The Thomas A. Edison Papers Digital Edition

These documents cover the years 1868-1921. Included are several letters from Edison to John C. Van Duzer, a civilian electrician with the U.S. Signal Corps. The letters, which date from the period September-December 1868, concern Edison's proposed invention of a facsimile telegraph and a method of secret signaling. Also included is an 1878 letter from Edison to John H. Long, an American student in Germany who later became a professor of chemistry at Northwestern University. It pertains to Edison's tasimeter, which was designed to measure heat. There is also a letter from Hannah Swan, wife of inventor Joseph W. Swan, who wrote Edison in 1888 requesting a phonograph. A similar request from 1890 is from Coleman Sellers, a prominent engineer. In addition, there is a 1921 letter to William M. Van der Weyde, president of the Thomas Paine National Historical Association, in which Edison describes Paine as "one of the greatest men of all time."