Thomas Edison of the Edison patent to charge a more reasonable rate for the use of the Edison patent rights and lowering the price of the electric lamp. On October 8, 1883, the US patent office ruled that Edison's patent was based on the work of William E. Sawyer and was, therefore, invalid. Litigation continued for nearly six years, until October 6, 1889, when a judge ruled that Edison's electric light improvement claim for "a filament of carbon of high resistance" was valid. To avoid a possible court battle with Joseph Swan, whose British patent had been awarded a year before Edison's,
Charles Edison Electric Company to form the McGraw-Edison Electric Company. Edison was board chairman of the merged company until he retired in 1961. On January 18, 1937, President Roosevelt appointed Charles Edison as Assistant Secretary of the Navy, then as Secretary on January 2, 1940, Claude A. Swanson having died several months previously. Edison himself only kept the job until June 24, resigning to run his gubernatorial campaign. During his time in the Navy department, he advocated construction of the large s, and that one of them be built at the Philadelphia Navy Yard, which secured votes for Roosevelt in Pennsylvania and