This company was probably organized in August 1875 by investors in the original Automatic Telegraph Company in order to contest the Atlantic and Pacific Telegraph Company's use of Edison's automatic patents without proper recompense. Edison assigned his patents to the new company in December 1875.
American Bell Telephone Company
This successor to the National Bell Telephone Company was formed in 1880 after acquisition of Western Union's telephone patents (including Edison's) in November 1879. Edison began working under a five-year agreement as a contact inventor for the company in 1884.
American District Telegraph Company
This company was incorporated in New York in May 1872 by Gold and Stock Telegraph Company investors to exploit the district telegraph system invented by Edward Calahan, who had also invented the Gold and Stock ticker. Edison's first caveat for improvements in district telegraphy and an unsuccessful patent application were both assigned to this company.
American Printing Telegraph Company
This company was incorporated in New York on July 1, 1870 to exploit the printing telegraph patents of Edison and Franklin Pope for private lines. By October 1870 control of the company had passed to the Gold and Stock Telegraph company, whose president Marshall Lefferts had been one of the incorporators of American Printing.