The disruption and lingering chaos of World War I obscured new developments in German science, and this work marked the first announcement to the English-speaking world of the theory of general relativity. The era's foremost astrophysicist, Sir Arthur Stanley Eddington, published these reports five years after the initial appearance of Einstein's landmark paper in 1915. The eight papers featured in this collection include "The Restricted Principle of Relativity," "The Relations of Space, Time, and Force," "The Theory of Tensors," "Einstein's Law of Gravitation," "The Crucial Phenomena," "The Gravitation of a Continuous Distribution of Matter," "The Principle of Least Action," and "The Curvature of Space." A popular lecturer, Eddington was celebrated for his ability to explain scientific concepts in lay terms. These informative reports reflect his interpretative skills and remain models of clarity.