2 4 6 D O C . 1 5 2 O R I G I N O F G E O M A G N E T I C F I E L D Akad d. W. XVII 1923. Gl. (6) und (15).” The reference is to Weyl 1923a and Einstein 1923n (Doc. 52). For a derivation of this equation, see Doc. 31. A similar equation also appears in Doc. 89. From this word on, the remainder of the text is written in Hermann Mark’s hand. Only one page of the manuscript is extant. Mark later recollected: “The manuscript page (started by Einstein and continued by me) is the beginning of the draft for a paper which was never published because a series of experiments which I carried out in 1923 at Einstein’s suggestion did not give any conclusive results. I do not know where the following pages are as far as I can remember, this draft was about three to four handwritten pages long” (see Hermann Mark to Peter Bergmann, 11 April 1967 [17 080]).