James Watt, Scottish engineer, early 19th century.
© Science Museum / Science & Society Picture Library
Etching by William Nicholson of James Watt, (1736-1819), Scottish engineer and instrument maker who invented the modern steam engine which became the main source of power in the textile mills in Britain. His engine had a separate condenser through which steam from the cylinder was pased and cooled, allowing the engine to be kept hot. This reduced fuel consumption, saving time.