The hands of Cornish miners bore scars of one of the most sophisticated traditions of hard-rock mining in the world.Toughened "Cousin Jacks" brought generations of toilsome underground experience to the Americas from one of the oldest mining regions of the world. Once here, their skill with granite and ore won their fame as the industrial elite of western mining camps. Heirs of a perfected system of excavation, a valuable terminology, and the technical...