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Thomas Edison, born in 1847 and died in 1931, was an American inventor, one of the greatest inventors of all time. Edison began to work at an early age and continued to work right up until his death. Throughout his prolific career as an inventor, he was well known for his focus and determination. During his career Edison patented more than 1,000 inventions, including the electric light, the phonograph, and the motion-picture camera. These three inventions gave rise to giant industries—electric utilities, phonograph and record companies, and the film industry—thus changing the work and leisure habits of people throughout the world. The period from 1879 to 1900, when Edison produced and perfected most of his devices, has been called the Age of Edison.
Edison acquired his knowledge of electricity and telegraphy, which means use of a telegraph system to communicate at a distance, as a teenager. In 1868, at age 21, he developed a telegraphic vote-recording machine, the first of his inventions to be patented. The next year, Edison invented an improved version of the stock ticker, which printed stock market quotations and gold prices on a paper tape. Unlike older stock tickers, Edison’s was fully automatic, and it did away with the need for a special attendant to operate each machine.
These early inventions brought Edison no financial returns. The first invention to bring him money was another improvement on the stock ticker. Edison created a central mechanism by which all the receiving tickers could be put in unison with the main sending apparatus. For this invention, Edison received $40,000, which would be worth $530,000 in 2000. He and a business partner, who operated a machine shop, used the money to start a new company to manufacture Edison’s improved stock ticker. For the next five years Edison spent up to 18 hours a day in his workshop in Newark, New Jersey, inventing and manufacturing a variety of electrical devices. One important device that he designed during this period was the quadruplex, a highly efficient telegraph that could send four messages at a time over a telegraph wire, instead of just one.
MENLO PARK LABORATORY
In 1876, Edison established a laboratory at Menlo Park, New Jersey, the first laboratory dedicated to industrial research in the world. Within ten years people throughout the world knew of Edison as the Wizard of Menlo Park.
Edison’s first major achievement at Menlo Park was an improvement on the telephone. The telephone that Alexander Graham Bell patented in 1876 could not operate over distances of more than 3 to 5 km (2 to 3 mi). After hundreds of experiments, Edison improved the telephone to such an extent that it could carry speech clearly over almost unlimited distances. In March 1878, Edison’s telephone system connected New York City to Philadelphia, Pennsylvania, a distance of 172 km (107 mi).
While working on the telephone, Edison also worked on perhaps his most original invention. He had noticed how the phone’s diaphragm, a thin membrane in the mouthpiece, vibrated in tune with the voice. He thought that if these vibrations could somehow be recorded, so that the diaphragm could be made to vibrate in exactly the same manner at any future time, then speech, music, and other sounds could be preserved and reproduced. Edison tested the strength of the diaphragm vibrations by holding a needle against the diaphragm with his finger, so that the needle pricked his finger with a force that varied with the loudness of the sounds.
In a later experiment, he applied one end of the needle to the diaphragm and the other end to a strip of waxed paper. He then pulled the paper along underneath the needle while repeatedly shouting, ‘Hello!’ The needle, activated by the vibrations of the diaphragm, created grooves in the paper. When the paper was again pulled along underneath the needle, the needle followed the grooves it had formed earlier and pushed against the diaphragm, making the diaphragm reproduce Edison’s shouts. This first crude experiment, performed in 1877, marked the beginning of the phonograph.
Edison obtained a patent on the phonograph in February 1878. By this time, he had replaced the waxed paper with metal cylinders covered with tinfoil. He postponed further development of the phonograph, however, for some years.
The Incandescent Lamp
After patenting the phonograph, Edison set out to develop an incandescent lamp, which would produce light by heating a wire until it glowed brightly. People already used electric arc lights, which produced light by creating an arc of electricity between two wires. However, the blinding glare these arc lights gave off made them unsuitable for home use. Edison, like others before him, conceived the idea of a light with a glowing wire, or filament, made of a substance that could endure very high temperatures without fusing, melting, or burning out. After hundreds of trials and more than a year of steady work, Edison developed a high-resistance carbon-thread filament that burned steadily for more than 40 hours. Although not the first incandescent electric light, it was the first practical one because it used a small current and, in addition, lasted a long time without burning out.
Electric Power Distribution Systems
Edison realized that widespread use of electric light bulbs would require an efficient system of delivering electricity to homes and businesses. He developed detailed plans for an entire distribution system for electric power. This system included generating the current by means of a central dynamo, which is a device that turns mechanical energy into electricity, and then distributing it in small quantities to thousands of homes and commercial buildings. Edison even developed a greatly improved dynamo to reduce the cost of generating electricity. The system Edison suggested in 1879 included the parallel circuits, safety fuses, insulating materials, and copper-wire networks used in modern electrical systems.
