Steam engines were the first source of mechanical power invented by mankind and led the way for the industrial revolution.
steam engine - Kids, Britannica Kids
Steam vs. Diesel
Great Smoky Mountains RR Steam Train Turntable - How Does it Work?
Cameco U101 - How Reactors Work
How do steam engines work? Who invented steam engines?
How steam locomotives work
Go Ask Your Father: Trains, Clouds, Supper, and Stars
The Steam Engine - Actuate Minds
Steamtown National Historic Site (U.S. National Park Service)
how steam engines work
Steam Engines: How Do They Work? – Steam Trains
How does a Steam Locomotive move? – Puralty