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Electric Lighting


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The development of the incandescent electric lightbulb by Thomas Edison changed America. Electric lights made it practical for ordinary families to stay up later, to read, socialize and otherwise conduct their lives.

The flourescent bulb was bulkier but more efficient. Smaller flourescent bulbs have been introduced in recent years.

Light-emitting diodes, or LEDS, have a multitude of computer-related applications because they can be made very small and housed in arrays, requiring relatively little power.


Electric Lighting - History

A H istory of S tage L ighting

Objective for this lesson:

Lighting cues seem to have been written into Greek plays - the festivals played from sunup to sunset, and many of the lines refer to times of day.

The sun was the first major source of lighting instrument, and clouds were the first dimmer (!).

The Romans moved pageants into the Great Halls.

1545:
Sabastiano Serlio -- colored light liquids in bottles (red wine, saffron (yellow), ammonium chloride in a copper vessel (blue).
Brightly-polished barber basin and a round bottle as a lens

3 qualities of light: distribution, intensity, color

1550:
Leone de Somi - full illumination for happy scenes, but tragedy much darker (candles, crude oil lamps, torches, and cressets (hanging lamps).
Stagehands walked around and snipped wicks, the audience was lit
Candles were of tallow and fat

1573:
Inigo Jones (or click here) (English - stage designer) returns from Italy with knowledge of the Proscenium Arch and footlights, and comes up with ideas for masques

1580:
Teatro Olimpico is the first permanent theatre in Italy

1618:
Teatro Farnese (see illustration in text) in Parma - the first theatre with a permanent proscenium arch and curtains

1628:
Joseph Furstenbach
Footlights (floats) and sidelights

1638:
Nicola Sabbatini- writes book on theatre - suggests system of dimmers lowering metal cylinders over the candles
Giacomo da Vignola - ideal lighting angle is along the diagonal of a cube
(1930's - Stanley McCandless writes it in book)

17th century (1600's)
Paris - many chandeliers
Gas becomes used

1783:
Candles ruled the day till the invention in 1783 in France of the kerosene lamp with adjustable wick
Followed closely with a glass chimney - could make individual float lights
Used for 100 years

1791:
Illuminating gas produced in quantity - William Murdock - each building could produce its own
However, gas required constant attention and wasn't easy to control

1803:
Limelight
Invented by Henry Drummond - heating a piece of lime with a flame of oxygen and hydrogen (for a followspot or to indicate sunlight). A green-ish tint.
Was used as the first spotlight in Paris Opera houses

1845:
Drury Lane Theatre is the first to use gas in England)

1809:
Electric Arc -- discovered by Sir Humphry Davy (or here)-- took 90 years to be fully accepted.

1816:
First fully gaslighted theatre -- Chestnut Street Theatre in Philadelphia
Greater control of and more brightness (colorsilk cloth or woven cotton).
Increased heat and many fires caused, and had gas smell and green-ish tint.

1878-1898:
Henry Irving (and click here) (England) initiated lighting rehearsals, transparent lacquers of colored class to limelight with electricity to incandescents, footlights of different colors and broken into sections, and wanted to dim the house lights

1841:
First incandescent lamp patent - Edison - not practical

1846:
The first electric carbon arcs used as spotlights at the Paris opera - inefficient -- not a serious threat to limelight

1879:
The Jablachkoff candle - the first useful lightbulb - "electric candle" - used at Paris Hippodrome - a carbon arc (invented 40-50 years earlier, but limelight was too ingrained, even well into the 1920's.
The first practical electric spotlight

1881:
Savoy Theatre in England - the first completely electric theatre

1882:
A big push - electric theatre at the exposition in Munich, Germany -- with a saltwater dimmer to control the new power source - went like wildfire.

As technology develops and advances at a more rapid rate, so did development of more effective lighting equipment

Edison - first practical lightbulb

Incandescent to tungsten -halogen lamps
Lacquer to gels.

Electric lighting went from the marquee to the outer lobby to the inner lobby to the house to the stage


History of Street Lighting

Lack of natural light during nighttime in the urban environment was always a problem. From basic inconvenience that people cannot see where they are going to the greater chance of being attacked or mugged during the night. Because the problem was there since humans started living together, history of street light is maybe longer than we think.

It is known that natural gas was led through bamboo pipes from volcano gas leaks to the streets of Peking to serve as a fuel for street lamps and that as early as 500 years BC. Ancient Romans used oil lamps filled with vegetable oil in front of their houses and had special slaves whose only duty was to take care of those lamps, to light them, extinguish them and watch that they always have oil. First organized method of public lightning was done on 1417, when Mayor of London, Sir Henry Barton first ordained that by law all houses must hang lanterns outside when night falls during the winter months. Paris street were illuminated first time by order in 1524 that said that all houses must have light in the windows at night if they face the streets. One more method to brighten the streets at nights were “link-boys”, children servants that wealthy citizens of London paid to carry torches while accompanying them through the city (practice that was sometimes dangerous because they sometimes led their costumers into dark alleys to be mugged by footpads).

Era of more efficient street lightning starts with William Murdock who, for the first time in 1802, lit the outside of the Soho Foundry in a public presentation with a gas light fueled with coal gas. After that, in 1807, London got its first gas lit street. Baltimore was the first city in the United States that started using gas for streetlight in 1816 while Paris started gas illumination of its streets in 1820. Gas was led through pipe installations to the gas lanterns that were placed on poles. Every evening the lamplighters, men whose job was to take care of the gas streetlights, were lighting the lanterns and every morning they were putting them off. This was done until the invention of the mechanism that lit the lamps when the gas was released in the lamp. After that came electricity and made street lightening even more efficient.

First electric streetlight used arc lamps, namely “Yablochkov candle”. It was first used in 1878 in Paris. By 1881, some 4000 were in use, replacing gas lanterns on the poles. After the spreading of the arc lamps in the United States, by 1890 there were more than 130,000 arc lamps installed as streetlights. Most of them were installed on the tops of so-called “moonlight towers” - tall, metal constructions that illuminated more city blocks at once. Arc lights had two major flaws: they made strong, harsh light and they did not last long. So in time they were replaced with incandescent lamps that were cheaper, brighter and lasted longer, while arc lamps remained useful on industrial sites. Today, streetlights use high-intensity discharge lamps, mostly HPS high-pressure sodium lamps.


The History of the Light Bulb

More than 150 years ago, inventors began working on a bright idea that would have a dramatic impact on how we use energy in our homes and offices. This invention changed the way we design buildings, increased the length of the average workday and jumpstarted new businesses. It also led to new energy breakthroughs -- from power plants and electric transmission lines to home appliances and electric motors.

Like all great inventions, the light bulb can’t be credited to one inventor. It was a series of small improvements on the ideas of previous inventors that have led to the light bulbs we use in our homes today.

Incandescent Bulbs Light the Way

Long before Thomas Edison patented -- first in 1879 and then a year later in 1880 -- and began commercializing his incandescent light bulb, British inventors were demonstrating that electric light was possible with the arc lamp. In 1835, the first constant electric light was demonstrated, and for the next 40 years, scientists around the world worked on the incandescent lamp, tinkering with the filament (the part of the bulb that produces light when heated by an electrical current) and the bulb’s atmosphere (whether air is vacuumed out of the bulb or it is filled with an inert gas to prevent the filament from oxidizing and burning out). These early bulbs had extremely short lifespans, were too expensive to produce or used too much energy.

When Edison and his researchers at Menlo Park came onto the lighting scene, they focused on improving the filament -- first testing carbon, then platinum, before finally returning to a carbon filament. By October 1879, Edison’s team had produced a light bulb with a carbonized filament of uncoated cotton thread that could last for 14.5 hours. They continued to experiment with the filament until settling on one made from bamboo that gave Edison’s lamps a lifetime of up to 1,200 hours -- this filament became the standard for the Edison bulb for the next 10 years. Edison also made other improvements to the light bulb, including creating a better vacuum pump to fully remove the air from the bulb and developing the Edison screw (what is now the standard socket fittings for light bulbs).

(Historical footnote: One can’t talk about the history of the light bulb without mentioning William Sawyer and Albon Man, who received a U.S. patent for the incandescent lamp, and Joseph Swan, who patented his light bulb in England. There was debate on whether Edison’s light bulb patents infringed on these other inventors’ patents. Eventually Edison’s U.S. lighting company merged with the Thomson-Houston Electric Company -- the company making incandescent bulbs under the Sawyer-Man patent -- to form General Electric, and Edison’s English lighting company merged with Joseph Swan’s company to form Ediswan in England.)

What makes Edison’s contribution to electric lighting so extraordinary is that he didn’t stop with improving the bulb -- he developed a whole suite of inventions that made the use of light bulbs practical. Edison modeled his lighting technology on the existing gas lighting system. In 1882 with the Holborn Viaduct in London, he demonstrated that electricity could be distributed from a centrally located generator through a series of wires and tubes (also called conduits). Simultaneously, he focused on improving the generation of electricity, developing the first commercial power utility called the Pearl Street Station in lower Manhattan. And to track how much electricity each customer was using, Edison developed the first electric meter.

While Edison was working on the whole lighting system, other inventors were continuing to make small advances, improving the filament manufacturing process and the efficiency of the bulb. The next big change in the incandescent bulb came with the invention of the tungsten filament by European inventors in 1904. These new tungsten filament bulbs lasted longer and had a brighter light compared to the carbon filament bulbs. In 1913, Irving Langmuir figured out that placing an inert gas like nitrogen inside the bulb doubled its efficiency. Scientists continued to make improvements over the next 40 years that reduced the cost and increased the efficiency of the incandescent bulb. But by the 1950s, researchers still had only figured out how to convert about 10 percent of the energy the incandescent bulb used into light and began to focus their energy on other lighting solutions.

