About Steam Engines:

Steam engines use heat energy to produce mechanical motion. Steam expands when heated, and so can be used to drive a piston which turns a shaft. If you've ever seen a car engine you will find the theory familiar.   

The first contraption which could reasonably be called a steam engine was patented in 1698 to pump water out of flooded mines. It had few moving parts; no piston or flywheel, just a system of valves and chambers that enabled it to draw water with suction. The engines became popular as water pumps in England, but weren’t useful for much else.

In 1712, Thomas Newcomen developed a more powerful engine which used a piston and a walking beam. This engine was still not very efficient because it required the steam chamber to be heated and then cooled with each cycle - a waste of energy. In the late 1700s James Watt created an engine with a separate condenser, and the steam engine was ready to take off. Steam engines became the power behind the industrial revolution and gave the 19th century the shape we remember today, from Mississippi steamers to the transcontinental railroad.  

 

Info from: Modern Engineering Thermodynamics by Robert T. Balmer, Chapter 13