Employment
Budapest
Following his unfinished studies Tesla left for Budapest and found employment in the Central Telegraphic Office of Hungary, where he participated in the construction of the city’s first telephone exchange. For two years he worked on the expansion of telephone network.
For the history of electrical engineering his stay in Budapest is important because it was there that he discovered the rotating magnetic field, in February of 1882.
Until Tesla's discovery of the rotating magnetic field, electrical engineering used only the direct current motor, and it was only after the resolution of this problem, which preoccupied him for a long time, that production of alternating current motors became possible, and with it its general application.
With this ingenious discovery Tesla laid the foundations of the technology of alternating current which still remains the backbone of the system of production, transmission and use of electrical energy.
Paris
After Budapest, Tesla became an employee of the Continental Edison Company in Paris. In 1883, while working in Strasbourg, but outside his normal working hours, he discovered the rotating magnetic field and constructed the first induction motor.
Tesla constructed the first alternating current motor in Strasbourg and on July 10, 1883, his 27th birthday, he demonstrated its operation in his laboratory using a phase breakthrough in two-phase current, one phase following the other.
He produced the electro-magnetic field in which the direction of north is not constant, but changes in a circular cycle, i.e. it rotates. Today 90% of all electric motors in the world are operating on the principle of Tesla's rotating magnetic field.
New York
In July 1884 he left for the USA where he first found employment with Thomas Edison.
Edison promised Tesla a sum of US$50,000 for the improvement of his power station, but when Tesla successfully accomplished the given task, Edison avoided payment with words: “When you become a real American, you'll be able to recognize an American joke.” Shocked and angry, Tesla immediately handed in his notice.
New York – after Edison
The next two years he spent undertaking odd jobs such as digging canals, and in 1887 he established his own laboratory. It was in that year and the following year that he made some of his most important discoveries: polyphase system of alternating currants, single phase and polyphase electric motor, polyphase transformer, and twenty other inventions.
These inventions caused a veritable “war” between Tesla and Edison, or better to say Tesla's concept of alternating current and Edison's concept of direct current.
Tesla's patents were purchased by the well known American industrialist George Westinghouse, himself an inventor, who was to win – with a project based on Tesla's inventions – a competition for the construction of the most advanced and largest hydro-electric power plant of that time – the power machinery on the Niagara Falls, which was indeed built in 1888. At threshold the power plant generators produced the voltage of 2200 V.
This power plant, the first modern hydro electric power plant, marked a great victory for Tesla's system of alternating current which, in contrast to the Edison's system, enabled transfer of large quantities of electrical power over long distances.
In 1893, at the World Exhibition in Chicago, with an experiment involving a metal egg Tesla demonstrated in a popular fashion one of the effects of the rotating magnetic field: subjecting it to rotation the egg is raised on its end. The World Exhibition was the ultimate confirmation of Tesla's concept.
Colorado Springs
Colorado Springs, where he investigated wireless telephony, wireless transfer of energy – on which occasion he turned on public lighting in distant places in the middle of the day, without anybody still probably not understanding how he did it – proving that the Earth could be used as a conductor. He also lit 200 bulbs without wires, at a distance of 40 km, each of which illuminated a 41 metre circle around it. Possibly the most important of Tesla's experiments were those carried out in 1899.
It was in Colorado Springs, where he stayed from May 1899 until early 1900, that Tesla made what is probably his greatest discovery – terrestrial stationary waves. By this discovery he proved that the Earth could be used as a conductor and would be as responsive as a tuning fork to electrical vibrations of a certain frequency.
Returning to New York
On his return to New York Tesla wanted to build a tower on Long Island which would have been the first radio station in the world, and he approached J.P. Morgan, the banker-millionaire, to co-finance his project. But when Morgan realized that Tesla was working on experiments which would enable the wireless transfer of energy, Morgan – proud owner of many copper mines – decided to withdraw his financial support, and Tesla was forced to halt experiments.
Tesla never did pay too much attention to money matters; it was his work that was of paramount importance to him.
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