Studies in Medieval Astronomy and Optics

In this selection of studies, J.L. Mancha explores aspects of the development of medieval optics and astronomy, including some medieval antecedents of the work of early modern astronomers. The articles deal with Latin, Hebrew and Arabic texts, and the process of translation and transmission of knowledge, and focus on three main themes. First, the theory and astronomical use of the pinhole camera in the 12th and 13th centuries; the texts edited here contain a solution to the problem of the formation of images cast by light through triangular apertures, equivalent to Kepler's, a description of the correct procedure for measuring solar apparent diameters using finite apertures, and a derivation of the Sun's eccentricity from its apparent diameters at apogee and perigee. Second, the characteristics of the Latin and Provenal versions of Levi ben Gerson's astronomical work, composed in collaboration with the author, as well as his tables and canons for finding syzygies and the mathematical methods used in the derivation of parameters. Third, different aspects of the survival of homocentric astronomy in the Middle Ages, especially al-Bitruji's model for trepidation and the technique for calculating the hippopede resulting from Eudoxan couples.