The invention: An electrochemical cell that directly converts energy
from reactions between oxidants and fuels, such as liquid
hydrogen, into electrical energy.
The people behind the invention:
Francis Thomas Bacon (1904-1992), an English engineer
Sir William Robert Grove (1811-1896), an English inventor
Georges Leclanché (1839-1882), a French engineer
Alessandro Volta (1745-1827), an Italian physicist
The Earth’s Resources
Because of the earth’s rapidly increasing population and the
dwindling of fossil fuels (natural gas, coal, and petroleum), there is
a need to design and develop new ways to obtain energy and to encourage
its intelligent use. The burning of fossil fuels to create energy
causes a slow buildup of carbon dioxide in the atmosphere,
creating pollution that poses many problems for all forms of life on
this planet. Chemical and electrical studies can be combined to create
electrochemical processes that yield clean energy.
Because of their very high rate of efficiency and their nonpolluting
nature, fuel cells may provide the solution to the problem of
finding sufficient energy sources for humans. The simple reaction of
hydrogen and oxygen to form water in such a cell can provide an
enormous amount of clean (nonpolluting) energy. Moreover, hydrogen
and oxygen are readily available.
Studies by Alessandro Volta, Georges Leclanché, and William
Grove preceded the work of Bacon in the development of the fuel
cell. Bacon became interested in the idea of a hydrogen-oxygen fuel
cell in about 1932. His original intent was to develop a fuel cell that
could be used in commercial applications.
The Fuel Cell Emerges
In 1800, the Italian physicist Alessandro Volta experimented
with solutions of chemicals and metals that were able to conduct electricity. He found that two pieces of metal and such a solution
could be arranged in such a way as to produce an electric current.
His creation was the first electrochemical battery, a device that produced
energy from a chemical reaction. Studies in this area were
continued by various people, and in the late nineteenth century,
Georges Leclanché invented the dry cell battery, which is now commonly
used.
The work of William Grove followed that of Leclanché. His first
significant contribution was the Grove cell, an improved form of the
cells described above, which became very popular. Grove experimented
with various forms of batteries and eventually invented the
“gas battery,” which was actually the earliest fuel cell. It is worth
noting that his design incorporated separate test tubes of hydrogen
and oxygen, which he placed over strips of platinum.
After studying the design of Grove’s fuel cell, Bacon decided
that, for practical purposes, the use of platinum and other precious
metals should be avoided. By 1939, he had constructed a cell in
which nickel replaced the platinum used.
The theory behind the fuel cell can be described in the following
way. If a mixture of hydrogen and oxygen is ignited, energy is released
in the form of a violent explosion. In a fuel cell, however, the
reaction takes place in a controlled manner. Electrons lost by the hydrogen
gas flow out of the fuel cell and return to be taken up by the
oxygen in the cell. The electron flow provides electricity to any device
that is connected to the fuel cell, and the water that the fuel cell
produces can be purified and used for drinking.
Bacon’s studies were interrupted byWorldWar II. After the war
was over, however, Bacon continued his work. Sir Eric Keightley
Rideal of Cambridge University in England supported Bacon’s
studies; later, others followed suit. In January, 1954, Bacon wrote an
article entitled “Research into the Properties of the Hydrogen/ Oxygen
Fuel Cell” for a British journal. He was surprised at the speed
with which news of the article spread throughout the scientific
world, particularly in the United States.
After a series of setbacks, Bacon demonstrated a forty-cell unit
that had increased power. This advance showed that the fuel cell
was not merely an interesting toy; it had the capacity to do useful
work. At this point, the General Electric Company (GE), an American corporation, sent a representative to England to offer employment
in the United States to senior members of Bacon’s staff. Three scientists
accepted the offer.
