Condensing Steam Engine

The Watt condensing steam engine is widely viewed as the primary machine responsible for the Industrial Revolution. It enabled the use of engines anywhere, not only next to coal mines. Whereas factories before the Watt engines needed to be near high-volume streams, to derive power for water wheels, the Watt engine operated at a low enough cost that it could be placed anywhere, enabling the creation of factories.


Watt worked at the University of Glasgow as a mathematical instrument maker making rulers, slide-rules, etc.

In 1763, Watt asked to repair a Newcomen engine the University owned. He realized the Newcomen engine lost enormous energy by expelling its steam every cycle. That is, the boiler would create enough steam to make the engine stroke then simply expel the steam into the atmosphere rather than recycle the hot water. This required the boiler to constantly boil cold water.

Watt’s technological innovation was to add a condenser that captures the steam, transforming it back into hot water, and returning it to the kettle where it can be boiled again. This keeps the overall water temperature much hotter by requiring vastly less coal than the Newcomen engine. Watt filed his first steam engine patent Jan. 5, 1769 though the device did not entirely function.

He worked to produce an engine, eventually selling part of the rights to industrialist John Roebuck for investment funds. Watt spent years trying to produce a working condenser, but blacksmiths of the time – more accustomed to making horseshoes and canons than condensers – did not have the skill. For about ten years, Watt worked odd jobs – at the University, as a land surveyor … whatever paid the bills – as he worked to commercialize his engine.

Roebuck eventually went bankrupt due to a financial crisis and sold his patent interest to Matthew Boulton, who worked with high-end blacksmith shops. They renamed the company Boulton & Watt.

Boulton & Watt

Boulton’s involvement made an enormous difference. He secured Watt’s patent in 1775 and found better tradesmen who perfected the condenser. The first working Watt engines were installed in 1776 but due to the Revolutionary War, they were banned for export to the US.

Boulton & Watt had a unique business plan. The firm charged one-third the cost of coal saved by using a Watt engine over a Newcomen engine. That is, they charged a percentage of the value the technology created. Whereas the Newcomen engine was only profitable at coal mines – where scrap coal was effectively free – the Watt engine was useful everywhere. Factories and mills that had relied on waterwheels, and were subject to weather conditions, could suddenly be placed anywhere and run in any weather.

The Industrial Revolution

Watt’s engines kicked off the first industrial revolution. Combined with Arkwright’s model for unskilled labor there was a sudden need for concentrated labor in urban areas.

Watt went on to create other improvements and patents; he was a prolific innovator. Obvious innovations included modifying the steam engine so it produced power on both the up and down stroke and less obvious ones included the sun and planet gear that eventually allowed gears in engines.

Watt failed to recognize two major innovations created at his company. One was the adoption of coal gas for lighting. Senior Boulton & Watt engineer William Murdoch harnessed coal gas to create coal lighting. Watt allowed the experiments to continue but, despite that coal-derived gas lighting in factories was a natural extension to coal-powered steam engines, forbid Murdoch from moving forward on a full-fledged commercialization project. The second was his aversion to high-pressure steam engines, that would eventually drive everything from locomotives to industrial sawmills.

Watt retired in 1800 and died in 1819 an extremely wealthy man. One overlooked coincidence is that while Watt was at the University of Glasgow developing the steam engine, that would usher in the industrial age and modern capitalism, Adam Smith was simultaneously at the same University writing Nature and the Causes of the Wealth of Nations, the seminal book describing capitalism.

Steam Engine (Newcomen)

The Newcomen steam engine removed water from mines. It worked but was extremely inefficient. Steam was not recycled (re-condensed) so the Newcomen engine required an enormous amount of coal to continually boil water. When used at a coal mine, where scrap coal was essentially free, this cost less than having workers remove water by the bucketful or mules walk in a circle turning a pump.

There were prior steam engines to the Newcomen engine, but none functioned well. Hero, of Alexandria, invented a device in the first century that heats water in the base of a closed device and, once boiling, steam propels the device in a circular motion. The device is little mentioned outside history and it appears too inefficient for any practical use. A commercial pump prior to Newcomen’s was Thomas Savery’s “Miners Friend,” patented 1698. Despite the name, the pump performed poorly and frequently exploded, injuring or killing miners. The Newcomen engine was stable, reliably and safely pumped water.

Newcomen was a Baptist pastor, not an engineer, and historians suggest his purpose in creating the pump was purely financial; he needed funds to maintain his church that struggled in Protestant England. Newcomen named his business Proprietors of the Invention for Raising Water by Fire.