Energy Shortages Lead to Fluorescent Breakthroughs

In the 19th century, two Germans -- glassblower Heinrich Geissler and physician Julius Plücker -- discovered that they could produce light by removing almost all of the air from a long glass tube and passing an electrical current through it, an invention that became known as the Geissler tube. A type of discharge lamp, these lights didn’t gain popularity until the early 20th century when researchers began looking for a way to improve lighting efficiency. Discharge lamps became the basis of many lighting technologies, including neon lights, low-pressure sodium lamps (the type used in outdoor lighting such as streetlamps) and fluorescent lights.

Both Thomas Edison and Nikola Tesla experimented with fluorescent lamps in the 1890s, but neither ever commercially produced them. Instead, it was Peter Cooper Hewitt’s breakthrough in the early 1900s that became one of the precursors to the fluorescent lamp. Hewitt created a blue-green light by passing an electric current through mercury vapor and incorporating a ballast (a device connected to the light bulb that regulates the flow of current through the tube). While the Cooper Hewitt lamps were more efficient than incandescent bulbs, they had few suitable uses because of the color of the light.

By the late 1920s and early 1930s, European researchers were doing experiments with neon tubes coated with phosphors (a material that absorbs ultraviolet light and converts the invisible light into useful white light). These findings sparked fluorescent lamp research programs in the U.S., and by the mid and late 1930s, American lighting companies were demonstrating fluorescent lights to the U.S. Navy and at the 1939 New York World’s Fair. These lights lasted longer and were about three times more efficient than incandescent bulbs. The need for energy-efficient lighting American war plants led to the rapid adoption of fluorescents, and by 1951, more light in the U.S. was being produced by linear fluorescent lamps.

It was another energy shortage -- the 1973 oil crisis -- that caused lighting engineers to develop a fluorescent bulb that could be used in residential applications. In 1974, researchers at Sylvania started investigating how they could miniaturize the ballast and tuck it into the lamp. While they developed a patent for their bulb, they couldn’t find a way to produce it feasibly. Two years later in 1976, Edward Hammer at General Electric figured out how to bend the fluorescent tube into a spiral shape, creating the first compact fluorescent light (CFL). Like Sylvania, General Electric shelved this design because the new machinery needed to mass-produce these lights was too expensive.

Early CFLs hit the market in the mid-1980s at retail prices of $25-35, but prices could vary widely by region because of the different promotions carried out by utility companies. Consumers pointed to the high price as their number one obstacle in purchasing CFLs. There were other problems -- many CFLs of 1990 were big and bulky, they didn’t fit well into fixtures, and they had low light output and inconsistent performance. Since the 1990s, improvements in CFL performance, price, efficiency (they use about 75 percent less energy than incandescents) and lifetime (they last about 10 times longer) have made them a viable option for both renters and homeowners. Nearly 30 years after CFLs were first introduced on the market, an ENERGY STAR® CFL costs as little as $1.74 per bulb when purchased in a four-pack.

LEDs: The Future is Here

One of the fastest developing lighting technologies today is the light-emitting diode (or LED). A type of solid-state lighting, LEDs use a semiconductor to convert electricity into light, are often small in area (less than 1 square millimeter) and emit light in a specific direction, reducing the need for reflectors and diffusers that can trap light.

They are also the most efficient lights on the market. Also called luminous efficacy, a light bulb’s efficiency is a measure of emitted light (lumens) divided by power it draws (watts). A bulb that is 100 percent efficient at converting energy into light would have an efficacy of 683 lm/W. To put this in context, a 60- to 100-watt incandescent bulb has an efficacy of 15 lm/W, an equivalent CFL has an efficacy of 73 lm/W, and current LED-based replacement bulbs on the market range from 70-120 lm/W with an average efficacy of 85 lm/W.

In 1962 while working for General Electric, Nick Holonyak, Jr., invented the first visible-spectrum LED in the form of red diodes. Pale yellow and green diodes were invented next. As companies continued to improve red diodes and their manufacturing, they began appeari


Electric Lighting - History

Early Delco-Light salesmen had to first sell the very concept of electric power to many farmers before talking about the Delco-Light system. The phrase "Delco-Light Sells Best at Night" was a popular and successful motto for many salesmen who would install a temporary demonstrator system that would be ready for operation just after dusk. Electric lights would illuminate the home while the salesmen made a pot of coffee with an electric coffee pot. The salesman, who was all the time working on closing the deal, might even offer to help with evening chores where he could also conveniently point out the many possible applications and benefits of Delco-Light around the farm.

High compression gasoline engines powered the first Delco-Light plants, however insurance regulations at the time prohibited having over one gallon of gasoline inside a home. In order to circumvent this issue light plants were simply ran on kerosene that was readily available on most farms. Running them on kerosene caused them to knock terribly leaving inventor Charles Kettering no choice but to reduce the compression thus reducing power. This posed a problem that Kettering was determined to solve. His research lead to the development of Ethel gasoline in 1923.


History

February 10, 1916: Acceptance of Honorary Membership by Thomas Alva Edison presented by John Lieb, an associate of Edison, with Mrs. Edison attending.

Most of the men who were the organizers, founders and early members of the Illuminating Engineering Society were born as the American Civil War was ending, or not long after. Their parents raised families in a society transformed by war. Most of the men involved came from Northern families and so with the post-war prosperity were able to obtain good educations. Louis B. Marks, for example, was educated at City College of New York and at Cornell, Louis Bell at Dartmouth and Van Rensselaer Lansingh at the Massachusetts Institute of Technology. They had among the best of the technical educations that could be acquired in the U.S. at the end of the 19th century.

For many, their entry into business and professional practice was marked by the Panic of 1893 and the serious economic depression that followed. Sparked by a run on treasury gold and the failure of the Philadelphia and Reading Railroad, there was wide-spread panic. Bank failures resulted, followed by other railroad bankruptcies and stock price collapses. The resulting economic depression lasted more than five years it was by far the most serious financial crisis to have hit the U.S. up to that time, and the lighting industry was not above this turmoil.

But recovery began near the end of the decade. One mark of this was the increase in construction activity. By the turn of the century, many major American cities were in the midst of a construction boom that would transform urban skylines and many industries—lighting among them.

1900-1905

Lighting in the five years just before the founding of the Illuminating Engineering Society was provided by technologies as varied as would ever be available. Depending on locale, construction and availability, any of these lighting sources might be found in use:

  • Kerosene lighting
  • Gas lighting
  • Incandescent gas lighting with mantles
  • Arc lighting
  • Flame-arc lighting
  • Incandescent electric lighting
  • Moore tube discharge lighting
  • Cooper-Hewitt mercury-vapor discharge lighting
  • Acetylene lighting

The competition between gas lighting and electric incandescent lighting was fierce and produced improvements that had fueled the see-saw of dominance for 20 years. It was not clear at the time what would become the dominant form of “artificial light” and the question of the most efficacious and economical source was far from settled. But as competitive as other forms of lighting were, incandescent electric lighting was growing the fastest. In 1905, 40 million incandescent lamps were sold in the U.S., and the total spent on electric lighting for the year was greater than $120 million.

This state of lighting technology meant that the men involved in lighting needed to have a command of and experience with a wide range of technologies.

At the turn of the 20th century, electricity was provided by so called central stations: buildings housing dynamos powered by steam engines and the necessary gear to control the electric power. Central stations owned the wiring that distributed the electric power and sold the final electric appliances to customers that used the electricity. The first central station in the U.S. was built in San Francisco in 1879 and powered the Brush arc lighting system. Companies owned central stations and were usually given an exclusive license by a manufacturer of lighting equipment for a territory. Lamps were not purchased from manufacturers they were not available from retailers or wholesalers. Lamps were sold by the major lamp manufacturers almost exclusively to central station operators.

The group that founded the Society and helped it flourish consisted of men from five areas of lighting. The men who operated central stations and those who worked for the lamp manufacturers constituted two groups of professionals involved in lighting.

Gas companies had been shocked into renovating their product and service as the competition from electric lighting grew. The men of these companies formed a third, entirely separate group involved in lighting.

A fourth group was those that worked for the many companies that manufactured lighting appliances. The Holophane Glass Company and its licensees made the refractive glass globes that had become widely used and critically important to electric lighting. Metal reflectors made by companies such as the Federal Electric Company, Benjamin Electric Manufacturing Company, and I. P. Frink, were even more widely used. A few men from companies that made combination fixtures—a gas burner and a socket for an incandescent lamp—were also involved.

The fifth and certainly smallest group was consultants and designers of lighting systems, academics and other scientists. Not surprisingly, these were among the most instrumental in founding the Society. The most prominent men in this group were Louis Marks, Louis Bell, Norman Macbeth, Clayton Sharp and Herbert Ives.

The professional societies most having to do with lighting at that time were the American Institute of Electrical Engineers and the American Gas Light Association. In many ways their inattention to lighting prompted the perceived need for a professional organization devoted exclusively to lighting. Both groups had been distracted by the tremendous growth in their industries—growth in areas other than lighting—and lighting was not getting leadership from either organization. A bellwether of this was the inability of either group to agree on a single standard of luminous intensity to be used in photometry.

