2 8 0 D O C U M E N T 2 6 7 A P R I L 1 9 2 6 slow rotation. Then an ether wind ought to provide a reasonable sinus line, whereas all disturbances would stand out aperiodically, provided one did not want to believe in ether weather (!) as some do. In order to avoid any disruption by inquisitive by- standers, etc., we are keeping this matter as secret as possible therefore kindly con- sider this information confidential (the publication in Leipziger Nachrichten was a blunder by Mr. Weber, who did not know that secrecy is important to us).[5] The optics itself is mounted on plates of melted quartz so that no changes in length can occur there. I remain yours respectfully, Georg Joos [6] meander profile [7] Fig. 1 of the text [8] sinus profile 267. To Erwin Schrödinger [Berlin,] 26 April 1926 Dear Colleague, Many thanks for your letter.[1] I am convinced that with your formulation of the quantum conditions you have found a decisive advance I am also convinced just as much that the Heisenberg-Born path is misguided. There the same condition of the additivity of the system is not fulfilled.[2] I have now found arguments that virtually exclude the existence of an elemen- tary spherical wave, so I am quite persuaded that my proposed experiment will come out negatively.[3] The simplest way to realize it is the following: [6] [7] [8] [4] [7] [5] [6]