[This note covers all of the Patent Application Files for Part IV.]

These files consist of formal patent applications, along with correspondence between Edison's attorneys and the U.S. Patent Office. Some of the folders also contain notes and drawings by Edison; draft specifications in Edison's hand and other specifications with Edison notations; memoranda from Edison to his patent attorneys; and related correspondence authored by or sent to Edison, his associates, and his companies. Included are applications pertaining to phonographs and phonograph records, motion pictures, storage batteries, ore milling, cement, and concrete buildings. There are also a few applications relating to electric lighting, telephones, telegraphs, and other subjects such as "flying machines."

Another set of application files for Edison's U.S. patents can be found in the National Archives (Record Group 241, Records of the Patent Office). The National Archives set is nearly complete for this period and is available on microfilm. For that reason, the formal specifications and the correspondence between Edison's attorneys and the Patent Office have not been selected in the case files for the successful applications in the Edison National Historical Park's collection. The selected material from these files consists primarily of notes, drawings, and draft specifications by Edison, along with occasional correspondence to or from Edison, his associates, and his companies. The case files for Edison's abandoned or forfeited applications have been selected in their entirety except for duplicates, printed patents by Edison and other inventors, and other printed material. In addition, two applications by Edison's son, William Leslie Edison, have been selected. The files are arranged in chronological order according to execution date—the date on which the formal application was signed and witnessed.