EDISON, THOMAS ALVA (1847-1931), American in ventor, born at Milan, O., Feb. i 1, 1847, of Dutch ancestry on his father's side and Scottish on his mother's. His education was limited to three months in the public school of Port Huron, Mich. At 12 he became a railroad newsboy and after 15 earned his living as a telegraph operator in various cities, always studying and experimenting in his spare time. In 1868 he took out his first patent for an electrical vote recorder. During the next few years he devised stock tickers, duplex, quadruplex and automatic tele graph systems, and incidentally the electric pen, which developed into the mimeograph, for the multiplication of typewriting. His invention (1877-78) of the carbon transmitter, in which corn pressed lamp-black buttons were used to obtain the necessary variable resistance in the circuit, marked a real advance in the art of telephony and aided materially in bringing the Bell telephone into practical use.
Most modern inventions result from the contributions of many minds, and it is often difficult for the courts to determine priority, but when Edison made application in 1877 for a "phono graph or speaking machine," the U.S. Patent office could discover no previous record of this sort. The original model, costing $18, was a cylinder covered with tinfoil and turned with a hand crank. Ten years afterwards he developed a motor-driven machine with cylindrical wax records which speedily became popular. Later he invented a disk form reproducing with a diamond point for music, and the "Ediphone" for office dictation.
On Oct. 21, 1879, after expending more than $40,00o in fruitless experiments, he succeeded in making an incandescent lamp in which a loop of carbonized cotton thread glowed in a vacuum for over 4o hours. The following decade was devoted to the invention and exploitation of methods for the generation and distribution of electric light, heat and power, including three-wire system, under ground mains, improved dynamos and motors, and an electric railway for carrying freight and passengers. From 1891 to 1900 he was chiefly engaged on a magnetic method of concentrating iron ores, and from 190o to I 91 o in the development of a new kind of storage battery, using an alkaline solution with nickel hydrate as the positive and iron oxide as the negative material. In 1891 he applied for a patent on a "kinetescopic camera" for taking motion pictures on a band of film to be viewed by peeping into a box, and later for projecting them on a screen.
In the Scientific American, Dec. he described an un known "etheric force," which manifested itself by sparks passing between carbon points at a distance from an interrupted current. In 1883 he patented what became known as "the Edison effect," the passage of electricity from a filament to a plate of metal inside an incandescent lamp globe (a forerunner of the radio tube), and in 1885 a method of transmitting telegraphic signals from moving trains or between ships by induction. During the World War he worked on naval problems for the Government and on the pro duction of phenol and other chemicals. In 1927 he was admitted to the National Academy of Sciences.
In his combined workshop and laboratory at Menlo Park and later at Orange, N. J., Edison had been incessantly engaged in various forms of invention for more than so years and had taken out 1,033 patents up to April 1928. He died Oct. 18, 1931.
See Frank L. Dyer and Thomas C. Martin, Edison, his Life and Inventions (1910, authorized biography with list of patents) ; W. H. Meadowcroft, The Boy's Life of Edison, Harper (1921) ; A Popular History of American Invention, edited by Waldemar Kaempffert, Scribners (1924)• (E. E. SL.)