Mr. Weiss is a whiz at demonstrating how things work and he has the keenness to perceive connections--here a pile driver and an hourglass paired as examples of gravity engines. Beginning meticulously with a definition of an engine as ""a machine that changes one form of energy into another form that can produce mechanical work,"" he then examines water engines (primitive water wheel to turbine, with a model to make in between), wind engines (sailboats as well as windmills, and more models) and spring engines. With steam engines, matters become somewhat more complicated, but there's a way to apply an earlier model to the making of a simple steam turbine. And of course, in the section on electricity, there's a motor powered by an electromagnet, a model crane and a buzzer, all set to go as school projects. Concluding appropriately if at a greater remove are chapters on gasoline and jet and rocket engines. An imaginative approach to basic technology that draws the reader in (it's good-looking) and keeps him revved up.