'Bell-crank' engine, c 1799.
© Science Museum / Science & Society Picture Library
Model of the bell-crank engine design which was devised for Boulton & Watt by William Murdock, one of their employees. It was the first 'independent' (self-supporting) engine to be built. 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.