A brief history of steam engines

Evangelista Torricelli1644

The barometer

BarometerTorricelli's chief invention was the mercury barometer, which arose from solving a practical problem. Pump makers of the Grand Duke of Tuscany attempted to raise water to a height of 12 meters or more, but found that 10 meters was the limit with a suction pump. Torricelli employed mercury, fourteen times more dense than water. In 1643 he created a tube approximately one meter long, sealed at the top, filled it with mercury, and set it vertically into a basin of mercury. The column of mercury fell to about 76 cm, leaving a Torricellian vacuum above. As we now know, the column's height fluctuated with changing atmospheric pressure; this was the first barometer. The discovery of the principle of the barometer has perpetuated his fame ("Torricellian tube", "Torricellian vacuum"). The torr, a unit of pressure used in vacuum measurements, is named after him.

Otto von Guericke

1654

Denis Papin

1690 The first piston steam

engine

1679Steam digester

(Safety valve 1695)

Capt Thomas Savery

1698

“The Miner’s friend”

Papin c1707

Thomas Newcomen

1711separate boiler from cylinder

James Watt

1765separate the condenser

• James Watt, as a near destitute mechanic, joined partnership with Boulton

• The pair made 496 engines, relying on current developments in tool making

• Some engines were still in operation for 120 years