James Watt, born at Greenock in 1736, was the son of a carpenter. He trained as an instrument maker in London and began to practise this trade in Glasgow. Watt soon developed a reputation as a high quality engineer and was employed on the Forth & Clyde Canal and the Caledonian Canal. He was also engaged in the improvement of harbours and in the deepening of the Forth, Clyde and other rivers in Scotland.
In 1763 he repaired the model of Newcomen's steam engine belonging to Glasgow University, and began experiments on properties of steam. The Newcomen engine was simple in design: it acted as a pump and a jet of cold water was used to condense the steam. Watt improved on this design by adding a separate condenser and a system of valves to make the piston return to the top of the cylinder after descending. He took out a patent for the separate condenser in 1769. He later adapted the engine to rotary motion, making it suitable for a variety of industrial purposes, and invented the flywheel and the governor.
In 1774 he went into partnership with Matthew Boulton to make steam engines at their works at Soho, Birmingham. The first engines were used in collieries and iron works and were the driving force behind the transformation of cotton spinning from a cottage to factory industry. Watt's inventive talents led him to patent a variety of machines and devices including a letter-copier and a smoke-consuming furnace.
James Watt died at Hatfield in 1819 and was buried in Handsworth Church. He had been elected Fellow by the Royal Society, Edinburgh, and London, in 1795, and awarded the degree of Honorary Doctor of Laws by Glasgow University.