The French coined the term Industrial Revolution in the 19th century as an analogy to their own political revolution. Although the phrase is in common use, it is not always clear what this phenomenon was or even when it occurred. For example, it has been pointed out that humans underwent an industrial revolution at the beginning of the Bronze Age; yet, it is clear that the Industrial Revolution is something else.

One theory holds that the Industrial Revolution happened when people stopped using human and animal power and began using inanimate power sources; this could place the Industrial Revolution as early as the first extensive use of wind and waterpower –– medieval times in the West and somewhat earlier in China. A different suggestion is that it began when mills began to centralize the production of textiles. This might be interpreted as occurring when fulling mills (mills to work cloth so that it is fuller) began, in the 13th century. Perhaps the date ought to be tied to the largescale production of iron in blast furnaces, which employed workers in something like a factory system. That postpones the revolution to the 15th and 16th centuries. Or maybe it started with the first factory, probably the six-story English silk-thread mill built in 1719 that employed 300 workers, mostly women and children.

A few years after that first factory John Kay made one of the key inventions that started what most historians would call the Industrial Revolution: the flying shuttle, which made weaving much faster. And a few years before that factory Abraham Darby discovered how to make steel using coal instead of wood –– actually, coke instead of charcoal. This allowed for a greater output of cheap steel, since coal was more plentiful than wood at that time in England.

The problem with using these early 18th-century inventions to date the revolution is that few employed them in their early days. It was over 50 years before other steel makers started following Darby’s example; and weavers afraid of losing their jobs destroyed Kay’s loom and sent him packing to France.

About 1750, however, cotton workers, with less of a tradition behind them than the wool workers who had attacked Kay’s loom, started using the flying shuttle. This set into motion a chain of events that revolutionized the textile industry. With the flying shuttle, cotton workers were able to weave so much faster that they ran out of yarn. Seeing an opportunity, James Hargreaves invented a machine that multiplied the amount of yarn produced, the spinning jenny. This time the spinners were upset, and they destroyed some of Hargreaves’s machines, but the cat was out of the bag.

The spinning jenny could make only one of the two types of yarn needed for weaving. Richard Arkwright also saw opportunity knocking: He invented the water frame, a machine that produced the other type of yarn. Unlike the spinning jenny, the water frame was too large and too expensive to put in a cottage. Arkwright had to build a factory to house his machine; he is, in fact, considered the founder of the modern factory system. By 1769 the Industrial Revolution had definitely begun; many date the start back to the 1740s when the cotton weavers first adopted the flying shuttle.

However, there is another key invention that is not yet in place in 1769. Since at least 1629, when Giovanni Branca suggested using steam to propel a turbine, people had been experimenting with steam power. Branca was followed by the Marquis of Worcester in England, Denis Papin in France, and, again in England, Thomas Savery. Savery, at the very end of the 17th century, was the first to make a practical steam engine, known as the Miner’s Friend. It wasn’t very efficient, however, and only a few were installed.

Soon Thomas Newcomen recognized the opportunity and developed a greatly improved steam engine that was more along the lines of the modern engine. Newcomen then got together with Savery, and the Newcomen version of Savery’s engine was successfully manufactured and sold to drain mines. Over 100 Newcomen engines were installed during the 18th century.

An engineer at Glasgow University, James Watt, in 1765 developed a new device, the steam condenser, which greatly improved the efficiency of the Newcomen engine. Ten years later, Watt teamed with a manufacturer of iron products, Matthew Boulton of Birmingham, to manufacture his new engine. Boulton had access to the technology needed to make finely machined parts that gave the Watt engine greater efficiency and durability. Boulton also convinced Watt in 1781 to convert the engine from a simple pump to a device producing rotary power –– the first steam engine that could power other machinery. Four years later the first steam-powered cotton mill opened in Papplewick, Nottinghamshire.

By this date, the revolution part of the Industrial Revolution in England had been completed. It would occur 30 years later in France and 20 years after that in Germany and the United States. Assigning the revolution a single date would be misleading. It took from the 1740s until the 1780s; after that came consolidation of power by the revolutionaries.