Thomas A. Edison earned his reputation as one of America’s greatest inventors and heroes. Full of innovation, ingenuity, and enterprise, Edison “embodie[d] much of what Americans have felt was positive about the national experience. ” Edison can put claim to 1093 US patents in addition to thousands more international patents. His works include such major contributions as advancements in telegraphy, the phonograph, a perfected nickel-iron-alkaline battery, and the first commercially successful incandescent lighting system. As shown by his many patents, Edison not only contributed innovative technologies to society, but he was also a successful entrepreneur. Edison’s success with the incandescent light was not only one of his greatest achievements, but also one of man’s greatest achievements. Edison began tinkering with the notion of incandescence in 1876 up to 1878, when he dedicated his efforts to produce an economical electric light. He combined both his stunning intellect with his spirit for hard work to produce some of the world’s greatest inventions. Finally in 1879, after nearly four years of tedious work, Edison’s first success came about with the use of a carbonized cotton thread.
Born on February 11, 1847 to Samuel and Nancy Edison, Thomas spent the first seven years of his life in Milan, Ohio, his place of birth. In 1854, opportunity took the Edison family to Port Huron, Michigan, a city twice the size of Milan. Edison’s formal education ended after only three months of private schooling; he “responded poorly to the regimented atmosphere of the school,” which caused some to see Edison as a “problem child. ” However, Edison’s mother, a former school teacher, began educating Thomas at home. Edison credits some of his creativity to his non-formal education, claiming that formal education, “cast ‘the brain into a mould’ and ‘[did] not encourage original thought or reasoning,’ laying ‘more stress on memory than on observation.’ “. Early on, Nancy provided Edison with physical science and chemistry books, from which he would experiment. This set in motion Edison’s interest and fascination with the scientific and inventive processes. At the age of twelve, Edison began his work as a railroad concessionist, selling newspapers and snacks on trains. During his breaks, Edison would experiment in the baggage cars, one of which he later set on fire.
The Term Paper on On 341 After Great Pain A Formal Feeling Comes
Clean th Brooks and Robert Penn Warren ["After great pain, a formal feeling comes"] is obviously an attempt to communicate to the reader the nature of the experience which comes "after great pain." The poet is using the imagery for this purpose, and the first line of the poem, which states the subject of the poem, is the only abstract statement in the poem. The pain is obviously not a physical ...
Edison’s shift in career to telegraphy was a fortunate event for him. “One day he saved a boy’s life and in gratitude the father taught Edison how to become a telegraph operator. ” Later, Edison migrated to New York and found himself in a high paying job for having repaired a broken stock ticker machine during a financial crisis. In 1869, Edison swore to move from being a simple operator to a scientific inventor, and later, he sold an improved stock ticker, which allowed him to open a workshop in New Jersey to become a full-time inventor. “The laboratory was a forerunner of today’s modern research facility, and itself was a great invention. ” Here, Edison improved the typewriter, making it possible for the first time to type faster than could be written by hand. And in 1876, Edison moved to the famous Menlo Park in New Jersey, where one of his first inventions included an improved telephone with a carbon transmitter so people would no longer need to shout into the phone. Over the next six years, Edison and the Menlo Park team produced more than 400 patents. One such major invention includes the phonograph, Edison’s personal favorite and “one of the most original inventions ever devised “, which he again later improved for commercial use.
The Essay on The Electric Light
On October 22, 1879 Thomas Edison created the electric light or what we know of it today as the light bulb. To make a statement like this that Thomas Edison invented the light bulb is both a huge hyperbole and a huge understatement all at the same time. A more correct view is that he perfected a practical light bulb and that his real plan and accomplishment was the invention of an electrical ...
He was trying to find a way to record telegraph messages automatically with the application of a paraffin-coated paper tape, embossed by a stylus with dots and dashes. The tape made a similar sound to human speach, and so Edison attempted to connect a telephone diaphragm to the embossing needle. In his first demonstration, Edison recited “Mary Had A Little Lamb,” which the phonograph was perfectly able to reproduce. With the ability to record, the phonograph led to the development of the music industry today. This invention earned Edison the nickname, “The Wizard of Menlo Park”. While the Wizard’s earliest hopes for the phonograph focused on education and business, Edison envisioned the phonograph as a “way to record books for blind people, to teach elocution, to record lectures, to preserve the voices of historically important people, to perform office dictation, to log telephone messages, and finally to record music. ” He even imagined the application of the phonograph towards talking dolls and other toys. Also at this time, Edison began his work with the development of the incandescent electric light. Although he did not invent the electric light or incandescent lamp, Edison was the first to construct an economically viable model.
