Abstract

Galileo’sGalileo’s assumptionDiscorsi e dimostrazioni matematiche intorno a due nuove scienze attenenti alla meccanica e i movimenti localiDiscorsi e dimostrazioni matematiche intorno a due nuove scienze attenenti alla mecanica & i movimenti locali(hereafter Discorsi) are[aut]Galilei, Galileo dated 1638 (Galilei 1890–1909, VIII, pp. 39–362). In 1639, Vincenzo Viviani[aut]Viviani, Vincenzoadded significant studies[aut]Galilei, Galileo(GalileiGalilei1890–1909, VIII, pp. 215–219, pp. 442–445). Since Galileo’s Discorsi(1638) and Viviani’s[aut]Viviani, Vincenzo additions (1639) are both published in Discorsi (1638), volume VIII of the Le opere di Galileo Galilei[aut]Galilei, Galileo (with also some ad hoc editorial specifications in the footnotes), henceforward for cross–matching references, I will refer to 1638 only, adding their corresponding pages in Le opere di Galileo Galilei[aut]Galilei, Galileo. By means of my comments, this will make clear the difference between Galileo’s work (1638) and Viviani’s[aut]Viviani, Vincenzoadditions (1639). In 1979, Paolo Galluzzi[aut]Galluzzi, Paolo, published “Momento”. InMomento ; Momentum this article, he identified a confusion made by Galileo between Archimedean Momentum and his own new Momentum. This confusion, he said, occurs in his Proofs Concerning the Inclined Plane. The aim of this paper is to show that there was no confusion in Galileo’s mind. It will be shown studying the free fall as well as the fall on an inclined plane in various of his own works suchDe motu antiquiora as De motu antiquiora (1589–1592), Le mecaniche (1593), theLe mecaniche various de motu and the Discorsi e i movimenti locali (1638) as well as Viviani’s[aut]Viviani, Vincenzo addition to the Discorsi. But our comparision will be extended to other authors such as Jordanus de Nemore[aut]De Nemore, IoradanusinDe ratione ponderis his De ratione ponderis (fl. 13th), Gregorius van Sto Vincentio[aut]Gregorius van Sto Vincentio, Theoremata mathematica scientiae staticae de ductu ponderum per planitiem recta and oblique horizontem decussantemTheoremata mathematica scientiae staticae de ductu ponderum per planitiem recta and oblique horizontem decussantem (Van Sto Vincentio Gregorius (1624) Theoremata mathematica scientiae staticae de ductu ponderum per planitiem recta et oblique horizontem decussantem, Louvain.), Torricelli with his de motu gravium (1644), andDe motu gravium a quick look at a letter of Johann Bernoulli[aut]Bernoulli, Johann, all concerning the same arguments. The work of Torricelli plays an important role in this story because he exchanged letters with Galileo and was his assistant for the three last monthes of Galileo’s life.