D O C U M E N T S 1 0 5 , 1 0 7 M A R C H 1 9 2 2 1 1 3 105. From Paul Langevin Paris, 10 Vauquelin Street, 22 March 1922 My dear Friend, I transmit to you the invitation relating to the lunch on 2 April.[1] On the other hand, the Société de Chimie Physique wishes to receive you for dinner on Friday, 7 April, after the last of our meetings at the Collège. Despite our wishes, it has been impossible to prevent an indiscretion from appearing in the press and your visit has been announced in magazines.[2] —The commentaries have been unanimously sympathetic.[3] I would like to know the hour of your arrival so that, if feasible, I can meet you ahead of your arrival in Paris and spare you all useless conversations as you are get- ting off the train. In any case, you will at least find me upon your arrival at Gare du Nord. Contact me by letter if possible or by telegram if you lack the time. Most affectionately yours, P. Langevin 106. From Paul Winteler [Firenze, 22 March 1922] [Not selected for translation.] 107. To Paul Ehrenfest [Berlin,] 23 March 1922 Dear Ehrenfest, My sister is seriously ill in Florence.[1] As she and her husband are additionally in financial difficulties, please immediately send her a thousand Swiss francs.[2] Her address is Florence (Firenze) Sanatorium, 5 Montughi Street.— I am presently reading a major talk by Bohr that makes his entire world of ideas become wonder- fully clear.[3] He is a truly ingenious person what luck that such a man exists at all. I have total confidence in his train of thoughts. The correspondence principle and the way in which he applies it has to be persuasive.[4] Regarding light emission, it