On some early Latin European measurements of the eccentricity of the solar orbit (1308–1314)

Manuscripts in Oxford and Erfurt preserve evidence of the earliest known efforts made in Latin Europe to remeasure the eccentricity and maximum equation of the Ptolemaic solar model. The present article analyses and contextualizes this evidence, while also revisiting Ernst Zinner’s hypothesis according to which the relevant observations were made by Alard of Diest ( fl.1308).