Well into the eighteenth century, Europe, like other areas of the world, relied mainly on wood for energy, and human beings and animals performed most work. This dependence meant that Europe and the rest of the world remained poor in energy and power.

By the eighteenth century wood was in ever-shorter supply in Britain. Processed wood (charcoal) was mixed with iron ore in blast furnaces to produce pig iron that could be processed into steel, cast iron, or wrought iron. The iron industry’s appetite for wood was enormous, and by 1740 the British iron industry was stagnating. As wood became ever more scarce, the British looked to coal as an alternative. The real breakthrough came when industrialists began to use coal to produce mechanical energy and to power machinery.

To produce more coal, mines had to be dug deeper and deeper and were constantly filling with water. Mechanical pumps, usually powered by animals walking in circles at the surface, had to be installed. Animal power was expensive and bothersome. In an attempt to overcome these disadvantages, Thomas Savery in 1698 and Thomas Newcomen in 1705 invented the first primitive steam engines. Both engines burned coal to produce steam that drove the water pumps.

In 1763 a gifted young Scot named James Watt (1736–1819) was drawn to a critical study of the steam engine. Watt worked at the University of Glasgow as a skilled craftsman making scientific instruments. In 1763 Watt was called on to repair a Newcomen engine being used in a physics course. Watt discovered that the Newcomen engine could be significantly improved by adding a separate condenser. This invention, patented in 1769, greatly increased the efficiency of the steam engine.

To make his invention a practical success, Watt needed skilled workers, precision parts, and capital, and the relatively advanced nature of the British economy proved essential. A partnership in 1775 with Matthew Boulton, a wealthy English industrialist, provided Watt with adequate capital and exceptional skills in salesmanship that equaled those of the renowned pottery king, Josiah Wedgwood. (See “Individuals in Society: Josiah Wedgwood.”) Among Britain’s highly skilled locksmiths, tinsmiths, and millwrights, Watt found mechanics who could install, regulate, and repair his sophisticated engines. From ingenious manufacturers, Watt was gradually able to purchase precision parts. By the late 1780s the firm of Boulton and Watt had made the steam engine a practical and commercial success in Britain.

The coal-burning steam engine of Watt and his followers was the Industrial Revolution’s most fundamental advance in technology. For the first time in history, humanity had, at least for a few generations, almost unlimited power at its disposal. Steam power began to replace waterpower in cotton-spinning mills during the 1780s, contributing greatly to that industry’s phenomenal rise. Steam also took the place of waterpower in flour mills, in the malt mills used in breweries, in the flint mills supplying the pottery industry, and in the mills exported by Britain to the West Indies to crush sugarcane.

The British iron industry was also radically transformed. After 1770 the adoption of steam-driven bellows in blast furnaces allowed for great increases in the quantity of pig iron produced by British ironmakers. In the 1780s Henry Cort developed the puddling furnace, which allowed pig iron to be refined with coke, a smokeless and hot-burning fuel produced by heating coal to rid it of impurities.

Cort also developed steam-powered rolling mills, which were capable of spewing out finished iron in every shape and form. The economic consequence of these technical innovations was a great boom in the British iron industry. Once scarce and expensive, iron became the cheap, basic, indispensable building block of the British economy.