In 1960, in honor of Tesla, the General Conference on
Weights and Measures for the International System of Units dedicated
the term "tesla" to the SI unit measure for magnetic field strength.
Working for Edison
In 1882, Tesla began working for the Continental Edison
Company in France, designing and making improvements to electrical
equipment.
In June 1884, Tesla relocated to New York City. During
his trip across the Atlantic, his ticket, money, and some of his luggage were
stolen, and he was nearly thrown overboard after a mutiny broke out on the
ship. He arrived with only four cents in his pocket, a letter of
recommendation, a few poems, and the remainder of his belongings.
In the letter of recommendation from Charles Batchelor,
a former employer, to Thomas Edison, it is claimed that Batchelor wrote,
"I know two great men and you are one of them; the other is this young
man." (The exact contents of the letter are disputed in McNichol's book.)
Edison hired Tesla to work for his Edison Machine Works. Tesla's work for
Edison began with simple electrical engineering and quickly progressed to
solving some of the company's most difficult problems. Tesla was even offered
the task of completely redesigning the Edison Company's direct current generators.
In 1885, Tesla claimed that he could redesign Edison's
inefficient motor and generators, making an improvement in both service and
economy. According to Tesla, Edison remarked, "There's fifty thousand
dollars in it for you—if you can do it"—this has been noted as an odd
statement from an Edison whose company was stingy with pay and who did not have
that sort of cash on hand. After months of work, Tesla fulfilled the task
and inquired about payment. Edison, claiming that he was only joking, replied,
"Tesla, you don't understand our American humor." Instead,
Edison offered a US$10 a week raise over Tesla's US$18 per week salary; Tesla
refused the offer and immediately resigned.
Middle years (1886-1899)
In 1886, Tesla formed his own company, Tesla Electric
Light & Manufacturing. The company installed electrical arc light based
illumination systems designed by Tesla and also had designs for dynamo electric
machine commutators, the first patents issued to Tesla in the US.
Tesla proposed that the company should go on to develop his
ideas for alternating current transmission systems and motors. The investors
disagreed and eventually fired him, leaving him penniless; Tesla was forced to
work as a ditch digger for US$2 per day. Tesla considered the winter of
1886/1887 as a time of "terrible headaches and bitter tears". During
this time, he questioned the value of his education.
In April 1887, Tesla started a company, the Tesla Electric
Company, with the backing of New York attorney Charles F. Peck and Alfred S.
Brown, the director of Western Union. They set up a laboratory for Tesla at 89
Liberty St. in Manhattan so he could work on his alternating current motor and
other devices for power distribution, with an agreement that they share
fifty-fifty with Tesla any profits generated from patents. It was here in
1887 that Tesla constructed a brushless alternating current induction
motor, based on a rotating magnetic field principle he claimed to
have conceived of in 1882. He received a US patent for the motor in May
1888. At that time many inventors were trying to develop workable AC
motors because AC's advantages in long distance high voltage transmission
were counterbalanced by the inability to operate motors on AC. The rotating
magnetic field induction motor seems to have been an independent invention by
Tesla but it was not a unique discovery at the time. Italian
physicist Galileo Ferraris published a paper on rotating magnetic
field based induction motor on 11 March 1888, a working model of which he
may have been demonstrating at the University of Turin as early as 1885. In
1888, a month before Tesla demonstrated his AC induction motor, Westinghouse
engineer Oliver B. Shallenberger invented an induction meter that
was based on the same rotating magnetic field principle and during Tesla's
demonstration English engineer Elihu
Thomson stated he was working on
an induction motor.
In 1888, the editor of Electrical
World magazine, Thomas Commerford Martin (a friend and
publicist), arranged for Tesla to demonstrate his alternating current system,
including his induction motor, at the American Institute of Electrical
Engineers (now IEEE). Engineers working for the Westinghouse
Electric & Manufacturing Company reported to George Westinghouse that
Tesla had a viable AC motor and power system—something that Westinghouse had
been trying to secure. In July 1888 Brown and Peck negotiated a licensing deal
with George Westinghouse for Tesla's polyphase induction motor and transformer
designs for $60,000 in cash and stock and a royalty of $2.50 per AC horsepower
produced by each motor. Westinghouse also hired Tesla for one year for the
large fee of $2,000 a month to be a consultant at the Westinghouse Electric
& Manufacturing Company's Pittsburgh labs.
During that year, Tesla worked in Pittsburgh, helping to
create an alternating current system to power the city's streetcars. He found
the time there frustrating because of conflicts between him and the other
Westinghouse engineers over how to best implement AC power. Between them they
settled on a 60-cycle AC current system Tesla proposed (to match the working
frequency of Tesla's motor), although they soon found that, since Tesla's
induction motor could only run at a constant speed, it would not work for
street cars. They ended up using a DC traction motor instead.
Tesla demonstrated wireless energy transmission (Tesla
effect) as early as 1891.
In 1891, Tesla patented the Tesla coil.
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