Cox attended San Francisco High School and Columbia School of Mines, graduating in 1887 as the school's first class of metallurgic engineers. After graduation, he was employed by the Government Survey of the Harlem Ship Canal, and became associated with the Pennsylvania Steel Company and Carnegie Steel Company. From 1897 until his death, he was the general manager of the Spanish-American Iron Company, situated near the village of Daiquirí, about 14 miles east south-east of Santiago de Cuba.
