widest possible publicity to Capra's eventual condemnation The hearing continued and Capra's position was further weakened when he refused to demonstrate to the tribunal how the compass was used The rectors found him guilty and ordered that all copies of his book were to be destroyed, though some had already been sent outside the Republic of Venice Galileo published their verdict in his favour, as well as a tract entitled Difesa contro alle calunnie et imposture di Baldessar Capra (Venice, 1607), which showed how Capra's accusations were false

Galileo apparently believed that it had been Simon Mayr who had instigated Capra's false claim, and in his great work The Assayer he accused Mayr of having translated his instructions on the compass into Latin and then having them printed using Capra's name After the hearing Capra left Padua and returned to Milan where he continued to teach the use of the compass His disgrace was apparently not forgotten however, as in 1620 he was refused admission into the city's College of Medicine.