First Meeting and Officers

In October of 1905, Louis Marks, then an independent consultant, contacted his colleague Van Rensselaer Lansingh at the Holophane Glass Company about forming a new society devoted to lighting. Their conversations eventually included E. Leavenworth Elliott who was about to begin publishing what he called “a technical journal devoted to the use of artificial light,” The Illuminating Engineer. They wanted to determine whether there was enough interest to form such a society, and so from Lansingh’s Holophane office the three issued the following letter to about 30 men in New York City and the surrounding area that they knew were interested in lighting. Responses were to be directed to Marks.

227 Fulton Street.
New York,
December 13, 1905.

Dear Sir:-
It has been proposed to form a Society of Illuminating Engineers, composed of those people who are especially interested in the question of light and its distribution. For this purpose, the undersigned have asked a number of those most prominently interested in such questions to meet at the Hotel Astor, 44th Street and Broadway, this city, on Thursday evening, December 21, at 6:30 o’clock, to talk over the formation of such a society and to discuss whatever is necessary to accomplish this purpose. We trust you will be able to attend this meeting and would ask that you kindly let Mr. L. B. Marks, 202 Broadway, New York City, know beforehand so that arrangements for an informal dinner may be made. The price of this dinner will be $1.00 each.

Trusting that we may have the pleasure of meeting you at that time, we are,

Very truly yours,
L. B. Marks,
E. Leavenworth Elliott,
Van Rensselaer Lansingh.

P.S.-The dinner will be purely informal and business suits will be in order.

Among the list of those contacted were Prof. Charles P. Matthews Prof. Edward L. Nichols Proctor Dougherty Albert Spies John W. Lieb and W.D. Weaver.

Charles P. Matthews was teaching at Purdue University and was very active in photometry, having developed one of the first flux integrators. He had published extensively on lighting topics and his interest in a new organization would have been natural.

Prof. Edward L. Nichols had been one of Marks’ instructors while he was at Cornell University earning his master’s degree. He was a nationally recognized leader in physics and an important figure in electrical engineering and lighting. His status and influence made him an obvious person to invite. Though Nichols was unable to attend the meeting, he was enthusiastic.

Lansingh knew Proctor Dougherty from his days at MIT and Dougherty’s connection with the federal government must have been considered promising.

The response from Albert Spies, editor of The Electrical Age, was measured but supportive.

At the time of Mark’s invitation, John W. Lieb was an important veteran of electric incandescent lighting, president of the American Institute of Electrical Engineers, the most famous central station engineer in the lighting industry and immensely influential. He would become vice president and general manager of the New York Edison Company. Lieb had been sent to Milan, Italy, to oversee the technical aspects of establishing Edison Central Stations. Lieb stayed 10 years, becoming well known throughout Europe. He returned in 1894 to work in the New York Edison Company. Lieb was enthusiastic but was aware of potential political problems.

The response from W.D. Weaver, editor of Electrical Word, was considerably more measured and reserved than any other arguing that it was premature to form a new organization, and describing several political problems that would likely arise should a new organization be formed. Weaver predicted a turf war between the American Institute of Electrical Engineers and any new organization that promoted the idea that specialists should be doing the lighting work that was then be done by electrical engineers. As it happened, though his letter stated he would not be able to attend, he did attend—indicating perhaps the importance of the development.

Twenty-five men gathered at the Astor Hotel in response to the invitation of Marks, Elliott and Lansingh. At that meeting, called to order by Lansingh, Marks’s position as instigator and leader was recognized and he was elected as temporary chairman. Elliott was elected to serve as temporary secretary. This later appointment was fortunate, for the details about this and subsequent meetings appeared in Elliott’s The Illuminating Engineer. Marks stated that the purpose of the meeting should be to determine the object of the proposed society and its relation to what he referred to as “its sister institution, the American Institute of Electrical Engineers.”

That there was a need for a new organization appears to have been obvious to all present. Three of the response letters that Marks received talked of a movement to establish illuminating engineering. The “Illuminating Engineering Movement” would soon become something that professionals discussed and later historians recognized. Work that was clearly recognized as illuminating engineering—separate from electrical engineering—was growing and all indications were that growth would be maintained. W. D’Arcy Ryan, one of the meeting’s attendees, stated:

“Five years ago it was almost impossible for a consulting illuminating engineer to get into an architect’s office. Three years ago the work had increased to such an extent that I was obliged to drop all other work and follow illuminating engineering exclusively. I have now six assistant engineers and every one of us is on the go…”

The most difficult question discussed that evening was the matter of the organization’s name. Not everyone was convinced that it should contain the word “engineer”—the thought being that it was elite and would antagonize the American Institute of Electrical Engineers. Elliott and Otis Mygatt, founder of the Holophane Glass Company, argued that part of the purpose of the new organization was to further the movement to establish lighting specialists—illuminating engineers—and the name of the organization should reflect that.

The meeting ended with all present agreeing that a Committee on Organization, consisting of seven of those present, would draft a constitution and by-laws and propose a name for the new organization. Evidently, everyone involved considered the matter of establishing a new organization appropriate and timely, not needing a great deal of research: the committee was to have its report ready in two weeks and the next meeting was scheduled to take place at that time.

On Wednesday evening, January 10, 1906, at the Hotel Astor, another meeting was convened “to complete the formation of a society devoted to the Science and Art of Illumination.” The report of the Committee on Organization was read and adopted without change. The contents had evidently been vetted by many interested parties and changes made before the meeting. Officers were then elected: L.B. Marks president, A.A. Pope and C.H. Sharp vice presidents, V.R. Lansingh treasurer and E.L. Elliott secretary. Tellingly, Marks was elected by acclamation, while the other offices had several candidates and required balloting. In addition to officers, a board of managers was also elected: W.D. Weaver, A.H. Elliott. W.S. Kellogg, E.C. Brown, F.N. Olcott and W. D’Arcy Ryan. The meeting ended with the agreement that the next meeting would take place on Tuesday evening, February 13, again at the Astor Hotel.

First Meeting, First Year

Original IES 1906 Insignia

The meeting scheduled for February 13, 1906 took place at the Hotel Astor and was the first full technical meeting of the Illuminating Engineering Society. In the intervening month, more than 150 members were enrolled in the new organization, and interest in establishing branches in other American cities was immediate.

At this meeting L.B. Marks delivered his presidential address, outlining “the present state of the science and art of illumination,” the scope of the new Society, its aims and objects, and the relation of the new society to other organizations. Marks summary of the present state of lighting focused on two issues: the problem of discomfort glare and providing better value for the consumer’s dollar. On discomfort glare he noted that:

“Though much attention has recently been given to the subject of globes, shades and reflectors, the fact still remains that unshaded or inadequately shaded lamps are the rule rather than the exception. In considering the present status of the science and art of illumination there is perhaps no question that is in need of more immediate attention than this one. The practice of placing lights of excessive intrinsic brightness within the ordinary field of vision is so common as to cause great apprehension among those who have studied the question from a physiological point of view that our eyesight is suffering permanent injury.”

Marks had done research with current U.S. Census Reports, Union Carbide (Acetylene) and Standard Oil, and listed the following consumer costs of lighting for 1905:

  • Electric light $120 million
  • Coal and water gas $40 million
  • Natural gas $1.7 million
  • Acetylene $2.5 million
  • Oil $60 million

The total, about $220 million, was probably an underestimate. About the scope of the society, Marks noted that:

“The term ‘engineering,’ as used in the name of this Society, unless viewed in its broad sense, is to a certain extent a misnomer, as the Society will deal with some phases of illumination that may not properly be said to come within the distinct field of engineering, such for instance as the physiological side of the question. The Society will be interested in every phase of the subject of illumination whether from an engineering point of view or otherwise, and will throw its doors quite as wide open to the layman as to the professional. It will not, however, deal with questions relating to the production or distribution of the energy from which the light produced.”

The discussion of Marks presidential address was long and detailed. Those present included representatives from all sectors of the lighting industry: electric and gas suppliers, equipment manufacturers, consultants and academics. Enthusiasm arose from every corner. The meeting and its participants drew the attention of the press. The following morning an editorial appeared in the New York Tribune entitled The Art of Lighting.

On January 28, 1907, the headquarters was moved from the temporary space that had been provided by the Holophane Glass Company, to an office in the Engineering Societies’ Building, at 29 West 39th Street. The first annual meeting was held on January 7, 1907. By then the organization had established itself nationally, with sections in New England, Chicago, Pittsburgh, Philadelphia and New York. Membership stood at 815 at the time of that first anniversary meeting and the first year’s budget had been $4000.

The Society began publishing immediately. Volume 1, Number 1 of the Transactions of the Illuminating Engineering Society appeared in February 1906. In the 11 months of its first publication year, the Society printed more than 400 pages of technical presentations and discussions dealing with all aspects of lighting. It has done so continuously for 100 years.


History of Electricity

Affordable, reliable electricity is fundamental to modern life. Electricity provides clean, safe light around the clock, it cools our homes on hot summer days (and heats many of them in winter), and it quietly breathes life into the digital world we tap into with our smartphones and computers. Although hundreds of millions of Americans plug into the electric grid every day, most of us don’t give the history of electricity a second thought. Where does it come from? What’s its story?

When we take a fresh look at electricity, we see that keeping America powered up is actually an amazing feat—an everyday miracle. Here’s the Story of Electricity.

Revolutionary Power

Although people have known about electricity since ancient times, they’ve only been harnessing its power for about 250 years. Benjamin Franklin’s electricity experiments – including his famous kite experiment in 1752 – showed just how little we knew about electricity in the era of the American revolution and the first industrial revolution.[1] In the time since Franklin’s experiments, our grasp of electricity has grown tremendously, and we are constantly finding new ways to use it to improve our lives.