His entrepreneurial skills allowed him to realize what people needed, which resulted in his many improvements of existing technology. Earlier in his life while still a telegraph operator, Edison had invented an electric vote-counting machine, his first perfected invention. Edison spoke to a Congressional committee about this, but was refused because the machine was too fast for the processes of that time. It was from this incident that Edison vowed “‘?never to invent anything that nobody wanted.’ ” Edison neither invented the electric light nor incandescent lamp, but he was the first to produce an economically viable model. He foresaw electricity as a great means for the future and desired a substitute for gas as a means of lighting the home. From his experience and background, Edison realized that the key would be finding the proper filament, some carbonized thread that did not contain air unlike the wires and rods applied by his peers. October 19, 1879 marked his first success with the application of a carbonized cotton thread which some say burned for forty hours, while others say fifteen. Nonetheless, this success was a major milestone. Later, Edison made lamps suitable for commercial use with bamboo filaments. In September of 1882, Edison opened the first commercial central station in New York with 400 lamps wired to his own dynamos (electric generators).
The Essay on Gas Vs Electric
The Greatest Challenge Facing the World Today Problems tend to exist no matter what part of the world you explore. As each day goes by many new problems arise involving people of all nationalities. There is never one distinct complication among the many presently introduced that needs attention. Yet there are problems that do deserve immediate action. One of these major dilemmas would be the ...
After only five years at Menlo Park, Edison and his team abandoned this facility. “Only a few years after its occupancy, the team deserted the building and left it to crumble. ” Did Edison fail? No, success not failure was the reason for this. Menlo Park served its occupants by isolating them and reducing the noise experienced in a big city. In 1887, Edison moved to a larger laboratory in West Orange, New Jersey, where he dedicated much of his time to perfecting his previous inventions. It was here that Edison developed the kinetoscope, a forerunner to the motion picture camera. Later when “George Eastman developed celluloid-based photographic film?flexible enough to thread through a wheel, ” Edison created the first movie studio in West Orange by connecting the phonograph and the camera to make talking pictures. However, the machine was flawed and Edison put it aside to allow others to correct its faults. Some of his later inventions and improvements include the storage battery, cement mixer, and his last invention, synthetic rubber from goldenrod plants. Edison died on October 18, 1931. Henry Ford, already an Edison fanatic and later a great inventor himself, moved the Menlo Park laboratory to Greenfield Village in Dearborn, Michigan.
His efforts helped to preserve the tremendous legacy of Edison. Conquering darkness has always been one of man’s perpetual goals. With the invention of fire in prehistoric times, man was able to conquer darkness so long as he had fuel (wood) to burn. This was later adapted to the torch with pitch, resin, or fat to extend the burning time. Soon the Egyptians developed a well shaped oil lamp, which remained unchanged for a long time. For thousands of years, people applied the dim flickering oil lamps, until physicist Aime Argand noticed his younger brother at play with a bottle and an oil lamp. Then glass cylinders for lamps came into use and increased the brightness of lighting. Pine torches, however, still filled the larger rooms of temples and palaces as they gave out more than ten or twenty times as much light as a lamp. By the end of the second century A.D., the Romans began to soak flax strings in tallow or beeswax, but candles held a high price. Until the nineteenth century, many improvements were made upon the wax candle, but even then, many rooms were still dimly lit. The next big innovation was the development of the gas lamp by William Murdock. One night, Murdock filled a pig’s bladder with gas, stuck one end of his pipe into it, and lit the gas on the other end.
The Essay on The Electric Lightbulb Gas Light
The Electric Lightbulb is one of the most important inventions ever created. An inventor named Thomas Alva Edison created the lightbulb back in 1879. The electric lightbulb is actually called an 'Incandescent lamp', this means that electricity flows through the filament of the lightbulb. Thomas invented the lightbulb in a lamp factory back at Menlo Park, In the United States of America. Edison was ...
