Capra, Balthasar; Vsvs et Fabrica Circini Cvivsdam Proportionis, per quem omnia fere tum Euclidis, tum Mathematicorum omnium problemate facili negotio refoluunter... 1st edition, H.E. de Duccijs, Bononiae (Bologna) 1655. Octavo, pp. 6, 80 and with many woodcuts including a full page one of the sector. & Difesa di Galileo Galilei Nobile Fiorentino, Lettore delle Matematiche nello Studio di Padoua. Contro alle Calunie & Impolture di Baldessar Capra Milanese.... H.E. de Duccijs, Bononiae (Bologna) 1655. Octavo, pp. 81-160 with many woodcuts.

The two works are bound in early parchment covered boards with gilt spine titles. The bindings are tight and lightly soiled. Owners book plate on paste downs and text is exceptionally clean.
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Capra (1580‑1626) an Italian astronomer and philosopher is best known for his challenge of Galileo as the inventor of the compass and the proportion or sectors. His first work in this two volume set was written in 1607 although not published until 1655 after Galileo’s first published work on the proportional compass about 1598. Galileo’s work is a major work for those interested in the history of 17th-century intellectual property rights, and also is closely tied to the development of the proportional compass. Galileo's version of the proportional compass included numerous additions and improvements that rendered it the most useful mathematical instrument of its period. Galileo's compass remained unsurpassed until the advent of the slide rule in the mid-nineteenth century. In 1606, to secure a form of copyright of his instrument, which was already beginning to be imitated, Galileo published a description of it.
Capra contested Galileo’s claim to the invention. But it was proven that Capra had plagiarized Galileo's proportional compass, translating Galileo's tract into Latin under his own name. Second, he manufactured and sold the instrument, encroaching on what had previously been Galileo's monopoly. More than the financial loss, however, was the threat to Galileo's prestige: as Capra's book contained a claim to priority of invention. The book makes a direct assault on Galileo's integrity, particularly as it implied that in dedicating the Compasso to Cosimo de Medici, Galileo was dedicating what was not his to give. Galileo took legal action against Capra and won. Copies of Capra's book were suppressed and thus the original two part work which was written in 1607 was not officially published until 1655.