By 1881 Edison had set up a complete electric lighting system at his Menlo Park home. That same year his system took top honors at the Paris Electrical Exhibition in France. In 1882 at Holborn Viaduct in London, the Edison Electric Lighting Company completed and began operating the first commercial generating station for incandescent lighting in the world. This installation used an underground main and feeder circuit to supply power for 2,000 lamps. Later in 1882 Edison established the first permanent incandescent light and power station for private consumers, called the Pearl Street generating station, in New York City.
The Edison Effect
While Edison was working on the electric light, he made a scientific discovery that would become important to future generations. Edison noticed that particles of carbon from the filament blackened the insides of his light bulbs. This effect was caused by the emission of electrons from the filament, although Edison made the discovery before he and other scientists knew the electron existed. Not until 1897 did British physicist J. J. Thomson prove that the blackening observed by Edison was caused by the emission of electrons. This so-called Edison effect became the foundation of all modern electronics. Radio, television, radar, and computers all depend on it.
In 1884 Edison received a patent for a device based on the Edison effect. The device was designed to indicate variations in the output from electrical generators. The indicator proved ineffective because obtaining a good vacuum in devices at that time was difficult, but this was the first patent for a device that made use of the emission of electrons. It marked the beginning of the field of electronics.
In 1884 Edison’s first wife died of typhoid fever, and thereafter the inventor rarely returned to his laboratories at Menlo Park. After his second marriage in 1886, Edison bought Glenmont, a large country estate in West Orange, New Jersey, where he established a new laboratory. He remained there for 45 years. Glenmont and the laboratory are preserved as part of the Edison National Historic Site in West Orange and are open to the public.
In 1888 Eadweard Muybridge, an English pioneer in stop-motion photography, showed Edison his photographs of horses in full gallop. Muybridge had taken the photographs using a series of cameras, equipped with fast-action shutters, which he arranged along the side of a racetrack. The shutter of each camera was released when a horse broke through a string stretched across the track. By this method, Muybridge obtained a series of pictures showing a short cycle of motion. The pictures could be passed in rapid succession in front of a peephole, giving the viewer the illusion that the horses were moving.
Muybridge’s visit inspired Edison, who had already recorded sound, to think of recording movement photographically. He began work almost immediately on what was to become the first motion-picture camera. His first crude apparatus consisted of a photographically sensitive cylinder that revolved in synchrony with the camera shutter to take about 40 pictures per second. In 1889 the Eastman Dry Plate and Film Company produced and patented a celluloid roll film, and Edison promptly replaced his bulky cylinder with 15-m (50-ft) strips of the Eastman film. The new machine, completed in 1890, was the prototype of all modern motion-picture cameras.
For the showing of his motion pictures, Edison built a mechanism, called the Kinetoscope, which used positive film moving past a peephole. (Positive film shows the correct areas of light and darkness in a photograph, while the negative shows the opposite.) Although only one viewer at a time could see the film, it gave much clearer and steadier pictures than did available screen and projector devices.
In 1893 Edison constructed the first motion-picture studio. The building was 15.2 m (50 ft) long and had a hinged roof that could be raised to admit sunlight. The whole building was mounted on a pivot and could swing around to follow the sun. Edison had the walls on the inside painted black because this background helped the cameras produce sharper pictures. In 1893 and 1894, Edison produced numerous one-minute films. His moving pictures included figures such as French ballet girls; Japanese dancers; American showman ‘Buffalo Bill’ Cody with accompanying Indians in the first Western movie; and American prizefighter ‘Gentleman Jim’ Corbett sparring with other boxers.
The Electric Battery
In 1900 Edison set out to produce an improved electrical storage battery. Batteries convert chemical energy into electrical energy. In storage batteries, two metal rods, called electrodes, are connected by a circuit and immersed in a liquid, called an electrolyte. The rods chemically react with the electrolyte to produce a flow of electrons through the circuit. The storage batteries of the time were called lead-acid batteries because they had electrodes made of lead and lead dioxide and an electrolyte made of acid. They were heavy, bulky, difficult to recharge, and susceptible to rapid corrosion. To reduce corrosion, Edison decided to use an alkaline solution instead of acid for the electrolyte in his battery. Finding a suitable electrode, however, proved difficult. After conducting thousands of experiments on various materials, Edison finally decided on a combination of nickel flake and nickel hydrate for the positive electrode and pure iron for the negative electrode. He used an electrolyte of potassium hydroxide with a small amount of lithium hydroxide.
By the time Edison had perfected his storage battery, he had spent eight years and a million dollars on it. The battery was widely used in electric cars and even to power submarines. People still use storage batteries based on Edison’s original principles in lamps for miners, powers signals along railroad tracks, isolated airway beacons, and emergency power supplies.
After his exhausting work on the alkaline storage battery, Edison again turned his attention to the phonograph. In 1912 he marketed the Edison Diamond Disk Phonograph and disk records. These records measured about 6 mm (about 0.25 in) thick and had a surface of Bakelite varnish, an early form of plastic.
