Early Inventive Career

In 1868 Edison became an independent inventor in Boston. Moving to New York the next year, he undertook inventive work for major telegraph companies. With money from those contracts he established a series of manufacturing shops in Newark, New Jersey, where he also employed experimental machinists to assist in his inventive work.Edison soon acquired a reputation as a first rank inventor. His work included stock tickers, fire alarms, methods of sending simultaneous messages on one wire, and an electrochemical telegraph to send messages by automatic machinery. The crowning achievement of this period was the quadruplex telegraph, which sent two messages simultaneously in each direction on one wire.The problems of interfering signals in multiple telegraphy and high speed in automatic transmission forced Edison to extend his study of electromagnetism and chemistry. As a result, he introduced electrical and chemical laboratories into his experimental machine shops.Near the end of 1875, observations of strange sparks in telegraph instruments led Edison into a public scientific controversy over what he called etheric force, which only later was understood to be radio waves.