The development of steam

Thomas Newcomen (1712): Built the first practical steam engine, used to pump water out of coal mines. Highly inefficient.

James Watt (1769): Improved Newcomen's engine with a separate condenser, dramatically increasing efficiency. Watt's engine became the standard power source for British industry. The unit of power, the watt, is named after him.

Robert Fulton (1807): Built the first commercially successful steamboat, the Clermont, which traveled the Hudson River.

George Stephenson (1825): Built the Rocket, the first practical steam locomotive. Launched the railroad age.