the greatest value. Several research assistants have each, for considerable periods, been identified with the experimental work and the reduction and calculation of the observations; among these the following should be especially mentioned: R. F. Hovey (1920–1923), H. A. Pritchard (1923), Willard Samuelson (1924), G. Brooks Earnest (1925), F. W. Taylor (1925– 1926), Donald H. Spicer (1926–1927) and James R. McKinney (1932–1933). Dr. R. M. Langer was a most efficient assistant throughout all the observations made at Mount Wilson in 1925 and 1926, which constitute the principal material for the conclusions of the present report. Professor Phillip M. Morse assisted very effectively in the first analysis of the general problem of the absolute motion of the solar system, and he made a considerable part of the calculations for the
first solution of this problem in 1925–1926. The writer’s research associates, Professor John R. Martin (1927–1931) and Mr. Robert S. Shankland (1932–1933), have been directly associated with the restudy of the problem which has resulted in the final determination of the absolute motion of the solar system and the orbital motion of the earth as presented in this report.
Case School of Applied Science has made possible the continuous prosecution of the study of the ether-drift problem. The Carnegie Institution of Washington and the Mount Wilson Observatory made available the exceptional facilities of Mount Wilson for observational work from 1921 to 1926. Mr. Eckstein Case provided funds for the very considerable expenses involved in making the elaborate series of experiments and tests.
