Born in McConnelsville, Morgan County, Ohio, Tompkins moved to Athens County, Ohio, in 1865. He attended the public schools and Ohio University at Athens. He studied law. He was admitted to the bar in 1875 and commenced practice in Athens, Ohio. City solicitor in 1876 and 1877. He served as mayor of Athens 1877-1879. He served as prosecuting attorney of Athens County in 1879. He served as delegate to the Republican State conventions in 1879, 1881, and 1883. He served as member of the Ohio House of Representatives 1886-1890. He moved to Columbus, Ohio, in 1889. He served as member of the board of trustees of Ohio University.
Tompkins was elected as a Republican to the Fifty-seventh Congress (March 4, 1901 – March 3, 1903). He resumed the practice of law in Columbus, Ohio. He was appointed trustee of Ohio University in 1908. He died in Columbus, Ohio, December 18, 1917. He remains were cremated in Cincinnati, Ohio, and the ashes returned to his home in Columbus, Ohio.
This article incorporates public domain material from the Biographical Directory of the United States Congress website http://bioguide.congress.gov.