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