Nikola Tesla

Nikola Tesla was a Serbian-American inventor and electrical engineer whose induction motor and polyphase alternating-current system became the basis of the way electricity is generated and distributed across the world. A brilliant and eccentric showman of science, he later pursued grand schemes for wireless power that never worked, and died poor in a New York hotel. Since the 1990s his reputation has grown into a popular legend, and separating the real engineer from the myth takes some care.

Tesla was born on 10 July 1856 in the village of Smiljan, in the Lika region of the Military Frontier, a border district of the Austrian Empire that is now part of Croatia. His family were ethnic Serbs; his father, Milutin, was an Orthodox priest, and Tesla credited his mother, Đuka, with his inventiveness and remarkable memory. He went to school in Gospić and Karlovac, survived cholera as a teenager, and in 1875 began studying engineering at the polytechnic in Graz, in Austria-Hungary. He did well at first but lost his scholarship, ran into gambling debts, and left without a degree in 1878. After his father's death he spent a short time in Prague, attending lectures without enrolling.

In 1881 he moved to Budapest to work for the city's new telephone exchange. Tesla later said that it was while walking in a park there in 1882 that the idea of a rotating magnetic field came to him: if several alternating currents, out of step with one another, were fed to coils arranged around a circle, they would create a magnetic field that turned, dragging a rotor round with it and producing a motor with no sparking brushes. Later that year he moved to Paris to work for the Continental Edison Company, installing lighting systems.

In June 1884 Tesla emigrated to New York and was hired at the Edison Machine Works, the company of Thomas Edison, where he improved dynamos. He stayed about six months, leaving in early 1885 after a dispute over pay. According to Tesla's own later account, a manager promised him 50,000 dollars for redesigning the company's generators and then told him the offer had been a joke. In retellings Edison himself makes the promise, but the story rests only on Tesla's memoir, written decades later, and cannot be confirmed. Historians note that Tesla probably met Edison only a few times.

The popular image of a lifelong personal duel between the two men is largely a modern creation. The so-called War of the Currents of the late 1880s was fought mainly between Edison's companies, which sold direct current (DC), and George Westinghouse's, which sold alternating current (AC). Tesla's patents strengthened the Westinghouse side, but he played little part in the public campaign. The two men did dislike each other's methods: Tesla mocked Edison's trial-and-error approach, and in 1931 he gave a sour comment on Edison's death. In 1915 newspapers reported that they would share a Nobel Prize in physics, but the report was false and neither was ever awarded one. Ironically, in 1916 Tesla was awarded the Edison Medal of the American Institute of Electrical Engineers.

After leaving Edison, Tesla started a company to make arc lights, but his investors pushed him out, and in 1886 and 1887 he worked as a labourer, digging ditches for about two dollars a day. New backers then set up a laboratory for him in Manhattan, where he built working models of his AC induction motor. He received patents in 1888 and in May that year demonstrated the system to the American Institute of Electrical Engineers.

Westinghouse quickly licensed the patents for 60,000 dollars in cash and stock, plus a royalty for each horsepower sold, and hired Tesla as a consultant in Pittsburgh. Tesla's motor was one key part of what made AC practical; the transformer, developed by others, and the work of many Westinghouse engineers were also essential. When Westinghouse ran into financial trouble around 1891, Tesla agreed to give up the royalty clause, a decision that cost him a fortune; the patents were later bought outright for 216,000 dollars. The popular claim that he tore up a contract worth billions exaggerates a real, but more modest, sacrifice.

AC won. Westinghouse lit the World's Columbian Exposition in Chicago in 1893 with Tesla's polyphase system, and Tesla advised on the hydroelectric plant at Niagara Falls, which began sending power to Buffalo in 1896 using Westinghouse generators based on his designs. Even Edison's former company, merged into General Electric in 1892, adopted alternating current.

In 1891 Tesla patented the Tesla coil, a resonant transformer that produced extremely high voltages at high frequencies, and became a US citizen. His lectures in New York, London and Paris, in which he lit lamps without wires and let currents pass through his body, made him famous. In 1898 he demonstrated a radio-controlled boat at Madison Square Garden. He experimented with X-rays soon after their discovery and worked on wireless transmission of signals.

Tesla is often said to have invented radio. In fact many people contributed, among them Heinrich Hertz, Oliver Lodge, Jagadish Chandra Bose and Guglielmo Marconi, who first sent a signal across the Atlantic in 1901. In 1943 the US Supreme Court invalidated Marconi's key tuning patent because earlier work by Lodge, John Stone Stone and Tesla anticipated it, but the court did not rule that Tesla invented radio.

In 1899 Tesla built a laboratory at Colorado Springs, where he produced artificial lightning and became convinced he could send power and messages through the earth itself. With 150,000 dollars from the banker J. P. Morgan he began a giant tower at Wardenclyffe on Long Island in 1901. Morgan declined to put in more money, especially after Marconi's success, and work stopped by 1906. Tesla's idea of transmitting useful amounts of power wirelessly over great distances was not workable with the physics he relied on.

His later decades were a decline. He announced inventions, including a bladeless turbine and, in the 1930s, a defensive "death ray", that never reached production. He moved from hotel to hotel, leaving unpaid bills, and devoted much care to the pigeons he fed in the city's parks. From 1934 Westinghouse quietly paid his rent at the Hotel New Yorker and a small monthly sum. He died there alone on 7 January 1943, aged 86.

Because his nephew was a Yugoslav official, US authorities had Tesla's papers examined; the engineer John G. Trump found nothing dangerous. The papers and his ashes were later sent to Belgrade, where the Nikola Tesla Museum was founded in 1952. Both Serbia and Croatia claim him with pride. In 1960 the international unit of magnetic flux density was named the tesla. Popular culture has since made him a symbol of the wronged lone genius, crediting him with inventions he did not make and secret technologies for which there is no evidence. The real record is impressive enough: the motors and AC power grids he helped create run much of the modern world.