Chapter 7: The Steam Engine

The steam engine was the product of centuries of experimentation, economic necessities, strong business acumen, and colorful personalities. This is how it happened.

Sources for this episode include:

Herreld, Donald J. "An Economic History of the World Since 1400." The Great Courses. 2016.

Rhodes, Richard. Energy: A Human History. Simon & Schuster. 2018.

Rosen, William. The Most Powerful Idea in the World: A Story of Steam, Industry, and Invention. University of Chicago Press. 2010.

Full Transcript

It’s not unusual for people to realize that the history they’ve learned in school isn’t always totally accurate.

Sometimes this is because educators must weigh the politics of the parents or the community, which is why several American states now have laws requiring history curricula to emphasize American exceptionalism. My parents didn’t grow up learning about Native American genocide. The role of slavery as a cause for the Civil War was downplayed. Thanks to some state lawmakers and Boards of Education, these truths are getting buried once again.

Sometimes it’s because the moral of the story is so important and so compelling, that the accuracy of the story is a secondary concern. Many of us were taught that George Washington chopped down a cherry tree as a child and admitted it to his father, explaining “I cannot tell a lie.” But of course, that story is probably a lie. There is no reliable evidence that it happened.

Sometimes it’s because the real story is far too complex for young children. Trying to explain the War of 1812 to an American child is somewhat pointless, because the intricacies of the European conflict are well outside the scope of what they can yet retain. As a result, it’s typically glossed over, with only a passing mention of how the British burned down the capital or the Battle of New Orleans.

And simplification is especially prevalent in how we teach scientific history. Sir Isaac Newtown did not discover gravity because an apple fell on his head. Benjamin Franklin did not discover electricity by flying a kite. Thomas Edison did not invent the lightbulb.

Not that these stories are far from the truths.

Newton was inspired to formulate his own theory about gravitational force – a concept that had been around since ancient times – after he saw an apple that fell from a tree in the 1660s. Electricity was known about since ancient times, and Franklin flew his kite to investigate whether lightning was a product of it. Edison was like the 20th guy to make a lightbulb, but he was the first to successfully produce lightbulbs at scale and market them.

And in the United Kingdom, children are sometime taught that the steam engine – the invention that gave the world the power to industrialize – was the product of James Watt watching his tea kettle.

Now, the story of Watt watching a tea kettle is probably true. Years after he produced his steam engine, his aunt recalled a story from when he was a child, watching the lid of the family tea kettle lift up as it produced steam.

And it’s not a bad story to teach children if you want to encourage them toward science. We want them to learn about the powers of observation, experimentation, hypothesis, and practical invention.

But it is an incredibly simplified version of events. For one thing, Watt was hardly the first person to notice the expansive properties of steam, nor was he the first to invent a steam engine. Instead, he was part of a long line of discoveries that led us to industrial power.

The truth is the steam engine was the product of centuries of experimentation, economic necessities, strong business acumen, and colorful personalities.

Here’s how it happened.


This is the Industrial Revolutions

Chapter 7: The Steam Engine


For most of history, there were only four forms of kinetic energy – that is, the physical power to create something, whether it’s food, or tools, or structure building, or whatever.

Number one was human labor – using one’s own muscles. Number two was animal labor – using the muscles of an ox or horse or something to pull a plough or carriage. Number three was wind power and number four was water power. Windmills and water mills have existed since antiquity, but became more common in the lead up to and early years of the first industrial revolution.

But in the City of Alexandria in Egypt, a teacher and engineer would invent the world’s first steam engine – in the 1st Century AD.

Well, it may have been the first. It’s the first we know of that definitely ran on steam power.

His name was Hero and his invention was called the aeolipile. It sat above a fire. The fire would heat a pot of water. Above the pot was a hallow sphere mounted on an axle, connected to the pot by two pipes. Coming out of the sphere were pair of elbow-shaped tubes. As the water boiled, steam would rise through the pipes, into the sphere, and escape through the elbow-shaped tubes, causing the sphere to rotate on the axle.

Now, what practical purpose did this engine serve?

Well, none actually. It was meant to be interesting more than anything else. Trying to use it as the power source for a mill would have been phenomenally inefficient.

You see, to make an early steam engine work efficiently, you needed more than steam. In fact, you needed the opposite of steam.