A high point in Bacon’s career was the announcement that the
American Pratt and Whitney Aircraft company had obtained an order
to build fuel cells for the Apollo project, which ultimately put
two men on the Moon in 1969. Toward the end of his career in 1978,
Bacon hoped that commercial applications for his fuel cells would
be found.Impact
Because they are lighter and more efficient than batteries, fuel
cells have proved to be useful in the space program. Beginning with
the Gemini 5 spacecraft, alkaline fuel cells (in which a water solution
of potassium hydroxide, a basic, or alkaline, chemical, is placed)
have been used for more than ten thousand hours in space. The fuel
cells used aboard the space shuttle deliver the same amount of power
as batteries weighing ten times as much. On a typical seven-day
mission, the shuttle’s fuel cells consume 680 kilograms (1,500 pounds)
of hydrogen and generate 719 liters (190 gallons) of water that can
be used for drinking.
Major technical and economic problems must be overcome in order
to design fuel cells for practical applications, but some important
advancements have been made.Afew test vehicles that use fuel cells as a source of power have been constructed. Fuel cells using
hydrogen as a fuel and oxygen to burn the fuel have been used in a
van built by General Motors Corporation. Thirty-two fuel cells are
installed below the floorboards, and tanks of liquid oxygen are carried
in the back of the van. A power plant built in New York City
contains stacks of hydrogen-oxygen fuel cells, which can be put on
line quickly in response to power needs. The Sanyo Electric Company
has developed an electric car that is partially powered by a
fuel cell.
These tremendous technical advances are the result of the singleminded
dedication of Francis Thomas Bacon, who struggled all of
his life with an experiment he was convinced would be successful.
The invention: 
The invention: The first major computer programming language,
FORTRAN supported programming in a mathematical language
that was natural to scientists and engineers and achieved unsurpassed
success in scientific computation.
The people behind the invention:
John Backus (1924- ), an American software engineer and
manager
John W. Mauchly (1907-1980), an American physicist and
engineer
Herman Heine Goldstine (1913- ), a mathematician and
computer scientist
John von Neumann (1903-1957), a Hungarian American
mathematician and physicist
Talking to Machines
Formula Translation, or FORTRAN—the first widely accepted
high-level computer language—was completed by John Backus
and his coworkers at the International Business Machines (IBM)
Corporation in April, 1957. Designed to support programming
in a mathematical language that was natural to scientists and engineers,
FORTRAN achieved unsurpassed success in scientific
computation.
Computer languages are means of specifying the instructions
that a computer should execute and the order of those instructions.
Computer languages can be divided into categories of progressively
higher degrees of abstraction. At the lowest level is binary
code, or machine code: Binary digits, or “bits,” specify in
complete detail every instruction that the machine will execute.
This was the only language available in the early days of computers,
when such machines as the ENIAC (Electronic Numerical Integrator
and Calculator) required hand-operated switches and
plugboard connections. All higher levels of language are implemented by having a program translate instructions written in the
higher language into binary machine language (also called “object
code”). High-level languages (also called “programming languages”)
are largely or entirely independent of the underlying
machine structure. FORTRAN was the first language of this type
to win widespread acceptance.
The emergence of machine-independent programming languages
was a gradual process that spanned the first decade of electronic
computation. One of the earliest developments was the invention of
“flowcharts,” or “flow diagrams,” by Herman Heine Goldstine and
John von Neumann in 1947. Flowcharting became the most influential
software methodology during the first twenty years of
computing.
Short Code was the first language to be implemented that contained
some high-level features, such as the ability to use mathematical
equations. The idea came from JohnW. Mauchly, and it was
implemented on the BINAC (Binary Automatic Computer) in 1949
with an “interpreter”; later, it was carried over to the UNIVAC (Universal
Automatic Computer) I. Interpreters are programs that do
not translate commands into a series of object-code instructions; instead,
they directly execute (interpret) those commands. Every time
the interpreter encounters a command, that command must be interpreted
again. “Compilers,” however, convert the entire command
into object code before it is executed.
