The Steam Engine
George Stephenson's Locomotion
The use of steam to move objects was invented
by a Greek called Hero. Although making an object turn around Hero's invention
had no real application at the time.
This first engine used steam which expands when heated in a boiler to
raise a piston up and down in a cylinder.
In the 1700's steam was used to work pumps to pump water out of mines
by an inventor called Thomas Savery. Savery developed the system whereby
steam from a boiler filled a cylinder and was then allowed to cool down.
The cooling turned the steam into a small amount of water but also left
a vacuum in the container. The pressure of the vacuum was used to suck
up the water from the mines.
James Watt an inventor at the time saw the potential of steam to drive
vehicles. Models were made and James Watt's engines were set in motion
in 1776. James Watt converted the up and down movement created in Thomas
Newcomen's engine, with the use of a piston, into round and round movement.
Watt's engines were used to power factory machinery and farm machinery.
It was not until 1885 that George Stephenson developed the 'Locomotion
Engine,'. This primitive engine made its first run on the Stockton to
Stephenson later went on to develop much more powerful engines such as
the 'Blutcher' in 1814 and the famous 'Rocket' which reached speeds of
22 m.p.h running with loads as heavy as 12 tons and covering 14 miles
in 69 minutes.
The power of steam was later used to run steam turbines. These turbines
work in a similar way to a windmill. The steam which is under high pressure
is directed towards the blades of the turbines which make them turn. The
steam is then passed on to stationary blades which then direct the steam
onto rotating blades. The steam expands as it turns the blades, this results
in both the temperature and the pressure of the steam being lowered. The
turbine can have three sets of blades that work at lower and higher steam
pressures. In this way heat energy is transformed into a power that is
able to move things.
Steam power is still used today. Thermal power stations, which burn fuel
such as coal and oil use steam turbines to drive electrical generators.