Five historical devices — bow and arrow, waterwheel, trebuchet, pendulum clock anchor escapement, and steam engine governor — capture the imagination of physicist Mark Denny. Here he shares not only the history of these influential machines, but how they actually work. Using accessible prose, along with diagrams, equations, and drawings, Denny explains the physics behind each machine, how it was used, how it evolved, and why it is significant in today´s world.