Much early effort went into creating ways to handle commonly
encountered problems—particularly scientific mathematical
calculations. A number of interpretive languages arose to
support these features. As long as such complex operations had
to be performed by software (computer programs), however, scientific
computation would be relatively slow. Therefore, Backus
lobbied successfully for a direct hardware implementation of these
operations on IBM’s new scientific computer, the 704. Backus then
started the Programming Research Group at IBM in order to develop
a compiler that would allow programs to be written in a
mathematically oriented language rather than a machine-oriented
language. In November of 1954, the group defined an initial version
of FORTRAN.A More Accessible Language
Before FORTRAN was developed, a computer had to perform a
whole series of tasks to make certain types of mathematical calculations.
FORTRAN made it possible for the same calculations to be
performed much more easily. In general, FORTRAN supported constructs
with which scientists were already acquainted, such as functions
and multidimensional arrays. In defining a powerful notation
that was accessible to scientists and engineers, FORTRAN opened
up programming to a much wider community.
Backus’s success in getting the IBM 704’s hardware to support
scientific computation directly, however, posed a major challenge:
Because such computation would be much faster, the object code
produced by FORTRAN would also have to be much faster. The
lower-level compilers preceding FORTRAN produced programs
that were usually five to ten times slower than their hand-coded
counterparts; therefore, efficiency became the primary design objective
for Backus. The highly publicized claims for FORTRAN met
with widespread skepticism among programmers. Much of the
team’s efforts, therefore, went into discovering ways to produce the
most efficient object code.
The efficiency of the compiler produced by Backus, combined
with its clarity and ease of use, guaranteed the system’s success. By
1959, many IBM 704 users programmed exclusively in FORTRAN.
By 1963, virtually every computer manufacturer either had delivered
or had promised a version of FORTRAN.
Incompatibilities among manufacturers were minimized by the
popularity of IBM’s version of FORTRAN; every company wanted
to be able to support IBM programs on its own equipment. Nevertheless,
there was sufficient interest in obtaining a standard for
FORTRAN that the American National Standards Institute adopted
a formal standard for it in 1966. Arevised standard was adopted in
1978, yielding FORTRAN 77.
Consequences
In demonstrating the feasibility of efficient high-level languages,
FORTRAN inaugurated a period of great proliferation of programming languages. Most of these languages attempted to provide similar
or better high-level programming constructs oriented toward a
different, nonscientific programming environment. COBOL, for example,
stands for “Common Business Oriented Language.”
FORTRAN, while remaining the dominant language for scientific
programming, has not found general acceptance among nonscientists.
An IBM project established in 1963 to extend FORTRAN
found the task too unwieldy and instead ended up producing an entirely
different language, PL/I, which was delivered in 1966. In the
beginning, Backus and his coworkers believed that their revolutionary
language would virtually eliminate the burdens of coding and
debugging. Instead, FORTRAN launched software as a field of
study and an industry in its own right.
In addition to stimulating the introduction of new languages,
FORTRAN encouraged the development of operating systems. Programming
languages had already grown into simple operating systems
called “monitors.” Operating systems since then have been
greatly improved so that they support, for example, simultaneously
active programs (multiprogramming) and the networking (combining)
of multiple computers.
The invention: It was long known that low temperatures helped to
protect food against spoiling; the invention that made frozen
food practical was a method of freezing items quickly. Clarence
Birdseye’s quick-freezing technique made possible a revolution
in food preparation, storage, and distribution.
The people behind the invention:
Clarence Birdseye (1886-1956), a scientist and inventor
Donald K. Tressler (1894-1981), a researcher at Cornell
University
Amanda Theodosia Jones (1835-1914), a food-preservation
pioneer
Feeding the Family
In 1917, Clarence Birdseye developed a means of quick-freezing
meat, fish, vegetables, and fruit without substantially changing
their original taste. His system of freezing was called by Fortune
magazine “one of the most exciting and revolutionary ideas in the
history of food.” Birdseye went on to refine and perfect his method
and to promote the frozen foods industry until it became a commercial
success nationwide.
It was during a trip to Labrador, where he worked as a fur trader,
that Birdseye was inspired by this idea. Birdseye’s new wife and
five-week-old baby had accompanied him there. In order to keep
his family well fed, he placed barrels of fresh cabbages in salt water
and then exposed the vegetables to freezing winds. Successful at
preserving vegetables, he went on to freeze a winter’s supply of
ducks, caribou, and rabbit meat.
