Who
Invented the Lightbulb?
(Photo by Alkivar licensed
under the Creative Commons Attribution-Share Alike 3.0 Unported
license.)
Quick
Facts
|
The first
electric arc lamp was demonstrated by Humphrey Davy in
1806 but was impractical for home lighting. |
Inventors
worked throughout the 19th century trying to use the principal
of incandescence (making an object glow by heating
it with electricity) to make practical lights. |
Inventors
like Frederick DeMoleyns and Joseph Swan tried using electricity
to heat an object in a vacuum enclosed by a glass bulb
to keep the oxygen away so the material would not burn,
but they were not entirely successful. |
Edison announced
he had solved the problem in 1878, but his idea also turned
out to be unworkable. |
By 1879 lab
staff working for Edison determined the best shape (a
long, thin, filament) and the best material (high resistance)
to be used in the bulb. |
By October
of 1880 Edison's staff had gotten Japanese Bamboo to incandesce
successfully for 600 hours. The first practical lightbulb. |
Swan observed
Edison work to improve his own and was sued by Edison.
Later they joined forces later to establish the Edison-Swan
United company. |
It was Thomas Edison
in 1879, wasn't it? That's what many people think and were taught
in school. Like most stories, however, there is a lot more behind
the creation of this important and ubiquitous object than just
Mr. Edison..
The story of the
lightbulb really starts almost seventy years earlier. In 1806
Humphrey Davy, an Englishman, demonstrated a powerful electric
lamp to the Royal Society. Davy's lamp produced its illumination
by creating a blinding electric spark between two charcoal rods.
This device, known as an "arc lamp," was impractical for most
uses. The light, similar to that of a welding torch, was simply
too bright to be used in residences and most businesses. The
device also needed a tremendous source of power and the batteries
which powered Davy's demonstration model were quickly drained.
As time went on,
electric generators were invented that could feed the arc lamp's
need for power. It found its way into applications where a brilliant
source of light was needed. Lighthouses and public assembly
areas were obvious uses. Later arc lamps were used in war to
power huge searchlights used to spot enemy planes. Today you
can see such searchlights lighting up the sky near movie theaters
or at the opening of a new stores.
The Incandescant
Light
Some 19th century
inventors wanted to find a way to "subdivide" the light from
Davy's arc lamp so that it could be used in the home and office.
Other scientists thought that a completely new technique for
making electric light held more promise. This method of generating
light was known as "incandescence."
Scientists knew that
if you took some materials and passed enough electricity through
them, they would heat up. They also knew that if the material
got hot enough, it would start to glow. The problem with this
method of making light was that before long either the material
would burst into flame or melt into a puddle. If incandescent
light was to be made practical, these twin problems would have
to be solved.
It occurred to inventors
that one way to keep their incandescent "burners" from catching
fire was to not let them come into contact with oxygen. Oxygen
is a necessary ingredient in the combustion process. Since oxygen
is in the atmosphere, the only way to keep it away from the
burners was to enclose the burner in a glass container, or "bulb,"
and pump out the air. In 1841 a British inventor named Frederick
DeMoleyns patented a bulb using just this technique in combination
with burners made of platinum and carbon. An American named
J. W. Starr also received a patent in 1845 for a bulb using
vacuum in conjunction with a carbon burner. Many others, including
an English chemist named Joseph Swan, improved and patented
versions of bulbs using a vacuum with burners of various materials
and shapes. None, however, proved practical for everyday use.
Swan's lamp, for example, used carbonized paper that would quickly
crumble after being lit a short time.
Edison Joins the
Fray
It was obvious,
though, that incandescent lighting would be a huge financial
success if it could be perfected, so many inventors continued
to work on finding a solution. It was into this environment
that the brash, young, inventor Thomas Alva Edison entered the
race to make-a-better-bulb in 1878. Edison was already world
famous for having created and commercialized several items,
including a better stock market ticker and the phonograph. In
October of that year, after working on the project for only
a few months, he declared to the newspapers "I have just solved
the problem of the subdivision of the electric light." This
rash pronouncement was enough to drive the stocks of the gas
companies (whose lamps supplied the current form of lighting)
down into the ground.
