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005 – Tesla – A Walk in the Park (1882)

The solution to Tesla’s alternating current motor problem came to him as a ‘eureka’ moment during a walk in the park in 1882: the rotating magnetic field, and the induction motor. The applications of this innovation would literally change the world.

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Hi. I’m Stephen Kotowych. Welcome to Tesla: The Life and Times

EPISODE 5 – A Walk in the Park (1882)

Last time, we looked at a particularly rough and disappointing 5 years in the life of Nikola Tesla, when everything from school to his personal life seemed to fall apart.

This week, we look at the first few months of 1882: a brief stretch of time that was nonetheless fairly momentous in Tesla’s life, and were in many ways where things started to turn around for him. And as we’ll see in both this episode and the next, 1882 was a crucial year for the development of electric power and power systems.

Since our episode only looks at part of 1882, our look at history today will also look just at the first few months of 1882.


On January 2, in secret, the Standard Oil Trust is created to control multiple corporations set up by John D. Rockefeller and his associates.

On the same day, and definitely not in secret, Irish-born author Oscar Wilde arrives in the United States for an extended lecture tour; when asked by a customs official if he had anything to declare, he replied "I have nothing to declare but my genius.” It’s a good line, but that kind of stuff will get you tasered these days.

On January 12, the Holborn Viaduct power station in the City of London begins operation. It is the world's first coal-fired public electricity generating station.

In March, Robert Koch announces the discovery of the bacterium responsible for that scourge of Romantic poets, tuberculosis.

Elsewhere, Charles J. Guiteau is found guilty of the assassination of James A. Garfield (President of the United States) and sentenced to death, despite an insanity defense raised by his lawyer. He is hanged on June 30.

In March, Queen Victoria escapes an assassination attempt at Windsor—the eighth (and last) time over a 40 year period that someone tried to kill the queen.

Less successful in avoiding assassination that year was famed outlaw Jesse James, shot in the back of the head by the coward Robert Ford. I’m not sure how many times people had tried to kill Jesse James, but I feel confident in guessing that it was probably more times than people had tried to kill old Queen Vickie.

In April, the "Elektromote", the world's first trolleybus, begins operation in Berlin. It is powered by two 2.2 kW, 550 V DC electric motors. See what I mean? A big year for electricity—and it’s only April!

It was also a big year for classical music—or as it was known back then ‘music.’ In April, Richard Wagner's opera Parsifal debuts in Bavaria; and Tchaikovsky's 1812 Overture debuts in Moscow much to the delight of cannon aficionados everywhere.

Notable births in 1882 include:
• American gangsters Arnold Rothstein (who helped fix the 1919 World Series) and Johnny Torrio, a mentor to Al Capone, and for a time in the 1920s the biggest gangster in America
• English authors Virginia Woolf—who I’m not afraid of, by the way--and A. A. Milne (he of Winnie the Pooh fame), who were both born in January. Just missing joining them is Irish writer James Joyce (born February 2)
• On February 8, Thomas Selfridge was born. In 1908 Selfridge, a United States Army officer, would be the first person in history killed in an airplane crash
• Also born in 1882 was Franklin D. Roosevelt, who would become the 32nd President of the United States, and another of the people who would help save Western civilization in the 20th Century

1882 proved a difficult year for American letters, as it saw in March the death of Henry Wadsworth Longfellow, and in April the death of Ralph Waldo Emerson.

And I’d like to highlight in particular somebody who doesn’t get enough acclaim: Mr. George Jennings, who passed away on April 17, 1882, aged 80. George Jennings was an English sanitary engineer and plumber who invented the first public flush toilets. As a father of two small children who without fail, no matter how many times you ask them, don’t have to go to the potty before you leave the house, but sure have to go in an emergency as soon as you go basically anywhere outside the house, I am deeply grateful to George Jennings for his innovation. It was a crappy job, but somebody had to do it.

When we left off last time, Tesla had just recovered from a serious bout of depression, which seems to have included some kind of sensory-overload component. His friend, Anthony Szigeti, had helped Tesla regain his health and strength in part by encouraging him to exercise, particularly by taking long walks around the city.

They would often walk in the Városliget (City Park), and this is where we find them as we begin this week

In his 1919 autobiography, Tesla recounts how the solution to his alternating current motor problem came to him during one of these walks as a ‘eureka’ moment. There they were, he and Szigeti, walking through the park at sunset discussing Tesla’s ideas for an improved motor (Tesla gives no specific date, though it is believed to have been sometime in February 1882). Inspired by the sunset, Tesla began reciting from Goethe’s Faust, his favorite poem:

See how the setting sun, with ruddy glow,
The green-embosomed hamlet fires.

