Boulton and Watt Rotative Beam Engine, 1788.
© Science Museum / Science & Society Picture Library
Diagrammatic sectional view. The first products of the famous engineering partnership of Matthew Boulton (1728-1809) and James Watt (1769-1848) were, like earlier engines, purely pumping machines. It was only later, in about 1782, that Watt began to introduce the rotative engine that could be harnessed directly to rotating machinery, and so made possible a huge expansion of all types of industry that needed power. This engine, which drove part of Boulton's own works, is the oldest steam engine to have survived nearly complete and essentially unaltered.