尼古拉·特斯拉

In 1881 he moved to Budapest, Hungary, to work for a telegraph company, the American Telephone Company. There, he met Nebojša Petrović, then a young inventor from Austria. Although their encounter was brief, they did work on a project together using twin turbines to create continual power. On the opening of the telephone exchange in Budapest, 1881, Tesla became the chief electrician to the company, and was later engineer for the country's first telephone system. He also developed a device that, according to some, was a telephone repeater or amplifier, but according to others could have been the first loudspeaker.[21] In 1882 he moved to Paris, France to work as an engineer for the Continental Edison Company, designing improvements to electric equipment. In the same year, Tesla conceived of the induction motor and began developing various devices that use rotating magnetic fields (for which he received patents in 1888).

Soon thereafter, Tesla hastened from Paris to his mother's side as she lay dying, arriving hours before her death in 1882. Her last words to him were, "You've arrived, Nidžo, my pride." After her death, Tesla fell ill. He spent two to three weeks recuperating in Gospić and the village of Tomingaj near Gračac, the birthplace of his mother.

In 1884, when Tesla first arrived in the US, he had little besides a letter of recommendation from Charles Batchelor, his manager in his previous job. In the letter of recommendation to Thomas Edison, Charles Batchelor wrote, "I know two great men and you are one of them; the other is this young man." Edison hired Tesla to work for his company Edison Machine Works. Tesla's work for Edison began with simple electrical engineering and quickly progressed to solving the company's most difficult problems. Tesla was offered the task of a complete redesign of the Edison company's direct current generators.

In 1919 Tesla wrote that Edison offered him the then-staggering sum of $50,000 (almost $1 million today, adjusted for inflation [1]) if he completed the motor and generator improvements. Tesla said he worked nearly a year to redesign them and gave the Edison company several enormously profitable new patents in the process. When Tesla inquired about the $50,000, Edison reportedly replied to him, "Tesla, you don't understand our American humor," and reneged on his promise.[22] Tesla resigned when he was refused a raise to $25 per week. At Tesla's salary of $18 per week the bonus would have amounted to over 53 years pay, and the amount was equal to the initial capital of the company.[23] He eventually found himself digging ditches for a short period of time—ironically for the Edison company. Edison had also never wanted to hear about Tesla's AC polyphase designs, believing that DC electricity was the future. Tesla focused intently on his AC polyphase system, even while digging ditches.[24]

In 1886, Tesla formed his own company, Tesla Electric Light & Manufacturing. The initial financial investors disagreed with Tesla on his plan for an alternating current motor and eventually relieved him of his duties at the company. Tesla worked in New York as a common laborer from 1886 to 1887 to feed himself and raise capital for his next project. In 1887, he constructed the initial brushless alternating current induction motor, which he demonstrated to the American Institute of Electrical Engineers (now IEEE) in 1888. In the same year, he developed the principles of his Tesla coil and began working with George Westinghouse at Westinghouse Electric & Manufacturing Company's Pittsburgh labs. Westinghouse listened to his ideas for polyphase systems which would allow transmission of alternating current electricity over large distances.

In April of 1887, Tesla began investigating what would later be called X-rays using his own single node vacuum tubes (similar to his patent #514,170 ). This device differed from other early X-ray tubes in that they had no target electrode. The modern term for the phenomenon produced by this device is bremsstrahlung (or braking radiation). We now know that this device operated by emitting electrons from the single electrode through a combination of field emission and thermionic emission. Once liberated, electrons are strongly repelled by the high electric field near the electrode during negative voltage peaks from the oscillating HV output of the Tesla Coil, generating X-rays as they collide with the glass envelope. He also used Geissler tubes. By 1892, Tesla became aware of what Wilhelm Röntgen later identified as effects of X-rays.

Tesla commented on the hazards of working with single node X-ray producing devices, incorrectly attributing the skin damage to ozone rather than the radiation:

“ As to the hurtful actions on the skin... I note that they have been misinterpreted... They are not due to the Röntgen rays, but merely to the ozone generated in contact with the skin. Nitrous acid may also be responsible, but to a small extent. ” —Electrical Review, 30 November 1895

Tesla later observed an assistant severely "burnt" by X-rays in his lab. He performed several experiments prior to Röntgen's discovery (including photographing the bones of his hand; later, he sent these images to Röntgen) but didn't make his findings widely known; much of his research was lost in the 5th Avenue lab fire of March 1895.

