engines that power large cargo ships.  (And I mean huge: Smil has a picture of an engine that is bigger and taller than my three-story house.) The best part, and the core, of Smil's book is chapters 2 through 5.  Chapter 2 sets the stage by telling the history of the gasoline powered Otto-cycle engine (the standard four-stroke gasoline engine).  The history is the context for his argument that although the Otto-cycle engine is important for the automobile, it is inadequate for long distance air travel and for large scale movements of freight (by truck and by sea) and passengers (by train).  Smil emphasizes the much higher ratio of weight to energy in the Otto-cycle engine compared to the diesel and the jet engine as well as the higher energy content of diesel and jet fuel compared to regular gasoline, both problems imposing severe limits on travel distance. Chapters 3 and 4 review the history and development of, respectively, the diesel engine and the gas turbine engine, and are replete with useful information.  Smil shows the challenges of developing new technology.  Rudolf Diesel committed suicide, beleaguered by critics of his engine.  Frank Whittle, who developed the gas turbine, retired from the Royal Air Force at age 41 in frustration and exhaustion.  Smil does a good job of explaining many of the problems that had to be overcome in engine development.  For example, marine diesels operate at a low rpm so that the engine can be connected directly to the screw,