The three books of Heron¿s Mechanics contain the first systematic theory of simple andcompound machines in the history of science, and many other remarkable mattersabout theoretical and practical mechanics, including three interesting unknowntheories by Archimedes. This treatise began to circulate among Western researchersthrough an Arabic manuscript discovered by Camille Carra de Vaux, who publishedit together with a French translation in 1893. A German critical edition by LudwigLeo Nix (1900) and an English one by Aage Gerhardt Drachmann (1963) were thenpublished after this edition. The new critical edition, with a full presentation of allthe manuscript sources for the work, is the consequence of the unexpected discoveryof four Persian manuscripts, all concerning the second book of this importanttreatise on mechanics, which opened an unexplored field of research and offerednew perspectives, both philological and scientific, in interpreting the text. At thesame time, analysis of the work has revealed passages very similar to correspondingpassages in works by Leonardo da Vinci and Galileo Galilei, advancing the possibilitythat Italian scientists of the Renaissance may have been familiar with all or at leastpart of Heron¿s Mechanics.