On July 30, 1891, he became a naturalized citizen of the United States at the age of 35. Tesla established his 35 South Fifth Avenue laboratory in New York during this same year. Later, Tesla would establish his Houston Street laboratory in New York at 46 E. Houston Street. There, at one point while experimenting with mechanical oscillators he generated a resonance of several surrounding buildings, but ironically due to the frequencies involved, not his own building, causing complaints to the police. As the speed grew he hit the resonant frequency of his own building and belatedly realising the danger he was forced to apply a sledge hammer to terminate the experiment, just as the astonished police arrived.[28] He also lit vacuum tubes wirelessly at both of the New York locations, providing evidence for the potential of wireless power transmission.[29] Some of Tesla's closest friends were artists. He befriended Century Magazine editor Robert Underwood Johnson, who adapted several Serbian poems of Jovan Jovanović Zmaj (which Tesla translated). Also during this time, Tesla was influenced by the Vedic philosophy teachings of the Swami Vivekananda.[30]

When Tesla was 36 years old, the first patents concerning the polyphase power system were granted. He continued research of the system and rotating magnetic field principles. Tesla served, from 1892 to 1894, as the vice president of the American Institute of Electrical Engineers, the forerunner (along with the Institute of Radio Engineers) of the modern-day IEEE. From 1893 to 1895, he investigated high frequency alternating currents. He generated AC of one million volts using a conical Tesla coil and investigated the skin effect in conductors, designed tuned circuits, invented a machine for inducing sleep, cordless gas discharge lamps, and transmitted electromagnetic energy without wires, effectively building the first radio transmitter. In St. Louis, Missouri, Tesla made a demonstration related to radio communication in 1893. Addressing the Franklin Institute in Philadelphia, Pennsylvania and the National Electric Light Association, he described and demonstrated in detail its principles. Tesla's demonstrations were written about widely through various media outlets.

At the 1893 World's Fair, the World's Columbian Exposition in Chicago, an international exposition was held which for the first time devoted a building to electrical exhibits. It was an historic event as Tesla and George Westinghouse introduced visitors to AC power by using it to illuminate the Exposition. On display were Tesla's fluorescent lights and single node bulbs. Tesla also explained the principles of the rotating magnetic field and induction motor by demonstrating how to make an egg made of copper stand on end in his demonstration of the device he constructed known as the "Egg of Columbus".

Also in the late 1880s, Tesla and Edison became adversaries in part due to Edison's promotion of direct current (DC) for electric power distribution over the more efficient alternating current advocated by Tesla and Westinghouse. Until Tesla invented the induction motor, AC's advantages for long distance high voltage transmission were counterbalanced by the inability to operate motors on AC. As a result of the "War of Currents," Edison and Westinghouse went nearly bankrupt, so in 1897, Tesla released Westinghouse from contract, providing Westinghouse a break from Tesla's patent royalties. Also in 1897, Tesla researched radiation which led to setting up the basic formulation of cosmic rays.[31]

When Tesla was 41 years old, he filed the first basic radio patent (U.S. Patent 645,576 ). A year later, he demonstrated a radio controlled boat to the US military, believing that the military would want things such as radio controlled torpedoes. Tesla developed the "Art of Telautomatics", a form of robotics.[32] In 1898, a radio-controlled boat was demonstrated to the public during an electrical exhibition at Madison Square Garden. These devices had an innovative coherer and a series of logic gates. Radio remote control remained a novelty until the 1960s. In the same year, Tesla devised an "electric igniter" or spark plug for Internal combustion gasoline engines. He gained U.S. Patent 609,250 , "Electrical Igniter for Gas Engines", on this mechanical ignition system. Tesla lived in the former Gerlach Hotel, renamed The Radio Wave building, at 49 W 27th St. (between Broadway and Sixth Avenue), Lower Manhattan, before the end of the century where he conducted the radio wave experiments. A commemorative plaque was placed on the building in 1977 to honor his work.