Luckily no air had mixed with the gas, or else Murdock would have been killed. In any case, with the help of Samuel Clegg, Murdock developed gas lighting after several years of work. Now Clegg needed to convince city officials to employ their gas lighting system, which he did very unusually. “Samuel Clegg invited the whole borough council, together with their expert advisor, to breakfast and afterward showed the gentlemen the site of the gasworks. When they entered the building housing the gas holder Clegg?seized a pickax, struck a hole in the gas holder, and set light to the jet of gas that poured out. ” Clegg had carefully locked the door, so the officials could not escape. Once they observed that they had survived the trial, the officials supported the institution of gas as a citywide lighting system. Once people realized that gas lighting was not dangerous, it became highly widespread, reaching Paris in 1817, Berlin in 1826, Vienna in 1833, and London in 1819. Then, the discovery of electricity provided another potential power source. People knew that electric signals could be sent along wires, but they also realized that electric current could be used to generate heat.
With the appropriate resistance, intense heat could be generated to produce light. The first to know and demonstrate this discovery was Sir Humphry Davy in 1808. By connecting two charcoal rods to the two terminals of the battery and moving these rods close to one another, “a dazzlingly brilliant ray of light formed between them. ” The evolution of cheaper power sources and materials increased the feasibility of this arc lighting system. Several advancements were made with the arc lighting, however all were too powerful for domestic use. This changed in 1848, when Heinrich Goebel produced a perpetually burning incandescent bulb, using eau-de-Cologne bottles for his vacuum and carbonized bamboo from his cane. From then on, the goal of inventors was not the basic idea of electric lighting but a practical application of these ideas. Here, Edison stepped into the electric light scene. “The name Thomas Alva Edison would have gone down in the history of inventions if he had created nothing else than the incandescent bulb, but he achieved a great deal more. ” In addition to developments with the electric light bulb, major advancements were occurring in the field of electricity.
The Essay on Light Bulb Electric Electrons Charges
Electricity Monica Smith Summary of Demonstration: This experiment will show us how energy current moves through circuits. I will be pointing out the different parts and telling what they do, and how they contribute so that the energy flows through them all. Finally, I will close the cardboard piece so that everyone will be able to actually see the result of the electric current. Scientific ...
French scientist Jean Benard Leon Foucault began the movement towards large, inexpensive power sources by instituting dynamo engines in place of galvanized batteries. Soon, Edison would also enter the field of power and electricity. Edison’s process of experimenting with the light bulb was a highly systematic form of trial and error. Edison’s search was highly focused because he had realized the need for the proper filament early in his experimenting; and Edison was no stranger to trial and error experimenting. Although later successful, Edison’s work with the storage battery is a clear example of this. His tests included nearly 10,000 experiments, all failed, yet Edison concluded, “‘?I have not failed. I’ve just found 10,000 ways that won’t work. ‘” Clearly, Edison was not only brilliant as a scientist but also hard working. Finally, after thousands of trials and failures with thousands of various filaments, the Menlo Park team had its greatest success in 1879 with a carbonized cotton thread. Edison was able to reduce the rapid burn-up of the filament by hermetically sealing the bulb with improved vacuum pumps. These major breakthroughs led to more interest and more experimentation, which led to the application of better filaments such as bamboo, osmium, and today’s tungsten.
The Term Paper on Thomas Edison Electric Light
... most complicated experiments of all his experiments. Edison is most famous for his development of the first electric light bulb. At ... mild, and inexpensive electric light. Edison searched for the proper 'filament' or wire that would give good light when electricity flowed ... during the day. He was too busy experimenting with electrical currents. Edison worked to improve a telegraph machine that would ...
Edison would later make his own improvements upon the vacuum pump. The discoveries of luminous tubes and mercury vapor luminescence further reduced the costs and increased the quality of electric lighting. In addition to the development of better filaments, Edison needed to devise a generator capable of powering buildings, ships, and even cities. This he called the dynamo, which also led to the development of the jumbo dynamo. Several of these jumbo dynamos were capable of powering city districts. Edison amazed crowds but still had far to go before producing a commercial setting for his light. After several years of additional work and experimenting in every aspect of electric lighting from power to resistance, Edison’s incandescent light bulb began to catch more public interest. In 1882, the Pearl Street Station operated to power nearly 1300 lamps and a year later 10,300 lamps in New York City. Electricity began to replace gas as the main power source for homes, despite defaming efforts by many gas companies. “The success of the Pearl Street Station marked the beginning of the electrical power era. ” The cornerstone of Edison’s scientific approach was his patience for trial and error experimentation.
