James Watt, Scottish engineer, 1801.
© Science Museum / Science & Society Picture Library
Engraving by C E Wagstaff, 1845, of the Scottish engineer James Watt (1736-1819), after an original oil painting by Sir William Beechey in 1801. Watt invented the modern steam engine, which became the main source of power in 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 remain hot, thus reducing fuel consumption. The SI (international standard) unit of power, the watt (W), is named after him. Published by Charles Knight of London, 1845. Dimensions (overall): 185mm x 140mm.