In Galileo Galilei and Motion. A Reconstruction of 50 Years of Experiments and Discoveries, Italian physicist Roberto Vergara Caffarelli confirms recent findings by other scholars that Galileo broke away from the qualitative Aristotelian doctrines by following a quantitative Archimedean thread. Among the many books on Galileo Galilei, only very few deal directly and in depth with his scientific accomplishments proper. This is one of them and among the correspondingly sparse literature the author of this work distinguishes himself by focusing on mechanics, in particular on the fundamental concept of motion and percussion - having performed crucial original experiments and in Galileo´s spirit. Indeed, while the author lets Galilei speak for himself when he explains his experiments and findings, he also makes full use of our present day knowledge of physics to make the reader better understand the perspective. The result of this very fine understanding is an unsurpassingly authoritative account on some of the foundations of preclassical mechanics as laid down by the great Pisan scientist, widely regarded as the first experimental physicist in the modern sense. This book will not only be an indispensable source of reference for historians of sciences but appeal to anyone interested in the foundations of experimental physics in general and of mechanics in particular. – Contents: Introduction.- 1. Problems of chronology.- 2. Around 1590: the old sequence of three versions of the De Motu.- a. The pendulum, an exact measure of time.- b. Natural motion (uniform velocity).- c. Early experiments in water.- d. What did Galileo see while he studied motion in water?- e. Bodies that stays atop water, or move in it.- f. The experiment with the "inverted tumbler".- g. Measuring adhesion with water.- h. Violent motion (non-uniform velocity).- i. The fundamental theorem of the inclined plane.- k. Some problems concerning the motion on the inclined plane.- l. Primigenial formulation of the principle of inertia.- m. Primigenial formulation of the action-and-reaction principle.- 3. The Mechanics (1592-1609).- 4. 1592-1610: "Li diciotto anni migliori di tutta la mia eta'" (The best eigtheen years of my life).- 5. 1602 The theorem of the chords and the pendulum isochronism. The letter to Guidobaldo del Monte.- 6. Before 1604: The law on the fall of heavy bodies.- 7. The 107v sheet: the experimental confirmation of the law of motion.- 8. Why 100 arms (=braccia: an Italian unit of measure of that time) in 5 seconds?- 9. Before 1607: the parabolic trajectories.- 10. Before 1610: The velocity acquired in going downwards is proportional to the square of the height.- 11. Before 1610: Throws on the inclined plane without a rectifier.- 12. The time required to descend along inclined planes of equal height and the final velocity theorem.- 13. The confront between two motions: the free fall and the descent along the inclined plane.- 14. Before 1606: experiments on a ship moving with uniform motion.- 15. the laws of motion: Galileo announces them in the "Dialogo" and presents them in the "Discorsi".- 16. Before 1610: The constant-flux chronograph.- 17. Making experiments with the new machine Galilei overcomes the difficulties due to rolling.- 18. The project of Galilei's machine: the vertical plane.- 19. Description of Galilei's machine and of the experiment one can perform with it.- 20. Marin Mersenne, "the one who wants to upset everything".- 21. Conclusions. M.-M. V.