Thomas Alva Edison

views updated

Thomas Alva Edison


American Inventor

Thomas Alva Edison is perhaps the most famous inventor in American history. He held a world record 1,093 patents for inventions such as the incandescent electric lamp, the phonograph, and the motion-picture projector. Edison also played a pivotal role in bringing the modern age of electricity to the world.

As a child, Edison developed hearing problems that left him partially deaf. He attended school on and off for five years, but he had difficulty hearing and his teachers considered him slow. To compensate, Edison became an avid and inquisitive reader.

Edison quit school at age 12, and took a job selling newspapers and snacks on the railroad. By that time, the rail line was using a telegraph to control the movements of its trains. Edison learned how to use the telegraph and in 1863 became an apprentice telegrapher, replacing one of many operators who went to fight in the Civil War.

Initially, messages received on the Morse telegraph were inscribed as a series of dots and dashes on a piece of paper that had to be decoded and read. The transformation of telegraphy to an auditory system left the partially deaf Edison at a disadvantage. He spent six years as a travelling telegrapher, devoting much of his time to improving upon the telegraph itself. By January 1869 Edison had made enough progress on a telegraph capable of transmitting two messages simultaneously on one wire, and a printer which converted electrical symbols to letters, that he was able to pursue a career as a full-time inventor in Newark, New Jersey. There, he continued working on the automatic telegraph system.

In 1876 Edison moved his operation to Menlo Park, New Jersey, where he made some of his most significant discoveries, including a carbon-based conductive system in which an electrical current could be changed according to the amount of pressure it was under. In 1877 Edison began experiments that used that same pressure system to amplify and improve the sound quality of the telephone, which Alexander Graham Bell (1847-1922) had patented the previous year. By the end of 1877, Edison had developed the carbon-button transmitter that is still used in telephone speakers and microphones.

The phonograph is considered Edison's most original discovery. In the summer of 1877 he was trying to come up with a machine that would transcribe the sound of a human voice as it came over a telephone line. Building on earlier theories that each sound, if it could be graphically recorded, would produce a distinct shape resembling shorthand, Edison used a stylus-tipped carbon transmitter to make impressions on a piece of waxed paper. When he pulled the paper back beneath the needle, the tiny indentations generated sound. Edison unveiled his first phonograph in 1877, but it took 10 years for it to become a commercial success.

Edison spent five years trying to come up with a safe, inexpensive electric light that would replace the gaslight. In September 1882 he turned on the lights to the world's first permanent, commercial central power system, located in lower Manhattan. It was years before incandescent lighting powered by central stations replaced gas lighting, but isolated plants for hotels, theatres, and stores were an instant hit. Edison quickly garnered a reputation as the world's greatest inventor.

In 1887 Edison moved his workshop to West Orange, New Jersey, where he built the world's first industrial research laboratory. The first major project at the new lab was the commercialization of the phonograph. It was during this time that Edison began work on the first movie projector. He succeeded in building a working camera and a viewing instrument, but synchronizing the sound and motion proved next to impossible, so he gave up and the silent movie was born. The original Kinetoscopes, as the viewing machines were called, had peepholes that allowed one person at a time to view the moving pictures. Rival inventors soon edged out the Kinetoscope with screen-projection systems that allowed for group screenings.

Edison spent his career inventing devices that could satisfy real needs and that could be used by everyone. He, more than any other inventor, laid the foundation for the modern electric world.