By William Tucker on 9.19.07 @ 12:08AM
Edison was not the inventor of our electricity.
Last week New York City's Con Edison brought to a conclusion one
of the most bitterly fought technological debates of all time when
it announced it would disconnect the last five customers in New
York City receiving direct current electricity.
"They're mostly small users," said Robert McGhee, a spokesman
for Con Edison, "nobody you ever heard of. One of them is a
residence. They may have to provide their own power if they want to
keep using direct current. But for us it wasn't worth the
expense."
Thomas Edison, whose name the company bears, lost this battle
long ago to Nikola Tesla, the Serbian immigrant who invented a
motor that utilized the rival system, alternating current. Edison
was not a gracious loser but his reputation survives pretty much
intact. Meanwhile, Tesla has sunk into obscurity -- although he did
make a cameo appearance in the 2006 movie The Prestige
(played by David Bowie). A $75,000 electric sports car recently
marketed by Silicon Valley entrepreneur Martin Eberhard has been
christened the Tesla Roadster. Still, the great electrical genius
of the early 20th century remains largely forgotten -- even though
he pioneered the technology that is creating our "wireless
world."
The electric battery -- the "Voltaic Pile -- had been invented
by Allessandro Volta in 1800. For the next 80 years it remained the
only source of electric current and most new devices -- the
electric light, for example -- were designed to take advantage of
it. In 1882, Edison opened the Pearl Street Station in Lower
Manhattan and started generating a few thousand kilowatts. The
station employed a coal-driven steam engine, which fired the
reciprocal motion of a piston engine. This back-and-forth movement
produced something different, however -- alternating current, in
which the electrons are constantly shifting back and forth at a
periodic frequency rather than moving all in one direction.
Alternating current did not seem useful, especially for driving
the rotary motion of an electric motor. So Edison had to "rectify"
the current by converting it to DC. This was done with a set of
"brushes," which bracketed the rotating shaft and only picked up
the half of the current that was moving in the right direction.
These metallic brushes were constantly arcing sparks, however, and
wore out at a phenomenal rate.
Direct current also had other shortcomings. In particular, its
voltage was used up in resistance from the transmission wires over
very short distances. It could not be transmitted for more than a
mile. This meant a city would have to be dotted with coal plants.
The prospects for clean air were not very bright.
All this challenged the 26-year-old Tesla as he pursued a degree
in electrical engineering in Budapest. Tesla noted the clumsy
inefficiency of the brushes and asked his professors if it wasn't
possible to build a rotary engine that ran on alternating current.
They told him it couldn't be done -- it would be akin to perpetual
motion. But Tesla pursued the subject in his fertile brain. One day
as he walked in the park in Budapest in 1882 the answer came to him
in a vision. He said later the engine that appeared before him was
as tangible as if it had been made from real metal.
The problem could be solved, he realized, by dispatching two
currents in phases 90 degrees apart. (We now use three currents.)
The wires would magnetize four metal terminals surrounding a
magnetized shaft. When the magnet at 12 o'clock was positive, it
would start the positive pole of the shaft rotating in a clockwise
direction. At 3 o'clock the second phased current would create a
north pole, pushing the shaft another quarter turn. When the north
pole reached 6 o'clock, however, the first current would have
reversed and this pole would also be magnetized north. At 9
o'clock, the second current would also reverse and be north again.
Thus, two alternating currents, fluctuating back and forth at a
regular rate (we use 60 cycles per second) would create the rotary
action of an electric motor. After that, everything became
easy.
Tesla worked for Edison's fledgling electric company in Paris
and excelled enough to be invited to New York, where he presented
his ideas for an alternating current engine to the master. The
rough-and-ready Edison didn't much enjoy the well-mannered ways of
the European immigrant, however, and they had a falling out over a
bonus that Edison had promised Tesla but then didn't deliver. Tesla
was cast into the streets. He worked as a laborer, carrying his
engine entirely in his head, until a few chance meetings put him in
touch with George Westinghouse, the other electrical pioneer, who
bought his patents. Westinghouse used alternating current to
harness Niagara Falls and transmit the power to nearby cities --
something that couldn't be done with direct current. He also won a
contract to illuminate the "City of Light" at the 1893 Chicago
Columbian Exposition. Edison took up the challenge and the "War of
the Currents" was on.
Edison played dirty at best, trying to terrify the public into
believing AC was uniquely dangerous. (In fact, AC and DC are about
equal.) His supporters electrocuted dogs at weekly press
conferences and arranged for the first electrocution of a condemned
murderer at Sing Sing. In 1903 Edison executed Topsy the Elephant
at Coney Island's Luna Park and made a motion picture of the event,
distributing "Electrocuting an Elephant" as one of the first films
to appear in theaters. (Coney Island belatedly erected a memorial
to Topsy in 2003.)
Alternating current's advantages proved far too great, however,
and by the 1920s had clearly won out. Electrical generation was
centralized at larger and larger power stations that could be cited
in remote locations. Hydropower from distant dams could be
transmitted across hundreds of miles. Only a few direct current
operations remained in Manhattan.
Edison's fame survived intact. He remained a national hero,
dying in 1929 just after helping open Henry Ford's Greenfield
Village only a week before the stock market crashed. Tesla, on the
other hand, became completely absorbed in the phenomenon of
electromagnetic radiation. As early as 1890 he realized that the
earth itself is a huge magnet and its electrostatic atmosphere can
be used to transmit information and even electrical power. With the
help of J.P. Morgan, he built an 18-story tower on Long Island
designed to broadcast both radio signals and electrical energy
across the globe. Unfortunately, no one was equipped to receive his
signals. When Guglielmo Marconi demonstrated the first
point-to-point broadcasts on a much more practical level a decade
later, he received credit for inventing radio.
Tesla became lost in dreams of a world brought together by
instant communications. He envisioned a world in which telephone
calls, stock quotes, daily news stories, photographs and
information of every kind could be instantly transmitted. By 1900
he had created remote-controlled vehicles that are the precursors
of today's guided missiles and Hasbro toys. He believed these
weapons could be made so powerful they would put an end to war. He
also believed a world brought together by instant information would
learn to live in peace. Yet he never mastered Edison's talent for
commercializing his ideas. He lived in a series of New York hotels,
rarely paying his bills and constantly pursued by creditors. Every
year he would hold a press conference in which he would unveil his
latest wonders, but reporters became more and more cynical. He died
in poverty in 1943.
McGee, of Con Edison, says the utility is planning a ceremony
when the last direct current customer is disconnected before the
end of the year. "We've selected a 51-year-veteran employee to snip
the wires," he says. "It's about as close to Thomas Edison as we're
going to get."
Tesla, on the other hand, will not be represented.
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