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