Work relations

Frank J. Sprague, a competent mathematician and former naval officer, was recruited by Edward H. Johnson and joined the Edison organization in 1883. One of Sprague's significant contributions to the Edison Laboratory at Menlo Park was to expand Edison's mathematical methods. Despite the common belief that Edison did not use mathematics, analysis of his notebooks reveal that he was an astute user of mathematical analysis conducted by his assistants such as Francis Upton, for example, determining the critical parameters of his electric lighting system including lamp resistance by a sophisticated analysis of Ohm's Law, Joule's Law and economics.^[39]

Another of Edison's assistants was Nikola Tesla, to whom Edison promised $50,000 if he succeeded in making improvements to his DC generation plants. Several months later, when Tesla had finished the work and asked to be paid, Edison said, "When you become a full-fledged American you will appreciate an American joke."^[40] Tesla immediately resigned. With Tesla's salary of $18 per week, the payment would have amounted to over 53 years' pay and the amount was equal to the initial capital of the company. Tesla resigned when he was refused a raise to $25 per week.^[41] Although Tesla accepted an Edison Medal later in life, this and other negative series of events concerning Edison remained with Tesla. The day after Edison died, the New York Times contained extensive coverage of Edison's life, with the only negative opinion coming from Tesla who was quoted as saying, "He had no hobby, cared for no sort of amusement of any kind and lived in utter disregard of the most elementary rules of hygiene" and that, "His method was inefficient in the extreme, for an immense ground had to be covered to get anything at all unless blind chance intervened and, at first, I was almost a sorry witness of his doings, knowing that just a little theory and calculation would have saved him 90% of the labour. But he had a veritable contempt for book learning and mathematical knowledge, trusting himself entirely to his inventor's instinct and practical American sense." It seems very likely that Tesla's description was accurate, considering one of Edison's famous quotes regarding his attempts to make the light globe: "If I find 10,000 ways something won't work, I haven't failed. I am not discouraged, because every wrong attempt discarded is another step forward"^[42]. When Edison was a very old man and close to death, he said, in looking back, that the biggest mistake he had made was that he never respected Tesla or his work.^[43]

There were 28 men recognized as Edison Pioneers.

Fluoroscopy

Edison is credited with designing and producing the first commercially available fluoroscope, a machine that uses X-rays to take radiographs. Until Edison discovered that calcium tungstate fluoroscopy screens produced brighter images than the barium platinocyanide screens originally used by Wilhelm Röntgen, the technology was only capable of producing very faint images. The fundamental design of Edison's fluoroscope is still in use today, despite the fact that Edison himself abandoned the project after nearly losing his own eyesight and seriously maiming his assistant, Clarence Dally. Dally had made himself an enthusiastic human guinea pig for the fluoroscopy project and in the process been exposed to a poisonous dose of radiation. He later died of injuries related to the exposure. In 1903, a shaken Edison said "Don't talk to me about X-rays, I am afraid of them."^[38]

War of currents

Edison's true success, like that of his friend Henry Ford, was in his ability to maximize profits through establishment of mass-production systems and intellectual property rights. This dampened the success of less profitable work by others who were focused on inventing longer-lasting high-efficiency technology.^[31][32] George Westinghouse and Edison became adversaries because of Edison's promotion of direct current for electric power distribution instead of the more easily transmitted alternating current (AC) system invented by Nikola Tesla and promoted by Westinghouse. Unlike DC, AC could be stepped up to very high voltages with transformers, sent over thinner and cheaper wires, and stepped down again at the destination for distribution to users.

In 1887 there were 121 Edison power stations in the United States delivering DC electricity to customers. When the limitations of Direct Current (DC) were discussed by the public, Edison launched a propaganda campaign to convince people that Alternating Current (AC) was far too dangerous to use. The problem with DC was that the power plants could only economically deliver DC electricity to customers about one and a half miles (about 2.4 km.) from the generating station, so it was only suitable for central business districts. When George Westinghouse suggested using high-voltage AC instead, as it could carry electricity hundreds of miles with marginal loss of power, Edison waged a "War of Currents" to prevent AC from being adopted.

