I.—The Einstein $5,000 Prize: How the Contest Came to be Held, and Some of the Details of Its Conduct. By the Editor 1

II.—The World—And Us: An Introductory Discussion of the Philosophy of Relativity, and of the Mechanism of our Contact with Time and Space. By various contributors and the Editor 19

III.—The Relativity of Uniform Motion: Classical Ideas on the Subject; the Ether and the Apparent Possibility of Absolute Motion; the Michelson-Morley Experiment and the Final Negation of this possibility. By various contributors and the Editor 47

IV.—The Special Theory of Relativity: What Einstein’s Study of Uniform Motion Tells Us About Time and Space and the Nature of the External Reality. By various contributors and the Editor 76

V.—That Parallel Postulate: Modern Geometric Methods; the Dividing Line Between Euclidean and Non-Euclidean; and the Significance of the Latter. By the Editor 111

VI.—The Space-Time Continuum: Minkowski’s World of Events, and the Way in Which It Fits Into Einstein’s Structure. By the Editor and a few contributors 141

VII.—Relativity: The Winning Essay in the Contest for the Eugene Higgins $5,000 Prize. By Lyndon Bolton, British Patent Office, London 169

VIII.—The New Concepts of Time and Space: The Essay in Behalf of Which the Greatest Number of Dissenting Opinions Have Been Recorded. By Montgomery Francis, New York 181

IX.—The Principle of Relativity: A Statement of What it is All About, in Ideas of One Syllable. By Hugh Elliot, Chislehurst, Kent, England 195

X.—Space, Time and Gravitation: An Outline of Einstein’s Theory of General Relativity. By W. de Sitter, University of Leyden 206

XI.—The Principle of General Relativity: How Einstein, to a Degree Never Before Equalled, Isolates the External Reality from the Observer’s Contribution. By E.T. Bell, University of Seattle 218

XII.—Force Vs. Geometry: How Einstein Has Substituted the Second for the First in Connection with the Cause of Gravitation. By Saul Dushman, Schenectady 230

XIII.—An Introduction to Relativity: A Treatment in which the Mathematical Connections of Einstein’s Work are Brought Out More Strongly and More Successfully than Usual in a Popular Explanation. By Harold T. Davis, University of Wisconsin 240

XIV.—New Concepts for Old: What the World Looks Like After Einstein Has Had His Way with It. By John G. McHardy, Commander R. N., London 251

XV.—The New World: A Universe in Which Geometry Takes the Place of Physics, and Curvature that of Force. By George Frederick Hemens, M.C., B.Sc., London 265

XVI.—The Quest of the Absolute: Modern Developments in Theoretical Physics, and the Climax Supplied by Einstein. By Dr. Francis D. Murnaghan, Johns Hopkins University, Baltimore 276

XVII.—The Physical Side of Relativity: The Immediate Contacts between Einstein’s Theories and Current Physics and Astronomy. By Professor William H. Pickering, Harvard College Observatory, Mandeville, Jamaica 287

XVIII.—The Practical Significance of Relativity: The Best Discussion of the Special Theory Among All the Competing Essays. By Prof. Henry Norris Russell, Princeton University 306

XIX.—Einstein’s Theory of Relativity: A Simple Explanation of His Postulates and Their Consequences. By T. Royds, Kodaikanal Observatory, India 318

XX.—Einstein’s Theory of Gravitation: The Discussion of the General Theory and Its Most Important Application, from the Essay by Prof. W.F.G. Swann, University of Minnesota, Minneapolis 327

XXI.—The Equivalence Hypothesis: The Discussion of This, With Its Difficulties and the Manner in Which Einstein Has Resolved Them, from the Essay by Prof. E.N. da C. Andrade, Ordnance College, Woolwich, England 334

XXII.—The General Theory: Fragments of Particular Merit on This Phase of the Subject. By Various Contributors 338