The effect steam has on an engine is to expand the air pressure. But to keep the engine moving you also needed to contract the air pressure. You needed to cool things back down to create a vacuum.

And in the years to come, this would be a bit of a problem. While many ancients, including Hero, understood the concept of the vacuum, there’s one guy who didn’t. Aristotle.

And right up to the Enlightenment, Aristotle’s word was final, on just about everything. He said that nature abhors a vacuum, and so everyone took it as a given that vacuums just didn’t exist.

This illustrates a broader problem in Europe before the Enlightenment: A historical inferiority complex. Folks believed the ancient Greeks and Romans were just better than them. They reasoned that, “the ancients had studied science, built great cities, written all this poetry and philosophy. Who are we to question them? The further in time we go, the stupider we become.”

When scientists like Galileo challenged ancient thinking, they got in trouble. This was also the case with Galileo’s successor at the Florentine Academy, Torricelli.

In the 1640s, the Grand Duke of Tuscany commissioned Torricelli to improve the water pumps his engineers were making. Torricelli went about this charge by conducting a number of experiments using mercury and glass tubes. He inadvertently invented the barometer during the process. More importantly, the experiments led him to conclude that Aristotle was wrong. Vacuums could exist.

But Torricelli knew full well the pressures his predecessor had faced with his astronomical research, and so he shut the hell up when the Aristotelian traditionalists of the Catholic Church criticized his findings.

But there was another scientist, up in the Protestant city of Leipzig, who didn’t face those pressures. His name was Otto Gericke and his experiments with vacuums excited all of Protestant Europe. Connecting two hollow hemispheres into a ball and then pumping the air out of it, he created a vacuum so strong that 30 horses tied to the ball couldn’t pull it apart.

Word of the flashy experiment made its way to England, to the philosopher Robert Boyle, who was excited enough to patron two scientists to investigate further. The first was Robert Hooke, an intellectual rival of Newton’s and a key early member of the new Royal Society.

The second was a lesser-known genius named Denis Papin.


Born in Blois in 1647, Papin was a French Huguenot who had been interested in water pumping and vacuums from an early age. With his mentor, Christian Huygens, he published five papers on experiments conducted with air pumps, and they may have worked together on a gunpowder-based piston.

But by 1675, he saw the writing on the wall. France was ramping up its persecution of Protestants. And so, in his late 20s, he left for England, where he would find a job as a lab assistant for Robert Boyle.

Among the things Papin would work on was a machine to clean bones for medical studies, using pressurized steam. This pressure cooker – or Steam Digester, as he called it – included a safety valve. Possibly using Huygens’ gunpowder pistons as inspiration, the valve allowed the excess steam to lift a stopper and escape. But when the pressure stopped, the weight of the stopper would bring it back to a normal position.

In 1690, Papin went a step further with that concept and designed an engine. The dual energies of the process would be contained in a cylinder, allowing it to drive a piston.

From what we can tell, Papin was a difficult man to work with, and before long he left England. He’d spend the rest of his life moving around Europe, serving in various academic roles. But his work with pistons would be an important component in the steam engines to come.

The other major component came out of Great Britain’s Royal Office of Ordnance.

Established at the Tower of London during the 1460s, the Office of Ordnance was something of an early DARPA – a government agency with the purpose of improving technologies for war. Its engineers were responsible for the design and fabrication of military engines, projectile machines, cannons, guns, and pontoon bridges for quickly moving men and weapons over streams.

Then, in 1639, the scope of their work expanded. They converted the ancient estate of Vauxhall into “a place of resort for artists, mechanics, etc.” where “experiments and trials of profitable inventions should be carried on.”

One of the engineers at Vauxhall was Thomas Savery, who had been influenced by a number of scientists working on water pumps.

As I mentioned last week, pumping water was becoming a greater and greater necessity because of the flooding in mines. As England’s timber resources were running low, coal mining became more and more important, and miners would have to go deeper and deeper.

As early as 1606, scientists were designing steam engines to pump water. These machines would boil water into steam. The steam would expand the air pressure. Once the air pressure was expanded, the heat would come off, creating a vacuum in the chamber. And that vacuum could be used to pump other water out of a mine.

But it was Savery’s predecessor at the Office of Ordnance, Thomas Moreland, who had correctly calculated the volume of steam and left behind his notes.

