Alessandra Fiocca

To solve the direct problem of central forces when the trajectory is an ellipse and the force is directed to its centre, Newton made use of the famous Lemma 12 (Principia, I, sect. II) that was later recognized equivalent to proposition 31 of book VII of Apollonius’s Conics. In this paper, in which we look for Newton’s possible sources for Lemma 12, we compare Apollonius’s original proof, as edited by Borelli, with those of other authors, including that given by Newton himself. Moreover, after having retraced its editorial history, we evaluate the dissemination of Borelli's edition of books V-VII of Apollonius’s Conics before the printing of the Principia.

This paper publishes the correspondence between S. Germain and C.F. Gauss. The mathematical notes enclosed in her letters are published for the first time. These notes, in which she submitted some of her results, proofs and conjectures to Gauss for his evaluation, were inspired by her study of the Disquisitiones Arithmeticae. The interpretation of these mathematical notes not only shows how deeply she went into Gauss’s treatise and mastered it long before any other mathematician, but also, more importantly, shows that she obtained interesting results in the theory of power residues that have never previously been attributed to her.

In this paper, we describe the genesis of Boscovich’s Sectionum Conicarum Elementa and discuss the motivations which led him to write this work. Moreover, by analysing the structure of this treatise in some depth, we show how he developed the completely new idea of “eccentric circle” and derived the whole theory of conic sections by starting from it. We also comment on the reception of this treatise in Italy, and abroad, especially in England, where—since the late eighteenth century—several authors found inspiration in Boscovich’s work to write their treatises on conic sections.

In this paper, we describe the genesis of Boscovich’s Sectionum Conicarum Elementa and discuss the motivations which led him to write this work. Moreover, by analysing the structure of this treatise in some depth, we show how he developed the completely new idea of “eccentric circle” and derived the whole theory of conic sections by starting from it. We also comment on the reception of this treatise in Italy, and abroad, especially in England, where—since the late eighteenth century—several authors found inspiration in Boscovich’s work to write their treatises on conic sections.