Boulton and Watt Chelsea Waterworks Pumping Engine, c 1780.

Coloured sectional drawing (scale 1:24) of pumping engine manufactured by Boulton & Watt of Soho, Birmingham, established by Matthew Boulton (1728-1809) and James Watt (1736-1819) in 1774. Water works to supply water to the urban population of west London were established on the banks of the River Thames at Chelsea in 1723. Initially these were powered by water wheels, and then by a Newcomen steam engine. By about 1780, this had been replaced by two powerful Boulton & Watt steam engines. In 1829, the world's first public reservoir purification system was installed here.