Thomas Edison

Edison, Thomas Alva, American inventor, whose development of a practical electric light bulb, electric generating system, sound-recording device, and motion picture projector had profound effects on the shaping of modern society. Edison was born in Milan, Ohio, on February 11, 1847. He attended school for only three months, in Port Huron, Michigan. When he was 12 years old he began selling newspapers on the Grand Trunk Railway, devoting his spare time mainly to experimentation with printing presses and with electrical and mechanical apparatus. The train left Port Huron about 7:00 in the morning and returned at 9:00 or 9:30 at night. The trip included a six-hour layover in Detroit, during which time he claims to have read "the entire public library." He was an omnivorous reader and loved to experiment with chemicals and machinery. He constantly wanted to investigate how things worked and liked to see if he could make things better. On the train he was allowed a table in an empty baggage car on which to work. He even brought a broken printing press, repaired it and taught himself to print. He may have produced the first newspaper printed on a moving train. Edison began noticing a loss of hearing around this time, which increased throughout his life. In 1862 he published a weekly, known as the Grand Trunk Herald, printing it in a freight car that also served as his laboratory. For saving the life of a station official's child, he was rewarded by being taught telegraphy. While working as a telegraph operator, he made his first important invention, a telegraphic repeating instrument that enabled messages to be transmitted automatically over a second line without the presence of an operator.

Edison next secured employment in Boston and devoted all his spare time there to research. He invented a vote recorder that, although possessing many merits, was not sufficiently practical to warrant its adoption. He also devised and partly completed a stock-quotation printer. Later, while employed by the Gold and Stock Telegraph Company of New York City he greatly improved their apparatus and service. By the sale of telegraphic appliances, Edison earned $40,000, and with this money he established his own laboratory in 1876. Afterward he devised an automatic telegraph system that made possible a greater speed and range of transmission. Edison's crowning achievement in telegraphy was his invention of machines that made possible simultaneous transmission of several messages on one line and thus greatly increased the usefulness of existing telegraph lines. Important in the development of the telephone, which had recently been invented by the American physicist and inventor Alexander Graham Bell, was Edison's invention of the carbon telephone transmitter.

In 1877 Edison announced his invention of a phonograph by which sound could be recorded mechanically on a tinfoil cylinder. Two years later he exhibited publicly his incandescent electric light bulb, his most important invention and the one requiring the most careful research and experimentation to perfect. This new light was a remarkable success; Edison promptly occupied himself with the improvement of the bulbs and of the dynamos for