AC/DC: Tesla Takes on Edison

In the fall of 1887, Nikola Tesla was scared. Three years earlier, he had emigrated from Europe to New York City, set on becoming an electrical inventor. He had pinned his hopes on inventing an electric motor that used alternating current (AC) instead of direct current (DC), and had just demonstrated such a motor to one of his backers, Alfred Brown.

But, when Brown saw that Tesla's amazing new motor consisted of a shoe-polish tin spinning around in the middle of a large doughnut-shaped coil, he was distinctly unimpressed. How could a spinning tin can represent a revolution in electrical technology? Why would anyone replace Thomas Edison's recently introduced DC-powered incandescent lamps with such a piddling AC motor?

Now, Tesla worried that Brown and his other backer, Charles Peck, might abandon him, and he would be back digging ditches on the streets of New York. He might even have to go back to Europe, where he would be a disgrace to his Serbian family. Tesla knew that the electrical industry could only grow if people could use electricity for more than just lighting and if the utility companies could deliver power across larger areas. He had chosen to work on a motor because it meant that electricity could then be used to run factory machines, elevators, and streetcars, and was focusing on AC because it could be transmitted over longer distances than DC.

Edison had bet on DC for his incandescent lighting system because it was simple and safe, but his early central stations could only reach customers within one mile. By 1887, even he was investigating both AC and high-voltage DC in order to deliver more power to more people. Tesla realized that to get Brown and Peck to consider the potential of AC, he had to get them past the spinning tin can. What he needed was a compelling story, one that would capture his patrons' imagination and prompt them to throw their support behind him and AC.

At their next meeting, Tesla asked them if they knew the story of the egg of Columbus. According to legend, Christopher Columbus overcame his doubters at Queen Isabella's court by challenging them to balance an egg on its end. After they failed, Columbus stood the egg upright by lightly cracking one end. Impressed at his resourcefulness, Isabella is said to have pawned her jewels to finance the venture.

When Peck and Brown acknowledged that they had heard the story, Tesla proposed that he could make an egg stand on end without breaking the shell. If he could go one better than Columbus, would they underwrite his experiments? "We have no crown jewels to pawn," replied Peck, "but there are a few ducats in our buckskins, and we might help you to an extent."

To gain those ducats, Tesla returned to his laboratory, fastened his doughnut coil to the underside of a wooden table, and then went out to buy a copper-plated egg as well as several metal balls. When his backers next came by, Tesla placed the egg on the tabletop and applied AC to the coil. They were sufficiently astounded when the egg and balls started spinning but truly stupefied when the spinning egg flipped up so that it was rotating around its long axis.

While it looked like magic, Tesla quickly explained that the egg and balls were spinning in response to the rotating magnetic field created by AC. Deeply impressed, Peck and Brown became ardent supporters of Tesla and AC. Over the next two years, they hired a gifted lawyer to help him secure strong patents, arranged for publicity in the engineering press, and negotiated a deal for Tesla with George Westinghouse. Working with Westinghouse engineers, Tesla perfected his AC motor, and the company began selling AC systems. Utility companies quickly saw the advantages of AC, and Westinghouse was soon giving Edison a run for his money.

Over the next two decades, AC replaced DC as the means by which electric power is generally distributed, and AC permitted electricity to become the cheap and ubiquitous means of supplying us with omnipresent energy. Such was the revolution that Tesla set into motion in 1887, when he not only got his motor to work but also came up with a compelling story to tell about it.