Using those notes, Savery built a new machine with a tall cylinder filled with water and connected to a boiler. Savery would produce steam in the boiler and push out the water in the cylinder. Then, the steam-filled cylinder would be sprayed with cold water – condensing the pressure in the cylinder and creating a vacuum. The vacuum would then pull water from a chamber below, creating a pumping action.

While still far from perfect, Savery’s machine was now the closest thing to a modern steam engine, thanks to the measurements left by Moreland. Savery got to work promoting it. In 1699, he demonstrated it to the Royal Society as “a new invention for raising water and occasioning motion to all sorts of mill work by the implement force of fire, which will be of great use and advantage for draining mines.”

But the most important thing Savery did was take out a patent in 1698. In fact, it was only the 356th patent issued in Great Britain since the patent protection law was passed 74 years earlier.

Savery and Papin had gone in very different directions when it came to steam power and water pumps, and they were bitter rivals who frequently disparaged each other’s work to the Royal Society. But soon, aspects of both their work – Savery’s steam-powered vacuum and Papin’s pressure-driven pistons – were finally combined in 1712 by Thomas Newcomen.

Now, it’s possible that he arrived at his design somewhat independently of Savery or Papin. At least, that’s what a friend of his claimed. But it seems unlikely. For how important his invention was – it was the first modern steam engine, after all – surprisingly little is known about Newcomen.

He was born in Dartmouth, England in 1664 to a Baptist family. As far as we can tell, his family was in the ship-building trade and young Thomas was apprenticed to an ironmonger.

The Baptist community in Dartmouth had hired a pastor named John Flavel. Among other things, Flavel had organized secret community banks for England’s nonconformists to pool their financial resources.

Funded by one of Flavel’s banks and communicating with Robert Hooke, Newcomen and a partner (of whom we know even less) spent 1700 through 1705 in Newcomen’s basement, working on a new machine. Not only did the eventual product apply Savery’s vacuum to Papin’s piston, it also introduced a few more components.

The first was a giant, horizontal beam.

Imagine this: A cylinder where steam pressure and vacuums move one side of a beam up and down. Let’s call that side of the beam Side A. The beam then acts as a seesaw. Side B of the beam moves up as the vacuum in the cylinder moves Side A down. And as Side B goes up, it creates its own vacuum in pipes going down into the shaft of a mine. As a result, it can pump out the water flooding the mine.

The second component was an injection valve. This came as the result of a happy accident, when a piece of tin on the cylinder melted away, creating a hole. When they poured cold water into the hole, it condensed the steam and created the vacuum much faster. So, in place of the hole they added a valve and attached it to the piston. This way, the piston would automatically close the injection valve when it reached the bottom of the cylinder, and at the same time, open a second valve so the water could flow back out.

Third, Newcomen added a plug rod. This was the best of several imperfect solutions he thought up to address the problem of keeping the engine’s motions regular and stable. While the movement of the horizontal beam was still jerky, the plug rod allowed it to be continuous.

Finally, he added a Y-shaped lever to control the steam entering the engine. Rather than have the fire constantly producing steam, this would serve as something of an on-off switch.

Now, for all these additions, the machine still relied on concepts patented by Savery, so in 1716 they came to a profit-sharing agreement. Three fourths of all profits would go to Savery’s family. Only one fourth would go to Newcomen.

Nevertheless, the new machine was super-beneficial to the coal mining industry and still managed to make Newcomen quite wealthy. In a 50-meter-deep mine, the Newcomen engine could lift 10 gallons of water out per stroke, at a rate of 12 strokes per minute. Not bad.

But everyone knew it could be better, too. Boiling that much water, and then cooling it, and then boiling it again requires a lot of thermal energy. That meant they needed to burn a lot of coal in order to get to the coal they were mining.

It would be another half century before another major advancement in steam power. And it would be thanks to the brilliant mind of a Scottish clockmaker – James Watt.


Born in a village on the Firth of Clyde in 1736, James Watt was the son of a shipbuilder in a thoroughly middle-class family. From an early age he demonstrated strong aptitudes for mechanics, and so when he was 17, he was sent to Glasgow to learn the trade of mathematical instrument makers. But he could find no teacher who would take him as an apprentice.