Despite Edison's contempt for capital punishment, the war against AC led him to become involved in the development and promotion of the electric chair (using AC current) as an attempt to portray AC to have greater lethal potential than DC. Edison went on to carry out a brief but intense campaign to ban the use of AC or to limit the allowable voltage for safety purposes. As part of this campaign, Edison's employees publicly electrocuted animals to demonstrate the dangers of AC;^[33][34] AC electric currents are slightly more dangerous in that frequencies near 60 Hz have a markedly greater potential for inducing fatal “Cardiac Fibrillation” than do DC currents.^[35] On one of the more notable occasions, in 1903, Edison's workers electrocuted Topsy the elephant at Luna Park, near Coney Island, after she had killed several men and her owners wanted her put to death.^[36] His company filmed the electrocution.

AC replaced DC in most instances of generation and power distribution, enormously extending the range and improving the efficiency of power distribution. Though widespread use of DC ultimately lost favor for distribution, it exists today primarily in long-distance high-voltage direct current (HVDC) transmission systems. Low voltage DC distribution continued to be used in high density downtown areas for many years but was eventually replaced by AC low voltage network distribution in many of them. DC had the advantage that large battery banks could maintain continuous power through brief interruptions of the electric supply from generators and the transmission system. Utilities such as Commonwealth Edison in Chicago had rotary converters, also known as motor-generator sets , which could change DC to AC and AC to various frequencies in the early to mid-20th century. Utilities supplied rectifiers to convert the low voltage AC to DC for such DC loads as elevators, fans and pumps. There were still 1,600 DC customers in downtown New York City as of 2005, and service was only finally discontinued on November 14, 2007.^[37] Most subway systems still are powered by direct current.

Electric power distribution

Edison patented a system for electricity distribution in 1880, which was essential to capitalize on the invention of the electric lamp. On December 17, 1880, Edison founded the Edison Illuminating Company. The company established the first investor-owned electric utility in 1882 on Pearl Street Station, New York City. It was on September 4, 1882, that Edison switched on his Pearl Street generating station's electrical power distribution system, which provided 110 volts direct current (DC) to 59 customers in lower Manhattan.

Earlier in the year, in January 1882 he had switched on the first steam generating power station at Holborn Viaduct in London. The DC supply system provided electricity supplies to street lamps and several private dwellings within a short distance of the station. On January 19, 1883, the first standardized incandescent electric lighting system employing overhead wires began service in Roselle, New Jersey.

Electric light

After many experiments with platinum and other metal filaments, Edison returned to a carbon filament. The first successful test was on October 22, 1879;^[25] it lasted 40 hours. Edison continued to improve this design and by November 4, 1879, filed for U.S. patent 223,898 (granted on January 27, 1880) for an electric lamp using "a carbon filament or strip coiled and connected to platina contact wires".^[26] Although the patent described several ways of creating the carbon filament including "cotton and linen thread, wood splints, papers coiled in various ways",^[26] it was not until several months after the patent was granted that Edison and his team discovered a carbonized bamboo filament that could last over 1,200 hours. The idea of using this particular raw material originated from Edison’s recalling his examination of a few threads from a bamboo fishing pole while relaxing on the shore of Battle Lake in the present-day state of Wyoming, where he and other members of a scientific team had traveled so that they could clearly observe a total eclipse of the sun on July 29, 1878 from the Continental Divide.^[27]

U.S. Patent#223898: Electric-Lamp. Issued January 27, 1880.

Edison allegedly bought light bulb U.S. patent 181,613 of Henry Woodward that was issued August 29, 1876 and obtained an exclusive license to Woodward's Canadian patent. These patents covered a carbon rod in a nitrogen filled glass cylinder, and differed substantially from the first commercially practical bulb invented by Edison.^{[citation needed]}

In 1878, Edison formed the Edison Electric Light Company in New York City with several financiers, including J. P. Morgan and the members of the Vanderbilt family. Edison made the first public demonstration of his incandescent light bulb on December 31, 1879, in Menlo Park. It was during this time that he said: "We will make electricity so cheap that only the rich will burn candles."^[28]

George Westinghouse's company bought Philip Diehl's competing induction lamp patent rights (1882) for $25,000, forcing the holders of the Edison patent to charge a more reasonable rate for the use of the Edison patent rights and lowering the price of the electric lamp.^[29]

On October 8, 1883, the U.S. patent office ruled that Edison's patent was based on the work of William Sawyer and was therefore invalid. Litigation continued for nearly six years, until October 6, 1889, when a judge ruled that Edison's electric light improvement claim for "a filament of carbon of high resistance" was valid. To avoid a possible court battle with Joseph Swan, whose British patent had been awarded a year before Edison's, he and Swan formed a joint company called Ediswan to manufacture and market the invention in Britain.

