EDISON, Thomas Alva, inventor, born in Alva, Ohio, 11 February 1847. His mother, who had been a teacher, gave him the little schooling he received, and at the age of twelve he became a newsboy on the Grand Trunk line running into Detroit. While thus engaged he acquired the habit of reading. He also studied qualitative analysis, and conducted chemical experiments on the train till an accident caused the prohibition of further work of the kind. Afterward he obtained the exclusive right of selling newspapers on the road, and, with the aid of four assistants, he set in type and printed the "Grand Trunk Herald," which he sold with his other papers, The operations of the telegraph, which he constantly witnessed in the stations along the road, awakened his interest, and he improvised rude means of transmitting messages between his father's home in Port Huron and the house of a neighbor. Finally a stationmaster, whose child he had rescued in front of a coming train at the risk of his own life, taught him telegraph operating, and he wandered for several years over the United States and Canada, acquiring great skill in this art, but frequently neglected his practical duties for studies and experiments in electric science. At this time he invented an automatic repeater, by means of which a message could be transferred from one wire to another without the aid of an operator, and in 1864 conceived the idea of sending two messages at once over the same wire, which led to his experiments in duplex-telegraphy.

Later he was called to Boston and placed in charge of the "crack" New York wire. While in that City he continued his experiments, and perfected his duplex telegraph, but it did not succeed till 1872. He came to New York in 1871, and soon afterward became superintendent of the gold and stock company, inventing the printing telegraphs for gold and stock quotations. For the manufacture of this appliance he established a large workshop at Newark, New Jersey, and continued there till 1876, when he removed to Menlo Park, New Jersey, and thenceforth devoted his whole attention to inventing. Among his principal inventions are his system of duplex telegraphy, which he subsequently developed into quadruplex and sextuplex transmission; the carbon telephone transmitter, now used by nearly all telephones throughout the world, in which the variation in the current is produced by the variable resistance of a solid conductor subjected to pressure, rendering more faithfully than any other telephone the inflections and changes in the intensity of the vocal sounds to be transmitted; the micro-taximeter, used for the detection, on the same principle, of small variations in temperature, and successfully employed during the total eclipse of 1878 to demonstrate the presence of heat in the sun's corona ; the earphone, which may be used to amplify sound without impairing the distinctness of articulation; and the megaphone, which, when inserted in the ear, so magnifies sounds that faint whispers may he heard at a distance of 1,000 feet.

The phonograph, which records sound in such a manner that it may be reproduced at will, and the phonometer and apparatus for measuring the force of soundwaves produced by the human voice, are inventions of this period. His attention then became absorbed in the problem of electric lighting. He believed that the process of lighting by the voltaic arc, in which Charles F. Brush had already achieved great results, would never answer for general illumination, and so devoted him to the perfection of the incandescent lamp.

After entirely perfecting a device for lamp with a platinum burner, he adopted a filament of carbon enclosed in a glass chamber from which the air was almost completely exhausted. He also solved the problem of the commercial subdivision of the light in a system of general distribution of electricity, like gas, and in December 1879, gave a public exhibition in Menlo Park of a complete system of electric lighting. This was the first instance of subdivision of the electric light, and created great interest throughout the world, especially as scientific experts had testified before a committee of the English House of Commons in the previous year that such a subdivision was impossible. His system is now in general use, and in 1882 Mr. Edison came to New York for the purpose of supervising its establishment in that City. In 1878 he received the degree of Ph.D. from Union, and during the same year was made a chevalier of the Legion of Honor by the French government.