It may be remarked by some that certain of the statements made in the book are not strictly accurate in that few details have been stated or exceptions made. This is true, but it seemed necessary if main facts were to be made to stand forth with the boldness required to accomplish the purpose which the author had in mind. The chapters are in no way intended to be an encyclopedia of the subject. The idea throughout has been to present only the main points and to show the derivation of the products from the raw materials and their relationships to each other. In other words the book is intended only as a sort of outline. References are given which will aid in the selection of works to be consulted by any who are sufficiently interested to go farther. Without the encouragement and coöperation of Crane Company and the kind assistance of friends, some within and some without the iron and steel industry, this little book would not have been possible. Special mention must be made of the aid given by Messrs. I. M. Bregowsky, J. A. Matthews, C. D. Carpenter, and others whose reading of and suggestions concerning parts of the manuscript were of much help. Thanks are due also to many individuals and firms for their very hearty coöperation in furnishing information and the photographs which appear in the pages of the book. L. W. S. _Illustrations are from the following sources:_ A. M. Byers Co., Pittsburg.—National Tube Co., Pittsburg.—U. S. Steel Corporation, New York.—Tennessee Coal, Iron & Railroad Co., Birmingham, Ala.—Shenango Furnace Co., Pittsburg.—Pickands, Mather & Co., Pittsburg.—United States Geological Survey.—Wellman-Seaver-Morgan Co., Cleveland, O.—Lackawanna Steel Co., Buffalo.—Cleveland-Cliffs Iron Co., Ishpeming, Mich.—J. H. Hillman & Sons Co., Pittsburg.—Harbison-Walker Refractories Co., Pittsburg.—By-Products Coke Corporation, Chicago.—H. Koppers Co., Pittsburg.—Federal Furnace Co., Chicago.—Crucible Steel Company of America, Pittsburg.—Crane Co., Chicago.—Interstate Iron & Steel Co., Chicago.—LaBelle Iron Works, Steubenville, O.—Morgan Construction Company, Worcester, Mass.—J. A. Matthews. Syracuse, N. Y.—McLain’s System, Milwaukee, Wis.—Allis-Chalmers Co., Milwaukee, Wis.—J. H. Williams & Co., New York.—Griffin Wheel Co., Chicago.—U. S. Molding Machine Co., Cleveland.—Bradley Manufacturing Co., Bradley, Ill. (Sears, Roebuck & Co., Chicago).—Snyder Electric Furnace Co., Chicago.—Commonwealth Steel Co., St. Louis.—John A. Crowley & Co., Detroit.—Illinois Steel Co., Chicago.—Pickands, Brown & Co., Chicago.—“Sketches of Creation,” by Alexander Winchell. Harper & Bros., New York.—“Descriptive Metallurgy of Iron,” by S. Groves.—“Materials of Engineering,” by R. H. Thurston. John Wiley & Sons, New York.—“Chambers’ Encyclopedia.” J. B. Lippincott, Philadelphia.—“Cast Iron in the Light of Recent Research,” by W. H. Hatfield. Charles Griffin & Co., Ltd.,