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This file consists of Edison's testimony in the case of Sawyer and Man v. Edison, which involved conflicting claims over the incandescent lamp. The Patent Office had declared an interference in September 1880 between Edison's application for a patent on an electric lamp with a filament composed of carbonized paper and an application filed by William E. Sawyer (d. 1883) and Albon Man (1826-1905) in January 1880. After a hearing, the Examiner of Interferences awarded priority of invention to Sawyer and Man in January 1882. A second hearing, ordered by the Commissioner of Patents, returned the same decision in June 1883. The Board of Examiners-in-Chief overturned that ruling on appeal on July 28, 1883, awarding priority to Edison. That decision was appealed to the Commissioner of Patents and reversed on October 8, 1883. After additional legal wrangling, U.S. Patent 317,676 was finally granted to Sawyer and Man in May 1885. Edison claimed that the outcome was immaterial because he no longer used filaments of carbonized paper, and the broader claims of Sawyer and Man, which would have covered all carbonized fibrous filaments, failed to withstand a long court battle over Edison's carbon-filament lamp patent (U.S. Patent 223,898).
Related interference records can be found in the Litigation Series in Thomas A. Edison Papers, Part II (1879-1886). Courtesy of the National Archives.