PhonographEdison's experiments with the telephone and the telegraph led to his invention of the phonograph in 1877. It occurred to him that sound could be recorded as indentations on a rapidly-moving piece of paper. He eventually formulated a machine with a tinfoil-coated cylinder and a diaphragm and needle. When Edison spoke the words "Mary had a little lamb" into the mouthpiece, to his amazement the machine played the phrase back to him. The Edison Speaking Phonograph Company was established early in 1878 to market the machine, but the initial novelty value of the phonograph wore off, and Edison turned his attention elsewhere.
Electric Light SystemEdison focused on the electric light system in 1878, setting aside the phonograph for almost a decade. With the backing of financiers, The Edison Electric Light Co. was formed on November 15 to carry out experiments with electric lights and to control any patents resulting from them. In return for handing over his patents to the company, Edison received a large share of stock. Work continued into 1879, as the lab attempted not only to devise an incandescent bulb, but an entire electrical lighting system that could be supported in a city. A filament of carbonized thread proved to be the key to a long-lasting light bulb. Lamps were put in the laboratory, and many journeyed out to Menlo Park to see the new discovery. A special public exhibition at the lab was given for a multitude of amazed visitors on New Year's Eve.
Edison set up an electric light factory in East Newark in 1881, and then the following year moved his family and himself to New York and set up a laboratory there.
Lighting Becomes a Commercial CommodityIn order to prove its viability, the first commercial electric light system was installed on Pearl Street in the financial district of Lower Manhattan in 1882, bordering City Hall and two newspapers. Initially, only four hundred lamps were lit; a year later, there were 513 customers using 10,300 lamps. Edison formed several companies to manufacture and operate the apparatus needed for the electrical lighting system: the Edison Electric Illuminating Company of New York, the Edison Machine Works, the Edison Electric Tube Company, and the Edison Lamp Works. This lighting system was also taken abroad to the Paris Lighting Exposition in 1881, the Crystal Palace in London in 1882, the coronation of the czar in Moscow, and led to the establishment of companies in several European countries.
Thomas Promotes DC Current UnsuccessfullyThe success of Edison's lighting system could not deter his competitors from developing their own, different methods. One result was a battle between the proponents of DC current led by Edison, and AC current led by George Westinghouse. Both sides attacked the limitations of each system. Edison, in particular, pointed to the use of AC current for electrocution as proof of its danger. DC current could not travel over as long a system as AC, but the AC generators were not as efficient as the ones for DC. By 1889, the invention of a device that combined an AC induction motor with a DC dynamo offered the best performance of all, and AC current became dominant. The Edison General Electric Co. merged with Thomson-Houston in 1892 to become General Electric Co., effectively removing Edison further from the electrical field of business.
RemarriageEdison's wife, Mary, died on August 9, 1884, possibly from a brain tumor. Edison remarried to Mina Miller on February 24, 1886, and, with his wife, moved into a large mansion named Glenmont in West Orange, New Jersey. Edison's children from his first marriage were distanced from their father's new life, as Edison and Mina had their own family: Madeleine, born on 1888; Charles on 1890; and Theodore on 1898. Unlike Mary, who was sickly and often remained at home, and was also deferential to her husband's wishes, Mina was an active woman, devoting much time to community groups, social functions, and charities, as well as trying to improve her husband's often careless personal habits.
In 1887, Edison had built a new, larger laboratory in West Orange, New Jersey. The facility included a machine shop, phonograph and photograph departments, a library, and ancillary buildings for metallurgy, chemistry, woodworking, and galvanometer testings.