As it turned out,
Edison's announcement was premature. He had an idea of how to
solve the problems of the electric incandescent light, but had
not yet perfected it. His idea was to enclose a platinum burner
in a vacuum. When other inventors had done this the platinum
melted, but Edison thought he had solved that problem by building
a temperature-sensitive switch into the bulb that would cut
off the current when the temperature got too high. This was
a great idea, but unfortunately it didn't work. To keep the
bulbs cool enough, the switches had to cut the current off very
quickly. This resulted in a constant flickering which made the
bulbs unusable (this same switching principle is currently used
in Christmas tree bulbs to make them blink on and off).
It was soon obvious
to everyone working on the incandescent light at Edison's Menlo
Park laboratory that another approach was needed. Edison decided
to hire a young physicist named Francis Upton from Princeton
University to work on the project. Up to this point Edison's
staff had been trying idea after idea to get the bulb to work.
Under Upton's guidance, they started looking at existing patents
and research to try and avoid repeating other people's mistakes.
The staff also started doing basic research on the properties
of the materials they had been working with.
One of the results
of testing the properties of the materials was the realization
that any burner chosen would have to have a high electrical
resistance. All materials have an amount of electrical "friction"
that resists electricity moving through it. This is known as
the material's electrical resistance. Materials with high resistance
more easily get hot when electricity passes through them. Edison
soon realized that any good burner would have to have a high
electrical resistance, otherwise too much electricity would
be needed to warm the material to the point where it would give
off light. This revelation meant that Edison's staff need only
to test high-resistance materials to find the one they wanted.
This information
also started Edison thinking about the electric lights not only
as an end to themselves, but how they fit as part of a whole
electrical system. How big would the generator need to be to
light a neighborhood? What voltage should be delivered to a
house?
By October of 1879
Edison's workers began to see some results. On the 22nd of that
month a thin, cotton "carbonized" thread burned for some 13
hours during an experiment. Longer times were achieved by modifying
the vacuum pumps and creating a better vacuum inside the bulb
(less oxygen inside the bulb slowed the burning process). More
carbonized organic materials were tested and Japanese bamboo
proved to be the best. By the end of 1880 Edison's carbonized
bamboo burners, now called filaments because they were fashioned
into a long, thin thread, were burning in bulbs as long as 600
hours. The "filament" proved to be the best shape to increase
the materials electrical resistance and physical strength.
The carbonized bamboo
had a high resistance and fit well into Edison's scheme for
building a whole electrical power system to provide lighting.
By 1882 he had established the Edison Electrical Light Company
which had a generating station located on Perl Street, providing
New York City with electrical lighting. In 1883 Macy's in New
York City became the first store to install the new incandescent
lamps.
Edison Vs. Swan
Meanwhile over in
England, Joseph Swan had again gotten involved in working on
the lightbulb after he saw that new pumps made it possible to
produce a better vacuum. Swan made a lamp which worked well
for demonstrations, but was impractical in actual use. Swan's
burner was made of a thick carbon rod that gave off gases that
soon covered the inside of the bulb in soot. Also, the low resistance
of the rod meant that the bulb used up too much power. After
seeing the success of a high resistance, thin filament in Edison's
lamps, Swan incorporated this improvement into his own bulbs.
After founding his own company in England, Swan found himself
sued by Edison for patent infringement. Eventually the two inventors
decided to stop fighting and join forces. The company they formed,
Edison-Swan United, became one of the world's largest manufacturer
of lightbulbs.
So did Edison invent
the lightbulb? Not really. Others had produced an incandescent
light before him. He did, however, create the first practical
lightbulb along with an electrical system to support it, certainly
a significant achievements in their own right.
Of all the inventions
Edison was involved in - the stock ticker, the phonograph, the
telegraph and the mimeograph - only the incandescent lightbulb
remains in general use today. It is a testament to how great
a job Edison and his workers at Menlo Park did in taking this
invention out of the laboratory and putting it into the home.
Thomas
Edison
Copyright Lee Krystek 2002.