In the 1920s it became apparent that in the event of a national emergency, the United States would not be able to obtain an adequate supply of rubber because it relied heavily on imports. At the age of 80, Edison set out to find plants that could grow in the United States and were suitable for producing rubber. In the next four years he tested 17,000 different plants, finding rubber in 1,200 of them but worthwhile quantities in only about 40. He chose to produce rubber from the goldenrod plant because it would grow in most parts of the country, it grew to maturity in just one season, and it could be harvested by machines. These characteristics made the plant easy to grow and harvest on the large scale required to produce rubber efficiently. By crossbreeding, Edison produced a goldenrod plant 4 m (13 ft) tall and raised its rubber content from 4 percent to 12 percent. Edison’s assistants vulcanized (chemically strengthened) this rubber to make it useful for products about ten days before his death.
LIFE OF EDISON
Thomas Alva Edison’s family was part Dutch and part British. His ancestors, who supported the king in the American Revolution (1775-1783), fled to Canada with more than 30,000 others when the war ended. In 1837 Edison’s father became engaged in an unsuccessful revolution against the Canadian government and was forced to flee back to the United States. Thus, Thomas was born in Milan, Ohio, in 1847.
In 1854 the family settled in Port Huron, Michigan, where Edison attended school for three months. This was his only formal public education. His mother continued his education, teaching him reading, writing, and arithmetic. She also read to him from well-known English writers, such as Edward Gibbon, William Shakespeare, and Charles Dickens.
Edison earned a job selling newspapers, apples, and candy on the Detroit and Port Huron branch of the Grand Trunk Railroad when only 12 years old. Around this time his hearing began to decline, possibly due to a childhood attack of scarlet fever. Edison once said that he sometimes considered his partial deafness almost an asset, particularly when he wanted to concentrate on an experiment. However, in a poignant entry in his diary some years later, he wrote, ‘I haven’t heard a bird sing since I was 12 years old.’
When 15 years old, while still working on the railroad, Edison bought a small secondhand printing press and 136 kg (300 lb) of type. He installed the press in a baggage car and soon began producing a newspaper, the Weekly Herald, which he printed, edited, and sold on the Grand Trunk Railroad.
In the summer of 1862, Edison saved a boy from being run over by a boxcar. The boy, only three years old, was the son of the stationmaster in Mount Clemens, Michigan. In gratitude, the stationmaster offered to teach Edison how to operate the telegraph. Edison had already experimented with the telegraph at home and gladly accepted the offer. For five months, he learned to send and receive dispatches, and for the next four years he traveled thousands of miles as a telegrapher. During this period he spent most of his salary on various laboratory and electrical instruments, which he would take apart and rebuild.
Edison met his first wife, Mary Stilwell, in 1871. She was 16 years old and working in one of his companies when the inventor first met her. Edison married Stilwell on Christmas Day of that year. They had a daughter, Marion, born in 1873, and two sons, Thomas, Jr., born in 1876, and William, born in 1878.
Soon after his first wife’s death in 1884, Edison met and fell in love with Mina Miller, the daughter of a wealthy manufacturer. The two married in February 1886. They had a daughter, Madeleine, born in 1888, and two sons, Charles and Theodore, born in 1890 and 1898.
Edison focused on his work so much that he spent little time with his family. He avoided most social situations, and he often wore dirty shirts and shabby working clothes. Many of his associates also spoke of Edison’s virtues, however, such as good humor, even disposition, honesty, and genuine affection for his family.
Attitude Toward Work
Edison worked on his experiments with extraordinary intensity. He lived in his laboratory, getting along on four hours of sleep a day and eating meals brought to him by an assistant. He often kept vigils of 48 and even 72 hours when an experiment neared completion. Often, as in the cases of the electric light, the storage battery, and the experiments on synthetic rubber, success or failure depended on the discovery of a suitable material. In each case, he conducted thousands of experiments to find the right materials.
Before starting an experiment, Edison tried to read all the literature on the subject to avoid repeating experiments that other people had already conducted. Perhaps the best illustration of Edison’s working methods is his own famous statement: ‘Genius is one percent inspiration and 99 percent perspiration.’
During Edison’s lifetime, he received honors from all parts of the world. In 1881 he was awarded the French Legion of Honor for developing electric power distribution systems. Italy made him a Grand Officer of the Crown in 1889, and he received awards from the governments of Chile, Britain, Japan, Russia, and many other nations. American businessman Henry Ford spent several million dollars to erect a museum of industry in Dearborn, Michigan. The museum consisted largely of a collection of Edison’s inventions. In 1929 the museum held a celebration, called Light’s Golden Jubilee, to mark the 50th anniversary of the invention of the electric light.
When Edison died, the U.S. government considered turning off all electric current in the country for a minute or two as a tribute to him. It became apparent, however, that the operation of the great electrical distribution systems of the nation could not be interrupted even for a moment without possibly disastrous effects. Within Edison’s lifetime, the system that he had pioneered had become essential to the nation’s way of life.