D O C U M E N T 1 7 7 M A Y 1 9 2 2 1 5 9 leads right to Bohr’s method of “secular perturbations.” Indeed, now we really do understand some of Bohr’s arguments. We also began to calculate orthohelium (2 coplanar electrons) and were immediately able to confirm Bohr’s old postulate that the inner electron revolves rapidly along an ellipse whose large axis is constantly pointing to the more slowly orbiting outer electron. Pauli took the paper with him to Hamburg and wants to finish it up over there because I don’t have any time, owing to the encycl. article. The con[founded] semester is just starting again, which is a real disruption to contempla- tive work. Franck has the entire institute teeming with doctoral students and all of them, tanked up with his ideas, are working on fine theses.[17] Hilbert is in Switzerland and is only coming back in 8 days. My family is well despite the constantly horrendous weather none of us has a cold right now. My wife sends all of you warm regards. Greet our Dutch and Berlin colleagues for me. Yours, Born. 176. From Paul Painlevé Paris, 18 rue Séguier, Paris VIe, 30 April 1922[1] [Not selected for translation.] 177. To Chenzu Wei Berlin, 3 May 1922 Highly esteemed Sir, With reference to your kind letter of 8 Apr. of this yr.,[1] I have the honor of informing you that I am gladly prepared to give a few lectures this winter, within a period of two weeks, at the Imperial University in Peking. I must note, however, that I see myself compelled to make other proposals respecting the envisioned com- pensation. I regard this step necessary because—as much as I would have liked to do this differently—by accepting your terms I would be placing other countries too much at a disadvantage that had offered me incomparably greater compensation, some of them, such as a few universities in the United States of America, having