In the following years, Birdseye experimented with many freezing
techniques. His equipment was crude: an electric fan, ice, and salt
water. His earliest experiments were on fish and rabbits, which he
froze and packed in old candy boxes. By 1924, he had borrowed
money against his life insurance and was lucky enough to find three
partners willing to invest in his new General Seafoods Company (later renamed General Foods), located in Gloucester, Massachusetts.
Although it was Birdseye’s genius that put the principles of
quick-freezing to work, he did not actually invent quick-freezing.
The scientific principles involved had been known for some time.
As early as 1842, a patent for freezing fish had been issued in England.
Nevertheless, the commercial exploitation of the freezing
process could not have happened until the end of the 1800’s, when
mechanical refrigeration was invented. Even then, Birdseye had to
overcome major obstacles.
Finding a Niche
By the 1920’s, there still were few mechanical refrigerators in
American homes. It would take years before adequate facilities for
food freezing and retail distribution would be established across the
United States. By the late 1930’s, frozen foods had, indeed, found its
role in commerce but still could not compete with canned or fresh
foods. Birdseye had to work tirelessly to promote the industry, writing
and delivering numerous lectures and articles to advance its
popularity. His efforts were helped by scientific research conducted
at Cornell University by Donald K. Tressler and by C. R. Fellers of
what was then Massachusetts State College. Also, during World
War II (1939-1945), more Americans began to accept the idea: Rationing,
combined with a shortage of canned foods, contributed to
the demand for frozen foods. The armed forces made large purchases
of these items as well.
General Foods was the first to use a system of extremely rapid
freezing of perishable foods in packages. Under the Birdseye system,
fresh foods, such as berries or lobster, were packaged snugly in convenient
square containers. Then, the packages were pressed between
refrigerated metal plates under pressure at 50 degrees below zero.
Two types of freezing machines were used. The “double belt” freezer
consisted of two metal belts that moved through a 15-meter freezing
tunnel, while a special salt solution was sprayed on the surfaces of
the belts. This double-belt freezer was used only in permanent installations
and was soon replaced by the “multiplate” freezer, which was
portable and required only 11.5 square meters of floor space compared
to the double belt’s 152 square meters.The multiplate freezer also made it possible to apply the technique
of quick-freezing to seasonal crops. People were able to transport
these freezers easily from one harvesting field to another,
where they were used to freeze crops such as peas fresh off the vine.
The handy multiplate freezer consisted of an insulated cabinet
equipped with refrigerated metal plates. Stacked one above the
other, these plates were capable of being opened and closed to receive
food products and to compress them with evenly distributed
pressure. Each aluminum plate had internal passages through which
ammonia flowed and expanded at a temperature of -3.8 degrees
Celsius, thus causing the foods to freeze.
A major benefit of the new frozen foods was that their taste and vitamin content were not lost. Ordinarily, when food is frozen
slowly, ice crystals form, which slowly rupture food cells, thus altering
the taste of the food. With quick-freezing, however, the food
looks, tastes, and smells like fresh food. Quick-freezing also cuts
down on bacteria.
Impact
During the months between one food harvest and the next, humankind
requires trillions of pounds of food to survive. In many
parts of the world, an adequate supply of food is available; elsewhere,
much food goes to waste and many go hungry. Methods of
food preservation such as those developed by Birdseye have done
much to help those who cannot obtain proper fresh foods. Preserving
perishable foods also means that they will be available in
greater quantity and variety all year-round. In all parts of the world,
both tropical and arctic delicacies can be eaten in any season of the
year.
With the rise in popularity of frozen “fast” foods, nutritionists
began to study their effect on the human body. Research has shown
that fresh is the most beneficial. In an industrial nation with many
people, the distribution of fresh commodities is, however, difficult.
It may be many decades before scientists know the long-term effects
on generations raised primarily on frozen foods.
