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This file consists of additional testimony entered by Edison in the case of Boehm v. Edison, which involved conflicting claims over a vacuum pump for the incandescent lamp. Ludwig K. Boehm, a German-born glassblower who worked at the Menlo Park laboratory, constructed the vacuum pumps and the globes used in Edison's incandescent light. He left Edison's employee in October 1880 and subsequently worked for the United States Electric Lighting Co. and the American Electric Light Co. During his tenure with the former company, Boehm filed a patent application on a modified Sprengel pump that he claimed to have invented at Menlo Park. His application was placed in interference with an application filed by Edison in January 1881, which was ultimately issued as U.S. Patent 248, 433. Edison later characterized Boehm as "the most extraordinarily conceited man I have ever come across."