4 8 0 D O C U M E N T 2 8 9 M A Y 1 9 2 6 was decided to make extended observations for the purpose of determining the di- rection of motion of the solar system. Observations were continued in July, August and September, 1925, and consist of 3600 turns. The results of this work of 1925 were presented in a paper at Kansas City on December 29, 1925, a copy of which is sent with this letter. The most extended series of all the ether-drift experiments was made in Febru- ary, 1926, consisting of 2000 turns of the interferometer. An account of this work was presented to the National Academy of Sciences at Washington on April 26, 1926, and is not yet published. I am enclosing an abstract of this last paper which summarises all of the work up to the present time. I have recently received an invitation from Sir William Henry Bragg to give an address at the Royal Institution in London, on June 2, describing the Mount Wilson experiments. I am sailing on May 22. I expect to remain abroad for some time, and to visit the Continent and go to Berlin before returning home. I hope I may have the pleasure of meeting you again. I would esteem it a privilege to have the op- portunity of explaining the present status of my experiments and of considering with you any possible way of accounting for the observed effects. I am pleased that you are contemplating a visit to this country to lecture at Pasadena and elsewhere, and I hope to see you at that time. With kindest regards, I am Very truly yours, Dayton C. Miller TLS. [17 274]. In Doc. 71, Einstein provided some details about a letter he sent to Miller around 18 September 1925. See Morley and Miller 1905. Edward W. Morley (1838–1923) had been Professor of Chemistry at Western Reserve College. Miller 1925a. Miller 1926. The lecture titled “The Interpretation of the Michelson-Morley Experiment in the Light of the Observations of the Years 1925 and 1926” was noted in the Report of the National Academy of Sci- ences, Fiscal Year 1925–1926 (Washington: United States Government Printing Office, 1927), p. 50. Miller gave two lectures at the Royal Institution. On 2 June, he spoke on “The Measurement of Ether-Drift,” and on 3 June, on “Interpretation of the Michelson-Morley experiment in the light of the observations of the years 1925 and 1926.” A report of the first lecture notes that: “The deflection of the light from the stars by the sun, as predicted by the theory of relativity, was put to test at the time of solar eclipse of 1919. The results were widely accepted as confirming the theory, and this revived Professor Miller’s interest in the ether-drift experiments, the interpretation of which had never been acceptable to him.” (See Fletcher 1943 and Modern Science, July 1926: 303–306, p. 305). They had met first on 25 May 1921, when Einstein, on his tour in the United States, visited Miller at the Case School of Applied Science (Vol. 12, Calendar). See Doc. 58 for the invitation to visit Pasadena extended to Einstein.