Letter from James Watt to Josiah Wedgwood, 1799.
© National Media Museum / Science & Society Picture Library
Rear side of letter. James Watt (1736-1819) was a Scottish engineer and instrument maker who invented the modern steam engine, which became the main source of power in the textile mills in Britain during the Industrial Revolution. His engine had a separate condenser through which steam from the cylinder was pased and cooled, allowing the engine to be kept hot, thus reducing fuel consumption and saving time.