This is a companion volume to March of the Iron Men. Once again he studies the inventions but this time he cross sections American history and economics and society, showing how invention has motivated American life. He takes successive forward steps, as telegraphy and cable linked the world together, as trains forged a continent, as cheapened steel centralized industry, as cities were made possible by architectural developments, health provisions, transit facilities and telephone. He shows the effect on business of easier communication (typewriter and linotype machines); how water power, light, photography, movies, automobiles, airplanes, radio and chemistry are changing the pattern of life. Good reading. A new angle on social history.