Instead, he met the University of Glasgow Professor Robert Dick, who advised him to go all the way down to London, and even wrote for him a letter of introduction. After a 12-day journey, Watt arrived in London and was able to procure an apprenticeship through the Worshipful Company of Clockmakers, a newer guild that appreciated innovative thinking.

While he was too old for a normal, 7-year apprenticeship, a guild member named John Morgan agreed to take Watt under his wing. Working pretty much constantly, Watt managed to cram 7 years of training into 1.

Now, clockmaking might not sound like an especially relevant line of work for a steam engine inventor. But it’s important to remember that, in the 18th Century, there were few other lines of work that required as much mathematical and engineering skill as clockmaking. The sizes of gears, placement of springs, and other components of clocks had to be super-precise. And it was this precision, this hyper-focused attention to detail, that helped Watt make a steam engine that would outshine its predecessors.

Watt returned to Glasgow in 1756, but the local clockmaking guild was not very accepting of his unorthodox training process, and he struggled to find work.

Once again, he got help from Professor Dick.

The University of Glasgow had recently been bequeathed a collection of several state-of-the-art astronomical instruments by an alumnus named Alexander Macfarlane. He had used them for navigating ships, carrying sugar back to Britain from the Caribbean. The salt air of the ocean voyages had damaged the instruments, and now Dick needed someone to restore them.

He hired the 20-year-old Watt, offering payment of £5, and subsequently allowed him to set up shop as the Mathematical Instrument Maker to the University. Rather than treat it like a maintenance worker position, Watt acted more like a member of the faculty.

In this role, he launched a scientific career and befriend some of the leading minds of the Scottish Enlightenment.

One friend, the mathematician John Robinson, noted Watt’s intense love of learning during these years. He learned German so he could read Leopold’s Theatricum Mechanicum and studied the philosophy of music when he was asked to build an organ.

But also during these years, Watt started to act like a businessman. In 1759 he partnered with John Craig in a manufacturing business for optical instruments. Four years later he invested in a pottery company.

And it was that same year, in 1763, that an eccentric professor at the university asked Watt to repair – or more accurately, to improve – a Newcomen engine he had.

For the next two years, Watt waded in eyeball deep in the physics of the steam engine, conducting experiments to figure out how to reduce the wasted heat problem. As it turned out, it would be the steam engine that would occupy his mind for the rest of his life.

And the intense work of these experiments – building cylinders, observing the heating and cooling process, taking meticulous measurements – gave him important insights that other scientists (caught up in the theory of steam power) were missing.

As he discovered, one reason the steam engines of the time were so inefficient was because the sizes of the boilers were imprecise. Not only did smaller boilers require less heat, they created different volumes of steam, and cooling it down required different amounts of water.

Another problem, you had to constantly heat and cool and heat and cool the cylinder, wasting as much as 75% of the steam.

It was during a casual Sunday stroll through the Glasgow Green, a famed city park on the River Clyde, that Watt had a breakthrough. As he put it, “I had not walked further than the Golf house when the whole thing was arranged in my mind.”

He realized you could separate the processes of heating water into steam and cooling steam to create a vacuum. You could have two cylinders instead of one. In the first cylinder, the water would be boiled into steam. And some of that steam would push up a piston. But, also, some of the steam would move through a connecting pipe into a second cooling cylinder, creating a vacuum. And that vacuum would pull the piston back down.

It only took him a few weeks to create a prototype. He borrowed what was a huge amount of money at the time – £1000 – from his friend, the physicist slash chemist Joseph Black, to create a large model. He also raised a significant investment from an English industrialist named John Roebuck.

Roebuck had made his fortune in iron and chemicals, and we’ll definitely talk more about him in a future episode. His gift as an early venture capitalist wasn’t so much in having great ideas of his own as much as recognizing those of others. And in Watt, he saw massive potential.

He took a two-thirds share in Watt’s business in exchange for paying off Watt’s debt to Black and for giving Watt a blank check for all expenses related to building steam engines. But Watt would not earn a salary from Roebuck’s investment. Instead, he supported his growing family by surveying canals in northern England.

And Watt continued to improve on his design. He added a wheel, inspired by the motions of water mills and operated on the mechanical principles of the clock trade he learned as a young man. Thanks to his friend, Dr. William Small, he figured out how to make the wheel and valves tighter with grooves and pasteboard.

