The book Petri Nonii Salaciensis Opera – The Works by Pedro Nunes from Alcácer do Sal – was first published in 1566 in Basel and is the most significant scientific work written by Pedro Nunes (1502–1578). It constitutes the most important work by the most renowned and influential Portuguese mathematician of all time, and is thus a book that occupies a unique place in the history of science in Portugal.
The Petri Nonii Salaciensis Opera is a collection of works that address nautical and astronomical matters from a mathematical perspective. It includes a text called ‘On two problems in the art of navigation’ (the Latin version of a work first published by Nunes in 1537) and a long treatise, ‘On the rules and instruments for discovering things both maritime and celestial using the mathematical sciences’. The fundamental importance of these two nautical treatises stems from the fact that they acted as the launchpad for a whole new discipline – theoretical or mathematical navigation. Among the many innovative ideas set out here, those that merit special attention include the very first complete mathematical study of a ‘rhumb line’ (later called a ‘loxodrome’), a concept that was first introduced by Pedro Nunes and would go on to have a major impact on the theory of navigation and cartography. Today, for instance, we know that these concepts and techniques form the very basis of the cartographic projection proposed by Gerard Mercator in 1569. The collection also discusses many other matters relating to the use of nautical instruments, the techniques used by navigators, the geometric features of sea charts, and so on. Together with the two treatises about seafaring, the Opera also contains an in-depth and highly innovative mathematical study of the mechanical problems of rowing boats, together with a long and sophisticated commentary on a celebrated text of theoretical astronomy (the Theoricae Novae Planetarum by Georg von Peurbach), which experts consider to be one of the most meticulous studies of the issue ever to have been published. The Opera of Pedro Nunes became widely distributed among the great scholars of Europe and was known and studied by the most notable mathematicians of the age. When the book was published, Nunes, who was already widely known since the appearance of his De crepusculis (1542), became one of the foremost mathematicians of his time. Today copies of the first edition of the Opera (1566) can be found in nearly every major library in the Western world. The fact that his work was so widely disseminated is evident from a new edition being published in 1573 in Coimbra, as well as its reprinting in 1592 by its editors in Basel after Pedro Nunes’ death. At no other time has a work by a Portuguese mathematician had such a huge impact.
There is a modern edition of the Petri Nonii Salaciensis Opera, including a translation of the Latin text and abundant explanatory notes, in volumes IV and V of the Obras de Pedro Nunes, published by the Lisbon Academy of Sciences and the Calouste Gulbenkian Foundation.
Henrique Leitão Lisbon University
