Two books and a plot: when mathematics meets history

This chapter explores two mathematical books of Spanish origin deposited in the Russell Library within the Salamanca collection, a compendium of administrative documents and books pertaining to the wide network of Irish colleges in the territories of modern-day Spain and Portugal. Through the examination of the two volumes: Juan de Aguilera’s Canones Astrolabii Universalis and Antonio Núñez de Zamora’s Liber de Cometis, written in the sixteenth and seventeenth centuries, respectively, topics such as the influence of astrological concepts in the treatment of astronomical questions, as well as the increasingly sought-after mathematical precision in the literature of the period, are considered. The chapter focuses mostly on the materiality of these books, in particular in the marks of ownership, the significance of annotations in the margins and of interspersed notes on their pages while discussing the collection's provenance and placing it in context with the relevance of mathematical sciences in the Iberian Peninsula in general and the collection's importance in the background of the Jesuit programme of instruction in particular. The analysis of these books, combined with the description of the Salamanca collection's provenance, provides us with a broad perspective that extends beyond mathematics to the social and political aspects of those centuries, which include not only the territories of the Spanish crown, but also the British Isles.