The invention: A method of broadcasting radio signals by modulating
the frequency, rather than the amplitude, of radio waves,
FM radio greatly improved the quality of sound transmission.
The people behind the invention:
Edwin H. Armstrong (1890-1954), the inventor of FM radio
broadcasting
David Sarnoff (1891-1971), the founder of RCA
An Entirely New System
Because early radio broadcasts used amplitude modulation (AM)
to transmit their sounds, they were subject to a sizable amount of interference
and static. Since goodAMreception relies on the amount
of energy transmitted, energy sources in the atmosphere between
the station and the receiver can distort or weaken the original signal.
This is particularly irritating for the transmission of music.
Edwin H. Armstrong provided a solution to this technological
constraint. A graduate of Columbia University, Armstrong made a
significant contribution to the development of radio with his basic
inventions for circuits for AM receivers. (Indeed, the monies Armstrong
received from his earlier inventions financed the development
of the frequency modulation, or FM, system.) Armstrong was
one among many contributors to AM radio. For FM broadcasting,
however, Armstrong must be ranked as the most important inventor.
During the 1920’s, Armstrong established his own research laboratory
in Alpine, New Jersey, across the Hudson River from New
York City. With a small staff of dedicated assistants, he carried out
research on radio circuitry and systems for nearly three decades. At
that time, Armstrong also began to teach electrical engineering at
Columbia University.
From 1928 to 1933, Armstrong worked diligently at his private
laboratory at Columbia University to construct a working model of
an FM radio broadcasting system. With the primitive limitations
then imposed on the state of vacuum tube technology, a number of Armstrong’s experimental circuits required as many as one hundred
tubes. Between July, 1930, and January, 1933, Armstrong filed
four basic FM patent applications. All were granted simultaneously
on December 26, 1933.
Armstrong sought to perfectFMradio broadcasting, not to offer
radio listeners better musical reception but to create an entirely
new radio broadcasting system. On November 5, 1935, Armstrong
made his first public demonstration of FM broadcasting in New
York City to an audience of radio engineers. An amateur station
based in suburban Yonkers, New York, transmitted these first signals.
The scientific world began to consider the advantages and
disadvantages of Armstrong’s system; other laboratories began to
craft their own FM systems.
Corporate Conniving
Because Armstrong had no desire to become a manufacturer or
broadcaster, he approached David Sarnoff, head of the Radio Corporation
of America (RCA). As the owner of the top manufacturer
of radio sets and the top radio broadcasting network, Sarnoff was
interested in all advances of radio technology. Armstrong first demonstrated
FM radio broadcasting for Sarnoff in December, 1933.
This was followed by visits from RCA engineers, who were sufficiently
impressed to recommend to Sarnoff that the company conduct
field tests of the Armstrong system.
In 1934, Armstrong, with the cooperation of RCA, set up a test
transmitter at the top of the Empire State Building, sharing facilities
with the experimental RCAtelevision transmitter. From 1934 through
1935, tests were conducted using the Empire State facility, to mixed
reactions of RCA’s best engineers. AM radio broadcasting already
had a performance record of nearly two decades. The engineers
wondered if this new technology could replace something that had
worked so well.
This less-than-enthusiastic evaluation fueled the skepticism of
RCA lawyers and salespeople. RCA had too much invested in the
AM system, both as a leading manufacturer and as the dominant
owner of the major radio network of the time, the National Broadcasting
Company (NBC). Sarnoff was in no rush to adopt FM. To change systems would risk the millions of dollars RCAwas making
as America emerged from the Great Depression.
In 1935, Sarnoff advised Armstrong that RCA would cease any
further research and development activity in FM radio broadcasting.
(Still, engineers at RCA laboratories continued to work on FM
to protect the corporate patent position.) Sarnoff declared to the
press that his company would push the frontiers of broadcasting by
concentrating on research and development of radio with pictures,
that is, television. As a tangible sign, Sarnoff ordered that Armstrong’s
FM radio broadcasting tower be removed from the top of
the Empire State Building.