The design still wasn’t perfect, but Roebuck wanted to start monetizing the business as soon as possible. At his insistence, Watt traveled to London where he was granted a patent for “a method of lessening the consumption of steam and fuel” used in steam engines. After picking up the document from the patent office, he had a meeting with a manufacturer named Matthew Boulton.

Born into a family that made small metal goods, Boulton had seen every aspect of the family business by the time he took it over and decided to make improvements. In particular, he decided to cut out the middle men who handled things like sales, transportation, and even the supply of raw materials. By the time he met Watt, Boulton was one of the richest manufacturers in England.

You see, as Roebuck was pushing Watt to get a patent, he was also communicating with Boulton about investing. Or more accurately, Roebuck was trying to cash in some of his shares.

Roebuck had invested in a coal mine that was both literally and figuratively underwater, and the steam engine wasn’t strong enough yet to fix the problem. So, in 1769, Boulton invested £1000 into the business in exchange for one-third of the rights to the patent.

Things got even worse for Roebuck in 1772, when the Bank of Ayr in Glasgow collapsed and took down nearly every bank in Scotland with it. Essentially bankrupt, Roebuck’s creditors went after everything, including his rights to the Watt patent. Seeing the opportunity, Boulton persuaded them to sell him the rights for the bargain price of £630. With that, Boulton now controlled 100% of the patent, forever tying Watt’s fate to his.

Boutlon convinced Watt to relocate to Birmingham, and set up shop next to his own metalworks. The firm would soon be known as Boulton & Watt.

It’s interesting how we overlook Boulton’s role today and focus so much on Watt, because Boulton was more than just the money in the operation. He was to James Watt what Steve Jobs was to Steve Wozniak. Watt was the genius behind the technology. Boulton was the genius behind the business.

For one thing, Watt hated the business of business. As he put it, “I would rather face a loaded cannon than settle an account or make a bargain.” But also, Boulton understood how Watt’s design – with its wheel and repetitive motions – could be applied to so much more than mine draining. As he put it, his goal was for the Watt steam engines to serve all the world.”

In fact, he frequently used the phrase “all the world.” Just like the many entrepreneurs of Silicon Valley today, Boulton had a vision to change the world forever with new technology.

Textile manufacturers were seeking power sources other than water so they wouldn’t be limited to river fronts for their mills. Metal works and grain mills could also adopt steam power if it was more fuel efficient. Not only was Boulton able to help sell steam engines, he was able to push Watt to tune his designs for a broader array of applications.

And Boulton also came up with novel ways of making the business practical. They would only manufacture a few pieces of the steam engine and sell them in a kit with the other necessary components. They’d also publish a manual for the buyer to assemble the steam engine once they had the kit. And they’d charge a royalty for using this patented technology – a percentage tied to the amount of money the user would save by using a Watt engine over a Newcomen engine.

To make it work, one of the first things they had to do was fix the patent problem. Roebuck had pushed for the patent too early. The technology was not ready. But even with the technology perfected, the firm would need until 1800 just to break even on all the investments so far. The patent, though, was set to expire in 1783.

So, they convinced a Member of Parliament – probably a Scottish member named William Adam – to sponsor a special bill called the Fire-Engine Act of 1775, which specifically gave Boulton & Watt a 25-year extension on their patent.

To this day, economists debate whether the act promoted or inhibited overall innovation in steam technology, but those who say “inhibited” admit that it caused at most a ten year delay in innovations. And as palpably corrupt as this act was by our modern standards, it may have been the most important single event of the first industrial revolution.

Next, Boulton & Watt had to produce some steam engines for their original purpose: draining mines. Watt got to work on a water pump for the Bloomfield Colliery outside Birmingham. On March 8th, 1776, this first Watt steam engine was unveiled in a public ceremony, where onlookers were reportedly gratified by its performance.

Watt also got working on a steam engine for an ironworks’ blast furnace. This engine would create the motion needed for a giant hammer that would pound huge slabs of iron. It was made for our old friend, John “Iron Mad” Wilkinson.

That’s right. He’s back. Aren’t you excited?

I know I am, because in the research for this episode, I learned a few more things about his love for iron. Apparently, he built an iron pulpit for his church. And for the school his children attended, he made iron writing tablets and iron pens.

