Valve-gear on Boulton & Watt rotative engine, 1788.

Sectional view of valve-gear on the 'Lap' Engine made by Boulton & Watt. 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 harnesed directly to rotating machinery, and so made posible a huge expansion of all types of industry that needed power.