This file consists of two exhibits entered in the case of Zipernowsky v. Edison, which involved conflicting claims over alternating current systems.
Karl (or Charles) Zipernowsky (1853-1942) was a Hungarian electrical engineer. Along with Otto Blathy and Maximilian Deri, he invented the ZBD alternating current transformer to convert high-voltage electric current to lower-voltage current. Zipernowsky and his partners received several patents on their inventions. This interference involved an application filed by Edison on November 19, 1886, and an application filed by Zipernowsky on March 19, 1888. Exhibit A is an agreement of November 1886 between Zipernowsky, acting on behalf of Ganz & Co. of Budapest, and Francis R. Upton, acting on behalf of the Edison Electric Light Co., granting the Edison company exclusive rights to Zipernowsky's alternating current patents in North America. Exhibit B is a letter from Zipernowsky to Upton written nine days earlier. Courtesy of the National Archives.