Rotary Steam Power Drives the Factories

Early steam engines moved up and down, which suited pumps but not machines that needed to turn. In 1781 Boulton and Watt patented the 'sun and planet' gear, a device credited largely to their employee William Murdoch, which converted the beam's motion into rotation. Watt then added double action, with steam pushing on both sides of the piston, and parallel motion to guide the piston rod, plus a centrifugal governor to regulate speed.

These rotative engines could drive mills, breweries and ironworks. Steam freed factories from fast rivers, letting them cluster in towns near coal, labor and markets. Yet water power remained important for decades, and many mills used both. Historians note that steam's biggest impact came only after about 1830, when cheaper, high-pressure engines spread, showing how slowly even revolutionary technologies diffuse.