You are here: Technology > Trains > Steam engines

Steam engines

Boulton and Watt steam engine (1796) at the National Museum of Scotland An engine is a machine that converts the energy stored in fuel into energy for operating other machines. In a steam engine, burning fuel heats water in a boiler, turning it to steam, which builds up in the boiler. The pressurized steam is used to operate the moving parts of the engine. In the 1st century AD, Greek inventor Hero built a device that was turned by jets of steam, but it was a curiosity rather than a useful machine. The first locomotive powered by a steam engine was built in 1804 by English engineer, Richard Trevithick. Steam engines were used to power trains until the 1950s and 60s, when they were replaced by electric and diesel-powered locomotives. 



Otto von Guericke's experiment demonstrating the principle of the vacuum

Atmospheric pressure

The first steam engines made use of the results of a simple scientific experiment carried out in 1606. Giovanni Battista della Porta (1535–1615) of Naples showed that when a flask full of steam was cooled, water could be sucked up into it as the steam condensed (turned back into droplets of water). Della Porta had created a vacuum, a space containing no air, inside his flask. The weight of air around it, called atmospheric pressure, forced water up into the empty space.
Savery's engine

Savery's engine

In 1690, having witnessed the mechanical power of atmospheric pressure, French inventor Denis Papin built a model of a piston steam engine—the first of its kind. He later (1704) constructed a ship powered by his steam engine, mechanically linked to paddles. This made him the first person to construct a steam-powered vehicle.

Q-files now has new sections specially written for younger readers. They are: Living world, Earth, Science, Human body, Prehistoric life, Space, History, Geography and Technology.


Find the answer