Ben Franklin’s famous kite experiment

One of the first major breakthroughs in electricity occurred in 1831, when British scientist Michael Faraday discovered the basic principles of electricity generation.[2] Building on the experiments of Franklin and others, he observed that he could create or “induce” electric current by moving magnets inside coils of copper wire. The discovery of electromagnetic induction revolutionized how we use energy. In fact, Faraday’s process is used in modern power production, although today’s power plants produce much stronger currents on a much larger scale than Faraday’s hand-held device.

In the era of modern power plants, coal has always generated more electricity in the U.S. than any other fuel source. In recent decades, we have seen other sources compete for second place: first hydroelectricity, then natural gas, nuclear power, and natural gas again.

Electricity generation mix by fuel type, 1949-2011

We also use electricity to power an increasing number of devices. Our modern electric world began with applications like the telegraph, light bulb, and telephone, and continued with radio, television, and many household appliances. Most recently, electrons have powered the digital age to create what energy expert Vaclav Smil calls our “instantaneously interconnected global civilization.”[3] Technology expert Mark Mills points out that electricity powers an increasing portion of our economy. The always-on data centers that support the internet and “cloud computing” will continue to increase demand for electricity, overwhelming the modest decreases in electricity use in other parts of the economy, such as manufacturing processes.[4][5]

The ever-growing applications of electricity explain the increasing use of fuels like natural gas, oil, and coal in power generation as opposed to direct uses such as heating or transportation. In 1900, for example, less than two percent of natural gas, oil, and coal were used to make electricity. A century later, 30 percent of our use of natural gas, oil, and coal was devoted to electric power.[6] Smil explains electricity’s appeal: “Electricity is the preferred form of energy because of its high efficiency, instant and effortless access, perfect and easily adjustable flow, cleanliness, and silence at the point of use.”[7]

Increased electricity access has lit corners of the world that were once dark. As international development groups and economists point out, access to electricity is a hallmark of advanced societies and a basic requirement for economic progress.[8] “Next to the increasing importance of hydrocarbons as sources of energy,” economist Erich Zimmermann wrote in 1951, “the rise of electricity is the most characteristic feature of the so-called second industrial revolution.”[9] In recent years, people in countries from China to Kenya have experienced rising living standards, as more people are able to use electricity to keep their homes and schools cool during torrid summers, to refrigerate food that would have otherwise spoiled, and to purify water that would have otherwise been unsafe to drink.

There is, of course, still much more to be done. In 2009, the International Energy Agency estimated that nearly 70 percent of people in Sub-Saharan Africa lacked access to electricity. That means 585.2 million people remain in the dark.[10]

Many parts of the world remain in the dark.

The Dawn of Electric Light in the U.S.

One of the greatest pioneers in electricity was Thomas Edison, who saw electricity as his “field of fields” to “reorganize the life of the world.” Working tirelessly on electricity from his laboratory in New Jersey in the 1870s, America’s greatest inventor brought the incandescent electric light bulb into practical use by the end of that decade and patented the incandescent light bulb in 1880.[11] “When Edison…snatched up the spark of Prometheus in his little pear-shaped glass bulb, ”German historian Emil Ludwig observed, “it meant that fire had been discovered for the second time, that mankind had been delivered again from the curse of night.”[12] Yet Edison’s electric light was even better than fire—it was brighter, more consistent, and safer than the flame of candles or lamps.

Edison’s light bulb was one of the first applications of electricity to modern life. He initially worked with J. P. Morgan and a few privileged customers in New York City in the 1880s to light their homes, pairing his new incandescent bulbs with small generators. Edison’s electric lighting systems were basic by today’s standards but bold at the time—they not only threatened the existing gas lighting industry but radically challenged the status quo by introducing people to an entirely new type of energy. In a few short years, Edison transformed electricity from a science experiment into an exciting, safe, and coveted luxury.

The light bulb—a symbol of innovation and the invention that sparked the electricity revolution.

The Rise of an Industry

In order for the magic of electricity to truly take hold in American life, new industries were needed to build the generators to supply electric power, as well as the new appliances and electric lights that used it. In 1882, with J.P. Morgan funding his efforts, Edison launched the businesses that would later be known as General Electric. In September of that year, he opened the United States’ first central power plant in lower Manhattan—the Pearl Street Station.

Pearl Street was a stroke of genius. Edison connected a large bank of generators to homes and businesses (including the New York Times) in the immediate area through a network of buried copper wires. At that time, there was no “electric grid.” Before Pearl Street, customers who wanted power for electric lights or motors relied on generators located on-site, typically in the basement. Pearl Street’s “central” power plant design was an important shift from small-scale, on-site generation to industrial-scale power, and soon became the model for the entire power generation industry.[13]

The Dynamo Room at the Pearl Street Station, the first power plant in the U.S.

Enter Samuel Insull

Although Edison was a brilliant inventor, he was a disorganized businessman. His inventions came to him faster than the financial capital necessary to carry them out, and Edison preferred to focus on the inventions themselves rather than the paperwork they created. The inventor needed a managerial counterpart. That counterpart arrived in 1881, in the form of a promising 21-year-old from England. Samuel Insull, who began his career in the U.S. as a personal assistant to Edison, astounded the inventor with his business prowess—so much so that Edison soon granted Insull power of attorney over his businesses.[14] But the work with Edison would be just the beginning for Insull—over the next four decades, he built an electricity business that made him the Henry Ford of the modern electricity industry.

Electricity required a different business model because it was different than virtually every other commodity. Electricity had to be consumed the moment it was produced. (Storage was very costly and limited—and still is.) In order for electricity to become accessible and affordable, someone needed to bring together mass efficiencies in production and consumption. Insull saw the opportunities in front of him. Whoever mastered the engineering and the economics of the power grid could take the reins of the rising electricity industry—an industry that was already toppling the stocks of gas light companies and attracting big investors like J.P. Morgan. In 1892, Insull left his job as an executive at the lighting company Edison started (General Electric near New York City) for Chicago Edison (an electricity generation/distribution company, later known as Commonwealth Edison).[15] It was a move that would indelibly change the industry.

Early transmission lines in rural America. Photo Credit: Towers

Insull Builds the Modern Power Grid

Insull was able to achieve what economists call “economies of scale” (cost savings from large-scale operations) by consolidating the mom-and-pop electricity providers and closing small generators in favor of larger, more efficient units manufactured by General Electric. He also found efficiencies in customer sales—the more customers he had, the more efficiently he could run his generators, and the cheaper it was to provide power. As Insull’s business grew, he was able to find better ways of providing electricity to more and more people.

1903 turbine hall at Fisk Street Station

Insull became a master salesman for all things electric. In order to use his generators more efficiently (i.e., run them at full capacity for more hours of the day), he offered to power elevators and streetcars during the daytime when there was less demand for electric lighting.

Insull also used high-voltage transmission lines to spread electricity to the suburbs and then to the countryside. Because customers inside and outside cities used power at different times, Insull was able to provide power to both types of customers more efficiently than if he had served them independently. Such diversification, served by ever-larger and more efficient generators, brought the price of a kilowatt-hour down. Electricity prices fell year after year as the young industry grew between 1902 to 1930.


Insull also created new electricity pricing schemes. For example, he introduced two-part pricing to handle customers whose electricity use fluctuated widely or spiked for brief periods. Given that electricity has to be produced and consumed simultaneously, providing power to a customer who demanded electricity in large surges could be unprofitable—new generators built to meet the intermittent surges in demand would only run a fraction of the time, but would have to remain constantly at the ready. Examples of customers that have “peaky” demand[16] include metal-smelting factories that use huge amounts of power in brief bursts to run electric furnaces.

To be able to provide power for “peaky” customers, Insull implemented a demand charge (a fixed fee) in addition to the typical usage charge. That way, the customer paid for the privilege to use a lot of electricity in a little time. In this way, Insull could profitably expand his business to include all types of customers.

Lastly, Insull found efficiencies by interconnecting or “networking” power grids for backup and reliability, eliminating the need to build (redundant) generation in the same service area.

Consolidation. Mass production. Mass consumption. Rural electrification. Two-part pricing. Networked power. Samuel Insull did for electricity what Henry Ford did for the automobile—he turned a luxury product into an affordable part of everyday life for millions of Americans. Where Edison provided the novelty of electric light to Manhattan’s upper class, Insull’s innovations made electricity accessible to all.

Electricity Becomes Politicized

The electricity industry in the U.S. was intertwined with politics from the beginning. Before Pearl Street ever opened, Edison had to bribe New York politicians just to begin laying the foundations of his work. As Time magazine recounts, Edison “obtained with great difficulty the consent of New York’s famously corrupt city government to build his proposed network on the southern tip of Manhattan. (He got their approval in part by plying them with a lavish champagne dinner at Menlo Park catered by Delmonico’s, then New York’s finest restaurant.)”[17] As the early electricity industry grew, it became more involved with city politics over lighting contracts. Electricity providers had to receive franchise rights from city officials in order to serve local areas, opening the door for those officials to extort power companies for campaign contributions or personal bribes.


Early on, electricity pioneers faced two populist threats from local governments. One was rate ordinances that could arbitrarily require rate rollbacks or impose rate ceilings, thus ruining profitability. The second was municipalization, whereby private investments in electricity infrastructure would be taken over by city or county government.[18] This was the political environment that Samuel Insull found in Chicago and other electricity entrepreneurs faced across the country.

