1 2 4 D O C . 1 4 6 O C T O B E R 1 9 1 9 . You may possibly find this quite interesting. Yesterday I heard from Harms that Zeeman in Amsterdam just now published a new experiment on the optics of moving bodies, in which the light propagates in a glass or quartz object instead of in water, as in Fizeau’s experiment.[5] This is one more reason to straighten out Harress’s experiment now as well. With cordial regards, also to Planck, yours, M. Laue. Recipient’s notes on verso: “ , “1. Ionization work in metals ?= lattice work. “2. Neutral separation work ?= work for loosening an electron from the [io]n. “From (1), lattice work independent of the remainder. “[From] (2), neutral separation work indep. of metal.” 146. From Hans Thirring Vienna, 20 October 1919 Dear Mr. Einstein, A moment ago I read in the Naturwissenschaften your little notice about the shift in fixed-star positions.[1] Ever since I understood gravitation theory, I never doub- ted the existence of this effect I was nonetheless mightily pleased about its discov- ery and congratulate you most heartily on it. If I had the effusive style of a d’Annunzio, I would now cry out: This day marks you as the greatest physicist in the world![2] In July I was in Berlin again for a week—unfortunately just at a time when you were not there.[3] Did you receive (about 8 months ago) the 10 separate offprints of my little lecture on gravitation theory?[4] I am presently engaged in some not uninteresting speculations about atomic and crystalline structure—a preliminary report about that will be going out to the Phys. Zeitschr. in the next day or so.[5] For it can be very strictly proved on the basis of the Sohnke-Schoenfliess theory that it is impossible to arrange axisymmetric atoms in a Bragg diamond lattice so that the symmetry class that had been experimentally found macroscopically for diamond comes out.[6] It can be shown analogously that with such axisymmetric atoms a structure with a regular holohedral symmetry (NaCl) can be built on the basis of Bragg’s NaCl lattice but not with the enantio- t′ t vx⎞ c2 -----⎠ – ⎝ ⎛ : 1 v:c)2 ( – = Na[+] Cl[-] Na+ Cl → NaCl Na Cl →