1 IN THE MONOGRAPH SERIES directed by Henri Villat , several fasci- cules have been devoted to Relativity. First there are the general presentations ofTh. De Donder (nos. 8, 14, 43, 58), and then those more specifically devoted to Einsteinian gravitation - notably Georges Darmois's contribution (no. 25) and that of J. Haag (no. 46) on the Schwarzschild problem. The present fascicule takes its place alongside the two latter monographs, but it has been conceived and composed in such a way that it may be read and understood by anyone with a knowledge of the principles of Absolute Differential...

1 IN THE MONOGRAPH SERIES directed by Henri Villat , several fasci- cules have been devoted to Relativity. First there are the general presentations ofTh. De Donder (nos. 8, 14, 43, 58), and then those more specifically devoted to Einsteinian gravitation - notably Georges Darmois's contribution (no. 25) and that of J. Haag (no. 46) on the Schwarzschild problem. The present fascicule takes its place alongside the two latter monographs, but it has been conceived and composed in such a way that it may be read and understood by anyone with a knowledge of the principles of Absolute Differential...