Félix Bertaut, space groups and the International Tables for Crystallography

The acquaintance between Félix Bertaut and myself started in 1953, more than fifty years ago, in `Penn State' (Pennsylvania State University, USA), where Félix was a research fellow in Ray Pepinsky's laboratory and where I often went from the MIT in Cambridge to do `automatic' Fourier syntheses on the famous analogue computer X-RAC. Our friendship developed even stronger when we found out that his birthplace, Leobschütz, and that of my mother, Kattowitz, were located rather close to each other in Upper Silesia (now Poland); the subsequent cordial family relations included one of his daughters, Isabelle, doing baby-sitting for our son in Frankfurt in 1963, and my wife and I being spontaneously invited in Grenoble to a swinging party celebrating the `thèse de troisième cycle' of one of Félix's students. These visits in Aachen and Grenoble became even more frequent when he was on the board of the KFA Jülich and I on the board of the ILL in Grenoble.

Our major scientific collaboration, however, occurred from 1972 onwards with the preparation of the new Volume A of International Tables for Crystallography, published in 1983. The official start of the new International Tables Commission, with Félix Bertaut among its founding members and one of its most active collaborators, was in 1972, but the real work began in August 1973 at St Nizier near Grenoble during a meeting prepared and organized by Félix. Already at this meeting and later at the various `Aachen meetings' in 1977–1979, the spirit was `high': the various national `schools' of crystallography clashed over such issues as trigonal versus rhombohedral and monoclinic c-axis versus b-axis setting (the so-called `monoclinic monster'). Félix, with his sharp and critical mind, stayed above such `professorial politics', realising quickly the merits but also the shortcomings of a proposed solution. Fortunately, after the working hours, international friendship was restored by `vin rouge et fromage'.

Félix Bertaut's contributions to Volume A are noteworthy and will not be forgotten. He wrote Chapter 4 on `Synoptic Tables of Space-Group Symbols' with extended Hermann–Mauguin symbols, many interesting and individualistic examples of group–subgroup relations and historic recourses to former editions of International Tables. As a second contribution, Yves Billiet and he wrote Chapter 13 on `Isomorphic Subgroups of Space Groups', opening the way to the treatment of this infinite set of subgroups in the actual space-group tables. Beyond these special topics, he has contributed greatly to the success of the entire volume by quick recognition of novel ideas and old errors.

As a German, this writer wants to stress that Félix Bertaut was an unusually strong and successful advocate of the French–German cooperation and friendship in science and among scientists after the last world war. This is not only obvious from Félix's contribution to neutron diffraction and the establishment of the ILL in Grenoble, but also from numerous visits in Germany, as well as personal contacts and support of young scientists. For these efforts he is highly respected in both countries.

I want to close this reminiscence of our friend Félix on a humerous note (which would be quite in his spirit), quoting a few passages from his letters which illuminate the personal and human side of this wonderful man.

(On his 80th birthday:) `For the group of order 80, I must tell you that I prefer 90, but it will take more time than the International Tables.'

`Le secret de la jeunesse d'esprit, en accord avec un collègue danois, c'est une action difficile à définir, mais facile à identifier.' (The secret of mental youth, according to a Danish colleague, is a phenomenon difficult to define, but easy to identify.)

`Reiselust ist eine Krankheit, die nur durch noch mehr Reisen geheilt werden kann.' (Travel urge is a desease which can be cured only by more travelling.)