Armstrong was outraged. By the mid-1930’s, the development of
FM radio broadcasting had become a mission for Armstrong. For
the remainder of his life, Armstrong devoted his considerable talents
to the promotion of FM radio broadcasting.
Impact
After the break with Sarnoff, Armstrong proceeded with plans to
develop his own FM operation. Allied with two of RCA’s biggest
manufacturing competitors, Zenith and General Electric, Armstrong
pressed ahead. In June of 1936, at a Federal Communications Commission
(FCC) hearing, Armstrong proclaimed that FM broadcasting
was the only static-free, noise-free, and uniform system—both
day and night—available. He argued, correctly, thatAMradio broadcasting
had none of these qualities.
During World War II (1939-1945), Armstrong gave the military
permission to use FM with no compensation. That patriotic gesture
cost Armstrong millions of dollars when the military soon became
all FM. It did, however, expand interest in FM radio broadcasting.
World War II had provided a field test of equipment and use.
By the 1970’s, FM radio broadcasting had grown tremendously.
By 1972, one in three radio listeners tuned into an FM station some
time during the day. Advertisers began to use FM radio stations to
reach the young and affluent audiences that were turning to FM stations
in greater numbers.
By the late 1970’s, FM radio stations were outnumberingAMstations.
By 1980, nearly half of radio listeners tuned into FM stations on a regular basis. Adecade later, FM radio listening accounted for
more than two-thirds of audience time. Armstrong’s predictions
that listeners would prefer the clear, static-free sounds offered by
FM radio broadcasting had come to pass by the mid-1980’s, nearly
fifty years after Armstrong had commenced his struggle to make
FM radio broadcasting a part of commercial radio.
lighting
The invention: A form of electrical lighting that uses a glass tube
coated with phosphor that gives off a cool bluish light and emits
ultraviolet radiation.
The people behind the invention:
Vincenzo Cascariolo (1571-1624), an Italian alchemist and
shoemaker
Heinrich Geissler (1814-1879), a German glassblower
Peter Cooper Hewitt (1861-1921), an American electrical
engineer
Celebrating the “Twelve Greatest Inventors”
On the night of November 23, 1936, more than one thousand industrialists,
patent attorneys, and scientists assembled in the main
ballroom of the Mayflower Hotel in Washington, D.C., to celebrate
the one hundredth anniversary of the U.S. Patent Office.Atransport
liner over the city radioed the names chosen by the Patent Office as
America’s “Twelve Greatest Inventors,” and, as the distinguished
group strained to hear those names, “the room was flooded for a
moment by the most brilliant light yet used to illuminate a space
that size.”
Thus did The New York Times summarize the commercial introduction
of the fluorescent lamp. The twelve inventors present were
Thomas Alva Edison, Robert Fulton, Charles Goodyear, Charles
Hall, Elias Howe, Cyrus Hall McCormick, Ottmar Mergenthaler,
Samuel F. B. Morse, George Westinghouse, Wilbur Wright, and Eli
Whitney. There was, however, no name to bear the honor for inventing
fluorescent lighting. That honor is shared by many who participated
in a very long series of discoveries.
The fluorescent lamp operates as a low-pressure, electric discharge
inside a glass tube that contains a droplet of mercury and a
gas, commonly argon. The inside of the glass tube is coated with
fine particles of phosphor. When electricity is applied to the gas, the
mercury gives off a bluish light and emits ultraviolet radiation.When bathed in the strong ultraviolet radiation emitted by the mercury,
the phosphor fluoresces (emits light).
The setting for the introduction of the fluorescent lamp began at
the beginning of the 1600’s, when Vincenzo Cascariolo, an Italian
shoemaker and alchemist, discovered a substance that gave off a
bluish glow in the dark after exposure to strong sunlight. The fluorescent
substance was apparently barium sulfide and was so unusual
for that time and so valuable that its formulation was kept secret
for a long time. Gradually, however, scholars became aware of
the preparation secrets of the substance and studied it and other luminescent
materials.