Insull’s solution was new legislation that would replace local regulation with statewide regulation of power companies by public utility commissions (modeled after state railroad commissions). In this arrangement, the state commissions would establish a maximum rate for the power company to charge its customers based on the company’s cost of providing electric service (plus a reasonable rate of return).

In exchange for such rate regulation, the state commissions gave the power company an exclusive franchise to serve a given geographical area (a legal monopoly). The early electricity industry was a natural monopoly (according to many economists and regulators, and Insull himself) which turned out to be a self-fulfilling prophecy: state regulators assumed power companies were bound to be monopolies, so they regulated them accordingly and gave them legal monopoly status. The prospect of a true, laissez-faire electricity market was never on the table.

Insull needed time and a huge public relations effort to convince the industry that statewide public utility regulation was the best way to provide low-cost power and dodge harsh local regulation or takeover. Wisconsin and New York were the first states to extend state-level rate regulation to the electricity industry in 1907. By 1914, forty-three other states had followed suit and created state-level commissions to oversee electric utilities.[19]

These state public utility commissions, formed in the early 20 th century, still regulate utilities. In theory, their rate regulation is supposed to protect the consumer, but in practice it often benefits other interest groups—or the utilities themselves—at the expense of consumers. Despite these regulations, Insull continued to provide inexpensive power to a greater number of customers through the first three decades of the 20 th century.

Tragically, the Great Depression financially ruined Insull’s expanding enterprises. His indebted holding company collapsed and legal battles ensued. Facing trial in 1934, he was quoted in newspapers as saying “I am fighting not only for freedom but for complete vindication. I have erred, but my greatest error was in underestimating the effects of the financial panic on American securities, and particularly on the companies I was trying to build. I worked with all my energy to save those companies.”[20]

Insull was acquitted but lost his companies and wealth, and fell into disrepute and obscurity. Public knowledge of his contributions as a pioneer of the modern power grid seems to have died along with him in 1938. As Forrest McDonald wrote of the acquittal in Insull’s biography, “For his fifty-three years of labor to make electric power universally cheap and abundant, Insull had his reward from a grateful people: He was allowed to die outside prison.”[21]

State regulation and Insull’s tragic fall ultimately led to federal intervention into electricity beyond hydroelectric licensing, the founding job of the Federal Power Commission (est. 1920.) In 1935, the Federal Power Act authorized the Federal Power Commission—now the Federal Energy Regulatory Commission (FERC)—to apply “just and reasonable” cost-based rate regulation to the wholesale power market (along the same lines as state-level regulation of retail rates). Another law, the Public Utility Holding Company Act of 1935, required multi-state companies to divest properties to operate in only one state.[22]

Federal intervention grew again in the energy-troubled 1970s. The Public Utility Regulatory Policies Act of 1978 required electric utilities to buy power from independent generators, successfully creating a new industry segment but also opening the door for intermittent generation from renewable sources to enter—and even destabilize—the growing grid. 23] In fear of using up limited energy and natural resources, Congress also passed new legislation designed to curb electricity use and promote environmental goals. New agencies such as the Environmental Protection Agency (1970) and the Department of Energy (1977) were created to regulate different aspects of electricity, including generation from coal-burning power plants.

In the 1990s, federal regulation of electricity shifted towards a market-based approach.[24] Deregulation had proven beneficial in reducing the cost and improving the quality of tightly regulated areas like the airline industry, and regulators were interested in bringing the same benefits to the electricity industry.

In 1996, FERC attempted to restructure the industry by imposing an “open access” model[25] on utilities.[26] FERC’s intent was to “remove impediments to competition in the wholesale bulk power marketplace.” Despite FERC’s focus on competition, electricity transmission remains heavily regulated. Hence, the “deregulation” of electricity in the 1990s was in fact “re-regulation.” Wholesale electricity markets continue to evolve, with market forces and federal regulations colliding at each step.

Currently, the electric power sector faces an unprecedented amount of federal intervention from several different agencies. Some of the most active are the Environmental Protection Agency (EPA), FERC, and the Department of Energy.[27]

The EPA proposed a new rule in 2014 to limit carbon dioxide emissions from existing power plants. The rule threatens to close a large portion of the reliable coal-fired electricity supply in the U.S. As a result, the rule will undercut power companies’ ability to meet electricity demand safely and reliably.[28] The EPA rule also comes at huge cost to American families and businesses that use electricity every day—by 2030, the rule is estimated to increase electricity bills by a combined $290 billion.[29]

FERC, with its mandate to ensure just and reasonable wholesale rates, has long been involved in every aspect of wholesale electricity markets. In 2005, it received increased authority from Congress to further regulate the reliability of the power grid, and to oversee wholesale electricity markets. Recent FERC rules favoring renewable sources of electricity have made the agency more political than ever before and raised its profile. Conflicts over FERC leadership—between Congress, the White House, and policy and industry groups—reached a fever pitch in 2013 and 2014 with two nominees to chair the agency being denied the job by Congress.

Meanwhile, the Department of Energy has also encouraged renewable sources of electricity through its national laboratories and essentially banned the use of certain technologies—such as the familiar incandescent light bulb—by establishing energy efficiency mandates. In short, nearly every aspect of electricity is now heavily regulated by multiple federal agencies.

A Powerful Vision

Electricity remains a growth industry today, in spite of political meddling at the local, state, and federal level. New vistas for electricity will always be there for people to discover, but that discovery will require the freedom to inspire new inventions. Let the next generation of electricity entrepreneurs be driven—like Edison and Insull—by the productive forces of human ingenuity and healthy competition.

Electricity is modern life. Without access to reliable power, our lives would be much more like they were before the industrial revolution (to quote Thomas Hobbes): “solitary, poor, nasty, brutish, and short.”[30] Nearly every feature of modern civilization depends on affordable, reliable electricity and the things it powers—lamps and heaters to safely keep our homes well-lit and comfortable, smart phones to stay in touch with loved ones, and always-on data centers to give us a reliable Internet—among countless others. It is so crucial to modern life, in fact, that the history of electricity is really the history of the modern world.


Electric Lighting - History

February 13th, 2007 | Author: Administrator

1752 By tying a key onto a kite string during a storm, Ben Franklin , proved that static electricity and lightning were the same. His correct understanding of the nature of electricity paved the way for the future.

1800 First electric battery invented by Alessandro Volta. The “volt” is named in his honor.

1808 Humphry Davy invented the first effective “arc lamp.” The arc lamp was a piece of carbon that glowed when attached to a battery by wires.

1820 Separate experiments by Hans Christian Oersted, A.M. Ampere, and D.F.G. Arago confirmed the relationship between electricity and magnetism.

1821 The first electric motor was invented by Michael Faraday.

1826 Georg Ohm defined the relationship between power, voltage, current and resistance in “Ohms Law.”

1831 Using his invention the induction ring, Michael Faraday proved that electricity can be induced (made) by changes in an electromagnetic field. Faraday’s experiments about how electric current works, led to the understanding of electrical transformers and motors.
Joseph Henry separately discovered the principle of electromagnetic induction but didn’t publish his work. He also described an electric motor.

1832 Using Faraday’s principles, Hippolyte Pixii built the first “dynamo,” an electric generator capable of delivering power for industry. Pixxi’s dynamo used a crank to rotate a magnet around a a piece of iron wrapped with wire. Because this devise used a coil of wire, it produced spikes of electric current followed by no current.

1835 Joseph Henry invented the electrical relay, used to send electrical currents long distances.

1837 Thomas Davenport invented the electric motor, an invention that is used in most electrical appliances today.

1839 Sir William Robert Grove developed the first fuel cell, a device that produces electrical energy by combining hydrogen and oxygen.

1841 James Prescott Joule showed that energy is conserved in electrical circuits involving current flow, thermal heating, and chemical transformations. A unit of thermal energy, the Joule, was named after him.

1844 Samuel Morse invented the electric telegraph, a machine that could send messages long distances across wire.
1860’s Mathematical theory of electromagnetic fields published. J.C. Maxwell created a new era of physics when he unified magnetism, electricity and light. Maxwell’s four laws of electrodynamics (“Maxwell’s Equations”) eventually led to electric power, radios, and television.

1876 Charles Brush invented the “open coil” dynamo (or generator) that could produce a study current of electricity.

1878 Joseph Swan, and Englishman, invented the first incandescent lightbulb (also called an “electric lamp”). His lightbulb burned out quickly.
Charles Brush developed an arc lamp that could be powered by a generator.
Thomas Edison founded the Edison Electric Light Co. (US), in New York City. He bought a number of patents related to electric lighting and began experiments to develop a practical, long-lasting light bulb.

1879 After many experiments, Thomas Edison invented an incandescent light bulb that could be used for about 40 hours without burning out. By 1880 his bulbs could be used for 1200 hours.

1879 Electric lights (Brush arc lamps) were first used for public street lighting, in Cleveland, Ohio.
California Electric Light Company, Inc. in San Fransicso was the first electric company to sell electricity to customers. The company used two small Brush generators to power 21 Brush arc light lamps.

1881 The electric streetcar was invented by E.W. v. Siemens

1882 Thomas Edison opened th Pearl Street Power Station in New York City. The Pearl Street Station was one of the world’s first central electric power plants and could power 5,000 lights. The Pearl Street Station was a direct current (DC) power system, unlike the power systems that we use today which use alternating current (AC).
The first hydroelectric station opened in Wisconsin.
Edward Johnson first put electric lights on a Christmas tree.

