Astronomical observations and the teaching of astronomy in Coimbra in the light of a letter from Cristoforo Borri to André de Almada (1626)

Abstract

This article presents an original, unpublished autograph letter, recently found in the General Library of the University of Coimbra-BGUC, written by the mathematician and astronomer Cristóforo Borri, a priest of the Society of Jesus, to the Theology Lens of the University of Coimbra, Dom André de Almada, a portioner of the College of São Paulo, a renowned scholar, mathematician and astronomer. The letter was written during the period when Borri was teaching at the Coimbra College of Arts, in 1626 and 1627, and was found between the pages of the copy of the work Tabulae frisicae lunae-solares quadruplices by Nicolaus Mulerius (Alkmaar, 1611), from the collection of the Biblioteca Joanina belonging to the BGUC. In addition to the precise dating of the missive, based on the ephemeris evoked by Borri, the article contextualizes Borri’s cosmological and astronomical research in the science of the time and his role in defending Tycho Brahe’s system and the scientific activities promoted in Coimbra by Almada. The article shows the development, in the second decade of the 17th century, of a program of astronomical observations, particularly of Mars, in Coimbra, which involved not only Borri but also a group of literati, led by Almada, who had a remarkable and up-to-date scientific library and astronomical instruments, which made up for the shortages in the college and university bookshops. The study reveals the relevance of this astronomical program in the course plans taught by Borri at the Jesuit colleges in Coimbra and at the Aula da Esfera at the Colégio de Santo Antão in Lisbon in 1627/28, and his major work Collecta Astronomica (Lisbon, 1631), considered the the most influent on astronomy in Portugal in the 17th century. The article includes a transcription and reading of the manuscript.