Further studies in fluorescent lighting were made by the German
physicist Johann Wilhelm Ritter. He observed the luminescence of
phosphors that were exposed to various “exciting” lights. In 1801,
he noted that some phosphors shone brightly when illuminated by
light that the eye could not see (ultraviolet light). Ritter thus discovered
the ultraviolet region of the light spectrum. The use of phosphors
to transform ultraviolet light into visible light was an important
step in the continuing development of the fluorescent lamp.
Further studies in fluorescent lighting were made by the German
physicist Johann Wilhelm Ritter. He observed the luminescence of
phosphors that were exposed to various “exciting” lights. In 1801,
he noted that some phosphors shone brightly when illuminated by
light that the eye could not see (ultraviolet light). Ritter thus discovered
the ultraviolet region of the light spectrum. The use of phosphors
to transform ultraviolet light into visible light was an important
step in the continuing development of the fluorescent lamp.
The British mathematician and physicist Sir George Gabriel Stokes
studied the phenomenon as well. It was he who, in 1852, termed the
afterglow “fluorescence.”
Geissler Tubes
While these advances were being made, other workers were trying
to produce a practical form of electric light. In 1706, the English
physicist Francis Hauksbee devised an electrostatic generator, which
is used to accelerate charged particles to very high levels of electrical
energy. He then connected the device to a glass “jar,” used a vacuum pump to evacuate the jar to a low pressure, and tested his
generator. In so doing, Hauksbee obtained the first human-made
electrical glow discharge by “capturing lightning” in a jar.
In 1854, Heinrich Geissler, a glassblower and apparatus maker,
opened his shop in Bonn, Germany, to make scientific instruments;
in 1855, he produced a vacuum pump that used liquid mercury as
an evacuation fluid. That same year, Geissler made the first gaseous
conduction lamps while working in collaboration with the German
scientist Julius Plücker. Plücker referred to these lamps as “Geissler
tubes.” Geissler was able to create red light with neon gas filling a
lamp and light of nearly all colors by using certain types of gas
within each of the lamps. Thus, both the neon sign business and the
science of spectroscopy were born.
Geissler tubes were studied extensively by a variety of workers.
At the beginning of the twentieth century, the practical American
engineer Peter Cooper Hewitt put these studies to use by marketing
the first low-pressure mercury vapor lamps. The lamps were quite
successful, although they required high voltage for operation, emitted
an eerie blue-green, and shone dimly by comparison with their
eventual successor, the fluorescent lamp. At about the same time,
systematic studies of phosphors had finally begun.
By the 1920’s, a number of investigators had discovered that the
low-pressure mercury vapor discharge marketed by Hewitt was an
extremely efficient method for producing ultraviolet light, if the
mercury and rare gas pressures were properly adjusted. With a
phosphor to convert the ultraviolet light back to visible light, the
Hewitt lamp made an excellent light source.
Impact
The introduction of fluorescent lighting in 1936 presented the
public with a completely new form of lighting that had enormous
advantages of high efficiency, long life, and relatively low cost.
By 1938, production of fluorescent lamps was well under way. By
April, 1938, four sizes of fluorescent lamps in various colors had
been offered to the public and more than two hundred thousand
lamps had been sold.
During 1939 and 1940, two great expositions—the New York World’s Fair and the San Francisco International Exposition—
helped popularize fluorescent lighting. Thousands of tubular fluorescent
lamps formed a great spiral in the “motor display salon,”
the car showroom of the General Motors exhibit at the New York
World’s Fair. Fluorescent lamps lit the Polish Restaurant and hung
in vertical clusters on the flagpoles along theAvenue of the Flags at
the fair, while two-meter-long, upright fluorescent tubes illuminated
buildings at the San Francisco International Exposition.
When the United States entered World War II (1939-1945), the
demand for efficient factory lighting soared. In 1941, more than
twenty-one million fluorescent lamps were sold. Technical advances
continued to improve the fluorescent lamp. By the 1990’s,
this type of lamp supplied most of the world’s artificial lighting.