Although known as a weak method, one which can fundamentally be applied to any type of problem, the process of trial and error served as the foundation of all Edison’s inventions. In many cases, he would notice a problem or a lack with a present device; from this, Edison would test various methods to eliminate this problem or fill the need. His inventions of the improved telegraphing methods, stock tickers, electric light bulbs, batteries, and many more demonstrate this. Edison summed up his own personal feelings about thinking and creativity when he said, “genius is 1% inspiration and 99% perspiration. ” This is truly a work ethic he followed as demonstrated by his hard work and dedication to inventing. Even still, many of Edison’s assistants refuted this statement with their own lack of intuitiveness, ingenuity, and invention. Edison was not bothered by the particulars of organization in his thoughts. He kept extensive records of his thoughts and findings, over four million pages of writing. Due to his constant observations and ideas, historians began to equate Edison and Leonardo da Vinci in the field of invention and ingenuity. In addition to his many patented inventions, Edison dabbled with many other ideas.
One example would be his thoughts on human flight nearly three decades before the Wright Brothers’ historic flight. Between inventive flurries, Edison’s mind would wander even into calligraphy or poetry, which he recorded with his notes. To limit distractions and noise from big cities, Edison conceived the idea of “invention factories.” By keeping a well-stocked laboratory, Edison was able to provide the proper work environment for his employees and assistants. By having a chemistry lab, machine shop, and brilliant group under one roof, Edison was able to produce hundreds of inventions at his laboratory. Edison’s core group of handpicked assistants included “university-educated men specially chosen because of their expertise in fields in which Edison felt himself to be deficient. ” From his work, Edison formed intimate relationships with Charles Batchelor, his chief assistant, and John Kruesi, head of his machine shop. Edison saw these bonds as essential for Menlo Park’s success and would suspend work in the absence of Batchelor. “Francis Upton, a newer member of the group, remarked that Edison, Bachelor, and Kruesi made and ideal combination, since ‘Mr.
Edison with his wonderful ideas?always thinks in three dimensions. Mr. Kruesi?would distribute work so as to get it done with marvelous quickness and great accuracy. Mr. Batchelor was always ready for any special fine experimenting or observation?’ ” Upton himself later became a vital part of the Menlo team as chief scientific assistant during the electric lighting project, Edison’s and Menlo Park’s greatest success. Batchelor provided Edison with his expertise of mathematics, while Upton brought highly developed skills in physics. Arthur Kennelly, Edison’s chief electrical engineer, became yet another important member of the Menlo team. Finally, although not directly involved with the inventing, Grosvenor Lowrey advised Edison on all his financial and political matters. This compiled effort allowed Edison to focus more on the problem at hand, inventing. Because he had received little in terms of formal schooling, Edison’s knowledge is a product only of his readings and self-experience. However, he had a wide background of careers, which provided him with a great deal of experience. To solve this problem with the incandescent light, Edison relied on his background in electromagnetism, relay mechanics, and circuitry laws from his work in telegraphy. In addition his work with the phonograph expanded his knowledge of conductivity. Edison’s work with batteries provided him with a background in electrochemistry. While working on the battery, Edison attended classes at Cooper Union to learn the necessary chemistry. He later applied this knowledge to his work with generators and dynamos as power sources. This broad background allowed Edison to realize the importance of not just electric lighting for the future, but also electricity in general (he was encouraged by friends to develop electric lighting).
The problem with contemporary electric lights was that the filaments would burn up too quickly, unless they were made of heavy (and costly) copper wire or the like. Once Edison realized this problem, he began to concentrate his efforts to determining the proper incandescent filament to prevent quick burn-up. Thus Edison realized that a regulator would prevent melting, initially experimenting with spiral shaped filaments. As stated earlier, Edison’s foresight carried to more than just electric lighting, but also creating a sufficient commercial power supply in order for light to become a marketable. Thus Edison’s work also included dedicated research towards developing inexpensive power sources. The development of all related areas of electric lighting were necessary steps towards incandescence. This included not only the discovery of the filament, but also creating the proper vacuum and providing the proper power supply. He had experimented with carbon paper filaments in 1876 and 1877, but he began a systematic assault on the electric light bulb and it complementary system in 1878. ” In October of 1878, work on finding the proper regulator governed the Park activities.
