The main purpose of the present volume is to consider and illustrate some questions of principle in the controversy on free trade and protection. The three chapters which constitute Part I state these questions and summarize the main conclusions. The succeeding Parts give illustrations and verifications drawn from the history of several industries,—sugar, iron and steel, and textiles. Something is thereby done, I trust, to make more precise and complete the theory of the subject, and to vivify it through illustrations from experience; and some contribution is offered also on the general economic history of the United States. [From the Preface]