CHRONOLOGY, MAY-JULY 1913 633 May Begins working with Michele Besso on calculations on the motion of the perihelion of Mercury (Vol. 4, Doc. 14). Visited by Ferdinand Springer to discuss Festschrift article on Max Planck for Naturwissenschaften, which Einstein agrees to do after some hesitation. May 26 As a referee for Mieczyslaw Wolfke's Habilitationsar- beit on optics at the ETH, Einstein recommends grant- ing the venia legendi. Provenance: Protokollbuch der Abteilung IX, SzZE Bibliothek, Hs. 1079:2. before May 28 Completes "Outline of a Generalized Theory of Relativ- ity and of a Theory of Gravitation" (with Marcel Gross- mann) (Vol. 4, Doc. 13). May 29 Planck and others announce in the physical-mathemati- cal class of the Prussian Academy of Sciences that they will be proposing Einstein for election at the next class meeting. June-July Visited by Paul Ehrenfest and Gunnar Nordström in Zurich. June 3 Leopold Koppel writes Walther Nernst agreeing to accept the obligation of granting 6000 marks a year for twelve years to raise Einstein's salary from 6000 marks to 12,000 marks in the Prussian Academy. June 5 Note granting permission to Robert Heller to use the library at the ETH. July 3 Physical-mathematical class of the Prussian Academy votes 21 in favor and 1 against (15 is required) to sup- port Einstein's nomination. July 11 Serves as expert (Referent) for Elsa Frenkel doctorate at the ETH. Provenance: Protokollbuch der Abteilung IX, SzZE Bibliothek, Hs. 1079:2. mid-July Max Planck, Walther Nernst, and their wives visit Ein- stein in Zurich, offering him membership in the Prus- sian Academy they probably also discuss with him the creation of a theoretical physics institute of the Kaiser Wilhelm Society under his direction as well as a posi- tion at the University of Berlin without teaching obliga- tions.