At the same time, the Menlo Park team devoted attention towards the electromagnetic generator. In December of this year, work on the lamp ceased as generator experiments were intensified. To fulfill his quest for incandescence, Edison drew heavily on his experience with telegraphy to visualize the system of relays and circuit breakers. Although the broad concepts of the research were his own, Edison relied on his staff and assistants to carry out important functions where he may have been lacking. Again in 1879, the Menlo team turned research back to developing the light itself. The application of Sprengel’s mercury pump aided the creation of a vacuum, but in failing to obtain a complete vacuum, “tests were conducted at Menlo Park to produce new vacuum techniques. ” Later in March, Edison submitted his patent application for his vacuum techniques and high resistance lamps. Edison’s knowledge allowed him to see that high currents would require thick and expensive copper wire to transfer energy, and as an alternative, Edison saw that high-resistance lamps required no more energy than low-resistance ones, which led him to experiment with spiraled platinum filaments.
However, following events would soon change this. In October of 1879, Carbon replaced platinum as the primary filament material, and a practical light bulb became a reality. “Edison had experimented with carbon early in his research. He had tested carbonized paper as early as 1877, but it burned up almost immediately. He eventually turned to platinum because of its high melting point. ” Now this return to carbonized materials combined with Edison’s practice of trial and error, may seem impractical, however the new vacuum pump made it possible to burn carbon much less quickly than in the atmosphere. In addition, Edison may have compared his situation to that of Joseph Swan who successfully applied carbon cylinders in low-resistance lamps. Another analogous situation may have been Edison’s own success with carbon transmitters in the telephone. In any case, on October 21 and 22, the team had abandoned the spiraled carbonized thread, which led to a major development. While Edison recalls this experiment as the culmination of their research, his staff viewed the success as just a promising new direction. Soon, Upton’s parlor, Edison’s house, and the Menlo Park boarding house for staff were lit up for public display.
On a New Year’s Eve demonstration, “forty bulbs were lit simultaneously, and they were switched on and off?this was an amazing feat. ” Even with the success of the cotton thread, Edison continued to seek better filaments for his lamp. He captured public attention by sending his men to various locations all over the world, testing bamboo from Japan and exotic plants from the Amazon and Sumatra. In the end, Edison had tested over 6,000 types of vegetation. Thomas Edison created inventions for two reasons: 1) more efficient technology and 2) profit. In order for the lamps to succeed, they needed to be placed in a commercially viable setting. The first public testing occurred on the SS Columbia, a steamship for the Oregon Railway and Navigation Company. These lamps burned for over 415 hours, which proved to be a successful field test. As experimenting continued, Edison began developed additional equipment towards commercial use by including lamp sockets and safety fuses. Now that the problem of the filament had been solved, Edison shifted his concerns towards developing power generation, distribution, and efficient and sustained illumination in addition to cost and utility.
He aspired to produce an energy system for broad application. Much of Edison’s inventing now became based upon their need towards commercializing the electric light. Such examples are junction boxes, switches, and meters. After the development of the necessary commercial technology, Edison set out to lay the distribution cables and underground mains. He realized that although overhead wiring was cheaper, underground distribution was much more reliable. Edison applied his own personal experience with the gas companies to know how efficient underground mains were. Edison’s choice was a wise one because in 1888, thousands of overhead wires were destroyed by an enormous blizzard. The operation of this Pearl Street Station demonstrated the viability of the central station concept for electrical power distribution. Pearl was never an experimental situation; it was a “consumer-based, urban oriented, site-specific commercial enterprise. ” To simply put it, the Pearl Street Station was the “real deal.” From now on, all components of the system had to be evaluated in terms of cost, especially lamp filaments and copper wiring. The benchmark was the cost of gas lighting; in order to be competitive with gas, the cost of electricity needed to be equal to or less than that of gas.
Cost factors had strongly affected technical and business decisions from the onset of the research, but now with success so close, every aspect needed to be considered. For example, the decision for high-resistance filaments was driven by cost rather than feasibility. Durable low resistance filaments would have worked, but the cost of the copper wiring would have prevented commercialization. Edison, with the help of Lowrey, formed several companies to keep manufacturing in the inventors hands. “The Edison Electric Illuminating Company of New York, incorporated in December 1880, was the operating company that built the Pearl Street Station. The Edison Machine Works (1881) built Dynamos; Edison Electric Tube Company (1881) fabricated underground conductors; Edison Lamp Works (1880) manufactured incandescent lamps. ” The many other problems facing Edison besides costs factors were competition from gas companies and arc-lighting companies. In addition, public safety and a discrimination between business customers and residential customers were crucial towards city implementation. Initially lamps cost $1.40 each to manufacture, however they were sold at $0.40 to establish a market.