1883 Nikola Tesla invented the “Tesla coil”, a transformer that changes electricity from low voltage to high voltage making it easier to transport over long distances. The transformer was an important part of Tesla’s alternating current (AC) system, still used to deliver electricity today.

1884 Nikola Tesla invented the electric alternator, an electric generator that produces alternating current (AC). Until this time electricity had been generated using direct current (DC) from batteries. AC electrical systems are better for sending electricity over long distances.
Steam turbine generator, capable of generating huge amounts of electricity, was invented by Sir Charles Algernon Parsons.

1886 William Stanley developed the induction coil transformer and an alternating current electric system.

1888 Nikola Tesla demonstrated the first “polyphase” alternating current (AC) electrical system. His AC system including everything needed for electricity production and use: generator, transformers, transmission system, motor (used in appliances) and lights. George Westinghouse, the head of Westinghouse Electric Company, bought the patent rights to the AC system.
The first use of a large windmill to generate electricity was built by inventor Charles Brush. He used the windmill to charge batteries in the cellar of his home in Cleveland, Ohio.

1893 The Westinghouse Electric Company used an alternating current (AC) system to light the Chicago World’s Fair.

A 22 mile AC powerline was opened, sending electricity from Folsom Powerhouse in California to Sacramento.

1896 An AC powerline that transmits power 20 miles from Niagra Falls to Buffalo, New York was opened.

1897 Electron discovered by Joseph John Thomson.

1900 Highest voltage transmission line 60 Kilovolt.

1901 First power line between USA and Canada at Niagra Falls.

1902 5-Megawatt turbine for Fisk St. Station (Chicago).

1903 First successful gas turbine (France).
World’s first all turbine station (Chicago).
Shawinigan Water & Power installs world’s largest generator (5,000 Watts) and world’s largest and highest voltage line—136 Km and 50 Kilovolts (to Montreal).

1908 Electric vacuum cleaner – J. Spangler.
Electric washing machine- A. Fisher.

1909 First pumped storage plant (Switzerland).

1911 Electric air conditioning – W. Carrier.

1913 T. Murray created the first air pollution control device, the “cinder catcher.”
Electric refrigerator – A. Goss.

1920 Federal Power Commission (FPC).

1921 Lakeside Power Plant in Wisconsin becomes the world’s first power plant to burn only pulverized coal.

1922 Connecticut Valley Power Exchange (CONVEX) starts, pioneering interconnection between utilities.

1923 Photoelectric cells were discovered.

1928 Construction of Boulder Dam begins.
Federal Trade Commission begins investigation of holding companies.

1933 Tennessee Valley Authority (TVA) established.

1935 Public Utility Holding Company Act.
Federal Power Act.
Securities and Exchange Commission.
Bonneville Power Administration.
First night baseball game in major leagues (Reds vs. Phillies) was played in Ohio on May 24th.

1936 Highest steam temperature reaches 900 degrees Fahrenheit vs. 600 degrees Fahrenheit in early 1920s.
Boulder (Hoover) Dam was completed. A 287 Kilovolt power line stretched 266 miles to Boulder (Hoover) Dam.
Rural Electrification Act.

1947 Transistor invented by scientists at Bell Telephone Laboratiories.

1953 First 345 Kilovolt transmission line.
First nuclear power station ordered in England.

1954 World’s first nuclear power plant (Russia) started generating electricity.
First high voltage direct current (HVDC) line (20 megawatts/1900 Kilovolts, 96 Km).
Atomic Energy Act of 1954 allows private ownership of nuclear reactors.


Electric Lighting - History

Competition to Edison's Lamp

"If you want to succeed, get some enemies."
(Edison, as quoted in the Ladies Home Journal , April 1898).

Successful inventions spawn competition which, in turn, often stimulates new inventions. Edison's lighting system was no exception and competitors very quickly introduced similar products. Some copied what he had done others used their own inventive talent to create new ideas and new devices. The competition provoked controversy and a great deal of activity.

By 1891 there were over 1,300 incandescent lighting central stations in the United States with a capacity of approximately three million lamps. Towns and cities across the country competed with each other for the privilege of being the first in their area to gain access to the new technology.

Developed in England in the 1790s, gas light technology spread quickly. In 1816 gas streetlights went into service in Baltimore, and by the time of Edison's 1879 lamp invention, gas lighting was a mature, well-established industry. The gas infrastructure was in place, franchises had been granted, and manufacturing facilities for both gas and equipment were in profitable operation. Perhaps as important, people had grown accustomed to the idea of lighting with gas.

Edison consciously modeled his plans for an electric lighting system on the gas light technology. Instead of gas-making plants, he designed generators. Where pipes ran under the streets distributing gas to end users, he planned to place electrical "mains" (conductors) to carry current. Since people were able to have gas lamps in many rooms and control them individually, Edison intended his lamps to be capable of independent operation.

Even before Edison demonstrated a working lamp, gas stocks began to fall in price. In late 1879 he and his men began making detailed cost studies of gas light in order to determine price goals that the electric light would have to meet. After the lamp invention, promotions for the Edison system duly reported deaths and injuries due to gas.

Despite nightmares like the one depicted above, gas manufacturers responded to the challenge with two major advances. The first was better quality gas. The second was an incandescent mantle invented by Carl Auer von Welsbach of Austria (who later invented the first commercial metal filament light bulb). Both innovations resulted in more brighter, more efficient light.

Gas proved a tough competitor since infrastructure already existed, whereas electric light could not be used until generating plants were built and wires were strung. Also, gas could be used for heating and cooking as well as light. In 1910, GE's William Coolidge invented a tungsten-filament lamp capable of giving 10 lumens per watt. That invention, combined with the growing level of electrification in the country effectively eliminated competition from gas lighting.

Edison was neither the first nor the only person trying to invent an incandescent electric lamp. In the U.S., Moses Farmer, William Sawyer and Albon Man, and Hiram Maxim were all pursuing the goal, as were St. George Lane-Fox and Joseph Swan in England.

Swan demonstrated a working lamp of the design seen to the left in several early 1879 lectures. But his lamp (like those of the other contenders) used a carbon rod of relatively low electrical resistance. It was practical only if used in series (where the current flowed successively through several lamps that would turn and off together) or if it was close to the power supply (so that the lead wires would be short).

Swan had experimented with carbonized paper filaments for some years, however. Once he learned that a high resistance filament was needed, he quickly adapted it to his own lamps and established the Swan Electric Light Company. It should be noted that Swan had been granted several patents for various lamp features before Edison's breakthrough. Indeed Swan's patent position in England was strong enough that in mid-1882 a merger was arranged and the Edison & Swan United Company ("Ediswan") was formed.

Hiram Maxim also quickly produced a lamp containing a high-resistance filament in 1880. One of the reasons Maxim was able to introduce a product so fast was that he had hired Ludwig Boehm (Edison's glassblower) away from Menlo Park earlier that year. Maxim soon moved on to other inventions (such as machine guns), but the United States Electric Lighting Company installed systems that used the Maxim lamp for several years. The company was purchased by George Westinghouse in 1888.

The company Elihu Thomson and Edwin Houston established in 1880 to sell arc lamp systems became quite successful and diversified into other electrical markets. In 1886 they purchased the Sawyer & Man Electric Co. and began making incandescent lamps under the Sawyer-Man patents. By 1890, Edison, Thomson-Houston, and Westinghouse were the "Big 3" of the American lighting industry. In 1892, J. Pierpont Morgan engineered a merger between the Edison interests and Thomson-Houston. The resulting company was named General Electric.

George Westinghouse's initial fame stemmed from his invention of an air-brake that vastly improved railroad safety. In the 1880s he too diversified into electrical equipment and then into electric lamps. At the time he bought U.S. Electric Lighting Co. and began making lamps, the company was being sued by Edison for patent infringement. In 1892 the courts decided in Edison's favor and forced Westinghouse to stop production. However, Westinghouse had obtained rights to the Sawyer-Man patents and quickly retooled to make non-infringing lamps based on those patents. He produced these "Stopper lamps" until Edison's patents expired in 1897.

Critical to any electrical system is the ability to measure at any moment the flow of electricity (the current) and the force on it (voltage). These techniques were well known, and it was a relatively simple matter to design instruments that could deal with the relatively high flow in lighting circuits (like the Elihu Thomson voltmeter shown here). For a commercial enterprise, it was also important to know how much energy the customer was using. Edison designed a chemical meter in which a portion of the current being supplied caused metal to be deposited on an electrode. The electrode could then be weighed to give a measure of the energy consumed. Later electromagnetic meters registered watt-hours directly by measuring the product of voltage and current over time.

Both alternating and direct current had been used for arc lights, and both could be used for incandescent lamps. However, in the early 1880s motors could function effectively only on DC. There was an expectation that electricity could be stored in batteries during off-peak hours, and this was possible only with DC. Finally, there was evidence that at the same voltages AC was more dangerous than DC. All of this led Edison to prefer a DC system.

An important advantage for AC became apparent with the invention of the transformer in 1883. This meant that the voltage from an AC generator could be efficiently increased for transmission and then decreased at the other end for use in the home or factory. (Electrical energy is proportional to voltage times current, so that boosting the voltage means that the same amount of energy can be transmitted with less current flow. Since heat produced in the line is a function of the current and the resistance, so with less current the loses are less.) For short lines (of a mile or so) this made little difference. But for long distances it would be critical.

The Westinghouse and Thomson-Houston companies preferred AC, and their faith was justified when Nikola Tesla invented a practical AC motor in 1888 (an early example is shown in the picture). Additional Tesla polyphase patents made AC systems more efficient. These patents were used by Westinghouse at Niagara Falls in 1895.