Mahen Theatre in Brno in what is now the Czech Republic, was the first public building in the world to use Edison's electric lamps, with the installation supervised by Edison's assistant in the invention of the lamp, Francis Jehl.^[30]

Electric light

Menlo Park (1876–1881)

Edison's major innovation was the first industrial research lab, which was built in Menlo Park, New Jersey. It was built with the funds from the sale of Edison's quadruplex telegraph. After his demonstration of the telegraph, Edison was not sure that his original plan to sell it for $4,000 to $5,000 was right, so he asked Western Union to make a bid. He was surprised to hear them offer $10,000,^{[citation needed]} which he gratefully accepted. The quadruplex telegraph was Edison's first big financial success, and Menlo Park became the first institution set up with the specific purpose of producing constant technological innovation and improvement. Edison was legally attributed with most of the inventions produced there, though many employees carried out research and development work under his direction. His staff was generally told to carry out his directions in conducting research, and he drove them hard to produce results. The large research group included engineers and other workers.

Edison's Menlo Park Laboratory, removed to Greenfield Village in Dearborn, Michigan. (Note the organ against the back wall)

William J. Hammer, a consulting electrical engineer, began his duties as a laboratory assistant to Edison in December 1879. He assisted in experiments on the telephone, phonograph, electric railway, iron ore separator, electric lighting, and other developing inventions. However, Hammer worked primarily on the incandescent electric lamp and was put in charge of tests and records on that device. In 1880, he was appointed chief engineer of the Edison Lamp Works. In his first year, the plant under General Manager Francis Robbins Upton turned out 50,000 lamps. According to Edison, Hammer was "a pioneer of incandescent electric lighting".

Thomas Edison's first successful light bulb model, used in public demonstration at Menlo Park, December 1879

Nearly all of Edison's patents were utility patents, which were protected for a 17-year period and included inventions or processes that are electrical, mechanical, or chemical in nature. About a dozen were design patents, which protect an ornamental design for up to a 14-year period. Like most patents, the inventions he described were improvements over prior art. The phonograph patent, on the other hand, was unprecedented as the first device to record and reproduce sounds.^[21] Edison did not invent the first electric light bulb, but instead invented the first commercially practical incandescent light. Several designs had already been developed by earlier inventors including the patent he allegedly purchased from Henry Woodward and Mathew Evans. Others who developed early and not commercially practical incandescent electric lamps included Humphry Davy, James Bowman Lindsay, Moses G. Farmer,^[22] William E. Sawyer, Joseph Swan and Heinrich Göbel. Some of these early bulbs had such flaws as an extremely short life, high expense to produce, and high electric current drawn, making them difficult to apply on a large scale commercially. In 1878, Edison applied the term filament to the element of glowing wire carrying the current, although the English inventor Joseph Swan had used the term prior to this. Swan developed an incandescent light with a long lasting filament at about the same time as Edison, but it lacked the high resistance needed for central station DC service. Edison took the features of these earlier designs and set his workers to the task of creating longer-lasting bulbs. By 1879, he had produced a new concept: a high resistance lamp in a very high vacuum, which would burn for hundreds of hours. While the earlier inventors had produced electric lighting in laboratory conditions, dating back to a demonstration of a glowing wire by Alessandro Volta in 1800, Edison concentrated on commercial application, and was able to sell the concept to homes and businesses by mass-producing relatively long-lasting light bulbs and creating a complete system for the generation and distribution of electricity.

In just over a decade Edison's Menlo Park laboratory had expanded to occupy two city blocks. Edison said he wanted the lab to have "a stock of almost every conceivable material". A newspaper article printed in 1887 reveals the seriousness of his claim, stating the lab contained "eight thousand kinds of chemicals, every kind of screw made, every size of needle, every kind of cord or wire, hair of humans, horses, hogs, cows, rabbits, goats, minx, camels ...silk in every texture, cocoons, various kinds of hoofs, shark's teeth, deer horns, tortoise shell ...cork, resin, varnish and oil, ostrich feathers, a peacock's tail, jet, amber, rubber, all ores ..." and the list goes on.^[23]

Over his desk, Edison displayed a placard with Sir Joshua Reynolds' famous quote: "There is no expedient to which a man will not resort to avoid the real labor of thinking."^[24] This slogan was reputedly posted at several other locations throughout the facility.

With Menlo Park, Edison had created the first industrial laboratory concerned with creating knowledge and then controlling its application.