D O C . 3 3 2 O N T H E E T H E R 5 2 5 tionship between general covariance and physical content, see Einstein’s response to Erich Kret- schmann (Einstein 1918e [Vol. 7, Doc. 4]). [16]Hermann Weyl, Arthur S. Eddington. [17]For a discussion of the problem of terrestrial and solar magnetism, see the Introduction, pp. xlviii–lii. [18]See Debye 1923a and Compton 1923. See also Einstein’s comments on this topic in Einstein 1924e (Doc. 236). [19]Bose 1924a (see Doc. 278). [20]In the manuscript, before “Hieraus,” the following half-sentence was deleted: “Nimmt man an, dass sonst keine undimensionierte Konstante hinzukommt,”. [21]“von der Hypothese der Undulations-Struktur der Strahlung” replaces “von dem geometrischen Gefüge der Strahlung, wie es von der Undulationstheorie gefordert wird” in the manuscript. [22]See Debye 1910 and Ehrenfest 1911. [23]Earlier, Einstein had used the conclusion that the lack of a relation between orbital frequencies of electrons and frequencies of emitted radiation puts the independent reality of radiation fields into doubt as an argument against the Bohr-Kramers-Slater theory (see Doc. 256, note 4). [24]The sentence following the semicolon is missing in the manuscript.