He sinks and fades, the day is lived and gone.

He hastens forth new scenes of life to waken.
O for a wing to lift and bear me on,
And on to where his last rays beckon.

“As I uttered these inspiring words,” he wrote in his autobiography, “the idea came like a flash of lightning and in an instant the truth was revealed. I drew with a stick on the sand the diagrams shown six years later in my address before the American Institute of Electrical Engineers…The images I saw were wonderfully sharp and clear and had the solidity of metal and stone, so much so that I told [Szigeti]: "See my motor here; watch me reverse it.”… Pygmalion seeing his statue come to life could not have been more deeply moved. A thousand secrets of nature which I might have stumbled upon accidentally I would have given for that one which I had wrestled from her against all odds and at the peril of my existence.”

Tesla certainly had a flair for the dramatic.

So what exactly had Tesla seen?

In short: the rotating magnetic field, which would allow for the development of what came be known as the induction motor.
The applications of this innovation would literally change the world.

Now, as I think I said in the first episode, it’s not my goal or desire with this podcast to dwell on the nitty-gritty technical details of Tesla’s inventions. I’m much more interested in their societal impacts.

However, since the AC induction motor with its rotating magnetic fields was the heart of Tesla’s innovation and of the AC system that would eventually go on the power the world, well, it seems like perhaps in this case we ought to make an exception and spend a bit of time trying to understand just what the big deal was about this new motor from a technical point of view.

So to begin, the rotating magnetic fields.

Tesla’s first breakthrough was to envision the use of two circuits in a motor instead of the typical single circuit to transmit electricity. Doing so generated dual electrical currents ninety degrees out of phase with each other. This gives rise to the induction motor, which relies on small speed differences (called slip) between the rotating magnetic field and the motor’s rotor shaft speed to induce current in the wires wound around the rotor.

So why are rotating magnetic fields so useful? Well, if you’ve ever tried to push together the positive ends of two magnets (or the two negative ends, for that matter) you’ve experienced the repulsive force of magnetism. Flip one magnet around, and the positive and negative poles of the magnets almost seem to reach out across the intervening space and pull themselves together. It is this principle that the AC motor relies on: the repulsive and attractive magnetic forces between the rotor and stator mean that the receiving magnet rotates in space, attracting a steady stream of electrons—and electrons equal electricity!—with the positive and negative poles of the magnetic fields pushing and pulling each other as they spin round and round.

This is all a bit hard to visualize, so I’ve put up a link in the show notes to a very helpful YouTube video that explains this way better than I’m able.

So the constant flow of electricity allows the motor to generate torque, which is capable of driving a given load at a given speed, depending on the size and power of the motor.

Okay—then on to the motor itself:

Tesla’s radical departure here (as I’ve hinted at for a couple of episodes) was in getting rid of an electric motor’s commutator. So what is a commutator and why would you want to get rid of it in the first place?

A commutator is a moving part of a rotating electrical switch in direct current motors. Its job is to periodically reverse the current direction between the rotor and the external circuit, changing it from alternating current to direct current. It consists of a cylinder or rings with multiple metal contact segments—called "brushes”—which provide a pathway for the movement of electricity on a rotating armature.

Are you with me so far?

And it is these metal contact brushes that really make the commutator a problem, as it robs the motor of efficiency in a number of ways.
Early machines, in particular, used brushes made from copper wire. These hard metal brushes tended to scratch and groove the smooth commutator segments, and the commutator eventually required resurfacing. As friction wore down the copper, the metallic dust and broken bits of copper brush wedged between commutator segments, causing shorts and reducing efficiency. Likewise, resistance between the brushes and the commutator can cause a voltage drop which can mean large power losses in low voltage, high current machines. And friction itself also robs some of the energy of the machine as the brush rubs against the commutator.

The switching action of the commutator causes sparking at the contacts, generating electromagnetic interference. And there is also a physical limit to maximum current density and voltage that can be switched with a commutator. Very large direct current machines, say, more than several megawatts rating, simply can’t be built with commutators. The largest motors and generators you find these days are all alternating-current machines.

Again, I’ll post some helpful YouTube video in this week’s show notes—one an explanation of DC motors and one a demo of a polyphase induction motor made out of a coffee can! When you watch the AC video, image the central shaft transferring that motion to machinery that could do work and when you scale it up (and not build it out of a coffee can) you get a sense of the power of an AC motor and the work it can do.

So really, while DC motors have their uses (even today) they face a lot of technical hurdles in both size and efficiency. Tesla’s innovation did away with all of these limits when it did away with the commutator.