And here’s something fun – if that’s the word for it – that I forgot to mention last time. Clearly obsessed with his own death and what would happen afterwards, Iron Mad promised that he would rise from the grave seven years after he died to visit his blast furnaces again. And so, in 1815, on the seventh anniversary of his death, thousands of iron workers showed up to see if his ghost would appear. It didn’t, obviously.

But anyway, Iron Mad’s business dealings with Boulton & Watt would be quite interesting. They’d supply him with the steam engine technology for his ironworks, and he’d provide for them iron parts needed for their steam engines.

But then, in 1795, Boulton & Watt found out that Iron Mad had been using their design to sell people the steam engine himself, without paying any royalties. Sneaky bastard. As a result, some violent letters were sent back and forth, and litigation followed. Boulton & Watt set up their own ironworks at the Soho Foundry in Birmingham to cut out their disloyal supplier.

Not only did Boulton & Watt continue to expand their business, but Watt continued to improve the technology. Thanks to the idea of an employee named William Murdoch – who actually drove Watt kind of crazy most of the time – they added a sun-and-planet gear to adopt the engine to the technologies used in mills. He also added a centrifugal governor to regulate the speed of the engine. And the Watt steam engine was even used for some of the first steam boats.

But it still fell short of producing the intense power needed for industrial developments of the 19th Century. And for the capstone of steam power technology, we need to turn to the brand-new United States of America.


The same year James Watt made his first trip from Glasgow to London, a man named Oliver Evans was born in the colony of Delaware. At the age of 16 he left for Philadelphia where he became apprenticed to a wheelwright.

Evans had one of these classically inventive minds. Before his apprenticeship was over, he invented a new cotton carding machine. In 1788, he built an automated grain mill that could run continuously. And for that, he received his new country’s third ever patent in 1790. The new president of the young nation, George Washington, installed the machine at his Dogue Run mill the very next year.

As early as 1783, Evans had an idea for a steam-powered locomotive, but failed to get it patented in Pennsylvania, due to a lack of a working model. But he didn’t give up the idea. The problem was he couldn’t get enough steam pressure to make it work. But in 1804, he patented a “vibrating steam engine” which put the furnace inside the water-filled cylinder. Not only did this greatly increase the pressure of steam, it eliminated the need for a condenser – that is, Watt’s cooling cylinder – because it created enough power to perform both motions of a piston.

In the years leading up to this patent, he had written to steam engineers in England to get their input. And it’s very likely that these letters came across the eye of a scientist named Davies Gilbert.

As the 1800 expiration date of the Boulton & Watt patent approached, a flurry of engineers tried to improve the technology again. One of these engineers was a mine operator named Richard Trevithick, a friend of Gilbert’s.

Trevithick came from a prominent family in the Cornwall copper mining community. The Cornish copper mine owners hated Boulton & Watt because of their royalty scheme. Trevithick also wanted to produce a smaller engine, and so he was interested in eliminating the condenser.

So, he asked Gilbert to run some calculations. How much power would be lost if you let some steam escape, rather than route it to a condenser?

When Gilbert wrote back to him, it opened his eyes to a world of possibilities. Using the same method as Evans, putting the boiler inside the steam cylinder, he was able to produce what was called “strong steam” – that is, steam creating pressure of over 30 pounds per square inch (or “psi” for short) a good three times as much as a Watt steam engine.

And when Trevithick built his engine, it was really, really strong steam: An unprecedented 145 psi that could run the engine at 40 strokes per minute.

High pressure steam engines could create power previously unthinkable. Trevithick himself would go on to use it to build one of the first ever locomotives. But that obvious application of the technology aside, it could be used to power and automate all sorts of production process in factories and mills. Mass production could happen at a scale never before imaginable, creating profits that turned out an ever-increasing accumulation of capital.

And with the mills no longer forced to locate on rivers, they started to cluster in major centers of industry. Small villages rapidly evolved into major world cities. Next week, on the Industrial Revolutions.


If I mispronounced anything in this episode or got a fact wrong, let me know! You can DM me @IndRevPod – that’s @ I-N-D – R-E-V – P-O-D on Facebook, Twitter, and Instagram. Be sure to follow that handle as well to stay up-to-date with the podcast.

And if you were expecting an announcement earlier this week, I do apologize. I ran into a little complication. But it has been fixed. That announcement is coming this Tuesday, March 19th, so please come back then.

Thank you.

Dave Broker