x l i v I N T R O D U C T I O N T O V O L U M E 1 3 over the years that support differing interpretations. In this Volume, we present the original printed version of Ishiwara’s notes for that lecture, in Japanese, together with a new English translation and an editorial note that summarizes the debate on the interpretation of this document (see Doc. 399 and the editorial note “Einstein’s Lecture at the University of Kyoto”). The significance of the Michelson-Morley experiment of 1887 is not restricted to its role in Einstein’s creation of the theory of relativity. On 6 August 1922, Max Born, in a letter to Einstein, appeared quite alarmed by news of an experiment car- ried out in the United States by Dayton C. Miller, who had repeated the Michelson- Morley experiment and had apparently found a positive ether drift. “I don’t believe a word of this rumor,” wrote Born (Doc. 320). Einstein had already learned about this experiment while visiting the United States in May 1921, and had then reacted in a similar manner (see entry of 9 May 1921 in Vol. 12, Calendar). Empirical tests also continued to play a role in the further development of the general theory of relativity. A joint German-Dutch expedition hoped to observe the solar eclipse of 21 September 1922 on Christmas Island in the Pacific Ocean and test Einstein’s theory. And although the German Foreign Ministry expressed inter- est in the expedition and in Einstein’s participation, he declined the request with various pretexts.[8] In the event, Einstein’s decision not to accompany the expedi- tion, in spite of his presence in the Far East at the time, made no difference: both the German-Dutch expedition and a second British expedition from the Greenwich Observatory—which also chose Christmas Island as its base—were clouded out during totality and recorded no useful data (Crelinsten 2006, p. 201). A central point of interest for Einstein in the further development of general rel- ativity concerned its cosmological interpretation. During the months of June and July, an exchange of letters took place between Einstein and George Jaffé, Extraor- dinary Professor of Physics at the University of Leipzig, concerning Einstein’s 1917 proposal to add a cosmological term to the field equation (Einstein 1917b [Vol. 6, Doc. 43]). Jaffé instead suggested a transformation of the Schwarzschild solution, one that amounted to a scaling of mass. In that way, he claimed, one could realize Mach’s postulate that a particle far distant from all others would have effec- tively zero mass. This was in apparent contrast to Einstein’s “Cosmological Con- siderations” of 1917. The correspondence between Einstein and Jaffé addresses various aspects of the issue, notably the question of the proper representation of classical dynamic quantities such as the particle’s momentum or energy.[9] In September 1922, Einstein published a short comment in Zeitschrift für Physik on a paper by the Russian physicist Alexander Friedmann. The paper by Fried- mann, published earlier in the year in the same journal, eventually became a cor- nerstone of modern cosmology (Friedmann 1922). In it, Friedmann showed that