Tesla had at last refuted Professor Poeschl from the Polytechnic School in Graz, who had (as you might recall from a few episodes ago) declared that it was impossible to build an AC motor without a commutator. “Mr. Tesla may do many things,” he had said, “but this he cannot accomplish.”

Well, take that Professor Poeschl!

Now, we’re jumping ahead a bit here: remember, at this point Tesla is still standing in the park with his friend, doodling in the dirt. It would be years before he had a working motor, or before he had even fully worked out the implications of his flash of insight.
Because despite his contention about the depth of his insight that day in Tesla’s own autobiographical account of this moment, it’s likely we’re seeing some of his later embellishment of his own genius and accomplishments. Why should we think so?

Well, the 1919 autobiography is a dramatic account, yes. But in sworn patent testimony given in 1903, Tesla mentioned nothing about having a eureka moment in the park, even though it would have been to his legal advantage to have established the moment of invention was in 1882.

Instead, and contradicting the myth of Tesla the genius who never wrote anything down and whose inventions worked the first time every time, Tesla’s patent testimony suggests that like any other mere mortal it actually took him time to work out his ideas.
Now, here’s one place that I think we need to correct a myth about Tesla: the idea you hear sometimes that Tesla “invented” alternating current. And I think this has more to do with a misunderstanding on our part today of the state of scientific knowledge in 1882, and probably some confusion that because Tesla invented the first practical AC system that means he invented or discovered alternating current itself. Not so.

That credit rightly belongs to English scientist Michael Faraday, who began experiments in 1831 that led him to the discovery of electromagnetic induction, which is the basis of the alternating current induction motor. Within a year of Faraday’s discovery, the first electric dynamo producing alternating current was built in France (albeit on a small, experimental scale).

So Tesla didn’t invent or discover alternating current. And he wasn’t even the first person to come up with a working, commerical AC motor: five years earlier, in 1878, Elihu Thomson built an AC generator used to power an arc light system in the United States.
Around this same time two Europeans, Gaulard and Gibbs, produced the first alternating-current transformer. George Westinghouse, an early advocate of AC who would later play an important role in bringing the Tesla AC system to America and then the world, bought the American rights to the Gaulard and Gibbs patents for the princely sum of $50,000 (about $1.2 million dollars today).

This system was even installed in Great Barrington, Massachusetts by William Stanley, Westinghouse’s head engineer. But neither the Thomson generator nor the Gaulard-Gibbs invention did away with the commutator, which was the whole point of Tesla’s design.
The fact was, none of these other systems had the simple elegance of Tesla’s motor. Most used only a single circuit, just as in DC motors, and either didn’t work or worked poorly.

And, as sometimes happens in the history of discovery and innovation, Tesla wasn’t even the only person to come up with an alternating current induction motor in the early 1880s. Such a motor—which did do away with the commutator, as Tesla’s did—was independently invented by Galileo Ferraris in Italy. Of course, the two men were completely unaware of one another’s work—it was literally a case of great minds thinking alike.

Ferraris demonstrated a working model of his single-phase induction motor in 1885, and Tesla built his working two-phase induction motor in 1887, demonstrating it a year later before the American Institute of Electrical Engineers. In 1888, Ferraris published his research to the Royal Academy of Sciences in Turin; at the same time, Tesla was already being granted a US patent for his motor.


It’s unlikely that Tesla understood everything about his AC motor that day in the park, including how to actually use two or more alternating currents, or how exactly a rotating magnetic field could be used in a motor. At this point, Tesla still had no practical firsthand experience building electrical machines, and he wouldn’t actually build his first AC motor prototype until a year later in Strasbourg. So his vision was incomplete—but he knew enough to know that he was on to something big, and that it involved upending the received wisdom and the standard practice of his day, a maverick style that was to be a hallmark of Tesla the inventor.

Because that, at last, is what he really was.

In practice that day in the park nothing had changed for Tesla: he was still working as draftsman in the Central Telegraph Office of the Hungarian Government and making only just enough to get by. But in another sense, and perhaps the only one that really matters, everything had changed for him. He was truly and at last an inventor.

“This was the one thing I wanted to be,” he recalled. “Archimedes was my ideal. I admired the works of artists, but to my mind they were only shadows and semblances. The inventor, I thought, gives the world creations which are palpable, which live and work.”


“For a while,” Tesla writes in his autobiography, “I gave myself up entirely to the intense enjoyment of picturing machines and devising new forms. It was a mental state of happiness about as complete as I have ever known in life. Ideas came in an uninterrupted stream and the only difficulty I had was to hold them fast. The pieces of apparatus I conceived were to me absolutely real and tangible in every detail, even to the minute marks and signs of wear. I delighted in imagining the motors constantly running, for in this way they presented to mind's eye a more fascinating sight…In less than 2 months I evolved virtually all the types of motors and modifications of the system which are now identified with my name.”

