Atmospheric Refraction and the Ramus Circle: Aspects of a Late Sixteenth-Century Dispute

Abstract

Summary When dealing with philosophical questions such as the choice of a world system or the substance of heaven, some sixteenth-century astronomers, including Tycho Brahe and Christophe Rothmann, devised more accurate experimental setups so that they could refine their celestial observations. With this desire to listen to nature arose new questions, in particular that of atmospheric refractions, the understanding and resolution of which became decisive to guarantee the best accuracy. However, to solve such practical problems, it was necessary to consider their philosophical and theological background, as well as the knowledge of optics inherited from the medieval period. We examine this heritage and its transmissions through the works of Peter Ramus's assistants, especially Jean Pena and Friedrich Risner. From this first survey, we try to analyse the lively debate on atmospheric refractions in the late sixteenth and early seventeenth centuries by exploring the argumentative structure, the philosophical background, and the epistemological grounds of the discourse of authors such as Tycho Brahe, Christoph Rothmann, and Johannes Kepler.