3 8 D O C U M E N T 1 8 O P I N I O N O N G O L D S C H M I D T the surface of the sphere = (twice).[6] If Mrs. Ripke-Kühn reads this, she will presumably believe it is a conclusion of the G[eneral] P[rinciple] of R[elativity]. (“Critics” of this Valkyrie genre are capable of anything!)– Might I now request that you at least leaf through my manuscript once? You will immediately recognize whether it is nonsense and then I would get it back soon in the alternate case I would then at least have a faint hope that “there’s something to it” and then you are welcome to keep it longer until you are in the mood to make the comments on it. It goes without saying that in a note in the publication I would make due reference to the “checking of the results” demanded of you, similar to your support of Cassirer with your authority in this sense.[7] For, whatever philos- ophers in general philosophize about in such matters has little standing without your “imprimatur.” Then [I] could incorporate the matter into the Philosophische Briefe [8] and be of a little service to the theory, or rather, to the people for whom the “new physics” remains a book with seven seals. I often converse with the Jena mathematician Prof. Köbe[9] about the spatial problem he is considering rework- ing the mathematical foundations in a “comprehensible” way, initially in a prepa- ratory lecture for the theory. Would you please examine in particular the expression: “invariance of the natural laws” = “invariance of the general analytic form of the natural laws.” This term should only express your own ideas. In great respect, most devotedly, Eberhard Zschimmer. 18. Expert Opinion on Goldschmidt Patent [Berlin, after 14 January 1922][1] Expert Opinion on American Patent No. 1386329[2] Goldschmidt Mr. Goldschmidt has asked me for my view on whether one of the patents men- tioned in the following had a limiting influence on the scope of his own patent as it is defined in the latter’s claim [no.] 1. After detailed examination of the material, I arrive at the secure finding that such a limitation on its scope is out of the question. The achievement of oscillatory motion created through rotation in continuous progressive stepwise motion in the direction of the oscillatory motion, as is explic- itly stated by Goldschmidt’s patent claim, is mentioned in none of the cited patent πr2