Ingenium is medieval English vernacular for "an ingenious contrivance." In this fascinating book, physicist Mark Denny considers five such contrivances -- the bow and arrow, the waterwheel, the counterpoise siege engine (including the trebuchet), the pendulum clock anchor escapement, and the centrifugal governor -- and demonstrates how they literally changed the world. Interweaving an entertaining narrative with diagrams, equations, and drawings, Denny shares the history of each device, explains the physics behind it, and describes how it was used, how it evolved, and why it is significant in today's world.

Bow and arrow -- Waterwheels and windmills -- Counterpoise siege engines -- Pendulum clock anchor escapement -- Centrifugal governor -- Inventiveness.