This contribution explores Gilles Personne de Roberval’s 1644 Aristarchi Samii de mundi systemate, partibus, & motibus eiusdem, libellus. I focus on the complex circumstances of publication, the intellectual context of the polemics of Copernicanism within the scientific community, as well as the natural philosophy of the treatise. Roberval’s strategy of publication provides a very sophisticated example of authorship in early modern natural philosophy. The strategy lies at the conflux of certain specific motivations. I contextualize these motivations by accounting for the (...) delicate debates around the motion of the Earth in mid-seventeenth century Europe, the institutional communities of the Collège Royal and Mersenne’s circle, and the disciplinary bounds of Roberval’s professional authority. Weighing in all the elements, I argue that Roberval’s publication is an interesting intellectual game, playing with the notion of ancient authority and humanistic recovery. By this somewhat libertine attitude, Roberval takes a stance in a complicated debate around heliocentrism and the status of hypothetical cosmology. Roberval’s position is supported by his natural philosophical speculations, which I situate in the contemporary debates of the community. Roberval borrows from many philosophers, but he aims at achieving a highly systematic speculative cosmology. One of the functions of this system is to confirm Copernicanism, while maintaining a very pessimistic attitude on the prospects of precise astronomical knowledge and, among others, prognostication issues. (shrink)

This paper deals with Descartes’s and Roberval’s attempts to devise and describe the center of agitation of a composite pendulum. This episode has received some attention in the recent literature. It is usually depicted as the first step in the development of a general procedure for establishing the center of oscillation of a pendulum. My aim is to explore the different physical concepts and assumptions which informed the two mathematical accounts of the composite pendulum. I will argue that force, agitation, (...) heaviness, or resis­tance of air essentially meant different things for Descartes and Roberval. As a result, the physical phenomena covered by the two geometrical procedures were quite distinct, and both mathematicians envisaged different roles of these phenomena within their agenda of studying nature. (shrink)