Again, I think it improbable that Tesla had worked out in his mind 100% all of the devices and systems which would later spin out of his initial AC motor idea. But I think he understood in part (or perhaps even just intuitively) not only single-phase motors (those with two separate circuits), but also polyphase induction motors (using three or more circuits out of phase with each other), split-phase induction, and polyphase synchronous motors (which unlike induction motors used magnetic fields that were, well, synchronized), as well as the whole polyphase and single-phase motor system for generating, transmitting, and utilizing electric current.

Because the discovery of how to effectively harness the rotating magnetic field was just a fraction of Tesla’s creation. To this point in the history of the young technology, electricity had to be generated locally and because it was DC power it could only be transmitted about a mile or so before it was too weak to be useful. So electric lighting was almost a novelty, as power couldn’t be produced or carried economically when a power station was required every two miles.

This DC power system was the system that Edison championed and Edison (being Edison) tended toward inflexibility when it came to his ideas and innovations.

We’ll get into some of the lengths he would go to in order to defend his system and try to take down AC power later on in the series when we discuss the War of the Currents, but for right now trust me: he was emotionally (and financially) locked into DC power as ‘the’ system.

But Edison’s carbon filament light bulbs could use either AC or DC power—the light bulbs didn’t care. And after Tesla’s innovation, vastly higher voltages were available via the use of alternating current, meaning that electrical power could be transmitted hundreds of miles for the first time, and not just for lighting but for running the household appliances and industrial machines that would follow in later years. Tesla’s creation was part of a technological revolution and in time practically all electricity in the world would be generated, transmitted, distributed, and turned into mechanical power by means of the Tesla Polyphase System.


While working in the Central Telegraph Office of the Hungarian Government, Tesla soon got noticed by the Inspector-in-Chief and began to be assigned new duties and responsibilities, including working out calculations, designs and cost estimates of new installations.

While in Budapest, Tesla also spent time essentially just hanging out (it’s unclear whether he was ever actually employed) at the manufacturing works of Ganz & Company.

Founded in 1844 by Abraham Ganz, the company had begun as an iron foundry but by 1882 had diversified into a number of other areas, including building and installing power systems for both arc and incandescent lamps. Reminds me a bit of Nokia, the Finnish company that started as a pulp mill, and now 150 years later focuses on large-scale telecommunications infrastructures and mobile phones.

For Tesla, the Ganz works must have been a kind of playground, and he learned much about AC power systems during his time there.

Once, when a ring transformer at the Ganz works was being powered by an AC generator, Tesla placed a metal ball on the transformers’ wooden housing. The ball began to spin. Because the wires in the coils were wound differently from one another they produced two different alternating currents, generating a rotating magnetic field. Here was confirmation of the hunch Tesla had had while walking in the park: alternating current could create the rotating magnetic field he needed for his motor.

From then on, the spinning ball and ring transformer became a key way that Tesla demonstrated his ideas. Whenever he had the chance to experiment with his new motor, he would place different metal objects in the field generated by a similar ring, watching as they spun in the rotating magnetic field.

When at last the Telephone Exchange started up—you remember, the whole reason Tesla had moved to Budapest in the first place?—he was hired on as ‘chief electrician,’ which we would think of as an electrical engineer these days. He later credited the knowledge and practical experience gained during his time at the exchange as being incredibly valuable to his inventive faculties.

In his autobiography he describes making improvements to various of the exchange’s apparatus, including what would have been the world’s first telephone amplifier (though Tesla never made any patent filing, nor did he try to publish details of his device in any technical journal).

But once the exchange was up and running it wasn’t long before the whole operation was sold off. Ferenc Puskas, the friend of the Tesla family who had originally hired Nikola, asked if he wanted a job helping run the new Edison lighting company in Paris. Tesla gladly accepted, as did his friend Szigeti.

Paris, Tesla must have thought, would be the perfect place to launch his AC motor on the world.

* * *

Next time, Tesla becomes a trusted fixer at the Edison works in Paris, and is dispatched all over Europe to troubleshoot Edison electrical systems. He will also acquire, for the first time, practical engineering knowledge about the craft of designing and building dynamos and motors that will be invaluable to him a few years later when he strikes out on his own. And we’ll see again hints of a pattern that will dominate Tesla’s later life: his inability to budget or handle money, as he quickly discovers all the many ways that Paris has to separate him from his pay cheque…


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Thanks for listening. I’m Stephen Kotowych.

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