Thomas Davenport (1802–1851), a blacksmith from Brandon, Vermont, built a road-worthy electric car in 1835. Twelve years later U.S. electrical engineer Moses Farmer (1820–1893) exhibited an electric-driven locomotive. In 1851, Massachusetts inventor Charles Grafton Page (1712–1868) drove an electric car on the tracks of the Baltimore and Ohio Railroad, from Washington to Bladensburg, at the rate of nineteen miles an hour.

However, the cost of batteries was too great at the time and the use of the electric motor in transportation not yet practical.


Electric Lighting - History

The First Form of Electric Light
History of the Carbon Arc Lamp
(1800 - 1980s)
All credits and sources are located at the bottom of each lighting page

Introduction & Statistics Design Variations

How They Work

Timeline

Inventors and Developments

Modern Day Ancestor: Xenon Arc Lamp

T he carbon arc lamp was the first widely-used type of electric light and the first commercially successful form of electric lamp.

Unlike the rest of the types of lighting described in our Electric Lighting pages, the arc light's development had to coincide with basic power generation developments. As batteries, generators and power conditioning technology developed arc lamps could be made more sophisticated. The carbon rod was often replaced by magnetite (iron ore) for longer life by 1905. The carbon arc lamp led to other arc discharge lamps like the mercury vapor, sodium and fluorescent lamps. Today the lamp has been replaced by the xenon short-arc lamp.

Left : Two arc lamps: single and double arc lamp designed by Elihu Thomson and E.W. Rice for the Thomson-Houston Electric Company 1880s

Carbon Arc Lamp:
Advantages:
-Super bright light, capable of lighting a large length of street or a large factory interior
-Was the ONLY electric light available to light large areas from 1800 - 1901
-Was cheaper to light streets with the arc lamp than gas or oil lamps

Disadvantages:
-Carbon rods had to be replaced after a short period of time, this became a full time job in a city
-Produces dangerous UV-A, UV-B, and UV-C rays
-Created a buzzing sound and flickering as the light burned
-Created large amounts of RFI (radio frequency interference)
-Dangerous: it was a fire hazard, many theaters burned as a result of the excessive heat or sparks emitted, also the unenclosed lamp could easily electrocute or severally burn technicians.
-Carbon Monoxide emissions (bad for indoor use!) It only worked in the past because buildings were poorly insulated and fresh air could enter. Some of today's energy efficient buildings are almost air tight.

Statistics
*Lumens per watt: 2 - 7 (best rating is for an enclosed lamp)
*Lamp life (life of carbon rods): 75 hrs average (1890s)
175 hrs (1911)
600 hrs (magnetite electrode)
Life depends on the length of the electrode (hrs per inch was used)
*CRI NA
*Color Temperature: NA
Warm up time: instant on

Common uses: outdoor lighting: street lighting, trolley route lighting, film and slide projector lamps, indoor factory and mill lighting, retail shop lighting and palace/ballroom lighting, search lights, spot lights

Below: 4 Minute Video on the Carbon Arc Lamp. Youtube must be accessible on your internet server for this to work.

1.) How it Works:

The lamp is a spark or electric arc through the air between two carbon rods. The rods must have a gap in between of the right size. If the gap is too big than the arc will flicker more or may go out, if the gap is to narrow than it will produce less light.

The first carbon was made of charcoal (made from wood). The carbon substance is vaporized in the high temperature of the arc (around 6500 F, 3600 C). The carbon vapor is highly luminous (very bright) and this is why we use carbon in the lamp. This light is much more useful and bright than that of an arc between steel like in the Jacobs Ladder example photo below. The carbon vapor and normal air ionizes easily which helps make light. When the atoms of the carbon and air ionize it means they give up and take on electrons. This happens as electric current passes from one electrode (in this case one of the carbon rods) to the other electrode. Lighting ionizes the air that is passes through.

Below: A Jacobs Ladder, a common science teaching toy shows the electric arc through air. The arc is not very bright compared to a carbon arc lamp. The study of the behavior of the electric arc through gas is covered in the field of plasma physics.

Sparks, Mercury, Containment and Buckyballs

The carbon arc lamp once lit produces a useful bright light, however undesirable aspects exist. The lamp produces hot sparks and buckyballs which can and have caused fires. Early arc lamps used in department stores were a concern because hot sparks would randomly fall to the floor, on people, or on merchandise. The lamp also produces UV-A, UV-B, and UV-C light which are harmful to both the eyes and skin. Early arc lamp makers didn't know about UV light yet, but did realize that diffusing the light made for better quality light.

Early arc lamp inventors created glass globes to fit around the lamp. Some globes were made of opal glass to diffuse the light and the silica glass blocked some of the harmful UV rays. Early globes often had an open top to allow heat to escape (see the various designs near the bottom of this page here). These protective globes are not to be confused with the "enclosed carbon arc".

The enclosed carbon arc was an arc lamp which completely enclosed the electrodes. The upper electrode was fed through a hole in the top. This enclosed lamp prevented oxygen from easily reaching the arc. With less available oxygen the arc burned slower and the lamp life was greatly improved.

The Mercury Arc: Some early visionaries discovered that by adding mercury into the enclosed arc lamp a green light was created. This was an early predecessor to the mercury vapor lamp. When the hot lamp struck it vaporized the mercury stuck to the inside of the bulb, this helped produce better light with a higher efficiency. The mercury arc was not popular and did not take over the market because it had an ugly greenish color. It did get used as a germicidal lamp due to its increased UV emission. We do not call this a "mercury vapor lamp", the "mercury vapor lamp" as we know today uses a sealed low or high pressure bulb/tube and the two electrodes are made of metal or tungsten, not carbon sticks. We have a separate page for this more advanced type of lamp here.

Buckyballs are made of Carbon-20 through 60. Buckyballs are giant molecules which border on being a 'solid' not a small particle. These large molecules behave strangely compared to normal molecules. There are up to 240 electrons total, they act collectively when excited and oscillate back and forth forming a surface plasmon. They are created in natural soot and charcoal which is part of the process of making the carbon rods for the lamp.

Mind the Gap :
One issue with the carbon arc lamp is that the rods of carbon are burned away over time. Therefore if you have two carbon rods firmly mounted the gap will grow bigger between as the carbon rod itself is vaporized. Eventually the arc will cease when the gap gets large enough. The solution to this problem in the first experimental lamps was to use insulated pliers and slide the rods close again as it burned.

To make a commercial product (which is a central issue in all of our lighting pages) inventors and engineers have to design a system that is RELIABLE. While scientists can do experiments and observations with handmade prototypes, it is up to the engineer to labor over ways to make a lamp useful (in other words reliable and easy to use/maintain) to the masses . This is difference between scientists and engineers.

In the carbon arc lamp inventors had to figure out a mechanical way to feed carbons into the device as it burned up. Control Engineering was used to figure out a way to sense the current and voltage draw of the lamp (which changes as the gap gets bigger) and control a set of magnets and devices that would keep the gap size constant and lamp working for hours.

Lamps in the 1870s and before used clockwork type feeding devices - gears, clutches and works by slowly feeding the carbons. Engineers at the Thomson-Houston Company figured out how to use a differential system which worked better than the early Brush clutch systems. Feeding devices for arc lamps are a large subject.


Above Left
: A lit arc lamp from the 1880s as was used in urban lighting and factories. Photo by Michael Spadafora

Components of the early arc light system:

A Controlling Magnet developed by Elihu Thomson

Thomson's dynamo for sale in the 1880s, used in Philadelphia

The arc lamp is not used today, however it is extremely important due to its role in history. So we have more material here than on the other lamp types.

The first installations were small ( 1-12 lights). The first installation was the lighting of the Mill of Heilmann, Ducommun, and Steinlein at Mulhausen, France (1875). Another installation was the lighting of La Chapelle railway station (France). Paris holds the record for the first street lighting in 1875. The Thames Embankment (London) was lit in 1878 (Using Jablochoff Candles). Despite these installations a lot of work needed to be done. Understanding of electric power was crude, and there was no way to measure power, or adequately control power systems to get more performance.

In 1878 Lord Armstrong installs the first residencial electrical lighting at Cragside House in Northumberland, England. The house also was probably the first home with a dedicated hydroelectric power house. Learn more about it here.

First Installations in North America:

Charles F. Brush developed the first commercially successful arc light systems in North America in Cleveland, OH (at Public Square 4/29/1879). His design of arc light AND dynamo (a dynamo generates DC power) was proven to be the best of several experimental systems by different inventors at an exposition at the Franklin Institute in Philadelphia in 1977. This event also inspired E.W. Rice Jr., Edwin J. Houston, and Elihu Thomson to create arc light systems of their own. When Thomas Edison traveled through Ohio, he was inspired by Brush's arc light work and he initiated his own electric light work. Brush improved not only the ability to add more lights to the circuit, but developed the Brush Dynamo. This dynamo was a monumental achievement in power generation.

The Electric Light's first commercial success, and happier whales.

In 1880 authorities in Wabash, Indiana discover that the Brush electric arc light system for it's streets would cost $800 less per year than gas lighting. Also they stated that they would get greater volume of illumination. This was the beginning of the revolution across the world to switch to the electric light. By proving to be economically better than oil and gas the future was set. This also stopped the complete eradication of certain whale species that provided the oil, these whales were already close to extinction in the 1880's due to over-hunting.

