Energy and Empire is a definitive biographical study of Lord Kelvin, the most famous mathematical physicist of nineteenth-century Britain. As part of this study, it delivers on a speculation long entertained by historians of science, that Victorian physics expressed in its very content the industrial society that produced it. Born into a family committed to liberal political reform and personal advancement, William Thomson identified himself as much with the shipyards and engineering works of his adopted city of Glasgow as with the democratic education offered in its university. Building outward from this secure base he integrated his national and international activities into that heady period of almost total British supremacy in industrial power, maritime expansion and imperial influence. This meticulously researched contextual biography of an eminent scientist will be of interest to historians of science and technology; intellectual, social and economic historians; physicists; engineers; geologists; and philosophers of science.