This consumer price remained constant while the manufacturer’s cost dropped to $0.22, however the average life a bulb increased from its original 400 hours, increasing their value. Metering schemes were devised to provide a legitimate determinacy of the cost of service. Much of Edison’s inventing, especially with the electric light included means-ends analysis. For all inventing, inventors envision their desired product, or at least they envision the purpose of the product. Thomas Edison was no different; in fact, Edison’s success may be dependent upon his great ability to envision his final creations. Through this, Edison would propose a broad range of connections in order to test not just for any successful method but for the optimal one. But more than that, Edison’s success as an inventor can be attributed to his attitudes, work habits, and methods of reasoning. Perseverance and patience built the foundation of Edison’s ability, as demonstrated by his quotes concerning genius and his 10,000 failed experiments. “[Edison] saw every failure as a success, because it channeled his thinking in a more fruitful direction. ” Edison may have inherited this attitude form his father who was not afraid to take risks and never crumbled when a business venture failed.
“On [one] occasion, unprotected chemical were damaged by sunlight. Instead of bemoaning the losses, Edison put aside all other projects to catalogue changes in the properties of the bottled substances. ” This clearly demonstrates Edison’s optimism in spite of seemingly apparent disaster. Although described as a workaholic, Edison’s curiosity can be described as childlike and fun loving. Edison’s process of generate and test was highly organized by his definitions of his goals, however his method of inventing was highly disorganized. While his own conceptualizations directed his trial experiments, “Edison would often go back and review his earlier sketches to see if, in light of the new knowledge he had acquired, abandoned ideas could be resurrected. ” Analogy, another weak method, was also to key to many of Edison’s inventions. He applied knowledge gained from his own inventions and experiments to his current projects. His “distinctive repertoire of forms, models and design solutions, ” applied to invention after invention, sometimes referred to as Edison’s “themes and variations.” Such a case can be seen when one compares his first drawings of the kinetoscope with his wax-cylinder phonograph.
Edison himself noted the similarity between the two when he stated, “‘I am experimenting upon an instrument which does for the eye what the phonograph does for the ear.’ ” Further description paralleled the spiral images of film and the spiral grooves on records. This distant analogy can also be seen when Edison applied his success with carbon transmitters in telephones to his research on the incandescent filament. Thomas Edison was a problem solver in both the creation and commercialization of his inventions. He developed his inventions by repeatedly trying his experiments in increasingly complex settings until he could duplicate the item’s performance. Edison’s ability to reason by analogy and to learn from failure proved to be his greatest assets towards his inventing the electric light. Edison’s work in the mechanical, electrical, and chemical fields contributed a great deal of knowledge related to incandescence. Often times Edison’s work employed a trial and error approach but by working through variations on a theme. Edison’s process followed a direction led by, as Upton put it, “guesses of marvelous accuracy. ” Edison could envision the general nature of a result long before it be reached by mathematical induction.
And Edison himself stated, “‘I do not regard myself as a pure scientist as many people insist I am?I am only a professional inventor, ” which he demonstrated with his methods of inventing. His purpose for inventing was solely for the object of commercial utility. Thomas Edison did not invent the incandescent light, but Thomas Edison did invent the practical incandescent light and the urban-based energy system. By combining the processes of invention, engineering, and production, Edison produced a complete and commercially viable electrical lighting system. With his abilities and innovations, Edison institutionalized inventing. Edison worked himself from being an inventor and entrepreneur to being an industrialist and businessman. While some may refer to the period of technolog
Bibliography:
McAuliffe, Kathleen. The Undiscovered World of Thomas Edison. http://www.theatlantic.com/issues/95dec/edison/edison.html Melosi, Martin V. Thomas A. Edison and the Modernization of America. Harper Collins Publishers. 1990. 8 Pretzer, William S. Working at Inventing: Thomas A. Edison and the Menlo Park Experience. Dearborn, Michigan; Henry Ford Museum and Greenfield Village. 1991. 15 Schwalbe, David. American History: Thomas Alva Edison. http://americanhistory.about.com/education/americanhistory/library/weekly/aa120197.
