D O C . 1 4 7 O C T O B E R 1 9 1 9 1 2 5 morphous hemihedral symmetry of the isometric system (KCl). Since according to my view nothing other than the valency electrons can be made responsible for the various expressions of crystal symmetry (cleavage, etch-figures, optical behavior), it necessarily follows that the C atoms of diamond and the K atoms of KCl cannot be plane planetary systems. Furthermore, it can be shown that atoms whose elec- tron orbits have polyhedral symmetry can explain the macroscopically found sym- metry relations. The more far-reaching problem I am now working on solving is the following. Crystalline structure is in any case determined by the structure of a crystal’s con- stituent atoms or molecules. So, can it be compellingly proved on the basis of the Kossel-Born-Landé interpretations that NaCl must be built just so and ZnS just so and FeS2 just so? I have found certain hints already, but I hope to be able to delve deeper still into the matter. Cordial regards to you, from yours truly, Hans Thirring My little sister sends her best regards and congratulations! 147. From Hugo Bergmann London W.C.1, 77 Great Russell Street, 22 October 1919 Esteemed Professor, I hope you still remember the times when we had you in Prague and when I could attend your seminar. I left Prague in the spring in order to help as managing secretary of the newly created Education Department of the Zionist Organization, organizing public instruction in Palestine, principally to participate in the prepara- tions for the Hebrew University. It is the issue of this university that prompts me to write you again after such a long time. In the very next few years this fine concept is supposed to materialize. The path from idea to reality is not an easy one. Plans for a structural organization of the university have to be drawn up, which should both serve the practical inter- ests of settlement in Palestine, as well as prove itself worthy, by its theoretical ac- complishments, of the name of a university of the Jewish people. Textbooks, build- ings must be prepared, the large financial funds raised. We do not want to do the job only halfway nor add a new university to the existing ones in the Levantine backwater but erect a good university that despite its limited resources still meets the full standard.