Who they were
Repairing a Newcomen engine, Watt saw how much steam it wasted and in 1765 conceived the separate condenser, making the steam engine far more efficient. In partnership with Matthew Boulton from 1775 he manufactured engines that drove factories, mines, and mills, and added rotary motion and other refinements that widened their use.
What they did
His engines freed industry from reliance on water power and vastly increased available mechanical energy.
Legacy
Watt’s engine is a symbol of the Industrial Revolution, and ‘watt’ became the SI unit of power. His work helped make Britain the world’s first industrial economy.