Gas used in lights was made from coal. The coal was shipped to cities, and cooked in a crucible, a gas resulted that supplied the town's light systems. This process was very dirty, it produced massive amounts of carbon monoxide and a coke remains that was then shipped out for other uses as dirty combustible fuel. The electric arc light eliminated the need for plants that produced urban localized pollution.

The Thomson-Houston Company

Elihu Thomson founded the Thomson-Houston Electric Company which later absorbed the Brush Electric Company. E. W. Rice Jr. helped develop a voltage regulation system along with Thomson's lighting arrestor system, these combine with Brush's work made the most successful arc light system in the world. You can see the documentary on this early period of history via our E.W. Rice documentary.

Growth of the Electric Light:

1890 - There were more than 130,000 arc lamps in use in the United States.

Today the evidence of the great number of carbon arc lamps is mostly gone. Most of the bodies of the lamps were melted down for scrap for World War 1.

The carbon arc lamp is the root of more than 50% of all electric lamps today as you can see in the diagram below, however it took almost 70 years to get a reliable carbon arc lamp out of the developmental stage.



1705 - Francis Hauksbee (France) builds a gas discharge lamp using an evacuated glass tube charged with static electricity. The tube glowed faintly.
1800 - Volta (Italy) develops the first battery in the western world, this immediately sparks a period of testing of electricity and discovery from Russia to England.

1800 - Vasily Petrov (Russia) first publicly describes the phenomena of the electric arc. The year of this is not yet confirmed.

1800 or 1809 - Sir Humphry Davy (England) - used charcoal sticks and batteries to make the first experimental arc lamp, the year of this is under debate.
1840s - Jean Bernard Leon Foucault developed mechanisms for feeding carbon rods to make an arc light last longer.
1844 - first major public demonstration of an arc lamp in Paris
1875 - Pavel Yablochkov - Yablochkov Candle, a form of arc lamp is developed, this lamp is reliable and uses two carbon sticks side by side, which solves the problem of figuring out how to keep the gap constant despite the burning away of carbon. Mechanical feeds were not sophisticated enough yet to be reliable. The first street lights are installed in Paris. The arc lamp enters the commercial stage.
1876 - Charles F. Brush, Wallace, Gramme - developed more advanced arc light designs and dynamos to go with it.
1877 -Charles F. Brush develops a better carbon stick by using 0.03% ash and electroplating the rods with copper to slow the stick's consumption.
1875 - Avenue de l'Opera is lit in Paris by Jablochkoff candles
1878 - Lord Armstrong installs what may be the first electric home lighting
1879 - Brush makes the first public lighting in the US at the Wanamakers department store in Philadelphia.
1879 - Brush developed the "Brush System" in which he could run a number of lights in series. Prior to this systems had one or a few lights. Inventors couldn't understand why electricity changed its properties by adding more lights, Brush understood the drop in voltage and current although he still had no way to measure electricity. It was later in the 1880s the importance of measurement allowed for better and more complex electrical devices.
1879 - William Wallace improves the life of the carbon rod with a design using copper and other ingredients.
1879 - Niagara Falls first lit by the electric light with 16 Brush arc lamps.
1879 - Elihu Thomson built a system that could handle up to 9 arc lamps in series with 10 Amps of current.

1880s
- Elihu Thomson, Thomas Edison, Frantisek Krizik, Nikola Tesla, E.W. Rice - all improved the arc lamp by improving the carbon composition, mechanical feed device, and other components.
1890s - After the end of the War of Currents at Frankfurt, Germany in 1891, AC systems were built across the world from Argentina to Sweden within 10 years. Arc Lamps were adapted to run off of 110 and 220 Volt systems.
1904 - Charles P. Steinmetz improves the lamp by replacing the carbon electrode with magnetite, a type of iron ore. Lamp life shoots to 600 hrs or 30 hrs per inch of electrode. At the same time carbon rods only had a max life of 125 hours (for the average carbon rod refill length)
1915 - Elmer Ambrose Sperry develops a carbon arc spot light, first used in Navel applications .

1900-1980s - The carbon arc light is used for intense spot lights and some projectors, and is mostly replaced by xenon and metal halide lamps. The newer lamps are superior in that they do not give off open sparks due to having their arcs placed in a glass envelope, and they do not burn up quickly as the carbon sticks used in carbon arc lamps.

The many types of arc lamps offered by Charles Brush, taken from his company catalogue

C.) Applications

The carbon arc lamp was first used for street and factory lighting due to its extreme brightness which could easily flood a large area. It was used in early film production but proved to be dangerous to the actors. The arc lamp was used a projector light source for some time. This light did cause fires in theaters due to the open sparks.
The carbon arc lamp was replaced by the incandescent lamp starting in the 1880's. It was still used for street and factory lighting into the early 1900's. Elmer Ambrose Sperry developed a spotlight which was used by NAVY ships in 1915.

Most of the hundreds of thousands of arc lamps and fixtures were scrapped for World War I. Some fixtures that remained in factories were gutted out and had sockets placed in them for the Mazda incandescent bulb.

The End of the Carbon Arc Lamp Era

Carbon arc lamps were being phased out after the 1910s. For general lighting the lamp was replaced by the 1920s and 30s in most cities. The lamp continued to be used for spot lights, film production lighting and film projector lamps. Most of the remaining carbon arc lamps ceased production by the 1980s due to the improved performance of the bright short-arc xenon and metal halide short-arc lamps. The new gas discharge lamps use a glass/quartz bulb filled with a nobel gas and other additives, they had longer life and more efficient than the carbon arc lamp. In the new lamps gas is ionized and free electrons smash into the additives (like metal halide) giving off photons with the same or better quality white light.

The carbon arc lamp still exists in an extremely limited application. It is used for a color fastness test of textiles. The lamps are part of testing machines that use the lamp to make UV light in a controlled environment. See one of these machines as part of the this list at Shinyei Corporation.

1800 Vasily V. Petrov discovers and demonstrates the carbon arc. Both Petrov and Davy used simple systems attached to primitive batteries.
Russia

1840s Jean Bernard Leon Foucault develops a mechanical feed device for the carbon rod, this is an important step towards a functional, commercial product. France

1875 Pavel Yablochkov had developed the Yablochkov Candle which was the first reliable carbon arc lamp and was used in Paris. He also developed power regulation systems, developed multi-lamp AC power circuits, and was the first commercial success in electric lighting. See his invention above. Russia/France

1879 William Wallace develops a copper plated carbon electrode and carbon doped with certain materials, his work resulted in a longer lasting carbon, he was one of many who were working on extending carbon life by adding materials to the carbon composition.
Connecticut, USA

1879 Charles F. Brush develops every part of the electrical system from new lamps to better dynamos (DC) and power conditioning. He becomes a commercial success with many installations in US cities.
Cleveland, OH, USA

1870s-1890s E.W. Rice Jr worked with Elihu Thomson, improving many parts of the arc light system both in DC and AC power.
Schenectady, NY, USA

1904 Charles P. Steinmetz develops an arc lamp with magnetite electrodes. This extends lamp life from 125 to 600 hours while only sacrificing a small amount of brightness. This meant that arc lamps needed to be "trimmed" (carbon replacement) with the same frequency as incandescent bulbs of the time. Later Steinmetz also invented the metal halide lamp.
Schenectady, NY, USA

1915 Elmer A. Sperry developed a high intensity spotlight up to 2 billion candlepower. Sperry's spotlights became vital for naval and air warfare during WWI and WWII.
Schenectady, NY, USA

Great engineer and arc lamp innovator Elihu Thomson mentions a few other names of important developers: Wallace Farmer, Weston, Wood, Hochhausen, and William Stanley who developed Westinghouse's arc lamp knowledge.

There are MANY others who helped develop the carbon arc lamp in many nations of Europe and North America between 1805 - 1915. Above we have listed the most prominent names, even so it was difficult to choose. History is a complex matter, the deeper you dig, the more ambiguity you find. If your interested in getting more detail about the fascinating history of the arc lamp we recommend book: A History of Electric Light and Power by B. Bowers and Men and Volts by John Hammond

The Xenon Short-Arc Lamp

The carbon arc lamp was replaced by the xenon short-arc lamp for many applications. The lamp makes an arc through ionized xenon gas in a very high pressure bulb. The high pressure give the lamp high efficiency. The light is highly intense and close in frequency to that of sunlight.The xenon arc lamp has the advantage over carbon arc lamps in that it does not need to be supplied with anything(like the rods), it does not flicker, it is more compact, and is less of a fire hazard because of having the arc enclosed.

The lamp is not safe for technicians, the extremely high pressure (440 psi / 3040 kPa) makes it similar to a small grenade if broken. Glass and metal shrapnel have killed and injured people who dropped or ruptured the lamps on installation. Injuries extend to the less-than-intelligent playing with the lamps (see the carnage here on youtube).

Ratings: 900 W - 15 kW
Materials: Tungsten, molybdenum, ultra pure synthetic fused silica (Suprasil), Invar alloy
Inventor: please contact us if you know

History:

The lamp was invented in the 40s and was in commercial use by the 1950s as a film projector lamp. The lamp was developed by Osram. If you know the inventor/s of this bulb and have a photo please let us honor them by contacting us.

Above : a large xenon arc lamp used in modern Imax projectors. Photo: Atlant

Right: A small xenon short arc bulb within plastic protective housing. Instructions say do not remove the housing until after the lamp is installed.

See another video of different sized xenon short arc lamps here (this video is not an Edison Tech Center video so the resolution/quality is limited).


Watch the video: Ηλεκτρικό μηχανικό κρεβάτι Manuthera E 3 (July 2022).


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