Dr. John Harth, Lexington County, SC, 1800s

My great grandfather, John Jacob Howell (1804-1868) owned with a Dr. John Harth a saw mill at Williamson's Millls in Lexington County, SC. John Howell's wife was a Williamson. Any information on Dr. Harth will be appreciated. He had a brother named William Harth. It's possible that Dr. harth married a Williamson also.